Impact of heat stress on health and performance of dairy animals: A review

Functional transcriptome analysis revealed major changes in pathways affecting systems biology of Tharparkar cattle under seasonal heat stress

Heat stress significantly disturbs the production, reproduction, and systems biology of dairy cattle. A complex interaction among biological systems helps to combat and overcome heat stress. Indicine cattle breed Tharparkar has been well known for its thermal adaptability. Therefore, present investigation considered RNA-seq technology to explore the functional transcriptomics of Tharparkar cattle with the help of samples collected in spring and summer season. Among differentially expressed genes, about 3280 genes were highly dysregulated, in which 1207 gene were upregulated and 2073 genes were downregulated (|log2fold change|≥ 1 and p ≤ 0.05). Upregulated genes were related to insulin activation, interferons, and potassium ion transport. In contrast, downregulated genes were related to RNA processing, translation, and ubiquitination. Functional annotation revealed that the pathways associated with nervous system (NPFFR1, ROBO3) and metal ion transport (KCNG2, ATP1A2) were highly activated while mRNA processing and translation (EIF4A, EIF4B) and protein processing pathway (VPS4B, PEX13) were highly downregulated. Protein-protein interactions identified hub genes such as ATP13A3, IFNGR2, UBXN7, EIF4A2, SLC12A8 found to play an important role in immune, ubiquitination, translation and transport function. Co-expression network includes LYZ, PNRC1, SQSTM1, EIF4AB and DDX17 genes which are involved in lysosomal activity, tumor inhibition, ubiquitination, and translation initiation. Chemokine signaling pathway associated with immune response was highly upregulated in cluster analysis. The findings of this study provide insights into transcriptome expression and regulation which may better explain complex thermal resilience mechanism of Tharparkar cattle in heat stress under natural conditions.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13205-024-04018-2.

Genetic analysis of phenotypic indicators for heat tolerance in crossbred dairy cattle

Climate change-induced rise in global temperatures has intensified heat stress on dairy cattle and is contributing to the generally observed low milk productivity. Selective breeding aimed at enhancing animals' ability to withstand rising temperatures while maintaining optimal performance is crucial for ensuring future access to dairy products. However, phenotypic indicators of heat tolerance are yet to be effectively factored into the objectives of most selective breeding programs. This study investigated the response of milk production to changing heat load as an indication of heat tolerance and the influence of calving season on this response in multibreed dairy cattle performing in three agroecological zones Kenya. First-parity 7-day average milk yield (65 261 milk records) of 1 739 cows were analyzed. Based on routinely recorded weather data that were accessible online, the Temperature-Humidity Index (THI) was calculated and used as a measure of heat load. THI measurements used represented averages of the same 7-day periods corresponding to each 7-day average milk record. Random regression models, including reaction norm functions, were fitted to derive two resilience indicators: slope of the reaction norm (Slope) and its absolute value (Absolute), reflecting changes in milk yield in response to the varying heat loads (THI 50 and THI 80). The genetic parameters of these indicators were estimated, and their associations with average test-day milk yield were examined. There were no substantial differences in the pattern of milk yield response to heat load between cows calving in dry and wet seasons. Animals with ≤50% Bos taurus genes were the most thermotolerant at extremely high heat load levels. Animals performing in semi-arid environments exhibited the highest heat tolerance capacity. Heritability estimates for these indicators ranged from 0.06 to 0.33 and were mostly significantly different from zero (P < 0.05). Slope at THI 80 had high (0.64-0.71) negative correlations with average daily milk yield, revealing that high-producing cows are more vulnerable to heat stress and vice versa. A high (0.63-0.74) positive correlation was observed between Absolute and average milk yield at THI 80. This implied that low milk-producing cows have a more stable milk production under heat-stress conditions and vice versa. The study demonstrated that the slope of the reaction norms and its absolute value can effectively measure the resilience of crossbred dairy cattle to varying heat load conditions. The implications of these findings are valuable in improving the heat tolerance of livestock species through genetic selection.

Climate change and broiler production

Climate change has emerged as a significant occurrence that adversely affects broiler production, especially in tropical climates. Broiler chickens, bred for rapid growth and high meat production, rely heavily on optimal environmental conditions to achieve their genetic potential. However, climate change disrupts these conditions and poses numerous challenges for broiler production. One of the primary impacts of climate change on broiler production is the decreased ability of birds to attain their genetic potential for faster growth. Broilers are bred to possess specific genetic traits that enable them to grow rapidly and efficiently convert feed into meat. However, in tropical climates affected by climate change, the consequent rise in daily temperatures, increased humidity and altered precipitation patterns create an unfavourable environment for broilers. These conditions impede their growth and development, preventing them from reaching their maximum genetic influence, which is crucial for achieving desirable production outcomes. Furthermore, climate change exacerbates the existing challenges faced by broiler production systems. Higher feed costs impact the industry's economic viability and limit the availability of quality nutrition for the birds, further hampering their growth potential. In addition to feed scarcity, climate change also predisposes broiler chickens to thermal stress. This review collates existing information on climate change and its impact on broiler production, including nutrition, immune function, health and disease susceptibility. It also summarizes the challenges of broiler production under hot and humid climate conditions with different approaches to ameliorating the effects of harsh climatic conditions in poultry.

Influence of thermal heat load accumulation on daily rumination time of lactating Holstein cows in a zone with temperate climate

In the future, conflicts between animal welfare and climate change will gradually intensify. In the present study, we investigated the daily rumination time (RT) of lactating Holstein-Friesian cows in a zone with temperate climate and the effects of heat load duration and heat load intensity. Responses of individual cows to heat load were assessed, adjusting for milk yield, lactation number, days in milk as well as reproductive status and season. A total of 27,149 data points from 183 cows in a naturally ventilated barn in Brandenburg, Germany, were collected from June 2015 to May 2017. Ambient temperature and relative humidity were recorded at eight positions inside the barn every 5 min, and the temperature-humidity index (THI) was calculated. Based on THI, the degree of heat load was determined, using critical thresholds of THI = 68, 72, and 80. Daily RT was measured with a microphone-based sensor system (collar) on the cow's neck. The analysis models included autocorrelations in time series as well as individual cow-related effects. With each 5 min exposure to contemporaneous heat load, a decrease of approximately 1.17 min d-1 in RT per cow from non-heat stress to heat stress conditions by exceeding THI ≥68 (p < 0.01). This effect was intensified by exceeding the critical THI thresholds of 68 and 72. As heat load duration and intensity increased, daily RT decreased in comparison to daily RT under non-stress conditions. High-yielding (>38.4 kg milk/day) cows were more influenced in rumination time than low-yielding (≤28.8 kg milk/day) cows. With moderate contemporaneous heat load, RT decreased by 0.14 min d-1 per 5 min in high-yielding cows compared to low-yielding cows under moderate heat load. A decrease of 0.1 min d-1 was found in daily RT of mid-yielding cows. However, the delayed effects of heat load (one to three days after the heat stress event) were associated with days in milk and reproduction status. When the heat load duration lasted for several days, the responses were less pronounced than the impacts of contemporaneous heat load (when the heat stress event lasted for one day). Delayed mild heat load resulted in an increase in RT by 0.13 min d-1 in lactating cows ≤60 DIM. This was also found with delayed moderate heat load. Lactating cows ≤60 DIM showed a rise of 0.09 min d-1 in RT. RT also showed interactions with reproduction status of cows under delayed moderate heat stress. Lactating cows with ≤180 days of pregnancy showed an increase of 0.61 min d-1 in RT. Similarly, cows with >180 days of pregnancy had 0.64 min d-1 more RT compared to non-pregnant cows. Further analysis with higher temporal resolution of RT than data accumulation in 24-h blocks as well as the assessment of the correlation between feed composition, intake and rumination will elucidate the influence of heat load on daily RT.

Faecal cortisol metabolites, body temperature, and behaviour of beef cattle exposed to a heat load

Feedlot cattle are at times exposed to high environmental temperatures. Faecal cortisol metabolites were related to possible indicators of heat stress that could be measured under field conditions: respiratory dynamics (respiration rate), body surface temperature and adaptive behaviours, such as water consumption, posture (standing, lying), and activity (eating, drinking and rumination). Twelve (12) yearling Black Angus steers were divided into two treatment groups: a hot treatment (HOT; n = 6) and a thermoneutral-treatment (TN; n = 6) and individually housed in a climate-controlled facility at The University of Queensland, Australia. In the TN treatment, all animals were exposed to an ambient temperature of 20.34 ± 0.25 °C, relative humidity 71.51 ± 3.26% and Temperature humidity index (THI) 66.91 ± 0.33 throughout. In the HOT treatment group, environmental conditions were exposed to different climatic phases from thermoneutral to hot conditions, where they remained for 7 d, and then returned to TN conditions in the recovery period. The dry bulb ambient temperature (TA) and relative humidity (RH) in the pens of cattle in the HOT treatment were increased from 28 °C (daily maximum ambient temperature) and 45% RH at 0700 h to a daily maximum TA and RH of 35 °C (daily maximum ambient temperature) and 50% (THI 77) at 1100 h, which was maintained until 1600 h, after which it declined until it reached the baseline at 2000 h. In both treatments, there was a significant decrease in faecal cortisol metabolite concentration from the start to the end of the experiments they adapted to the experimental facility. The concentration of faecal cortisol metabolites was greater in the HOT treatment, compared to the TN treatment during the heat exposure period, but there was no difference in the transition or recovery periods. Respiration rate was greater in the HOT treatment during heat exposure, and it increased with ambient dry bulb temperature above 26 °C, the latter being the upper critical temperature. Although positive correlations were detected between faecal cortisol metabolites and body surface temperature measurements, particularly the shoulder and rump, as well as standing time, panting score and drinking, a stepwise regression found that faecal cortisol metabolites were only significantly correlated with one variable, respiration rate. It is concluded that respiration rate is the best indicator of the stress induced by hot conditions for cattle.

