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.

Tibetan Plateau yak milk: A comprehensive review of nutritional values, health benefits, and processing technology

Yak milk is a characteristic animal product of yaks in the Qinghai-Tibet Plateau. Although yak milk production is low, it is richer in nutrients such as protein, fat, and lactose, a more comprehensive range of bioactive components, and unique microbial resources than Holstein cow milk. The plateau environment makes yak milk resistant to hypoxia, anti-fatigue, antioxidant, antibacterial, and relieves chronic diseases. In this paper, based on the systematic analysis of yak milk research results in the past 20 years using CiteSpace 6.1.R2, we reviewed yak lactation performance and nutritional efficacy of yak milk. This paper summarizes the improvement of traditional yak dairy processing technology, and also focuses on the microbial diversity of yak milk sources and their beneficial effects. The purpose of this review is to provide scientific support for the development of a quality yak milk industry on the Tibetan plateau.

Effect of fermented dandelion on productive performance, meat quality, immune function, and intestinal microbiota of broiler chickens

BACKGROUND

Dandelion has a great potential to be used as feed additive. Using microbial fermentation technology to degrade cell walls is conducive to enable better release of bioactive compounds of dandelion. This study intended to explore the effect of fermented dandelion (FD) on production performance, meat quality, immune function, and intestinal microbiota of broiler chickens. One-hundred and twenty 1-day-old male Arbor Acres broiler chickens were randomly allotted into three treatments: CON (basal diet, control), LFD and HFD (basal diet with 500 and 1000 mg/kg FD, respectively), with five replicates of eight birds each. The experiment lasted for 42 days.

RESULTS

The results showed that birds in HFD group had increased ADG during 1-21 days (P < 0.05). On day 21, the bursa of Fabricius index of birds in LFD group was higher (P < 0.05), while the serum contents of IFN-γ and TNF-ɑ were lower in HFD group (P < 0.05). FD supplementation decreased the observed_species, shannon, chao1 and ace indexes (P < 0.05) as well as the abundance of Bacteroidota, Bacteroides, and Alistipes (P < 0.05). Birds in HFD group had higher abundance of Firmicutes and lower abundance of Verrucomicrobiota (P < 0.05). LFD group had lower abundance of unidentified_bacteria (P < 0.05). On day 42, the abdominal fat yield of HFD group was decreased (P < 0.05). Birds in LFD group had lower L* and b* values of breast muscle (P < 0.05), while higher spleen index. The CAT activities of breast muscle of FD groups were higher (P < 0.05).

CONCLUSION

In summary, dietary FD supplementation at 1000 mg/kg improved production performance and immune function and modulated microbiota composition in ileum of broiler chickens. FD can be supplemented in the diet to enhance performance and health of broiler chickens, of which 1000 mg/kg FD is more effective.

Effects of dietary Lactobacillus rhamnosus GG supplementation on the production performance, egg quality, eggshell ultrastructure, and lipid metabolism of late-phase laying hens

BACKGROUND

Toward the late phase of laying, the production performance of laying hens decreases, egg quality deteriorates, lipid metabolism weakens, and hepatic lipid accumulation is exacerbated. Probiotics as an alternative to antimicrobials have been employed in poultry-related industries. Lactobacillus rhamnosus GG (LGG) is currently the most researched and clinically validated probiotic, showing promising effects in multiple application areas. However, few studies have been conducted on livestock (including poultry) production.

RESULTS

Compared with the CON group, the feed conversion ratio (P < 0.01) declined significantly in the LGG group. Eggshell strength (P < 0.001) and eggshell thickness (P < 0.001) were significantly increased by supplementation with LGG in the diet. The height (P < 0.001) and proportion (P < 0.05) of the effective layer and the mammillary knob density (P < 0.01) in the eggshell ultrastructure of the LGG group increased significantly, while the mammillary layer (P < 0.05) and knob width (P < 0.01) decreased significantly. The LGG-treated hens had significantly lower serum concentrations of low-density lipoprotein (P < 0.05), free fatty acids (P < 0.01), and liver triglyceride (P < 0.05) levels than those in the CON group.

CONCLUSIONS

LGG supplementation significantly decreases the feed conversion ratio, improves eggshell quality by altering the ultrastructure, and improves lipid metabolism in the late laying period.

Influence of targeted selective anthelmintic treatment on the productive performance of wool and hair lambs naturally infected with gastrointestinal nematodes in Brazil

Targeted selective treatment (TST) is an alternative method to reduce the use of anthelmintics and delay the development of resistant nematode populations. However, there is limited information on the actual effects of this type of treatment on livestock productivity. The objective of this study was to evaluate the production performance of Santa Ines (hair) and Ile de France (wool) lambs naturally infected with gastrointestinal nematodes (GIN) under TST based on packed cell volume (PCV) versus suppressive anthelmintic treatments. Thirty-eight lambs were divided into two treatment groups: Suppressive treatment, animals were drenched with monepantel every two weeks and TST, animals were treated with the same anthelmintic when they presented PCV ≤ 20%. Feces, blood, and weight were measured weekly to determine eggs per gram of feces, PCV, total plasma protein, and weight gain. After animals were slaughtered, carcasses were weighed to determine carcass yield. In the TST group, substantial productive losses of approximately 21.3% in the wool and 25.9% in the hair lambs were observed in body weight compared to their counterparts. Significant differences in hematological variables occurred over the experimental period, especially in the wool lambs under TST. Favorable environmental conditions enabled infective larvae to survive and thrive on pasture. Haemonchus contortus and intestinal nematodes were the most common parasites found in the Ile de France lambs and the Santa Ines lambs, respectively. Although TST prevented mortality, it did not prevent production losses. Both breeds showed a significant drop in production due to GIN parasitism.

Effects of a complex probiotic preparation, Fengqiang Shengtai and coccidiosis vaccine on the performance and intestinal microbiota of broilers challenged with Eimeria spp

BACKGROUND

Coccidiosis, a prominent intestinal protozoan disease, carries significant economic implications for the poultry industry. The aim of this study was to evaluate the effects of Fengqiang Shengtai (BLES), a probiotics product, and coccidiosis vaccine in modulating the intestinal microbiome and providing insight into mitigating the occurrence and management of avian coccidiosis.

