Delineation of temperature-humidity index (THI) as indicator of heat stress in riverine buffaloes (Bubalus bubalis) of a sub-tropical Indian region

Encapsulated sodium butyrate without or with a botanical extract for transitioning neonatal calves

Butyrate (C4) is known to enhance ruminal papillae development for transitioning neonatal calves from liquid to dry feed, and botanical extracts (BE) have demonstrated enhanced DMI and improved gut health. The hypothesis was that these additives, based on their mechanism of action, could be synergistic to neonatal calf growth performance by improving ruminal function for transitioning from liquid milk replacer (MR) to dry calf starter (CS). Eighty 2- to 5-d old Holstein bull calves were randomly assigned to 1 of 4 treatments using a randomized complete block design with a 2 × 2 factorial treatment arrangement with main effects being 2 MR (C4- vs. C4+) and 2 CS (BE- vs. BE+). The 4 individual treatments were (1) calves fed MR and CS without additives (control; C4-BE); (2) calves fed control MR with CS containing BE at 0.05% (496 mg/kg; C4-BE+); (3) calves fed MR with C4 added at 0.3% at feeding time with control CS (C4+BE-); and (4) calves fed MR with C4 and CS with BE added at same the inclusion rates (C4+BE+). Calves were fed 2×/d at 0630 and 1800 h along with ad libitum CS and free choice water. The MR was fed at 0.55 (DM basis) kg/d for d 1 to 14, then increased to 0.82 kg/d for d 15 to 42, and feeding reduced to 0.415 kg/d fed 1×/d for d 42 to 49, with weaning occurring after the 49-d experimental period. Three calves were excluded from data analysis because 2 calves died and 1 was a statistical outlier. The MR× CS interaction was nonsignificant for BW, BW gain, ADG, CS intake, and total DMI. The main MR effect demonstrated calves fed C4+ having greater BW (54.7 and 56.2 kg, for C4- and C4+, respectively), BW gain (29.0 and 31.7 kg), and ADG (591 and 648 g/d), but similar DMI (0.96 and 0.96 kg/d) compared with calves fed C4-. The number of days required for calves to consume 0.9 kg/d CS for 3 consecutive days (47.3 and 45.7 d) as a weaning criterion was lower (P < 0.05) for calves fed C4+ compared with calves fed C4-. The main CS effects for calves fed without or with BE were similar in BW, BW gain, ADG, CS intake, and total DMI. The overall study (0-49 d) feed conversion demonstrated a MR × CS interaction, with calves fed C4-BE- and C4+BE+ being greater than calves fed C4-BE+ with calves fed C4+BE- being intermediate and similar. The MR × CS interaction was nonsignificant for frame measurements, frame measurement gains, and fecal, nasal, and eye and ear scores, and similar for MR or CS main effects when fed without or with C4 and BE. Feeding neonatal calves C4 in the MR improved growth performance by reducing the days to achieve the weaning criteria. The feeding of a BE did not improve growth performance and did not improve growth performance in the presence of C4.

Physiological responses of Munjal sheep to variations in temperature humidity index in subtropical climate

Understanding the relationship between physiological parameters of livestock and temperature humidity index (THI) is essential for developing effective management strategies aimed at mitigating heat stress, especially during periods of elevated temperatures. The present study examined the physiological parameters of rectal temperature (RT), respiration rate (RR), and pulse rate (PR) in Munjal sheep reared in a subtropical climate, focusing on their association with THI. Data were collected from 29 female Munjal sheep at 15-day intervals, during morning (8:00 a.m.-10:00 a.m.) and afternoon (2:00 p.m.-4:00 p.m.) over one year. Results showed that RT was significantly higher in the afternoon compared to the morning for both lambs and adults. Likewise, RR and PR were elevated in the afternoon across both groups. In young lambs, RT (r = 0.86) and RR (r = 0.71), and in adults, RR (r = 0.89) and PR (r = 0.91) demonstrated a significant positive correlation (P < 0.05) with THI. These findings indicate that higher physiological parameters during hotter periods necessitate additional care for young lambs. In conclusions, this study highlighted the critical need for targeted management practices to support the physiological well-being of Munjal sheep in subtropical climates, particularly during periods of high temperature humidity index, ensuring optimal health and productivity.