Dataset for performance of superior dairy cattle sires based on daughter's milk yield in tropical country

Sire has an important role because they could have more offspring than dam does. The research aims to determine the production performance of Friesian Holstein, estimation of heritability values, estimation of breeding values, and ranking of dairy cattle sires. The objects of the study were the complete record of milk production, lactation length, lactation peak, and dry period length from first to fourth lactation from 2017-2021. This study used the descriptive method. The results of the research showed that productivity performance is great, 1st lactation milk production was 8,029.28±1,112 kg, the lactation length was 321.26±38.48 days, the condition of average peak production was obtained on day 85.35±29.25 with milk production of 32.55±4.16 kg, and dry period length was 51.37±9.33 days. 2nd Lactation milk production was 7,761.66±1,145, the lactation length was 323.66±43.06 days, the condition of average peak production was on day 58.43±21.11 with milk production of 40.79±5.30 kg and the dry period length was 65.10±22.69 days. 3rd lactation milk production 3 was 7,788.92±1,148 kg, the lactation length was 326.64±46.74 days, peak production was on day 61.88 ±22.72 with milk production of 43.62±5.11 kg; the dry period length was 65.00±20.49 days. 4th Lactation milk production was 7,484.18±1,133 kg, lactation length was 323.04±42.23 days, peak production was on day 66.39±24.26 with the milk production of 43.82±5.68, the dry period length was 65.78±21.60 days. The estimated heritability value for milk production, 0.03 ± 0.02, is included in the low category. The ranking of 10 sires that have the potential to increase the genetic based on their estimated breeding value is 595.91 kg (O.S.Elmer-XA), 264.16 kg (M.Z.Merlin.-XA), 252.38 kg (L.Muscadet-XA), 247 .12 kg (C.Toyjet), 239.01 kg (S. Gypsy B), 214.82 kg (WestCoastPldge), 188.14 kg (M.Z.Merlin-ET), 178.56 kg (Brasilia), 166.43 kg (L.JetBowser-XA), 162.06 kg (MRMUDD-XA).

Repeated Cross-Sectional Survey of Ectoparasites in Sheep from Central Tunisia: Does Low Prevalence Indicate Good Hygiene or Resistance to Ectoparasites?

Sheep ectoparasites such as chewing lice, fleas and ticks are serious constraints to sheep productivity and are the cause of skin lesions in animals that decrease their market value. This study aims at investigating the ectoparasite fauna infesting small ruminants in the district of Sidi Bouzid (central Tunisia). A total of 1243 Barbarine and Queue Fine de l'Ouest (QFO) sheep were examined every two months for one year. Of the total animals examined, 74 were infested by at least 1 parasite group (5.95%). Three ectoparasite groups were identified as Psoroptes ovis (0.48%; 6/1243), ticks (5.3%; n = 66/1243) and one specimen of Ctenocephalides canis (0.08%; n = 1/1243). The most abundant tick among the 358 specimens was Rhipicephalus sanguineus sensu lato (n = 337; 94.1%), followed by Hyalomma impeltatum (n = 7/358; 1.9%), H. dromedarii (n = 7/358; 1.9%), H. excavatum (n = 5/358; 1.4%) and only two specimens of H. scupense (n = 2/358; 0.55%). The sheep herds showed low infestation prevalence by ectoparasite over the year, with a significant difference according to the seasons (p < 0.05). A higher infestation prevalence was recorded in March (14.36%). Barbarine sheep breed showed significantly higher infestation prevalence (16.8%) compared to QFO (0.8%) (p < 0.01). There were no differences in infestation prevalence according to sex of the animal or age groups. Knowledge of the ectoparasite population harboured by sheep, its activity dynamics and risk factors is required to develop effective ectoparasite control options. The low prevalence of ectoparasite infestation in sheep reported here may be due to possible genetic resistance or simply to successful hygiene measures implemented by farmers.

Selection Signal Analysis Reveals Hainan Yellow Cattle Are Being Selectively Bred for Heat Tolerance

Hainan yellow cattle are indigenous Zebu cattle from southern China known for their tolerance of heat and strong resistance to disease. Generations of adaptation to the tropical environment of southern China and decades of artificial breeding have left identifiable selection signals in their genomic makeup. However, information on the selection signatures of Hainan yellow cattle is scarce. Herein, we compared the genomes of Hainan yellow cattle with those of Zebu, Qinchuan, Nanyang, and Yanbian cattle breeds by the composite likelihood ratio method (CLR), Tajima's D method, and identifying runs of homozygosity (ROHs), each of which may provide evidence of the genes responsible for heat tolerance in Hainan yellow cattle. The results showed that 5210, 1972, and 1290 single nucleotide polymorphisms (SNPs) were screened by the CLR method, Tajima's D method, and ROH method, respectively. A total of 453, 450, and 325 genes, respectively, were identified near these SNPs. These genes were significantly enriched in 65 Gene Ontology (GO) functional terms and 11 Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways (corrected p < 0.05). Five genes-Adenosylhomocysteinase-like 2, DnaJ heat shock protein family (Hsp40) member C3, heat shock protein family A (Hsp70) member 1A, CD53 molecule, and zinc finger and BTB domain containing 12-were recognized as candidate genes associated with heat tolerance. After further functional verification of these genes, the research results may benefit the understanding of the genetic mechanism of the heat tolerance in Hainan yellow cattle, which lay the foundation for subsequent studies on heat stress in this breed.

Utilization of Infrared Thermography in Assessing Thermal Responses of Farm Animals under Heat Stress

Heat stress is a condition that can affect the health, performance, and welfare of farm animals. The perception of thermal stress leads to the activation of the autonomic nervous system to start a series of physiological and behavioral mechanisms to restore thermostability. One of these mechanisms is vasodilation of peripheral blood vessels to increase heat loss through the skin. Due to this aspect, infrared thermography has been suggested as a method to assess the thermal state of animals and predict rectal temperature values noninvasively. However, it is important to consider that predicting rectal temperature is challenging, and its association with IRT is not always a direct linear relationship. The present review aims to analyze the neurobiological response associated with heat stress and how thermal imaging in different thermal windows can be used to recognize heat stress in farmed ungulates.

Investigation of Climate Effects on the Physiological Parameters of Dairy Livestock (Cow vs. Buffalo)

Nowadays climate change is affecting the planet's biodiversity, and livestock practices must adapt themselves to improve production without affecting animal welfare. This work investigates the influence that some climatic parameters such as Environment Temperature, Relative Humidity, Thermal excursion and Temperature-Humidity Index (THI), can have on milk quantity and quality in two different dairy species (buffaloes and cows) raised on the same farm. A further aim was to understand if THI threshold used for cows could also be used for buffaloes. The climatic parameters were recorded daily through a meteorological station located inside the farm. Milk quantity (converted into ECM) and quality (Fat Percentage-FP; Protein Percentage-PP; Somatic Cell Count-SCC) were measured. Data were analyzed with Spearman's correlation index, separately for buffaloes and cows. The results indicate a greater sensitivity of cows to heat stress and a strong negative correlation of the ECM with meteorological data (p < 0.01). The results of this study may stimulate the use of integrated technologies (sensors, software) in the dairy sector, since the IoT (sensors, software) helps to enhance animal well-being and to optimize process costs, with a precision livestock farming approach.

Influence of Heat Stress on Body Surface Temperature and Blood Metabolic, Endocrine, and Inflammatory Parameters and Their Correlation in Cows

This study aimed to determine whether heat stress affected the values and correlations of metabolic, endocrinological, and inflammatory parameters as well as the rectal and body surface temperature of cows in the early and middle stages of lactation. This experiment was conducted in May (thermoneutral period), June (mild heat stress), and July (moderate to severe heat stress). In each period we included 15 cows in early lactation and 15 in mid-lactation. The increase in rectal and body surface temperatures (°C) in moderate to severe heat stress compared to the thermoneutral period in different regions was significant (p < 0.01) and the results are presented as mean and [95%CI]: rectal + 0.9 [0.81-1.02], eye + 6 [5.74-6.25], ear + 13 [11.9-14.0], nose + 3.5 [3.22-3.71], forehead + 6.6 [6.43-6.75], whole head + 7.5 [7.36-7.68], abdomen + 8.5 [8.25-8.77], udder + 7.5 [7.38-7.65], front limb + 6 [5.89-6.12], hind limb + 3.6 [3.46-3.72], and whole body + 9 [8.80-9.21]. During heat stress (in both mild and moderate to severe stress compared to a thermoneutral period), an increase in the values of extracellular heat shock protein 70 (eHsp70), tumor necrosis factor α (TNFα), cortisol (CORT), insulin (INS), revised quantitative insulin sensitivity check index (RQUICKI), urea, creatinine, total bilirubin, aspartate transpaminase (AST), gamma-glutamyl transferase (GGT), lactate dehydrogenase (LDH), and creatin kinase (CK) occurred, as well as a decrease in the values of triiodothyronine (T3), thyroxine (T4), non-esterified fatty acids (NEFA), glucose (GLU), β-Hydroxybutyrate (BHB), calcium, phosphorus, total protein (TPROT), albumin (ALB), triglycerides (TGCs), and cholesterol (CHOL). In cows in early lactation compared to cows in mid-lactation, there was a significantly larger increase (p < 0.01) in the values of eHsp70, TNFα, GLU, RQUICKI, and GGT, while the INS increase was smaller during the three experimental periods. The decrease in the values of Ca, CHOL, and TGC was more pronounced in cows in early lactation compared to cows in mid-lactation during the three experimental periods. Rectal temperature was related to eHsp70 (r = 0.38, p < 0.001) and TNFα (r = 0.36, p < 0.01) and showed non-significant poor correlations with other blood parameters. Blood parameters correlate with body surface temperature, with the following most common results: eHsp70 and TNFα showed a moderately to strongly significant positive correlation (r = 0.79-0.96, p < 0.001); CORT, INS, and Creat showed fairly to moderately significant positive correlations; T3, T4, NEFA and GLU showed fairly to moderately significant negative correlations (r = 0.3-0.79; p < 0.01); RQUICKI, urea, AST, and GGT showed fairly and significantly positive correlations; and TGC, CHOL, TPROT, and ALB showed fairly and significantly negative correlations (r = 0.3-0.59; p < 0.01). Measuring the surface temperature of the whole body or head can be a useful tool in evaluating the metabolic response of cows because it has demonstrated an association with inflammation (TNFα, eHsp70), endocrine response (CORT, T3, T4), the increased use of glucose and decreased use of lipids for energy purposes (INS, NEFA, GLU, and RQUICKI), and protein catabolism (ALB, TPROT, urea, Creat), which underlies thermolysis and thermogenesis in cows under heat stress. In future research, it is necessary to examine the causality between body surface area and metabolic parameters.