METHODS

Broilers included in the study were divided into four pre-treatment groups: the Pre-Con group (commercial diet), Pre-BLES group (BLES supplement), Pre-Vac group (coccidiosis vaccination) and Pre-Vac-BLES group (combined vaccination and BLES). Body weight gain, feed consumption and feed conversion ratio were monitored from age 25 to 55 days. Cecum contents were collected at 8 and 15 days of age for comparative analysis of intestinal microbiomes. In the Pre-BLES and Pre-Vac-BLES groups, probiotics were administered at a dose of 0.01 g per chicken between ages 3 to 6 days and 10-13 days. At 3 days of age, chickens in the Pre-Vac and Pre-Vac-BLES groups were vaccinated with 1700 sporulated oocysts of the live coccidiosis vaccine per chicken. At the age of 25 days, Eimeria spp. challenge experiments were performed based on the aforementioned immunization strategy, and the oocysts per gram (OPG) in the feces, intestinal lesion score and intestinal pathological characteristics were evaluated. Specifically, 30 chickens were randomly selected from each group and orally administered 34,000 sporulated oocysts of Eimeria spp. per chicken, re-defined as Eimeria group, BLES-Eimeria group, Vac-Eimeria group and Vac-BLES-Eimeria group, respectively. Additionally, 30 chickens were randomly selected from the Pre-Con group and included as negative control without Eimeria spp.

CHALLENGE

Intestinal microbiota was sequenced and analyzed when the broilers were 32 days old.

RESULTS

A significant improvement was observed in body weight gain of the broilers in the Pre-BLES and Pre-Vac-BLES group at 45 days of age. Analysis of the intestinal microbiota revealed a positive correlation between the experimental groups receiving BLES and coccidiosis vaccines at 8 and 15 days of age with the Enterococcus genus and Lachnospiraceae NK4A136 group, respectively. In addition to the reduced lesion score and OPG values, the combination of coccidiosis vaccine and BLES also reduced the intestinal epithelial abscission induced by coccidiosis vaccines. The results of intestinal microbial function prediction demonstrated that N-glycan biosynthesis and ferroptosis were the prominent signal pathways in the Vac-BLES-Eimeria group.

CONCLUSIONS

Taken together, the results of the present study suggest that supplementation of BLES with coccidiosis vaccine represents a promising strategy for improving growth performance, alleviating clinical manifestations and inducing favorable alterations to the intestinal microbiota in broiler chickens affected by coccidiosis.

Effect of small peptide chelated iron on growth performance, immunity and intestinal health in weaned pigs

BACKGROUND

Small peptide chelated iron (SPCI), a novel iron supplementation in pig diets, owns growth-enhancing characteristics. Although a number of researches have been performed, there is no clear-cut evidence to show the exact relationship between the dose and effects of small peptide chelated minerals. Therefore, we investigated the effect of dietary supplementation of SPCI at different doses in the growth performance, immunity, and intestinal health in weaned pigs.

METHODS

Thirty weaned pigs were randomly assigned into five groups and feed with basal diet or the basal diet containing 50, 75, 100, or 125 mg/kg Fe as SPCI diets. The experiment lasted for 21 d and on day 22, blood samples were collected 1 h later. The tissue and intestinal mucosa samples were collected following.

RESULTS

Our results showed that the feed to gain ratio (F:G) decreased with different levels of SPCI addition (P < 0.05). The average daily gain (ADG) (P < 0.05) and digestibility of crude protein (P < 0.01) decreased with 125 mg/kg SPCI addition. With dietary different levels of SPCI addition, the serum concentrations of ferritin (quadratic, P < 0.001), transferrin (quadratic, P < 0.001), iron content in liver (quadratic, P < 0.05), gallbladder (quadratic, P < 0.01) and fecal (quadratic, P < 0.01) increased quadraticly. While the iron content in tibia (P < 0.01) increased by 100 mg/kg SPCI supplementation. Dietary 75 mg/kg SPCI addition increased the serum insulin-like growth factor I (IGF-I) (P < 0.01) and SPCI (75 ~ 100 mg/kg) addition also increased the serum content of IgA (P < 0.01). The serum concentrations of IgG (quadratic, P < 0.05) and IgM (quadratic, P < 0.01) increased quadraticly by different levels of SPCI supplementation. Moreover, different levels of SPCI supplementation decreased the serum concentration of D-lactic acid (P < 0.01). The serum glutathione peroxidase (GSH-Px) (P < 0.01) elevated but the malondialdehyde (MDA) (P < 0.05) decreased by 100 mg/kg SPCI addition. Interestingly, SPCI supplementation at 75 ~ 100 mg/kg improved the intestinal morphology and barrier function, as suggested by enhanced villus height (P < 0.01) and villus height/crypt depth (V/C) (P < 0.01) in duodenum, as well as jejunum epithelium tight-junction protein ZO-1 (P < 0.01). Moreover, SPCI supplementation at 75 ~ 100 mg/kg increased the activity of duodenal lactase (P < 0.01), jejunal sucrase (P < 0.01) and ileal maltase (P < 0.01). Importantly, the expression levels of divalent metal transporter-1(DMT1) decreased with different levels of SPCI addition (P < 0.01). In addition, dietary SPCI supplementation at 75 mg/kg elevated the expression levels of critical functional genes such as peptide transporter-1(PePT1) (P = 0.06) and zinc transporter 1 (ZnT1) (P < 0.01) in ileum. The expression levels of sodium/glucose co-transporter-1 (SGLT1) in ileum (quadratic, P < 0.05) increased quadraticly by different levels of SPCI addition and amino acid transporter-1 (CAT1) in jejunum(P < 0.05) also increased by 100 mg/kg SPCI addition.

CONCLUSIONS

Dietary SPCI supplementation at 75 ~ 100 mg/kg improved growth performance by elevated immunity and intestinal health.

Production performance, protein digestibility, gut health and economic efficiency in sexed broilers with super dozing of lysine

Modern commercial broiler is growing very rapidly and its amino acid requirement is not fulfilling. An experimental trial was conducted to study the effect of super-dosing of lysine in fish meal-based diets (50% fish meal and 50% SBM) on production performance, protein digestibility and economic efficiency in male and female broiler chickens. Four hundred and eighty (480) one-day-old male and female broiler chicks were divided into forty experimental units of 12 birds each. Five levels of dietary lysine i.e. 90, 100, 110, 120 and 130% of Ross-308 recommendation in male and female birds were separately used. Weight gain and feed intake were higher (p < 0.05) in birds received 100 and 110% recommended lysine than other levels. Feed conversion ratio and EPEF were improved (p < 0.05) in birds received 100% recommended lysine than other levels. Higher (p < 0.05) CP digestibility and lower production cost per kg live weight were noted for birds fed diet containing lysine 100, 110 and 120% than 90 and 130%. Male birds had higher (p < 0.05) WG, FI, EPEF, protein digestibility and lower production cost per kg live weight than female birds. In conclusion, lysine levels below 100% and above 110% of Ross recommended levels had poor production performance, protein digestibility and economic efficiency.