Breed-Specific Responses and Ruminal Microbiome Shifts in Dairy Cows Under Heat Stress

Holstein and Jersey cows, as excellent dairy breeds, have their own advantages in milk yield, milk quality, disease resistance, and heat resistance. However, the adaptability and rumen microbiome changes in Holstein and Jersey cows under heat stress are not clear. Therefore, the main objective of this study was to compare the differences in heat tolerance and the changes in the ruminal microbiome in Holstein and Jersey cows under heat stress. The experiment comprised a 7-day thermo-neutral (TN) period and a 7-day heat stress (HS) period. Five Jersey cows and five Holstein cows with similar parity and days in milk were selected, and rumen fluid was collected from five of them each. Compared with the TN period, heat stress increased the respiratory rate (p < 0.05), whereas decreased the milk yield (p < 0.01) in the Holstein and Jersey cows. Also, heat stress increased the rectal temperature (p < 0.01) in the Holstein cows. Jersey cows had a significantly (p < 0.05) lower level of acetic acid, propionic acid, butyric acid, valeric acid, and TVFA during HS compared with the TN period. Furthermore, high-throughput sequencing revealed that the relative abundance of Bacteroidetes and Prevotella increased while the relative abundance of Firmicutes decreased in Holstein cows during the HS period, whereas Christensenellaceae and Clostridium were more abundant in Jersey cows during the HS period than in the TN period. Simultaneously, the dominant fungi in Holstein cows were Ascomycota, Neocallimastigomycota, and Aspergillus. Correlation analysis also provided a link between the significantly altered rumen microbiota and animal production. These results suggest that heat stress has negatively influenced the physiological parameters, milk production, and rumen microbiota of Holstein and Jersey cows. Changes in the rumen fermentation and ruminal microbiome in Holstein cows may be associated with a better adaptation ability to heat stress. Our findings may inform future research to better understand how heat stress affects the physiology and productivity of dairy cattle breeding in southern China and the development of mitigation strategies.

A systematic review on the trend of transcriptomic study in livestock: An effort to unwind the complexity of adaptation in a climate change environment

Heat stress has been proven to cause negative effects on livestock leading to lower productivity and economic value. Understanding how heat stress manifests within an animal's body is the first step in devising a heat stress mitigation strategy; transcriptomic studies are one of the methods used. Here, using a systematic literature review methodology, we examine the recent decade of transcriptomics' application to the study of livestock adaptation. We identified 152 studies that met our criteria for using transcriptome methods to heat stress adaptation and were published within the last ten years. Our analysis demonstrates the growing popularity and application of transcriptome approaches in the investigation of the response of ruminants, pigs, and poultry livestock to heat stress. Majority of the works was done in chicken and cattle using multiple organs as the sample, with qRT-PCR as the most employed technique. It has been established that a variety of biomarkers can be used to assess animals under heat stress, such as the HSPs, ILs, and TLRs. Although transcriptomics has lately been employed extensively to uncover the mechanism of heat adaptation, this adaptive feature's complex mechanism remains unclear, leaving many knowledge gaps for investigation. A more complex studies involving more various cell types, organs, or even model organisms using multi-omics approach could be the future research direction in understanding the heat stress effects on livestock better.

Advancing mastitis assessment in dairy bovines via short milking tube thermography: A seasonal perspective

In India, where dairy production leads globally, infrared thermography (IRT) and short milking tube thermography specifically are vital for managing mastitis. Therefore, the present study focuses on thermal imaging of the udder and short milking tube (SMT) of the milking machine during the peak milking process of Sahiwal cows and Murrah buffaloes during winter, summer, rainy and autumn seasons to identify sub-clinical (SCM) and clinical mastitis (CM) cases using the Darvi DTL007 camera. The udder health was assessed using the California Mastitis Test, Somatic Cell Count (SCC) and IRT throughout the year. Log10SCC and thermogram analysis revealed a difference (p < 0.01) between healthy, SCM, and CM cases during different seasons in both breeds. Further results showed an increase (p < 0.01) in SMT thermograms of SCM and CM cases compared to healthy quarters in Sahiwal cows during winter, summer, rainy, and autumn were 4.26 and 7.51, 2.37 and 4.47, 2.20 and 3.64, 2.90 and 4.94 ºC, respectively and for Murrah buffaloes were 3.56 and 5.55, 2.70 and 3.81, 1.72 and 3.10, 3.14 and 4.42ºC, respectively. The highest degree of increase in milking udder skin surface temperature and SMT of SCM and CM cases compared to healthy quarters was observed during the winter and the least during the rainy season. Thus, regardless of the seasons examined in this study, SMT thermograms effectively assessed SCM and CM.