Plasma and milk metabolomics revealed changes in amino acid metabolism in Holstein dairy cows under heat stress

Our understanding of metabolic alterations triggered by heat stress is incomplete, which limits the designing of nutritional strategies to mitigate negative productive and health effects. Thus, this study aimed to explore the metabolic responses of heat-stressed dairy cows to dietary supplementation with vitamin D3/Ca and vitamin E/Se. Twelve multiparous Holstein cows were enrolled in a split-plot Latin square design with two distinct vitamin E/Se supplementation levels, either at a low (ESe-, n = 6, 11.1 IU/kg vitamin E and 0.55 mg/kg Se) or a high dose (ESe+, n = 6 223 IU/kg vitamin E and 1.8 mg/kg Se) as the main plot. Treatment subplots, arranged in a replicated 3 × 3 Latin square design, comprised heat challenge (Temperature Humidity Index, THI: 72.0-82.0) supplemented with different levels of vitamin D3/Ca: either low (HS/DCa-, 1 012 IU/kg and 0.73%, respectively) or high (HS/DCa+, 3 764 IU/kg and 0.97%, respectively), and a pair-fed control group in thermoneutrality (THI = 61.0-64.0) receiving the low dose of vitamin D3/Ca (TN). The liquid chromatography-mass spectrometry-based metabolome profile was determined in blood plasma and milk sampled at the beginning (day 0) and end (day 14) of each experimental period. The results were analyzed for the effect of (1) TN vs. HS/ESe-/DCa-, and (2) the vitamin E/Se and vitamin D3/Ca supplementation. No group or group × day effects were detected in the plasma metabolome (false discovery rate, FDR > 0.05), except for triglyceride 52:2 being higher (FDR = 0.03) on day 0 than 14. Taurine, creatinine and butyryl-carnitine showed group × day interactions in the milk metabolome (FDR ≤ 0.05) as creatinine (+22%) and butyryl-carnitine (+190%) were increased (P < 0.01) on day 14, and taurine was decreased (-65%, P < 0.01) on day 14 in the heat stress (HS) cows, compared with day 0. Most compounds were unaffected by vitamin E/Se or vitamin D3/Ca supplementation level or their interaction (FDR > 0.05) in plasma and milk, except for milk alanine which was lower (-69%, FDR = 0.03) in the E/Se+ groups, compared with E/Se-. Our results indicated that HS triggered more prominent changes in the milk than in the plasma metabolome, with consistent results in milk suggesting increased muscle catabolism, as reflected by increased creatinine, alanine and citrulline levels. Supplementing with high levels of vitamin E/Se or vitamin D3/Ca or their combination did not appear to affect the metabolic remodeling triggered by HS.

Viola yedoensis Makino alleviates heat stress-induced inflammation, oxidative stress, and cell apoptosis in the spleen and thymus of broilers

ETHNOPHARMACOLOGICAL RELEVANCE

Viola yedoensis Makino (VYM) is a traditional Chinese herbal medicine widely distributed in China. It has many pharmacological effects such as anti-inflammatory, immune regulation and anti-oxidation. However, the protective effect of VYM on the spleen and thymus of broilers induced by heat stress has rarely been reported.

AIM OF THE STUDY

We established a heat stress model of broilers to explore the protective effect of VYM on spleen and thymus of broilers.

MATERIALS AND METHODS

In this experiment, a heat stress model was made by adjusting the feeding temperature of broilers. The protective effect of VYM on the spleen and thymus of heat-stressed broilers were evaluated by detecting immune organ coefficient, histological observation, Enzyme-Linked Immunosorbent Assay, production of antioxidant enzymes and peroxides, TUNEL Staining, Quantitative Real-time PCR.

RESULTS

In this study, 60 healthy male AA broilers were divided into 6 groups: Control, 4.5% VYM, HS, HS + 0.5% VYM, HS + 1.5% VYM, HS + 4.5% VYM. After 42 days of feeding, serum, spleen and thymus were collected for detection and analysis. The study revealed that heat stress can lead to pathological damage in the spleen and thymus of broilers, reduce the content of immunoglobulin and newcastle disease (ND), infectious bursal disease (IBD) antibody levels, increase the expression of inflammatory factors IL-1β, INF-γ, heat shock 70 kDa protein (HSP70), heat shock 90 kDa protein (HSP90). Heat stress inhibits the activity of antioxidant enzymes CAT and SOD, promotes the production of MDA, and then lead to oxidative damage of the spleen and thymus. In addition, apoptotic cells and the ratio of Bax/Bcl-2 was increased. However, the addition of VYM to the feed can alleviate the adverse effects of heat stress on the spleen and thymus of broilers.

CONCLUSIONS

This study showed that the addition of VYM to the diet could inhibit oxidative stress and apoptosis, and reduce the inflammatory damage of heat stress on the spleen and thymus of broilers. This study provides a basis for further exploring the regulatory role of VYM in heat stress-induced immune imbalance in broilers. In addition, this study also provides a theoretical basis for the development of VYM as a feed additive with immunomodulatory effects.

Impacts of climate change-induced heat stress on pig productivity in China

The economic impacts of climate-induced heat stress on pig farming have not been sufficiently investigated, despite the significant threat it poses to the industry. In this study, we coupled consecutive years of county-scale meteorological data with operational-level economic data to estimate the impact of climate-induced heat stress on the productivity of the Chinese pig industry using a stochastic frontier production function model. Based on model results, we projected the impact of heat stress on pig production in 2030 and 2050 with and without technological advances. Results showed that heat stress has a significant negative impact on pig production, with southern regions being more affected. However, considering technological advances, losses will decrease by 21 % and 52 %, respectively, compared with the scenario without technological advances. Simultaneously, we calculated the costs of climate change mitigation and adaptation and found that increasing production inputs to reduce production losses from heat stress costs one-fifth of forgoing production losses. Therefore, we recommend a positive climate change response strategy.

Production performance, haematological parameters, serum biochemistry, and expression of HSP-70 in broiler chickens fed dietary ascorbic acid during heat stress

An experiment was carried out to assess the efficacy of supplemental ascorbic acid (AA) on broiler chicken production performance, blood haematological profile, biochemical profile, and carcass traits under heat stress conditions. A total of 192-day-old broiler chicks were divided into four groups, each with six replicates of eight each (4 × 6 × 8). Four corn-based dietary treatments were formulated: T1 (control diet), T2 (T1 + AA at 200 mg/kg), T3 (T1 + AA at 400 mg/kg), and T4 (T1 + AA at 600 mg/kg) for a period of 42 days. Despite the high temperature and humidity, the 600 mg AA supplemental groups (T4) gained significantly (P ≤ 0.05) more body weight and had a higher feed intake and better feed conversion ratio (FCR) than the control group (T1). After 28 days of feeding the three AA-supplemented diets, antibody titres (humoral immune response) were significantly higher (P ≤ 0.05). The response to intradermally injected phyto-haemagglutinin (PHA-P), an index of the in vivo cell-mediated immune response, was found to be increased (P ≤ 0.05) in the 400 and 600 mg AA-supplemented groups after 35 days. Higher levels of AA (T4) supplementation significantly (P ≤ 0.05) improved haematological values such as haemoglobin (Hb), total erythrocyte count (TEC), total leukocyte count (TLC), and differential leukocyte count (DLC), heterophil:lymphocyte (H:L) in comparison to the control group (T1). The supplemented group improved the serum biochemical profile of the birds, with an increase (P ≤ 0.05) in total serum protein, albumin, and globulin and a decrease in serum cholesterol and corticosterone levels in the T4 group compared to the control group. Heat shock protein-70 (HSP-70) was gradually elevated after increasing the ascorbic acid concentration (P ≤ 0.05) at 14 and 21 days. As a result, it can be concluded that supplementing ascorbic acid at 600 mg/kg is beneficial for improving the performance, immunity, and blood haematological biochemical profile and upregulating the HSP-70 gene of broiler chickens under heat stress conditions.

Heat stress adaptation in cows - Physiological responses and underlying molecular mechanisms

Heat stress is a key abiotic stressor for dairy production in the tropics which is further compounded by the ongoing climate change. Heat stress not only adversely impacts the production and welfare of dairy cows but severely impacts the economics of dairying due to production losses and increased cost of rearing. Over the years, selection has ensured development of high producing breeds, however, the thermotolerance ability of animals has been largely overlooked. In the past decade, the ill effects of climate change have made it pertinent to rethink the selection strategies to opt for climate resilient breeds, to ensure optimum production and reproduction. This has led to renewed interest in evaluation of the impacts of heat stress on cows and the underlying mechanisms that results in their acclimatization and adaptation to varied thermal ambience. The understanding of heat stress and associated responses at various level of animal is crucial to device amelioration strategies to secure optimum production and welfare of cows. With this review, an effort has been made to provide an overview on temperature humidity index as an important indicator of heat stress, general effect of heat stress in dairy cows, and impact of heat stress and subsequent response at physiological, haematological, molecular and genetic level of dairy cows.

N-3 Polyunsaturated Fatty Acids as a Nutritional Support of the Reproductive and Immune System of Cattle-A Review

This paper focuses on the role of n-3 fatty acids as a nutrient crucial to the proper functioning of reproductive and immune systems in cattle. Emphasis was placed on the connection between maternal and offspring immunity. The summarized results confirm the importance and beneficial effect of n-3 family fatty acids on ruminant organisms. Meanwhile, dietary n-3 fatty acids supplementation, especially during the critical first week for dairy cows experiencing their peripartum period, in general, is expected to enhance reproductive performance, and the impact of its supplementation appears to be dependent on body condition scores of cows during the drying period, the severity of the negative energy balance, and the amount of fat in the basic feed ration. An unbalanced, insufficient, or excessive fatty acid supplementation of cows' diets in the early stages of pregnancy (during fetus development) may affect both the metabolic and nutritional programming of the offspring. The presence of the polyunsaturated fatty acids of the n-3 family in the calves' ration affects not only the performance of calves but also the immune response, antioxidant status, and overall metabolism of the future adult cow.

Review of the Heat Stress-Induced Responses in Dairy Cattle

In the dairy cattle sector, the evaluation of the effects induced by heat stress is still one of the most impactful and investigated aspects as it is strongly connected to both sustainability of the production and animal welfare. On the other hand, more recently, the possibility of collecting a large dataset made available by the increasing technology diffusion is paving the way for the application of advanced numerical techniques based on machine learning or big data approaches. In this scenario, driven by rapid change, there could be the risk of dispersing the relevant information represented by the physiological animal component, which should maintain the central role in the development of numerical models and tools. In light of this, the present literature review aims to consolidate and synthesize existing research on the physiological consequences of heat stress in dairy cattle. The present review provides, in a single document, an overview, as complete as possible, of the heat stress-induced responses in dairy cattle with the intent of filling the existing research gap for extracting the veterinary knowledge present in the literature and make it available for future applications also in different research fields.