Production performance of Giant African Land Snails (Archachatina marginata) at the Sudano-Guinean highland zone of Cameroon

A study on the production performance of Giant African Land snails was carried out within the Joint Initiative Group of Agro-pastoral Producers United Hands of Foungwo-Santchou (CIG-PAMUFOSA). The general objective of this study was to contribute to a better knowledge of the production performance of the Giant African Land Snail in captivity in Cameroon. For this purpose, the snails were monitored for two months and data on growth and reproductive performance were collected. Growth parameters were estimated from 183 snails aged between 6 and 8 months as a starting number. The results obtained show that the average daily weight gain was 0.06 ± 0.07 g and the shell length and diameter gain was 0.0019 ± 0.0077 mm/day and 0.016 ± 0.0012 mm/day, respectively. Food intake was 1.86 ± 0.17 g/day with a consumption index of 25.87 ± 2.60 and a mortality rate of 40%. Reproductive characteristics were estimated a starting number of 1095 adult snails aged between 1.5 and 2.5 years as it appears that the age at sexual maturity was greater than or equal to 11 months of age. For an average breeding weight of 93.09 ± 25.03 g, they produce clutches averaging 5.66 ± 1.80 eggs per clutch with an average weight of 8.18 ± 3.30 g. The weight of an egg was 1.44 ± 0.35 g, the individual large and small diameter of the eggs were 14.97 ± 1.45 mm and 11.28 ± 1.13 mm, respectively. The incubation period was 35.62 ± 8.16 days and hatching percentage was 76.08%. The factors influencing reproduction and growth performance of Giant African Land Snail would be: housing conditions (high density, breeding substrate), incubation condition, feed quality, and neglect. For an improvement in production performance on this farm, it would be wise to feed the animals with concentrated feed and to follow the strict standard guidelines regarding stocking density.

Deoxynivalenol damages the intestinal barrier and biota of the broiler chickens

Background

In the livestock feed industry, feed and feed raw materials are extremely susceptible to mycotoxin contamination. Deoxynivalenol (DON) is one of the main risk factors for mycotoxin contamination in broiler feed and feedstuff, however, there is still little knowledge about this. Hence, the purpose of this study was to explore the toxicity effect of DON on the intestinal barrier and the microecological balance of the biota in broiler chickens.

Results

In our present study, we compared the pathological scores of the small intestines of broilers on the 5^th, 7^th, and 10^th day, and chose the 7^th day to analyze the small intestine histomorphology, tight junctions, and cecal biota of the broilers. The results showed the damage to the small intestine worsened over time, the small intestinal villi of broilers were breakage, the tight junctions of the small intestine were destroyed, the cecal biota was unbalanced, and the growth performance of broilers was reduced on the 7^th day.

Conclusions

DON could damage the functional and structural completeness of the intestinal tract, disorder the Intestinal biota, and finally lead to declined broiler performance. Our study provided a basis for the prevention and treatment of DON in broiler production.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12917-022-03392-4.

SeMet attenuates AFB1-induced intestinal injury in rabbits by activating the Nrf2 pathway

The aim of this study was to investigate the role of selenomethionine (SeMet) in alleviating AFB1 induced intestinal injury by inhibiting intestinal oxidative stress. Forty 35-day-old rabbits were divided randomly into 4 groups (control group, AFB1 group, 0.2 mg/kg Se + AFB1 group, 0.4 mg/kg Se + AFB1 group). From the first day of the experiment, the two treatment groups were fed 0.2 mg/kg SeMet or 0.4 mg/kg SeMet daily for 21 days. On the 17th day, all rabbits in the model group and the two treatment groups were given intragastric AFB1 daily for 5 days. The ADG, ADFI and FCR of the rabbits were examined. Rabbit jejunum tissue was collected for hematoxylin- eosin staining (HE), PCNA detection, immunofluorescence and WB. Intestinal tissue IL-1β, IL-6 and TNF-α were examined by enzyme-linked immunosorbent assay (ELISA). The results showed that the production performance was decreased, the levels of ROS and MDA were increased in intestinal tissues, the activity of antioxidant enzymes was decreased and the expression levels of Nrf2 and HO-1 were decreased in AFB1-exposed rabbits. In addition, AFB1 induces an inflammatory response in the jejunum and promotes the expression of TNF-α, IL-6 and IL-1β. SeMet pretreatment significantly improved the performance of the rabbits, alleviated intestinal oxidative stress and the inflammatory response. Therefore, we confirmed that SeMet protects against AFB1 induced oxidative damage and improves productivity in rabbits by activating the Nrf2/HO-1 signaling pathway.

Characterization and mitigation option of greenhouse gas emissions from lactating Holstein dairy cows in East China

BACKGROUND

This study investigated greenhouse gas (GHG) emission characteristics of lactating Holstein dairy cows in East China and provided a basis for formulating GHG emission reduction measures. GreenFeed system was used to measure the amount of methane (CH₄) and carbon dioxide (CO₂) emitted by the cows through respiration. Data from a commercial cow farm were used to observe the effects of parity, body weight, milk yield, and milk component yield on CH₄ and CO₂ emissions.

RESULTS

Mean herd responses throughout the study were as follows: 111 cows completed all experimental processes, while 42 cows were rejected because they were sick or had not visited the GreenFeed system 20 times. On average, lactating days of cows was 138 ± 19.04 d, metabolic weight was 136.5 ± 9.5 kg, parity was 2.8 ± 1.0, dry matter intake (DMI) was 23.1 ± 2.6 kg/d, and milk yield was 38.1 ± 6.9 kg/d. The GreenFeed system revealed that CH₄ production (expressed in CO₂ equivalent, CO₂-eq) was found to be 8304 g/d, [Formula: see text]/DMI was 359 g/kg, [Formula: see text]/energy-corrected milk (ECM) was 229.5 g/kg, total CO₂ production (CH₄ production plus CO₂ production) was 19,201 g/d, total CO₂/DMI was 831 g/kg, and total CO₂/ECM was 531 g/kg. The parity and metabolic weight of cows had no significant effect on total CO₂ emissions (P > 0.05). Cows with high milk yield, milk fat yield, milk protein yield, and total milk solids yield produced more total CO₂ (P < 0.05), but their total CO₂ production per kg of ECM was low (P < 0.05). The total CO₂/ECM of the medium and high milk yield groups was 17% and 27% lower than that of the low milk yield group, respectively.

CONCLUSIONS

The parity and body condition had no effect on total CO₂ emissions, while the total CO₂/ECM was negatively correlated with milk yield, milk fat yield, milk protein yield, and total milk solids yield in lactating Holstein dairy cows. Measurement of total CO₂ emissions of dairy cows in the Chinese production system will help establish regional or national GHG inventories and develop mitigation approaches to dairy production regimes.