A comparative study on effect of heat stress on physiological and cellular responses of crossbred cattle and riverine buffalo in subtropical region of India

The study was carried out to compare the in vitro and in vivo heat shock responses of cattle and buffaloes. The expression of heat responsive genes (HSP70 and HSF family) were studied in vitro in peripheral blood mononuclear cells (PBMCs) of cattle and buffalo. In vivo observations on animals were carried out to investigate the physiological responses of cattle and buffalo at different THI over a period of 14 months. The study indicated that onset and severity of heat stress at different THI varied significantly between cattle and buffalo. Rectal temperature (RT) showed a significant (p < 0.05) increase at THI 67 in buffaloes and at THI 68 in cattle. Significant (p < 0.01) differences in RT between the species were observed at THI 71, 72, and 73. Respiration rate (RR) significantly (p < 0.05) increased at THI 70 in both the species and significant (p < 0.05) differences in RR were observed between the species at THI 65, 68, 69, and 74. THI had significant (p < 0.05) effect on blood glucose and blood electrolytes of the species with increased levels at higher THI. Serum AST and ALT levels showed less pronounced changes over increasing THI. Heat stress-associated expressions of HSP 70 genes followed temporal changes with incremental THI. The expression of HSPA8 was consistent at lower THI whereas upregulation of HSPA1A and HSPA1L was evident at higher THI. The study concludes that changes in physiological parameters such as RT and RR occur in a phasic pattern in both species and onset of heat stress was early in buffalo as compared to cattle.

Thermoregulatory reactions of female buffaloes raised in the sun and in the shade, in the climatic conditions of the rainy season of the Island of Marajó, Pará, Brazil

Buffaloes are well-adapted to hot, humid climates and muddy terrain, however they show signs of thermal discomfort when exposed to direct sunlight due to their specific structural features such as dark skin, small number of sweat glands/skin area and thick skin. Epidermis layer of the skin, making heat dissipation difficult. The study aimed to evaluate the thermal comfort of female buffaloes raised in traditional and silvopastoral systems, on the island of Marajó, Pará, during the rainy season of the year. The experiment was carried out in Cachoeira do Arari, Retiro Grande, Marajó, Pará (00°55'37.814424”S 48°43'48.143060”W). Twenty female Murrah buffaloes, aged between 2 and 3years and average weight of 282 ± 29 kg, were used. They were fed on pasture and divided into two groups: WS group (with shade) and NS group (without shade). The WS group (n = 10) remained grazing in a silvopastoral system, with access to the shade of red Jambeiro (Syzygium malaccense) trees. The NS group (n = 10) was kept in grazing, in a traditional system, without access to the shade of trees or shades. The physiological variables rectal temperature (RT), respiratory rate (RR) and body surface temperature (BST) (forehead, left side of the thorax and left flank) were measured at 6:00, 10:00, 14:00, 18:00, and 22:00 h. At the same times, data on air temperature, relative air humidity, wind speed (WSP), solar radiation (SR) and Temperature and Humidity Index (THI) were also recorded. THI, WSP and SR were higher at 14:00 h (P < 0.05). At 10:00, 14:00, and 18:00 h there was difference of RT between treatments (P < 0.05), where animals of the NS group had the highest values. In the NS group, the highest value of RT was observed at 14:00 h (39.38 ± 0.43°C), when THI and SR were higher. At 10:00 and 14:00 h, BST was higher in the NS group (p < 0.05), of 34,55 ± 1.03 and 35.35 ± 1.51°C, respectively, and both groups had the highest value of BST at those same times. There was difference of the RR between treatments at 10:00 h and 14:00 h (p < 0.05), where the highest values were found in the NS group (33.71 ± 7.58 e 50.40 ± 18.41 mov./min., respectively). Even in the rainy season of the year, the climatic conditions of Ilha do Marajó are unfavorable to the welfare of buffaloes, especially at 2:00 pm, when the SR is higher. Thus, the use of the system with access to shade, such as silvopastoral, is recommended, in order to provide greater thermal comfort to animals and improve their productivity.