Genetic diversity, population structure, and selective signature of sheep in the northeastern Tarim Basin

Local sheep in the northeastern Tarim Basin can adapt to dry and low-rainfall regional environments. In this study, three local sheep breeds in the northeastern Tarim Basin, LOP (LOP) sheep, Bayinbuluke (BYK) sheep, and Kunlun (KUN, also known as the Qiemo sheep) sheep, and three introduced sheep breeds, Suffolk (SUF) sheep, Dorset (APD) sheep, and Texel (TEX) sheep, were analyzed for genetic diversity, population structure, and selective signature using the Illumina OvineSNP50K BeadChip. We found that LOP, BYK, and KUN had lower observed heterozygosity and expected heterozygosity than TEX, SUF, and ADP, which were differentiated based on geographic distribution. We performed fixation index (FST) analysis on three local sheep breeds in the northeastern Tarim Basin (LOP, BYK, and KUN) and introduced sheep breeds (TEX, SUF, and ADP) to measure genetic differentiation. Nucleotide diversity (PI) analysis was performed on single-nucleotide polymorphism (SNP) data of LOP, BYK, and KUN. A total of 493 candidate genes were obtained by taking the intersection at a threshold of 5%. Among them, SMAD2, ESR2, and HAS2 were related to reproductive traits. PCDH15, TLE4, and TFAP2B were related to growth traits. SOD1, TSHR, and DNAJB5 were related to desert environmental adaptation. Analyzing the genetic patterns of local sheep in the northeastern Tarim Basin can protect the germplasm resources of local sheep and promote the development and utilization of sheep genetic resources.

A new proposal for the use of the focal animal technique in buffaloes in the Eastern Amazon

This study aims to present a proposal for using the focal animal recording technique to evaluate the welfare of buffaloes and to verify the association between each behavior and thermal comfort indices. The study was conducted in an experimental paddock located in Santarém, Pará, Brazil. A total of 10 female Murrah animals were used. The behavior of the animals was recorded during the day, with the use of three trained observers, for 72 consecutive h. Climatic variables were collected, and the Temperature-Humidity Index (THI) and the practical Buffalo Comfort Climatic Conditions Index (BCCCIp) were determined. The multivariate technique of principal components and Spearman's correlation were employed. BCCCIp and THI were outside the thermal comfort zone at different times of the day. Grazing (P) was more frequent in the coldest hours of the day, while rumination occurred at different periods, mainly during the daytime and frequently in a lying position. There was a positive correlation between idle lying behavior and average temperature-Tmed (r = 0.583; p < 0.028), THI (r = 0.432; p < 0.034), and BCCCIp (r = 0.554; p < 0.049). There was a positive correlation between grazing and Tmed (r = 0.665; p < 0.0004) and BCCCIp (r = 0.583; p < 0.036). The standing idle behavior negatively correlated with Tmed (r = -0.718; p < 0.0001), THI (r = -0.522; p < 0.008), and BCCCIp (r = -0.8076; p < 0.0008). The lying ruminating behavior had a positive correlation with Tmed (r = 0.586; p < 0.002), THI (r = 0.477; p < 0.018), and BCCCIp (r = 0.8033; p < 0.0009). Furthermore, ruminating while standing correlated positively with Tmed (r = 0.680; p < 0.0003). The adaptation of the focal animal technique, with six observers evaluating each animal for 6 min through filming, proved to be efficient in pointing out the different behaviors of buffalo raised in Eastern Amazon fields under heat stress at different times of the day.

Physiological, haematological and electroencephalographic responses to heat stress in Katjang and Boer goats

The present study aimed to determine the effect of repeated heat stress on serum levels of cortisol (CORT), acute phase proteins (APP) and heat shock protein (HSP) 70, haematological indicators, and electroencephalographic (EEG) response in the native Katjang and exotic Boer goats. Six female Katjang (15.7 kg ± 0.68) and six female Boer (16.8 kg ± 1.16) goats aged 5 to 6 months old were exposed to 38 ± 1℃ for 8 h, and the procedure was repeated at three different weeks (weeks 1, 2 and 3). Measurements of rectal temperatures and EEG activity and collection of blood samples were conducted before heat exposure (0 h), immediately after the heat exposure (8 h), and 8 h after completion of heat exposure (16 h) (recovery period). The current results revealed that the Boer animals had significantly higher rectal temperatures (RT), haemoglobin (Hb) and packed cell volume (PCV) counts than their Kajang counterparts. There were significant breed × stage of heat treatment (SHT) × week of heat treatment (WHT) interactions for neutrophil to lymphocyte ratios (NLR). In general, the Katjang animals had elevated NLR compared to those of Boer. The Boer goats had reduced capacity to express serum HSP70 compared to their Katjang counterparts following the heat challenge at week 3. Boer goats demonstrated higher delta waves than the Katjang group, which suggested the former were more stressed following the heat exposure. Breed had a negligible effect on CORT, APP, WBC counts and backfat thickness. Our findings suggested that the Katjang breed, as measured by RT, HB and PCV count, and EEG activity, could be more tolerant to heat stress than Boer. The Katjang goats showed higher HSP70 expression than their Boer counterparts, suggesting improved thermoregulation in the former.

Heat Stress Mitigation: Impact of Increased Cooling Sessions on Milk Yield and Welfare of Dairy Buffaloes in a Semiarid Summer

The current study aimed to evaluate the impact of increasing cooling sessions from three to five times a day on milk yield and the welfare of dairy buffaloes during a semiarid summer in Pakistan. Eighteen Nili Ravi buffaloes were randomly assigned to three cooling strategies: (1) CTL, where buffaloes were cooled with a handheld hosepipe twice daily for 5 min each; (2) 3CS, where buffaloes were cooled using sprinklers three times daily; and (3) 5CS, where buffaloes were cooled using sprinklers five times daily. Each sprinkler cooling session lasted 1 h, with a 6 min cycle of 3 min of water on and 3 min off. Results showed that the 5CS group produced 1.6 and 3.2 kg more milk per day compared to the 3CS and CTL groups, respectively (p < 0.001). Both the 5CS and 3CS groups had consistently lower core body temperatures and respiration rates than the CTL group. Buffaloes in the 5CS group spent significantly more time eating (p < 0.001). Additionally, the 5CS group exhibited lower cortisol and blood urea nitrogen levels (p = 0.001) and higher glucose levels than the CTL group (p = 0.006). In conclusion, increasing cooling sessions to five times daily improved milk yield and welfare compared to the traditional cooling strategy (CTL) in dairy buffaloes during semiarid summers, highlighting the benefits of optimized cooling practices.

Livestock health and disease economics: a scoping review of selected literature

Animal diseases in production and subsistence environments have the potential to negatively affect consumers, producers, and economies as a whole. A growing global demand for animal sourced food requires safe and efficient production systems. Understanding the burden of animal disease and the distribution of burden throughout a value chain informs policy that promotes safe consumption and efficient markets, as well as providing more effective pathways for investment. This paper surveys existing knowledge on the burden of animal disease across economic categories of production, prevention and treatment, animal welfare, and trade and regulation. Our scoping review covers 192 papers across peer-reviewed journals and reports published by organizations. We find there exists a gap in knowledge in evaluating what the global burdens of animal diseases are and how these burdens are distributed in value chains. We also point to a need for creating an analytical framework based on established methods that guides future evaluation of animal disease burden, which will provide improved access to information on animal health impacts.

Glucose Supplementation Improves Performance and Alters Glucose Transporters' Expression in Pectoralis major of Heat-Stressed Chickens

Glucose level in birds' tissue decreases due to heat stress (HS)-induced reduction in feed intake (FI); impairing metabolism and growth. The effect of glucose supplementation on the performance of broiler chickens was evaluated under thermoneutral (TN) and HS conditions. Glucose was supplemented at 0 and 6% under TN-(25 °C) and HS-(25 °C-35 °C-25 °C) conditions. The treatments were TN + 0%-glucose (TN0); TN + 6%-glucose (TN6), HS + 0%-glucose (HS0) and HS + 6%-glucose (HS6). There were 6 replicates (19 birds each)/treatment. Heat and glucose supplementation were applied from d28-35. At d35, Pectoralis (P.) major was sampled from one bird/replicate to determine glucose transporters' mRNA expression. Heat application lowered (p < 0.05) FI, body weight gain, and increased feed and water conversion ratios. Glucose supplementation increased total energy intake by 4.9 and 3.2% in TN and HS groups, respectively but reduced FI under TN and HS conditions. The P. major- and drumstick-yield reduced (p < 0.05) in HS0 compared to TN0, TN6 and HS6. Under HS, glucose supplementation improved eviscerated carcass weight by 9% and P. major yield by 14%. Glucose supplementation increased SGLT1 expression with/without heat treatment while HS independently increased the expression of GLUT 1, 5 and 10. Glucose supplementation under HS could improve performance of broilers.

Non-Invasive Techniques Reveal Heifer Response to Fescue Endophyte Type in Grazing Studies

Cattle grazing tall fescue (Schedonorus arundinaceous) infected with wild-type endophytes (WE) leads to a syndrome commonly known as fescue toxicosis. Replacing WE tall fescue with a novel endophyte-infected (NE) tall fescue can mitigate this problem but adoption of this technology has been limited. This study measured and determined the physiological and behavioral responses of heifers that grazed either WE or NE tall fescue, utilizing relatively non-invasive techniques including hair cortisol, thermography (for extremity temperatures), small loggers for intravaginal temperature, and remote observation of in-field behavior. Heifers that grazed WE had greater (p < 0.0001) hair cortisol levels, lower extremity temperatures (p ≤ 0.0075), and 0.3-0.9 °C greater (p ≤ 0.02) intravaginal temperatures (particularly during the daytime) than heifers that grazed NE. From 1200 h-1700 h each day, heifers on WE pastures spent 1.5 more (p = 0.0003) hours standing up and 0.9 fewer (p = 0.0402) hours lying down than heifers on NE pastures. Differences (p = 0.0160) in ADG were small (0.1 kg d^-1) and were only observed in the first year of these 8-week studies. However, even in the mild environment of the study site, grazing NE tall fescue provided clear welfare benefits as evidenced by heifer behavioral changes, temperature differentials, and hair cortisol levels. This study underscores the potential utility of non-invasive techniques, such as thermographic imaging and hair cortisol analysis, for evaluating animal responses to stress in extensive grazing systems.