Effects of dietary supplementation with Ampelopsis grossedentata extract on production performance and body health of hens

To investigate the potential of Ampelopsis grossedentata extract used as a feed additive, laying performance, egg quality, yolk cholesterol, plasma biochemical parameters, intestinal histology, and gut microbiota of hens (n = 60) were determined between basal diet (CK) and dietary supplementation with A. grossedentata extract (RT) for 11 weeks. The laying rate in RT group was 6.3 percentage points higher than in CK group together with feed conversion rate decreasing. Significant upregulation of immunoglobulin indexes and downregulation of lipid-related indexes in RT group were also found in comparison with CK group, suggesting that dietary supplementation with A. grossedentata extract benefited in immunity enhancing and blood-fat depressing. Meanwhile, the villus height in duodenum and villus height to crypt depth ratio in duodenum and jejunum of RT group were significantly higher than that of CK group, indicating that dietary supplementation with A. grossedentata extract facilitated nutrient adsorption via intestinal histology changing. Moreover, the richness, diversity, and composition of gut microbiota in RT group significantly altered with a comparison of CK group, including beneficial bacterium and pathogenic bacterium, revealing that dietary supplementation with A. grossedentata extract could modify gut microbiota communities to affect intestinal adsorption and pathogen invasion. In addition, the lipid metabolism-related insulin signing pathway was significantly enriched by gut microbiota in RT group, which were conducive to egg production elevation via facilitating blood lipid amelioration and insulin resistance alleviation. These results provided a basis for A. grossedentata extract served as a feed additive in the hen industry.

Effects of a traditional Chinese medicine formula containing the Coix seed and Lotus seed on the intestinal morphology and microbiota of local piglets

A traditional Chinese medicine formula based on the Coix seed and Lotus seed has been used as a general treatment of malnutrition, excessive fatigue, dysfunction of the spleen and stomach, and disorders of water transport in humans in China. However, there is limited information on its effects on the gut microbiota of piglets in vivo. In this study, the mix of Coix seed and Lotus were added the diet of forty weaned piglets (local piglets), and then evaluated it's affected on the gut microbiota of piglets and on the relations within the gut bacterial community. The results indicated that this traditional Chinese medicine formula (LM) and the extract of the traditional Chinese medicine formula (LMT) downregulated pH of succus gastricus and raised pH of the ileum, and LMT obviously decreased the feed conversion ratio. Further study showed LMT and LM also significantly increased the thick and long of gastrointestinal villi. And then, 16S ribosomal DNA sequencing revealed that groups LMT and LM have higher relative abundance of the genus Lactobacillus in the colon, succus gastricus, and jejunum, which are beneficial bacteria sold as dietary supplements to aid digestion or to augment health. Meanwhile, the relative abundance levels of Prevotellaceae, Alloprevotella, and Prevotella in the colon and Clostridium in succus gastricus and jejunum were lower. These experiments highlight the usefulness of the traditional Chinese medicine formula based on the Coix seed and Lotus seed for decreasing pH in succus gastricus, for improving the structure of intestinal villi and gut microflora, and then for achieving improvements in pig production performance.

The incidence of necrotic enteritis in turkeys is associated with farm, season and faecal Eimeria oocyst counts

Background

Specific studies on the epidemiology of necrotic enteritis in turkeys are absent in the literature. Necrotic enteritis is common in turkeys and a leading cause of use of therapeutic antibiotics. This study describes the incidence of necrotic enteritis in turkey farms, and the association between incidence and bird age, season, faecal oocyst counts, grow-out size and feed mill.

Results

Necrotic enteritis was diagnosed post mortem in 20.2 % of 545 grow-outs of commercial female and male B.U.T. 10 turkeys started during the years 2010–2016. 80 % of all cases occurred at four to seven weeks of age. Median (minimum-maximum) age at disease detection was 37 (18–115) days. Turkey age at detection was influenced by season, and varied from 33 days among grow-outs hatched in February to 42 days among those hatched in July-August. The incidence also varied with season, showing peak occurrence among grow-outs hatched during February-March and the lowest incidence in turkeys hatched in July-August. 59 % of all cases were detected in 25 % of the farms. The incidence per farm varied from below 4 to 59 %. A multilevel mixed-effects logistic regression model indicated clear impacts of farm and season on incidence, and border-line impacts of grow-out size and feed mill. Grow-outs diagnosed with necrotic enteritis had higher counts of faecal Eimeria oocysts than grow-outs without a diagnosis. This difference was particularly clear during the high-risk period at five to seven weeks of age. Necrotic enteritis was the cause of treatment with therapeutic antibiotics in 88.2 % of all cases of treatment.

Conclusions

Our data indicate that necrotic enteritis incidence in turkeys can be substantially influenced by risk factors at farm level. The incidence showed two seasonal peaks; a moderate peak in turkeys hatched in October/November and a marked peak in turkeys hatched during February/March. Mitigation measures at the farm may therefore be of particular importance during these months in farms located in the Northern temperate zone. Measures which effectively reduce counts of faecal Eimeria oocyst are likely to be among the more promising actions to take both at the farm and at population level.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12917-021-03003-8.

Effect of chromium methionine supplementation on lactation performance, hepatic respiratory rate and anti-oxidative capacity in early-lactating dairy cows

Chromium may regulate dairy cow metabolism; a chelated formation of chromium methionine (Cr-Met) is available to the feed industry. The objective of this study was to investigate the effect of Cr-Met supplementation on lactation performance, hepatic respiratory rate and anti-oxidative capacity in early-lactating Holstein dairy cows. 64 multiparous cows were assigned to 16 blocks based on parity and milk yield and then the four cows in a block were randomly allocated to four treatment groups with 0, 4, 8 or 16 g/d of Cr-Met per cow supplemented to a basal diet. Cows were moved from an open dry lot to a naturally ventilated tie stall barn 2 weeks before treatment to adapt to this facility, fed and milked at 0630, 1400, and 1930 h every day. The experiment lasted for 12 weeks. Milk yield and composition were recorded weekly. Dry matter intake was measured every 2 weeks for a total of six times throughout the trial. The plasma variables were measured in weeks 4, 8 and 12 of the experiment. Supplementation of Cr-Met did not affect DM intake of cows. As the supplementation of Cr-Met increased, yields of milk, fat, energy corrected milk (P < 0.01) and lactose (P = 0.01) increased in a linear manner. In terms of plasma variables, insulin concentration decreased in a linear manner with Cr-Met supplementation. As for variables relating to hepatic respiration rate, concentrations of pyruvate and NAD in the plasma were increased in quadratic manners, and lactic dehydrogenase activity was linearly increased as Cr-Met feeding levels increased. Moreover, plasma glutathione peroxidase and superoxide dismutase activity were increased in a linear manner. In conclusion, our study suggested that Cr-Met supplementation improved lactation performance of early-lactating dairy cows through enhancing antioxidant capacity and hepatic cellular respiration.