Effect of Dietary Supplementation with Mannose Oligosaccharides on the Body Condition, Lactation Performance and Their Offspring of Heat-Stressed Sows

The aim of this study was to determine the effects of dietary supplementation with mannose oligosaccharide (MOS) on the condition of the body and the reproductive and lactation performances of sows. Eighty pregnant sows were randomly assigned to four groups with a 2 × 2 factorial design: with or without MOS (1 g/kg) and with or without heat stress (HS) challenge. The temperature in the HS groups (HS and HM group) was controlled at 31.56 ± 1.22 °C, while the temperature in the active cooling (AC) groups (AC and AM group) was controlled at 23.49 ± 0.72 °C. The weight loss of sows in the AC group was significantly lower than that of sows in the HS group (p < 0.01). The weight and backfat thickness loss of sows supplemented with MOS displayed a downward trend. The average birth weight of the litter significantly increased in the HM group (basic diet + MOS) compared with the HS group (p < 0.05). The milk protein of sows significantly decreased under the HS condition at 2 and 12 h after delivery (p < 0.05). However, the milk immunoglobin G (IgG) of sows in the HS group increased significantly compared with that of sows in the HM group (p < 0.05) at 12 and 24 h after delivery. The levels of serum urea nitrogen (UREA) and glucose (GLU) decreased significantly under the HS condition (p < 0.05), while the level of interleukin-6 (IL-6) increased significantly under the HS condition (p < 0.05). Dietary supplementation with MOS also significantly reduced TNF-α under the AC conditions (p < 0.05). In conclusion, HS significantly affected the body condition, lactation performances and their offspring of sows. However, dietary supplementation with 1 g/kg MOS did not result in statistically significant changes.

Effects of Heat Stress on the Ruminal Epithelial Barrier of Dairy Cows Revealed by Micromorphological Observation and Transcriptomic Analysis

Heat stress (HS) alters the rumen fermentation of dairy cows thereby affecting the metabolism of rumen papillae and thus the epithelial barrier function. The aim of the present study was to investigate if HS damages the barrier function of ruminal epithelia. Eight multiparous Holstein dairy cows with rumen cannula were randomly equally allocated to two replicates (n = 4), with each replicate being subjected to heat stress or thermal neutrality and pair-feeding in four environmental chambers. Micromorphological observation showed HS aggravated the shedding of the corneum and destroyed the physical barrier of the ruminal epithelium to a certain extent. Transcriptomics analysis of the rumen papillae revealed pathways associated with DNA replication and repair and amino acid metabolism were perturbated, the biological processes including sister chromatid segregation, etc. were up-regulated by HS, while the MAPK and NF-kB cell signaling pathways were downregulated. However, no heat stress-specific change in the expression of tight junction protein or TLR4 signaling was found, suggesting that HS negatively affected the physical barrier of the ruminal epithelium to some extent but did not break the ruminal epithelium. Heat stress invoked mechanisms to maintain the integrity of the rumen epithelial barrier by upregulating the expression of heat shock protein and repairments in rumen papillae. The increase in amino acid metabolism in rumen papillae might affect the nutrient utilization of the whole body. The findings of this study may inform future research to better understand how heat stress affects the physiology and productivity of lactating cows and the development of mitigation strategies.

Performance and welfare of dairy buffaloes subjected to different cooling strategies during subtropical summer

This study aimed to evaluate the effects of different cooling strategies on milk yield and physiological and behavioral responses of Nili Ravi buffaloes during subtropical summer in Pakistan. Thirty Nili Ravi buffaloes were randomly assigned to three treatments: (1) CNT buffaloes cooled with the application of water using handheld hosepipe twice daily, 3 min each with a water flow rate of 40 L/min; (2) 2SS, buffaloes cooled with sprinklers twice daily; (3) 3SS, buffaloes cooled with sprinklers thrice daily. Each of the sprinkler sessions lasted for 1 h with a 12-min cycle (3 min water on, 9 min off). The trial was carried out from mid-July until the end of September 2019. The average ambient afternoon temperature humidity index was 86.9. The results indicated that the buffaloes in the 3SS group had lower respiration rate and rectal temperature than those in the CNT and the 2SS groups (P < 0.01). The 3SS group had more daily milk yield (P = 0.019) and milk fat % (P < 0.01) than the CNT and 2SS groups. The lying time and the lying bout length were significantly longer in the 3SS than in the CNT and 2SS groups. The blood cortisol levels tended to be lower in the 3SS group than in the CNT and 2SS groups (P = 0.051). In conclusion, the 3SS cooling strategy had more milk yield, more milk fat, and better welfare than the CNT strategy using less groundwater and both performed better than the 2SS strategy.