Heat Stress as a Barrier to Successful Reproduction and Potential Alleviation Strategies in Cattle

In recent decades, the adverse effects of global warming on all living beings have been unanimously recognized across the world. A high environmental temperature that increases the respiration and rectal temperature of cattle is called heat stress (HS), and it can affect both male and female reproductive functions. For successful reproduction and fertilization, mature and healthy oocytes are crucial; however, HS reduces the developmental competence of oocytes, which compromises reproduction. HS disturbs the hormonal balance that plays a crucial role in successful reproduction, particularly in reducing the luteinizing hormone and progesterone levels, which leads to severe problems such as poor follicle development with a poor-quality oocyte and problems related to maturity, silent estrus, abnormal or weak embryo development, and pregnancy loss, resulting in a declining reproduction rate and losses for the cattle industry. Lactating cattle are particularly susceptible to HS and, hence, their reproduction rate is substantially reduced. Additionally, bulls are also affected by HS; during summer, semen quality and sperm motility decline, leading to compromised reproduction. In summer, the conception rate is reduced by 20-30% worldwide. Although various techniques, such as the provision of water sprinklers, shade, and air conditioning, are used during summer, these methods are insufficient to recover the normal reproduction rate and, therefore, special attention is needed to improve reproductive efficiency and minimize the detrimental effect of HS on cattle during summer. The application of advanced reproductive technologies such as the production of embryos in vitro, cryopreservation during the hot season, embryo transfer, and timed artificial insemination may minimize the detrimental effects of HS on livestock reproduction and recover the losses in the cattle industry.

Therapeutic effects of avocado (Persea americana Mill.) seed powder against reproductive toxicity induced by Mancozeb (herbicide) in female rabbits

Pesticides like Mancozeb are being increasingly indispensable in the control of crop pests. Unfortunately, they have been implicated in genotoxicity due to their ubiquity, toxicological properties, persistence and presence in the food chain. This study sought to evaluate the efficacy of powdered avocado seed on reproductive parameters in the management of oxidative stress in female rabbits caused by the herbicide Mancozeb. Twenty-eight female rabbits aged 7-8 months and weighing between 2780.4 g and 3143.7 g were randomly divided into four groups of seven rabbits each. Each group received for 90 consecutive days distilled water or Mancozeb associated or not with avocado seed powder orally as follows: T1: 10 ml distilled water; T2, T3 and T4: 100 mg/kg bw Mancozeb. This was followed by oral administration of 250, 500, and 0 mg/kg of avocado seed powder for T2, T3, and T4, respectively. Water and feed were distributed ad libitum. Collected data concerned growth, carcass and reproductive performances, hematological and biochemistry characteristics. Results demonstrated that pregnant and lactating female rabbits administered Mancozeb exhibited a significant decrease (P < 0.05) in food intake, body weight, and body weight gain. Female rabbits exposed to Mancozeb had a decrease in litter size and weight from birth to weaning, as well as in weaning body weight and weight increase, fertility and prolificacy rate, milk yield, and daily milk efficiency. However, administration of avocado seed powder reversed (P < 0.05) the trends in these parameters in a dose-dependent manner. The increase in relative weight of the kidney and liver, concentrations of urea, creatinine, alanine and aspartate aminotransferases, mean cell volume, white blood cells, and lymphocytes were all associated with increased Mancozeb rates (P < 0.05). On the contrary, administration of the Mancozeb caused decrease in hemoglobin (Hb), Red blood Cell (RBC) and protein content. Administration of avocado seed powder significantly (P < 0.05) ameliorated the Mancozeb effects on these parameters. Applying 500 mg/kg b.w Avocado seed powder may be suggested as an alternative therapy for reproductive defects induced by Mancozeb in female rabbits.

Impact of heat stress on dairy cattle and selection strategies for thermotolerance: a review

Climate change is a problem that causes many environmental issues that impact the productivity of livestock species. One of the major issues associated with climate change is an increase of the frequency of hot days and heat waves, which increases the risk of heat stress for livestock species. Dairy cattle have been identified as being susceptible to heat stress due to their high metabolic heat load. Studies have shown heat stress impacts several biological processes that can result in large economic consequences. When heat stress occurs, dairy cattle employ several physiological and cellular mechanisms in order to dissipate heat and protect cells from damage. These mechanisms require an increase and diversion in energy toward protection and away from other biological processes. Therefore, in turn heat stress in dairy cattle can lead numerous issues including reductions in milk production and reproduction as well as increased risk for disease and mortality. This indicates a need to select dairy cattle that would be thermotolerant. Various selection strategies to confer thermotolerance have been discussed in the literature, including selecting for reduced milk production, crossbreeding with thermotolerant breeds, selecting based on physiological traits and most recently selecting for enhanced immune response. This review discusses the various issues associated with heat stress in dairy cattle and the pros and cons to the various selection strategies that have been proposed to select for thermotolerance in dairy cattle.

Plasma metabolic profiling reveals that chromium yeast alleviates the negative effects of heat stress in mid-lactation dairy cows

Chromium yeast (CY) supplementation has the potential to alleviate the negative effects of heat stress in dairy cows, but the mechanism remains elusive. We aimed to identify the metabolic mechanisms whereby CY supplementation alleviates the negative effects of heat stress in mid-lactation dairy cows. Twelve Holstein dairy cows with similar milk yield (24.6 ± 1.5 kg/d), parity (2 or 3) and days in milk (125 ± 8 d) were fed the same basal diet containing 0.09 mg of Cr/kg DM. They were allocated randomly to 2 groups: a control group (CON, without CY supplementation) and a CY group (CY, administered 0.36 mg Cr/kg DM). The experiment was performed over 8 weeks during a hot summer, in which the mean temperature-humidity index was 79.0 ± 3.13 (>72), indicating that the dairy cows were exposed to heat stress. Chromium yeast supplementation reduced rectal temperature (P = 0.032), and increased the lactation performance by increasing the yield of milk (+2.6 kg/d), protein, lactose and total solid, and protein and lactose percentages in the milk of the heat-stressed dairy cows (P < 0.05). Supplementation with CY increased the serum glucose and thyroxine concentrations, but reduced the urea nitrogen, insulin, and triiodothyronine concentrations on d 56 (P < 0.05). Furthermore, plasma metabolomic analysis was performed using liquid chromatography tandem-mass spectrometry, which identified 385 metabolites in the two groups. Subsequently, 16 significantly different metabolites in the plasma, were significantly higher in the CY group (variable importance for the projection >1.0, P < 0.05), and found to be involved in 6 Kyoto Encyclopedia of Genes and Genomes pathways, including those involved in nicotinate and nicotinamide metabolism. Specifically, plasma concentration of nicotinamide was higher after CY supplementation, which might also contribute to the reduction of rectal temperature, the regulation of glucose homeostasis, and an improvement in the lactation performance of heat-stressed dairy cows. In conclusion, CY supplementation reduces rectal temperature, influences metabolism by reducing serum insulin concentration and increasing serum glucose and plasma nicotinamide concentrations, and finally increases lactation performance of heat-stressed dairy cows.

Increased dietary vitamin D3 and calcium partially alleviate heat stress symptoms and inflammation in lactating Holstein cows independent of dietary concentrations of vitamin E and selenium

Twelve multiparous Holstein cows (42.2 ± 5.6 kg of milk/d; 83 ± 27 d in milk) were used in a split-plot design testing the effects of mineral and vitamin supplementation on the time course of animal performance, metabolism, and inflammation markers during heat stress. The main plot was the average concentrations of dietary vitamin E and Se (adequate: 11.1 IU/kg of vitamin E and 0.55 mg/kg of Se, and high: 223 IU/kg of vitamin E and 1.8 mg/kg of Se, respectively). Within each plot, cows were randomly assigned to (1) heat stress (HS) with adequate concentrations of vitamin D₃ and Ca (1,012 IU/kg and 0.73%, respectively), (2) HS with high concentrations of vitamin D₃ and Ca (HS+D₃/Ca; 3,764 IU/kg and 0.97%, respectively), or (3) pair-feeding (PF) in thermoneutrality with adequate concentrations of vitamin D₃ and Ca (1,012 IU/kg and 0.73% Ca) in a Latin square design with 14-d periods and 7-d washouts. The highest rectal temperature was recorded at 1700 h for HS (39.4°C; mean of d 1 to 14), being 1.2 and 0.8°C greater than for PF and HS+D₃/Ca, respectively. Respiratory rate and water intake were higher in HS (73 breaths/min and 115 L/d, respectively) relative to PF (28 breaths/min and 76 L/d). Heat stress decreased dry matter intake progressively, reaching a nadir on d 5 to 7 (33% reduction) and was not different between treatments. Milk yield decreased progressively in all treatments, but remained greater in PF relative to HS from d 3 to 14 (10%), whereas HS and HS+D₃/Ca were not different. Milk fat, protein, and lactose concentrations and yields were lower in HS relative to PF from d 3 to 14, but not different between HS and HS+D₃/Ca. Relative to PF, preprandial insulin concentrations were increased in HS, whereas plasma nonesterified fatty acids were decreased on d 7 and 14. Plasma lipopolysaccharide-binding protein concentrations increased in HS cows on d 7 and 14, respectively, relative to PF, whereas they were reduced in HS + D₃/Ca on d 14. Plasma C-reactive protein, tumor necrosis factor-α, and fecal calprotectin were increased in HS relative to both PF and HS+D₃/Ca on d 7 and 14. Rectal temperature was positively associated with plasma lipopolysaccharide-binding protein (r = 0.72), tumor necrosis factor-α (r = 0.74), C-reactive protein (r = 0.87), and with milk somatic cells (r = 0.75). Plasma 8-hydroxy-2-deoxyguanosine concentrations presented a 3-way interaction, where 8-hydroxy-2-deoxyguanosine was lower in HS than in PF on d 7 and 14, and lower in HS+D₃/Ca relative to HS on d 14 in the adequate vitamin E and Se treatment, but no effects were observed in the high vitamin E and Se group. Plasma superoxide dismutase concentrations increased over time, and were higher in HS relative to PF on d 14, whereas HS+D₃/Ca was similar to HS. Heat stress markedly reduced milk production and milk components while increasing markers of leaky gut and inflammation. In contrast, vitamin D₃ and Ca supplementation reduced hyperthermia (d 7-14), markers of leaky gut, and inflammation independent of dietary concentrations of vitamin E and Se.