Using mixed silages of sweet sorghum and alfalfa in total mixed rations to improve growth performance, nutrient digestibility, carcass traits and meat quality of sheep

Combining sweet sorghum (SS) with alfalfa for ensiling has the potential to make a high-quality silage with relatively a better nutrient balance. However, the existing data are insufficient about how changes in ratios of SS to alfalfa in different silage mixtures affect animal performance and meat quality. Therefore, the objective of this study was to determine the effect of feeding total mixed rations containing mixed silages of SS and alfalfa on growth performance, nutrient digestibility, carcass traits and meat quality of Karakul sheep. Five total mixed rations were formulated with different SS proportions at 100%, 80%, 60%, 40%, and 20% on a fresh weight basis. Thirty 4-month old male Karakul sheep with 25.5 ± 1.4 kg BW were randomly allocated into five treatment groups, each with six lambs for this experiment. The results indicated that the Karakul sheep consuming total mixed rations containing SS-Alfalfa (SS-AF) silage mixtures with a lower proportion of SS tended to increase nutrient digestibility, growth performance, carcass traits, and meat quality. Feeding diets with SS at 40% and 20% inclusion rate showed a significant linear increase in the apparent digestibility of DM, CP and NDF, as well as subcutaneous fat thickness and water holding capacity (P < 0.5). Moreover, reduction in SS inclusion rate in these diets caused significant (P < 0.05) linear and quadratic increases in DM intake, final BW, average daily gain, carcass weight, and the amino acid contents of meat (P < 0.05). Conversely, feeding diet with lower SS inclusion rate led to decrease in feed conversion ratio and shear force significantly (P < 0.05) for these sheep. It appears that 40% inclusion of SS was the optimal rate in making the SS-AF silage mixture for lambs to achieve a superior production performance and high-quality meat products in Karakul sheep. However, further research is needed to investigate the effect of feeding SS-AF silage mixtures alongside contrasting ingredients on rumen function, ruminal microorganisms and digestive enzyme activity of sheep and other ruminant animals.

Phenotypic characterisation of Meatmaster sheep using quantitative and qualitative trait analysis

A phenotypic analysis of the Meatmaster breed was done, using linear body measurements, qualitative assessment, slaughter data and pedigree performance data. The linear body measurements and pedigree performance data were collected from 187 rams and 222 ewes of all age categories. The following means were recorded in rams and ewes respectively: Body weight (kg) (80.47±13.33; 57.51±12.43), head length (cm) (23.93±1.55; 22.68±2.05), neck length (cm) (28.35±5.16; 29.61±3.82), chest girth (cm) (102.45±8.42; 92.95±8.08), tail length (cm) (38.24±4.88; 36.64±4.70), wither height (cm) (63.91±4.04; 58.99±4.86), chest depth (cm) (37.51±2.97; 34.47±2.97), chest width (cm) (23.47±2.56; 21.24±2.85), body length (cm) (78.95±5.59; 72.67±6.06), rump length (cm) (21.82±3.29; 20.77±1.93), rump width (cm) (23.87±2.82; 21.36±3.15), skin thickness (mm) (2.846±0.5; 2.805±0.5), pelvic length (cm) (7.66±.98), pelvic width (cm) (7.66±.90), pelvic area (cm²) (46.69±10.62) and scrotal circumference (cm) (35.12±3.03). The pedigree performance data of 177 ewes showed the following means: age at first lambing (15.242±3.8 months), number of times lambed (3.33±1.8), number of lambs born (4.36±3.4), number of lambs weaned (3.44±2.5) and average inter-lambing period (258.64±151.3 days). Slaughter data was compiled from 2251 animals of different genders and ages; the means are as follows: measured in (kg): A-grade carcass (16.77±4.1), AB-grade carcass (24.039±13.8), B-grade carcass (26.904±13.3) and C-grade carcass (24.88±4.9). A predictive value of R²= 0.140 was observed between wither height and average inter-lambing period as well as a R²= 0.154 between the wither height and number of lambs born. This seems to be a characteristic of the Afro-type breeds which have a higher wither height and also have a higher tendency to birth multiple lambs per lambing opportunity.

Phenolic compounds as natural feed additives in poultry and swine diets: a review

Due to ban on using antibiotics in feed industry, awareness of using natural feed additives have led to a great demand. The interest of plants phenolic compounds as a potential natural antioxidant source has been considered in research community due to their predictable potential role as feed additives in poultry and swine production. However, the mode of action for their functional role and dosage recommendation in animal diets are still remain indistinct. Taking into account, the present review study highlights an outline about the mode of action of phenolic compound and their experimental uses in poultry and swine focusing on the growth performance, antioxidant function, immune function, antimicrobial role and overall health status, justified with the past findings till to date. Finally, the present review study concluded that supplementation of phenolic compounds as natural feed additives may have a role on the antioxidant, immunity, antimicrobial and overall production performance in poultry and swine.

Dietary soluble non-starch polysaccharide level and xylanase supplementation influence performance, egg quality and nutrient utilization in laying hens fed wheat-based diets

The aim of this study was to evaluate the effects of dietary soluble non-starch polysaccharide (sNSP) content and xylanase supplementation on production performance, egg quality parameters, and nutrient digestibility in Hy-line Brown layers from 25 to 32 wk of age. A total of 144 Hy-line Brown laying hens (25 wk of age) were randomly allocated to 1 of 4 wheat-based dietary treatments in a 2 × 2 factorial experimental design, with 36 replicates of individual hens per treatment. The diets were formulated to contain either a high or low sNSP level (at 13.3 or 10.8 g/kg) and were supplemented with either 0 or 12,000 BXU/kg exogenous xylanase. Birds were fed these treatment diets for an 8-wk period, and hen production performance, including daily egg production, average egg weight, daily egg mass, feed conversion ratio and proportion of dirty and abnormal eggs were measured at bird age 25 to 28 wk and 29 to 32 wk. An interaction between sNSP content of the diet and xylanase supplementation was observed on daily egg production from 25 to 28 wk of age (P = 0.018); birds fed the high sNSP diet without xylanase had lower egg production than those fed any other treatment. An interaction between the 2 dietary factors was also observed on hen weight gain at 29 to 32 wk of age (P = 0.014), with birds fed the low sNSP diet with 12,000 BXU/kg xylanase presenting greater weight gain compared to those fed the high sNSP diet with 12,000 BXU/kg xylanase. Feed intake at 29 to 32 wk of age was reduced by xylanase supplementation (P = 0.047). Xylanase supplementation also increased yolk colour score at both 28 and 32 wk of age, and decreased yolk weight at 32 wk of age (P = 0.014, 0.037 and 0.013, respectively). Birds fed the low sNSP diet presented lower protein digestibility (P = 0.024) than those fed the high sNSP diet. Additionally, birds fed high sNSP presented higher shell reflectivity at both 28 and 32 wk of age (P = 0.05 and 0.036, respectively). The influence of duration of feeding the treatment diets on egg quality was also determined. It was observed that egg weight, yolk weight and yolk colour score consistently increased over time, regardless of experimental treatment effects. In contrast, Haugh Unit and albumen height significantly decreased throughout the study period in all treatments, although this was less pronounced in hens fed the treatment with high sNSP and no supplemental xylanase. A reduction in shell breaking strength over time was observed only in hens fed the treatments without xylanase addition, and shell thickness was improved over time only in birds fed the low sNSP diet with xylanase. The impacts of the dietary treatments were largely inconsistent in this study, so a solid conclusion cannot be drawn. However, these findings do indicate that dietary NSP level influences layer production performance, and thus should be considered when formulating laying hen diets. It also proved that further research is warranted into how to optimize the benefits of xylanase application in laying hens.