Inflammatory responses of bovine endometrial epithelial cells are increased under in vitro heat stress conditions

Cattle exposed to heat stress have reduced fertility, reduced milk production and increased incidence of postpartum uterine infection. Heat stress is suggested to alter immune function of cattle; however, the mechanisms underlying heat stress mediated uterine infection are unknown. We hypothesized that exposure of endometrial cells to heat stress would further increase expression of inflammatory mediators in response to bacterial components due to altered heat-shock protein expression. Bovine endometrial epithelial cells (BEND) were exposed to Escherichia coli lipopolysaccharide (LPS) or a synthetic triacylated lipopeptide (Pam3CSK4) under heat stress (41.0 °C) or thermoneutral (38.5 °C) conditions for 24 h. Exposure of BEND cells to LPS or Pam3CSK4 increased the expression of the proinflammatory mediators IL1B, IL6, and CXCL8 compared to control medium. However, exposure of BEND cells to heat stress increased LPS and Pam3CSK4 induced expression of IL1B compared to cells exposed to thermoneutral conditions, and expression of LPS induced IL6 was also increased when BEND cells were exposed to heat stress. To determine if heat shock proteins increased BEND cell expression of inflammatory mediators, HSP1A1 and HSF1 were targeted by siRNA knock down. Expression of HSP1A1 and HSF1 were reduced following siRNA knockdown; however, knockdown of HSP1A1 or HSF1 further increased heat stress mediated increased expression of inflammatory mediators. These data suggest that heat stress increased BEND cell inflammatory responses to bacterial components, while heat shock proteins HSP1A1 and HSF1 help to restrain inflammatory responses. These mechanisms may contribute to the increased incidence of uterine infection observed in cows under heat stress conditions.

Seasonal Variation in Raw Milk VOC Profile within Intensive Feeding Systems

The study aimed to assess the seasonal variation in raw milk volatile organic compounds (VOCs) from three indoor feeding systems based on maize silage (n = 31), silages/hay (n = 19) or hay (n = 16). After headspace solid-phase microextraction (HS-SPME), VOC profiles were determined by gas chromatography (GC). Chemical and VOC (log₁₀ transformations of the peak areas) data were submitted to a two-way ANOVA to assess the feeding system (FS) and season (S) effects; an interactive principal component analysis (iPCA) was also performed. The interaction FS × S was never significant. The FS showed the highest (p < 0.05) protein and casein content for hay-milk samples, while it did not affect any VOCs. Winter milk had higher (p < 0.05) proportions of protein, casein, fat and some carboxylic acids, while summer milk was higher (p < 0.05) in urea and 2-pentanol and methyl aldehydes. The iPCA confirmed a seasonal spatial separation. Carboxylic acids might generate from incomplete esterification in the mammary gland and/or milk lipolytic activity, while aldehydes seemed to be correlated with endogenous lipid or amino acid oxidation and/or feed transfer. The outcomes suggested that VOCs could be an operative support to trace raw milk for further mild processing.

Chronic heat stress induces the expression of HSP genes in the retina of chickens (Gallus gallus)

Introduction: Chronic heat stress during summer is a major challenge imposed by global warming. Chickens are more sensitive to heat stress than mammals because they lack sweat glands. Thus, chickens are more susceptible to heat stress during summer than other seasons. Induction of heat shock protein (HSP) genes is one of the primary defense mechanisms against heat stress. Tissue-specific responses exhibited by different classes of HSPs upon exposure to heat stress have been reported previously in different tissues including the heart, kidney, intestine, blood, and muscle, but not in the retina. Therefore, this study aimed to investigate the expression levels of HSP27, HSP40, HSP60, HSP70, and HSP90 in the retina under chronic heat stress.

Methods: This study was conducted during the summers of 2020 and 2021 in Kuwait. Chickens (Gallus gallus) were divided into control and heat-treated groups and sacrificed at different developmental stages. Retinas were extracted and analyzed by using Real Time quantitative Polymerase Chain Reaction (RT-qPCR).

Results: Our results from the summer of 2021 were similar to that from the summer of 2020, regardless of whether GAPDH or RPL5 was used as a gene normalizer. All five HSP genes were upregulated in the retina of 21-day-old heat-treated chickens and stayed upregulated until 35 days of age, with the exception of HSP40, which was downregulated. The addition of two more developmental stages in the summer of 2021 showed that at 14 days, all HSP genes were upregulated in the retina of heat-treated chickens. In contrast, at 28 days, HSP27 and HSP40 were downregulated, whereas HSP60, HSP70, and HSP90 were upregulated. Furthermore, our results showed that under chronic heat stress, the highest upregulation of HSP genes was seen at the earliest developmental stages.

Discussion: To the best of our knowledge, this is the first study to report the expression levels of HSP27, HSP40, HSP60, HSP70, and HSP90 in the retina under chronic heat stress. Some of our results match the previously reported expression levels of some HSPs in other tissues under heat stress. These results suggest that HSP gene expression can be used as a biomarker for chronic heat stress in the retina.

Animal welfare and effects of per-female stress on male and cattle reproduction—A review

Thermal stress causes severe effects on the wellbeing and reproduction of cattle, including changes in oogenesis and spermatogenesis, generating great concerns, which last for decades. In cattle, the occurrence of thermal stress is associated with a reduction in the production of spermatozoids and ovarian follicles, in addition to the increase of major and minor defects in gametes or in their intermediate stages. In bovine females able to reproduce, a reduction in the rate of estrus manifestation and an increase in embryonic mortality has been observed. Therefore, keeping animals on good welfare conditions, with water supply and in shaded areas can favor the improvement of different reproductive parameters. For all this, the present study aimed to gather, synthesize and argue recent studies related to animal welfare, focusing on the effects of thermal stress on the reproduction of cattle, aiming to support possible strategies to mitigate the harmful effects of thermal stress in this species.

The effects of ration particle size and live yeast supplementation on dairy cows performance under heat stress conditions

The objectives of this experiment were to evaluate the effects of ration particle size and dietary supplementation of live yeast (LY; Saccharomyces cerevisiae) on dry matter intake, milk yield and milk quality, apparent nutrient digestibility, ruminal fermentation parameters, and ruminal volatile fatty acids in dairy cattle under heat stress condition. Four multiparous Holstein dairy cattle in midlactation were fed 4 diets: high particle size (HPS), high particle size with 1 g/d/cow LY (Levucell® Sc 10 ME Titan® CNCM I-1077 (10 × 10⁹ cfu/g) (HPS + LY), short particle size (SPS), short particle size with 1 g/d/cow LY (Levucell® Sc 10 ME Titan® CNCM I-1077 (10 × 10⁹ cfu/g) (SPS + LY). Treatments were arranged in a 2 × 2 factorial within a 4 × 4 Latin square design. Decreasing ration particle size increased intakes of dry matter (DM), neutral detergent fiber (NDF) (P < 0.05) but decreased peNDF intake (P < 0.0001). Milk production and milk fat percentage were similar in cows. Cows fed SPS had lower milk protein percentage (P < 0.05). No treatments had any significant effect on apparent nutrient digestibility. Ruminal pH was higher in cows supplemented LY (P < 0.05). The ruminal total volatile fatty acid (VFA) concentration and percentage of VFAs were not significantly affected by ration particle size or dietary LY supplementing. Rectal temperature (^oC) and respiratory rate (breaths/min) were similar between the groups. In conclusion, it may be concluded that decreasing ration particle size increased DM, and NDF intakes, without affecting milk yield or feed efficiency in cows exposed moderate heat stress.

Effects of management strategies on animal welfare and productivity under heat stress: A synthesis

Climate change includes different dramatic events, and among them, heat stress exposition is the strongest phenomenon affecting the livestock sector. The effects of heat stress events on animal welfare are complex and the economic impacts for the livestock sector are relevant. Management measures may contribute to improve the resilience to heat stress, but the extent to which they impact on livestock performances and management strategies depend on the magnitude of the stress conditions. Through a pioneering synthesis of existing knowledge from experiments conducted in controlled conditions, we show that management strategies, both adaptation and mitigation measures, halved the negative impacts on the ruminants' performances and welfare induced by heat stress, but the efficacy is low in extreme conditions, which in turn are more and more frequent. These novel findings emphasize the need to deepen research on more effective adaptation and mitigation measures.

A comparative study of effects of curcumin and its nanoparticles on the growth, immunity and heat stress resistance of Nile tilapia (Oreochromis niloticus)

This study evaluated the effects of dietary supplementation with free- or nano-curcumin on the growth performance, immune status and heat stress resistance of Nile tilapia (Oreochromis niloticus). Seven isonitrogenous (28% protein) and isocaloric (445 kcal/100 g DM) diets were prepared. Six diets were supplemented with three levels of nano-curcumin (50 (CN50), 100 (CN100), 200 (CN200) mg kg^-1 diet) or free-curcumin (50 (C50), 100 (C100), 200 (C200) mg kg^-1 diet), and the control diet was left without an additive (CON). Fish (13.54 ± 0.32 g) (mean ± SD) fed the experimental diets for 65 days. Following the feeding trial, the fish were exposed to the acute heat stress by gradually raising the water temperature from 25 to 40 °C within 3 h. The fish were then exposed to 40 °C for 4 h. Results revealed the superiority of nano-curcumin over its free-form in enhancing the growth performance, with the highest results obtained at CN100, followed by CN200. Only heat stress, not the experimental diets, increased the platelets, mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), leukocytes and neutrophils count, while lymphocytes decreased. The CN50 and CN100 groups showed lower activity of liver enzymes (alanine aminotransferase (ALT) and aspartate aminotransferase (AST)) than the other treatments, while C200 gave the highest activity of these enzymes. The highest immunoglobulin (IgM) levels were detected in CN100, CN200, C100 and C200, followed by CN50. The C200 group showed higher levels of complement 3 and complement 4 (C3 and C4, respectively) than the other treatments. The C50 and CON groups gave the lowest values of IgM, C3 and C4. Cortisol levels were significantly lower in the CN50 and CN100 groups compared to the other groups. After the heat stress, ALT, AST, IgM, C3, C4, cortisol and glucose increased. Thus, nano-curcumin is more effective than its free-form in enhancing the resistance to heat stress, inducing innate immunity, lowering the stress indicators and promoting growth performance of Nile tilapia with the best concentration at 100 mg kg^-1 diet.