Influence of a raised slatted area in front of the nest on leg health, mating behaviour and floor eggs in broiler breeders

European farms for broiler breeders often have raised slatted areas in front of the nests, but in other regions of the world no raised slatted areas are provided. This study aimed to investigate the effects of a raised slatted area on leg health, mating behaviour and floor laying behaviour. Ten groups of 33 broiler breeder hens and three males were housed in two pen types: with or without a raised slatted area in front of the nests. Each pen had one plastic and one wooden nest. Between 25 and 31 weeks of age, ten marked hens per pen were weighed and assessed weekly on foot pad dermatitis, hock burn and wounds. At the end of week 31, animals were euthanized and bone strength of the tibia and humerus of these individuals was assessed. At 24, 27 and 30 weeks of age, mating behaviour was observed for an hour per pen, noting both numbers of successful and unsuccessful copulations. The number of eggs laid in the nests and on the floor was recorded daily between 20 and 31 weeks of age. Foot pad dermatitis scores were affected by age, but not by pen type. Generally, there were only minor issues with foot pad dermatitis (scores <11 on a 0-100 scale), probably due to the young age of the hens. Body weight was not affected by pen type, while the prevalence of hock burns was too low to analyse and no difference in bone strength was found for the tibia and the humerus. Overall, mating behaviour was less frequent in pens with raised slats than in pens without raised slats (29 ± 2 vs 35 ± 3 times/h) and more frequent at 27 weeks of age than at 24 and 30 weeks of age (38 ± 1 vs 31 ± 4 and 27 ± 2 times/h). The pens with raised slats had a lower percentage of floor eggs than pens without raised slats (11.2 ± 0.4 vs 19.3 ± 0.5%). The wooden nest was preferred over the plastic nest as on average 63% of the eggs were laid in the wooden nest. This study shows that providing raised slats decreases mating behaviour and percentage of floor eggs, although its effects on leg health remain inconclusive.

Effect of Bacillus velezensis to substitute in-feed antibiotics on the production, blood biochemistry and egg quality indices of laying hens

BACKGROUND

The excessive use of antibiotics in the livestock feed industry caused inevitable side effects of microbial resistance. Besides this residual antibiotics in animal-derived foodstuff imposed serious health problems for humans. So this study aimed to investigate the potential use of Bacillus velezensis to substitute antibiotics for poultry production. A total of 468, 49-week-old Hy-Line Brown chickens, were randomly divided into four groups the control group (regular diet), experiment group I (0.1% B. veleznesis), experiment group II (0.2% B. veleznesis), and antibiotic group (50 mg/kg flavomycin), with three replicates per group and trial period consisted on 42 days.

RESULTS

The results showed that, compared with the control group, the average egg production rate and daily feed intake of experimental groups I and II increased significantly (P < 0.05), while the average egg weight was increased in experimental group II as compared to (I) (P < 0.01). The feed conversion ratio was decreased (P > 0.05) in group (II) Egg quality parameters such as yolk weight of the experimental group II was increased, but that of the antibiotic group and experiment group I was decreased, neither significant (P > 0.05). Moreover, the eggshell strength, yolk color, albumen height, and Haugh unit were significantly increased (P < 0.05). Compared with the control group, probiotic groups can increase the progesterone and motilin (P > 0.05) but decrease the secretin and cholecystokinin in the blood plasma (P > 0.05).

CONCLUSIONS

This study suggested that B. velezensis can substitute in-feed-antibiotics and improved most of the study parameters significantly. Which suggested that B. velezensis has potential future application value to replace the feed antibiotics.

Effects of dietary cadmium supplementation on production performance, cadmium residue in eggs, and hepatic damage in laying hens

This study was conducted to investigate the adverse effects of cadmium (Cd) on the production performance, serum biochemistry, liver antioxidant status, histopathology, and egg residue in laying hens. A total of 72 healthy Hy-Line brown laying hens at 40-week-old were randomly assigned to four diets containing 0 (control diet), 15, 30, or 60 mg/kg Cd for 6 weeks. Laying hens exposed to 60 mg/kg Cd had lower egg production rate and worse feed to egg ratio (P < 0.05). Dietary Cd exposure (≥ 15 mg/kg) significantly decreased hepatic glutathione peroxide (GPX) activities, while increasing malondialdehyde (MDA) (P < 0.05). Hepatic histopathology and ultrastructure also showed damage and the symptoms were exacerbated in a dose-dependent manner. The residue of Cd in the yolk was increased with increasing dietary Cd concentration. The mRNA expression levels of mt4L, mt3, sod1, sod2, gpx1, gpx3, and gpx4 in the liver of laying hens exposed to 60 mg Cd/kg feed were significantly decreased (P < 0.05). In conclusion, dietary Cd exposure at ≥ 15 mg/kg induced hepatic damage in laying hens, indicating that the content of Cd in feed must be critically controlled.

Production analysis of broiler farming in central Punjab, Pakistan

This study examined the analysis of personal and production performance of broiler farming in 10 cities of central Punjab (Lahore, Sheikhupura, Kasur, Okara, Sargodha, Sahiwal, Gujranwala, Gujrat, Nankana, and Kamalia) of Pakistan. These districts are densely populated and renowned for broiler production. Primary data were collected through a survey of 100 poultry farmers. Personal and production information were collected from the respondents. Descriptive statistics was employed in the form of averages and percentages. The comparison among different districts was made through one-way ANOVA technique followed by Tukey's HSD test. Parameters were observed significantly in experience of farmer, age, number of sheds, capacity of farm, and flock/annuum during the survey of Gujranwala and Kasur, while the high percentage of graduate farmers was observed in Lahore and Sheikhupura regions. Significant results were observed during the production performance feed efficiency and mortality in Okara and Kasur as well as maximum administration of both live and killed vaccine in Lahore through drinking water in Nankana. In the districts of Sheikhupura and Kamalia, farmers due to lake of education left their dead birds on the surface ground. In conclusion, this study pointed out the exact trend of modern broiler farming and its price fluctuation in Punjab (Pakistan) as well as the reason behind the losses to the farmers.

Effects of long-chain fatty acid supplementation on the growth performance of grower and finisher pigs: a meta-analysis

Background

Supplementation of feed with long-chain fatty acids (LCFAs) during the grower and finisher phases has long been discussed as a growth promotion strategy in pigs, but its effects are inconsistent. The purpose of our study was to comprehensively evaluate its effects on the growth performance based on the average daily gain (ADG), average daily feed intake (ADFI) and gain: feed (G:F) ratio and to unveil the roles of the basal diet, LCFA concentration and LCFA saturation.

Results

We searched the PubMed and Web of Science databases (articles published from Jan 1^st, 2000, to Sep 30^th, 2018; restricted to English) and compared LCFA-supplemented diets with control diets. We retrieved 2346 studies, 18 of which (1314 pigs, 26 records) were eligible for our analysis. We used a random-effects model to calculate the weighted mean differences (WMDs) and 95% confidence intervals (CIs). LCFA supplementation in the grower-finisher phase improved the ADG (WMD = 41.74 g/d, 95% CI: 8.81 to 74.66, P = 0.013) and G:F ratio (WMD = 0.019, 95% CI: 0.006 to 0.032, P = 0.003). For supplementation solely in the finisher phase, we found a similar performance in the ADG (WMD = 39.93 g/d, 95% CI: 26.48 to 53.38, P < 0.001) and G:F ratio (WMD = 0.019, 95% CI: 0.006 to 0.032, P < 0.001) but a reduction in the ADFI (WMD = − 83.863 g/d, 95% CI: − 156.157 to − 11.569, P = 0.023). Specifically, approximately 5% LCFA supplementation in the finisher phase had significant effects on the ADG (WMD = 51.385 g/d, 95% CI: 35.816 to 66.954, P < 0.001), ADFI (WMD = − 102.869 g/d, 95% CI: − 189.236 to − 16.502, P = 0.02) and G:F ratio (WMD = 0.028, 95% CI: 0.018 to 0.039, P < 0.001), whereas a concentration of approximately 1% exhibited no effects.

Conclusions

Overall, regardless of the basal diet and saturation, LCFA supplementation greatly improves the growth performance of grower and finisher pigs, primarily by increasing the energy density.

The effect of ginger powder and Chinese herbal medicine on production performance, serum metabolites and antioxidant status of laying hens under heat-stress condition

This study was done to evaluate the effects of Chinese herbal medicine (CHM) and ginger powder on layers-production performance, serum metabolites and antioxidant status under heat stress condition. Two hundred and fifty Lohmann layers were randomly divided into 5 different, including two controls and three experimental groups (H1, H2, and H3). Control groups were fed the basic diet without supplementation, while, the feed of three experimental groups was supplemented with 3.32 g CHM, 10 g ginger powder, and 10 g ginger powder+ 3.32 g CHM per kg of diet, respectively. Results showed that feed consumption and production rate were decreased in the HC group, while, feed intake and production significantly improved when birds were given supplemented diet. The production rate and feed intake of the H3 group were even significantly higher than the NC group. The birds that received supplemented diet had higher glucose level compared to HC. Triglycerides and serum cholesterol had significantly decreased level in supplemented groups compared to HC. Fungal catalase (CAT) level was significantly improved in H2 and H3 groups. Nitric oxide (NO), glutathione peroxidase (GSH-PX) and Total Protein (T-AOC) level were significantly improved in supplemented groups. Findings showed that ginger powder and CHM could be a viable alternative to the synthetic antibiotic in poultry feed.

Performance, feed utilization, and hepatic metabolic response of weaned juvenile Atlantic bluefin tuna (Thunnus thynnus L.): effects of dietary lipid level and source

Two trials were performed using extruded diets as on-growing feeds for weaned Atlantic bluefin tuna (Thunnus thynnus; ABT) to establish adequate dietary levels of both lipid and omega-3 long-chain polyunsaturated fatty acids (LC-PUFAs), and impacts on lipid metabolism via liver gene expression. In trial A, ABT were fed with either a commercial feed (Magokoro®; MGK) as a reference diet or two experimental feeds differing in lipid levels (15 or 20%) using krill oil (KO) as the single lipid source in order to estimate suitable lipid content. Fish fed MGK displayed the highest growth, followed by 15KO, and therefore a dietary lipid content of 15% was considered preferable to 20% at this stage. In trial B, fish were fed MGK, 15KO, or a feed containing 15% lipid with a blend of KO and rapeseed oil (RO) (1:1, v/v; 15KORO). Fish fed 15KO and 15KORO showed no difference in weight gain, specific growth rate, and fork length. Increasing dietary lipid level or including vegetable oil, RO, in the feeds did not increase liver lipid content. Liver fatty acid compositions largely reflected dietary profiles confirming very limited endogenous LC-PUFA biosynthesis. Liver of ABT fed 15KO and 20KO displayed the highest contents of docosahexaenoic acid (DHA). The hepatic expression of genes encoding enzymes and transcription factors involved in lipid and fatty acid metabolism, as well as genes encoding antioxidant enzymes, showed that many of these genes were regulated by dietary lipid and LC-PUFA content. Results suggested that ABT juveniles can be on-grown on inert dry feeds that support good fish growth and the accumulation of DHA.

Dietary effects of commercial probiotics on growth performance, digestibility, and intestinal morphometry of broiler chickens

This study compared five commercially available probiotics vis-à-vis antibiotic growth promotant (AGP) supplementation and absence of feed additive based on efficiency, intestinal morphometry, and energy digestibility in improving broiler chicken production. A total of 630 straight run (Cobb) day-old broiler chicks were distributed to seven treatments following a completely randomized design, with ten replicates per treatment and nine birds per replicate per cage. Dietary treatments consisted of basal diet in combination with the following: without probiotics and AGP supplementation (treatment 1); 75 ppm each of chlorotetracycline (CTC) and Zn bacitracin (treatment 2); probiotic A, Bacillus subtilis (treatment 3); probiotic B, Bacillus subtilis (treatment 4); probiotic C, Enterococcus faecium (treatment 5); and probiotic D, Bacillus subtilis (treatment 6); probiotic E, Enterococcus faecium, Bifidobacterium spp., Pediococcus spp., and Lactobacillus spp. (treatment 7). At day 42, energy digestibility was determined by fasting three randomly selected birds from each treatment for 12 h and then subjecting them to their corresponding dietary treatments. Excreta were collected and pooled after 24 h of feeding. Pooled excreta were weighed, oven-dried, and subjected to energy analyses after 3-day collection. Apparent total tract metabolizable energy was then computed. At day 47, three birds were randomly selected per treatment for intestinal morphometry (villi height and crypt depth) of the duodenum, jejunum, and ileum. Dietary supplementation using probiotics showed no significant effect on overall body weight, weight gain, feed consumption, feed efficiency, dressing percentage, mortality, harvest recovery, carcass quality parameters (e.g., meat to bone ratio and abdominal fat content), intestinal morphometry, and energy digestibility. Birds under treatment 7 (basal feed + probiotic E) generated the highest income over feed and chick cost.