Phenotypic analysis of heat stress in Holsteins using test-day production records and NASA POWER meteorological data

Weather station data and test-day production records can be combined to quantify the effects of heat stress on production traits in dairy cattle. However, meteorological data sets that are retrieved from ground-based weather stations can be limited by spatial and temporal data gaps. The National Aeronautics and Space Administration Prediction of Worldwide Energy Resources (NASA POWER) database provides meteorological data over regions where surface measurements are sparse or nonexistent. The first aim of this study was to determine whether NASA POWER data are a viable alternative resource of weather data for studying heat stress in Canadian Holsteins. The results showed that average, minima, and maxima ambient temperature and dewpoint temperature as well as 4 different types of temperature-humidity index (THI) values from NASA POWER were highly correlated to the corresponding values from weather stations (regression R² > 0.80). However, the NASA POWER values for the daily average, minima, and maxima wind speed and relative humidity were poorly correlated to the corresponding weather station values (regression R² = 0.10 to 0.49). The second aim of this study was to quantify the influence of heat stress on Canadian dairy cattle. This was achieved by determining the THI values at which milk, protein, and fat yield started to decline due to heat stress as well as the rates of decline in these traits after the respective thresholds, using segmented polynomial regression models. This was completed for both primiparous and multiparous cows from 5 regions in Canada (Ontario, Quebec, British Columbia, the Prairies, and the Atlantic Maritime). The results showed that all production traits were negatively affected by heat stress and that the patterns of responses for milk, fat, and protein yields to increasing THI differed from each other. We found 3 THI thresholds for milk yield, 1 for fat yield, and 2 for protein yield. All thresholds marked a change in rate of decrease in production yield per unit THI, except for the first milk yield threshold, which marked a greater rate of increase. The first thresholds for milk yield ranged between 47 and 50, the second thresholds ranged between 61 and 69, and the third thresholds ranged between 72 and 76 THI units. The single THI threshold for fat yield ranged between 48 and 55 THI units. Finally, the first and second thresholds ranged between 58 and 62 THI units and 72 and 73 THI units for protein yield, respectively.

Drivers and indicators of dairy animal welfare in large-scale dairies (review)

While animal welfare concerns are rising globally, this has not been the case with lower- and middle-income economies in Africa and Asia such as Zimbabwe. These developing countries have their own problems which are not reported in developed countries, such as the harsh economic environment, limited technologies and different political and food security priorities. These factors limit focusing on animal welfare. Meanwhile, studies on animal welfare in these countries have been limited. The task of determining animal welfare is a very complex and can sometimes be very subjective since there is no gold standard protocol to be used in many developing countries. This paper reviews the main factors that are used to assess dairy animal welfare at a farm situation. The factors were categorised and generally discussed as drivers and indicators of dairy animal welfare. Key indicators reviewed in this study include but are not limited to production performance indicators, body condition scores, cleanliness scores, presence of clinical disease signs and physiological and behavioural indicators. Dairy animal welfare drivers discussed in this paper include but not limited to the general design of dairy cattle housing, presence of foot bath and shading facilities, presence and use of maternity paddocks, state of feeder and water troughs.

Protective effects of dietary dimethyl itaconate supplementation on oxidative stress, inflammation, and apoptosis in broilers under chronic heat stress

This study was conducted to evaluate the effects of dietary dimethyl itaconate (DI) supplementation on oxidative stress, inflammation, and apoptosis in broilers under chronic heat stress (HS). Twenty-one-day-old male Ross 308 broilers (n = 120) were randomly allocated to 5 groups: a control group, HS group, HS + 50 mg/kg DI group, HS + 150 mg/kg DI group, and HS + 200 mg/kg DI group. The birds in the control group received the basal diets and were maintained at 21 ± 1 °C for 24 h daily. The birds in the HS group and HS + DI groups were raised at 32 ± 1 °C for 8 h daily and received basal diets containing DI at the indicated dose (0, 50, 150, or 200 mg/kg). The results showed that the contents of alanine aminotransferase, aspartate aminotransferase, and malondialdehyde (MDA) in serum were markedly elevated by exposure to chronic HS (P < 0.01), and this elevation was alleviated by 150 and 200 mg/kg DI supplementation (P < 0.05). Chronic HS-induced declines (P < 0.05) in total antioxidant capacity (T-AOC) and activities of peroxidase (POD), superoxide dismutase (SOD), and catalase (CAT) in serum were markedly attenuated after 200 mg/kg DI treatment in broilers (P < 0.05). Moreover, broilers subjected to chronic HS exhibited higher contents of MDA, protein carbonyl, and hydrogen peroxide (P < 0.01), but lower T-AOC and activities of antioxidant enzymes (P < 0.05), as well as reduced inhibition of superoxide and hydroxyl free radicals (P < 0.01) in the liver compared to the control group; these changes were effectively mitigated by treatment with 200 mg/kg DI in broilers (P < 0.05). In addition, 50-200 mg/kg DI effectively ameliorated chronic HS-stimulated upregulation of the mRNA levels of pro-inflammatory mediators in the livers of broilers (P < 0.01). Dietary supplementation with 150 and 200 mg/kg DI significantly alleviated chronic HS challenge-induced upregulation of the mRNA levels of Bcl-2-associated X, caspase 3, and caspase 9 (P < 0.01), but downregulation of Bcl-2 mRNA levels (P < 0.01) in broilers (P < 0.05). Importantly, chronic HS-induced downregulation of the mRNA or protein levels of nuclear factor (erythroid-derived 2)-like 2 (NRF-2), NADPH quinone acceptor oxidoreductase 1 (NQO1), heme oxygenase-1 (HO-1), SOD2, or glutathione-S-transferases (GST) (P < 0.01) was markedly improved by 150 and 200 mg/kg DI (P < 0.05). The above results indicated that DI can ameliorate oxidative stress, inflammation, and apoptosis in broilers under chronic HS.

Dietary Betaine improves the intestinal health and growth performance of heat-stressed growing rabbits in summer

The main objective of this study is to explore how various amounts of Bet affect growth performance, nutritional digestibility, and intestinal health of growing rabbits under high-temperature environment in summer. A total of 150 healthy 35-d-old weaned QiXing meat rabbits (Germany White rabbit × Sichuan White rabbit) were individually assigned to five treatments, each with 30 replicates and one rabbit per replicate. The control group was fed with basal diet, while the experimental group received a basal diet supplemented with 0.75, 1.0, 1.5, and 2.0 g Bet/kg diet, respectively. During the whole experimental stage, all animals can eat and drink freely, and they were kept in the rabbit house with an average daily temperature of 30.11 ± 0.5 ℃ and a relative humidity of 71.02 ± 5.07%. The results showed that dietary supplementation with 1.5 g/kg Bet increased average daily gain and decreased feed to gain ratio from days 1 to 42 as compared to the control group (P < 0.05), adding 0.75, 1.0, 1.5, and 2.0 g/kg Bet increased average daily gain and average daily feed intake from days 22 to 42 (P < 0.05), and increased the nutritional digestibility of acid detergent fiber (P < 0.05). Furthermore, dietary supplementation with 1.0, 1.5, and 2.0 g/kg Bet reduced d-lactate content and diamine oxidase activity in the serum (P < 0.05). Compared to the control group, supplementation of 0.75 and 1.5 g/kg Bet improved glutathione peroxidase activities in the duodenum and ileum, adding 0.75, 1.0, 1.5, and 2.0 g/kg Bet decreased malonaldehyde content in the duodenum and jejunum (P < 0.05). Moreover, the supplement of 1.5 and 2.0 g/kg Bet upregulated JAM-2 and IL-10 levels in the jejunum (P < 0.05). In conclusion, supplementation with Bet in the diet improves the growth performance, nutrient digestibility, and intestinal health of growing rabbits under high-temperature environments, and the 1.5 g Bet/kg diet group has the best effect.

The Role of BTBD7 in Normal Development and Tumor Progression

BTB/POZ domain-containing protein 7 (BTBD7) has a relative molecular weight of 126KD and contains two conserved BTB/POZ protein sequences. BTBD7 has been shown to play an essential role in normal human development, precancerous lesions, heat-stress response, and tumor progression. BTBD7 promotes branching morphogenesis during development and participates in the salivary gland, lung, and tooth formation. Furthermore, many studies have shown that aberrant expression of BTBD7 promotes heat stress response and the progression of precancerous lesions. BTBD7 has also been found to play an important role in cancer. High expression of BTBD7 affects tumor progression by regulating multiple pathways. Therefore, a complete understanding of BTBD7 is crucial for exploring human development and tumor progression. This paper reviews the research progress of BTBD7, which lays a foundation for the application of BTBD7 in regenerative medicine and as a biomarker for tumor prediction or potential therapeutic target.

Providing baseline data for conservation-Heart rate monitoring in captive scimitar-horned oryx

Heart rate biologging has been successfully used to study wildlife responses to natural and human-caused stressors (e.g., hunting, landscape of fear). Although rarely deployed to inform conservation, heart rate biologging may be particularly valuable for assessing success in wildlife reintroductions. We conducted a case study for testing and validating the use of subcutaneous heart rate monitors in eight captive scimitar-horned oryx (Oryx dammah), a once-extinct species that is currently being restored to the wild. We evaluated biologger safety and accuracy while collecting long-term baseline data and assessing factors explaining variation in heart rate. None of the biologgers were rejected after implantation, with successful data capture for 16-21 months. Heart rate detection accuracy was high (83%-99%) for six of the individuals with left lateral placement of the biologgers. We excluded data from two individuals with a right lateral placement because accuracies were below 60%. Average heart rate for the six scimitar-horned oryx was 60.3 ± 12.7 bpm, and varied by about 12 bpm between individuals, with a minimum of 31 bpm and a maximum of 188 bpm across individuals. Scimitar-horned oryx displayed distinct circadian rhythms in heart rate and activity. Heart rate and activity were low early in the morning and peaked near dusk. Circadian rhythm in heart rate and activity were relatively unchanged across season, but hourly averages for heart rate and activity were higher in spring and summer, respectively. Variation in hourly heart rate averages was best explained by a combination of activity, hour, astronomical season, ambient temperature, and an interaction term for hour and season. Increases in activity appeared to result in the largest changes in heart rate. We concluded that biologgers are safe and accurate and can be deployed in free-ranging and reintroduced scimitar-horned oryx. In addition to current monitoring practices of reintroduced scimitar-horned oryx, the resulting biologging data could significantly aid in 1) evaluating care and management action prior to release, 2) characterizing different animal personalities and how these might affect reintroduction outcomes for individual animals, and 3) identifying stressors after release to determine their timing, duration, and impact on released animals. Heart rate monitoring in released scimitar-horned oryx may also aid in advancing our knowledge about how desert ungulates adapt to extreme environmental variation in their habitats (e.g., heat, drought).

Dietary Supplementation of Capsaicin Enhances Productive and Reproductive Efficiency of Chinese Crossbred Buffaloes in Low Breeding Season

The present study investigated the role of dietary capsaicin (CPS) supplementation on milk yield (liters/head) and milk composition (total solids, lactose, albumin, protein, fat, milk urea nitrogen (MUN), somatic cell count (SCC) and somatic cell score (SCS), serum metabolites (lipoprotein esterase (LPL) and aspartate aminotransferase (AST)), and reproductive physiology (follicular development, estrus response, ovulation and pregnancy) following synchronization during the low breeding season. One hundred (n = 100) crossbred buffaloes were randomly assigned to four dietary groups consisting of CPS supplementation dosages (0, 2, 4 or 6 mg/kg of total mixed ration; TMR) as CPS-0 (n = 26), CPS-2 (n = 22), CPS-4 (n = 25) and CPS-6 (n = 27), respectively, in a 30-day feed trial. The results revealed that the CPS-4 group of buffaloes had a better estrus rate (72%) along with improved (p < 0.05) ovulatory follicle diameter (13.8 mm), ovulation rate (68%) and pregnancy rate (48%) compared to other treatment groups. Milk yield improved (p < 0.05) in CPS-4 supplemented buffaloes after day 20 of the trial, comparatively. There was a significant effect (p < 0.05) of milk sampling day (day 30) on total milk solids, lactose, milk protein and MUN levels, whereas lactose, MUN, SCC and SCS were influenced by supplementation dosage (CPS-4). Glucose levels were affected in buffaloes by sampling time (artificial insemination (AI) and 50-day post-AI) and CPS-dose (CPS-4 and CPS-6), respectively. LPL level changed in CPS-2 and CPS-4 groups at AI time and 50 days after AI. In addition, the AST level was different in CPS-4 at AI time and 50 days after AI. Therefore, our data suggest that a medium dose (~4 mg/kg of TMR) of CPS provided a better response in the form of milk yield, milk composition, serum metabolites and reproductive performance in crossbred buffaloes during the low breeding season.

Suckling behavior, performance, and Kleiber index in calves of different genetic groups under shaded and unshaded environments

The aim of this study was to evaluate the effect of heat stress on the suckling behavior and performance of Nelore (NE), ½ Nelore × ½ Angus (NA), and ½ Nelore × ½ Pantaneiro (NP) crossbred calves, in environments shaded or unshaded, using the temperature-humidity index (THI) and Kleiber index (KI) equations. Twenty-five animals were evaluated, from 30 days of age distributed as follows: 9 NE, 8 NA, and 8 NP calves, from 7:00 A.M. to 5:00 P.M., under shaded and unshaded environments. Data were collected on number of suckling episodes per day (NS), mean suckling duration (MSD), surface body temperature (SBT), THI, weight gain, and KI. THI showed difference (P < 0.05) between environments, being lower in the shaded area. NA cattle had higher SBT (33.00 ± 2.31), differing (P < 0.05) from NE (31.71 ± 1.65) and NP (31.38 ± 1.99), and lower (P < 0.05) suckling activity, suggesting reduced thermal comfort. However, their weight gain and KI were higher, differing (P < 0.05) from the other genetic groups. NE and NP cattle did not differ (P > 0.05) in weight gain and KI. Thus, the results suggest that NA calves, despite the greater thermal discomfort, used thermolysis mechanisms to maintain higher weight gain and feed efficiency (KI) than the other groups. NP showed greater thermal adaptability, in addition to weight gain and KI similar to NE cattle.

Thermal stress-related physiological, behavioral, and serum biochemical responses in indigenous pigs adapted to Eastern Himalayan region

Introduction

The current study was carried out to investigate the effect of micro-environmental variations on physiological, behavioral, and serum biochemical parameters of indigenous (Niang Megha), Hampshire, and crossbred (75% Hampshire X 25% Niang Megha).

Methods

Rectal temperature (T_R), skin surface temperature (T_SS), respiration rate (RR), and heart rate (HR) were recorded at 0,900 and 1,600 h weekly once for 2 months for each season in grower pigs of each genotype. CCTV video cameras were utilized to observe the behavioral changes. Five milliliters of blood samples was collected to estimate different biochemical parameters.

Results

Season affected (p < 0.05) all physiological parameters which generally increased during summer except T_R and RR of indigenous pig. T_R, T_SS, RR, and HR were significantly (p < 0.05) higher for Hampshire than for indigenous and crossbred in the summer season. The frequency and behavioral activities to heat loss or to conserve heat such as shivering and wallowing were lower except for physical activity that was higher at all times in indigenous pigs. Seasonal variations influenced metabolic activity and serum activity of alkaline phosphatase (ALP) and alanine transaminase (ALT), which rose in summer in all genotypes. Serum ALP and thyroxine (T₄) were significantly (p < 0.05) higher for indigenous pig in both the seasons. The insulin level was significantly (p < 0.05) higher in indigenous pigs with no significant difference between Hampshire and crossbred in summer whereas there was significant difference among the genotypes in winter. However, superoxide dismutase (SOD) showed no significant difference in the study. Indigenous pigs had the lowest serum cortisol concentrations, whereas Hampshire had the highest.

Conclusion

The current study's findings on several parameters of three different genotypes suggest that indigenous pigs in this region are more adaptable to the region's changing climatic conditions.

Chronic heat stress promotes liver inflammation in broilers via enhancing NF-κB and NLRP3 signaling pathway

Background

This study investigated the effects of chronic heat stress on liver inflammatory injury and its potential mechanisms in broilers. Chickens were randomly assigned to the 1-week control group (Control 1), 1-week heat stress group (HS1), 2-week control group (Control 2), and a 2-week heat stress group (HS2) with 15 replicates per group. Broilers in the heat stress groups were exposed to heat stress (35 ± 2 °C) for 8 h/d for 7 or 14 consecutive days, and the rest of 26 hours/day were kept at 23 ± 2 °C like control group broilers. Growth performance and liver inflammatory injury were examined for the analysis of liver injury.

Results

The results showed that heat stress for 2 weeks decreased the growth performance, reduced the liver weight (P < 0.05) and liver index (P < 0.05), induced obvious bleeding and necrosis points. Liver histological changes found that the heat stress induced the liver infiltration of neutrophils and lymphocytes in broilers. Serum levels of AST and SOD were enhanced in HS1 (P < 0.01, P < 0.05) and HS2 (P < 0.01, P < 0.05) group, compared with control 1 and 2 group broilers. The MDA content in HS1 group was higher than that of in control 1 group broilers (P < 0.05). Both the gene and protein expression levels of HSP70, TLR4 and NF-κB in the liver were significantly enhanced by heat stress. Furthermore, heat stress obviously enhanced the expression of IL-6, TNF-α, NF-κB P65, IκB and their phosphorylated proteins in the livers of broilers. In addition, heat stress promoted the activation of NLRP3 with increased NLRP3, caspase-1 and IL-1β levels.

Conclusions

These results suggested that heat stress can cause liver inflammation via activation of the TLR4-NF-κB and NLRP3 signaling pathways in broilers. With the extension of heat stress time, the effect of heat stress on the increase of NF-κB and NLRP3 signaling pathways tended to slow down.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12917-022-03388-0.

Effect of live yeast supplementation on energy partitioning and ruminal fermentation characteristics of steers fed a grower-type diet in heat-stress conditions

The objective of this trial was to determine the influence of live yeast supplementation (LY), environmental condition (ENV), and their interaction (TRT) on energy partitioning, nitrogen metabolism, and ruminal fermentation dynamics of steers receiving a grower-type diet. The effects of LY and ENV were investigated using a 2 × 2 crossover design that spanned five periods. Eight Angus-crossbred steers were randomly split into pairs and housed in four outdoor pens outfitted with an individualized feeding system. Animals were limit-fed a grower diet (DIET) at 1.2% shrunk body weight (SBW) with no live yeast supplementation (NOY) or a grower diet top-dressed with 10 g LY/d for 14 d (1.2 × 1012 CFU/d). On days 13 and 14, animals were subjected to one of two ENV conditions, thermoneutral (TN; 18.4 ± 1.1 °C, 57.6 ± 2.8% relative humidity [RH]) or heat stress (HS; 33.8 ± 0.6 °C, 55.7 ± 2.7% RH), in two side-by-side, single-stall open-circuit, indirect respiration calorimetry chambers. Data were analyzed using a random coefficients model. Carryover effects were examined and removed from the model if not significant. Gross (GE), digestible, metabolizable, heat, and retained energies were not influenced by DIET, ENV, or TRT (P ≥ 0.202). Gaseous energy, as a percentage of GE, tended to increase during HS (P = 0.097). The only carryover effect in the study was for oxygen consumption (P = 0.031), which could be attributed to the tendency of NOY (P = 0.068) to have greater oxygen consumption. DIET, ENV, or TRT (P ≥ 0.154) had no effects on total animal methane or carbon dioxide emissions. Similarly, DIET, ENV, or TRT (P ≥ 0.157) did not affect ruminal pH, redox, protozoa enumeration, ruminal ammonia concentrations, and acetate-to-propionate ratio. Propionate concentrations were the greatest in animals in TN conditions receiving LY (P = 0.034) compared to the other TRT. This effect is mirrored by TN-LY tending to have greater acetate concentrations (P = 0.076) and total VFA concentrations (P = 0.065). Butyrate concentrations tended to be greater for animals fed LY (P = 0.09). There was a tendency for LY to have elevated numbers of Fusobacterium necrophorum (P = 0.053). Although this study lacked effects of LY on energy partitioning, nitrogen metabolism, and some ruminal parameters during HS, further research should be completed to understand if LY is a plausible mitigation technique to enhance beef animals' performance in tropical and sub-tropical regions of the world.