Interferon-γ acts as a regulator in the trade-off between phagocytosis and production performance in dwarf chickens

Background

Interferon-γ (IFN-γ) is critical for innate and adaptive immunity against viral and bacterial infections. IFN-γ reportedly affects the phagocytic ability of monocytes and macrophages as well as regulates pituitary function in humans and mice. The present study analyzed the impact of IFN-γ on monocyte and macrophage phagocytosis, production performance, and pituitary function in vivo and in vitro (in dwarf chickens). IFN-γ was injected into dwarf chickens through a vein, and then, the laying rate, average egg weight, and levels of follicle-stimulating hormone (FSH) and IFN-γ were measured in treatment and control groups. For the in vitro experiment, the pituitary tissues were supplemented with IFN-γ, and the mRNA expression levels of follicle-stimulating hormone beta subunit (FSH-β), interferon gamma receptor 1 (IFNGR1), and interferon gamma receptor 2 (IFNGR2) in the pituitary were assessed.

Results

Monocyte and macrophage phagocytosis product (PP) was decreased by IFN-γ treatment in a dose-dependent manner in vitro. In the in vivo experiment, the level of IFN-γ in the treatment group was higher than that in the control group at 7 d (P < 0.05), 14 d (P < 0.01), and 21 d (P < 0.01) post-injection. Compared with the control group, monocyte and macrophage PP was lower in the treatment group after injection (P < 0.01). The laying rate was higher in the treatment group than in the control group at 2 and 3 wk post-injection (P < 0.05). There was a significant difference between the treatment and control groups in the levels of FSH at 1, 3, 7, and 14 d post-injection (P < 0.01). In the in vitro experiment, increased mRNA expression levels of FSH-β, IFNGR1, and IFNGR2 were observed in the treatment group after stimulation with 100 U/mL IFN-γ for 24 h compared to those in the control group (P < 0.05).

Conclusions

IFN-γ inhibited the phagocytosis of monocytes and macrophages; up-regulated the mRNA expression levels of the FSH-β, IFNGR1, and IFNGR2; enhanced the secretion of FSH; and improved the laying rate. IFN-γ might be an important regulator in the trade-off between the immune effect and production performance in dwarf chickens.

Depression of leukocyte protein synthesis, immune function and growth performance induced by high environmental temperature in broiler chickens

In tropical and semitropical regions, raising broiler chickens out of their thermal comfort zone can cause an added economic loss in the poultry industry. The cause for the deleterious effects on immunity and growth performance of broilers under high environmental temperatures is still poorly understood. Therefore, the aim of the current investigation was to evaluate the effect of heat stress on leukocytes protein synthesis and immune function as a possible direct cause of low performance in broiler chickens under such condition. In this study, 300 one-day-old male broiler chicks (Cobb500™) were randomly assigned into 2 groups with 5 replicates of 30 chicks each. From 21 to 42 days of age, one group was exposed to non-stressed condition at 24 °C and 50% relative humidity (control group), while the other group was exposed to heat stress at 35 °C and 50% relative humidity (HS group). At 42 days of age, blood samples were collected from each group to evaluate stress indicators, immune function, and leukocytes protein synthesis. Production performance was also recorded. Noteworthy, protein synthesis in leukocytes was significantly (P < 0.05) inhibited in HS group by 38% compared to control group. In contrast, the phosphorylation level on threonine 56 site (Thr⁵⁶) of eukaryotic elongation factor (eEF2), which indicates the suppression of protein translation process through altering the protein elongation phase, was significantly threefold higher in HS group than in control (P < 0.05). In addition, an increase in stress indicators was markedly (P < 0.05) presented in the HS birds by twofold increase in heterophil/lymphocyte (H/L) ratio and threefold increase in plasma corticosterone level compared to control. Furthermore, the immune function was significantly (P < 0.05) suppressed in HS birds than control (0.99 vs. 1.88 mg/mL plasma IgG, 89.2 vs. 148.0 μg/mL plasma IgM, 4.80 vs. 7.20 antibody titer against SRBC, and 1.38 vs. 3.39 stimulation index of lymphocyte proliferation in HS vs. control group, respectively). Moreover, results on the broiler performance indicate that HS birds had a significant (P < 0.05) lower body weight gain by 58%, lower feed consumption by 39%, higher conversion ratio by 27%, and higher mortality by more than three times, compared to control birds. In conclusion, our results demonstrate that the inhibition of leukocyte protein synthesis through increasing the level of eEF2 Thr⁵⁶ phosphorylation may play a key role in the observed decrease in immune function and growth performance with the high mortality rate encountered in broiler chickens under heat stress environment.

Effects of pantothenic acid on growth performance, slaughter performance, lipid metabolism, and antioxidant function of Wulong geese aged one to four weeks

This experiment was conducted to study the effects of pantothenic acid on the growth performance, slaughter performance, lipid metabolism, and antioxidant function of one-to four-week-old Wulong geese and determine the appropriate supplemental level of pantothenic acid. A total of 360 one-day-old Wulong geese were randomly divided into 6 groups with 6 replicates per group and 10 geese (5 males and 5 females) per replicate. The geese in group Ⅰ (control group) were fed a basal diet, and the geese in groups Ⅱ to Ⅵ (experimental groups) were given the basal diet supplemented with 8, 15, 30, 60, and 120 mg/kg pantothenic acid, respectively. The experiment lasted for 4 weeks. Based on the results of unrelated comparative analysis, the body weight was the highest when the dietary pantothenic acid level was 27.57 mg/kg. When the dietary pantothenic acid level was 26.17 mg/kg, the average daily gain peaked. When the dietary pantothenic acid level was 15.50 mg/kg, the feed:gain ratio was the lowest. The percentage of abdominal fat in groups Ⅲ and Ⅳ was significantly lower than that in group Ⅰ (P < 0.05). The content of total cholesterol in serum in groups Ⅲ to Ⅴ was significantly lower than that in group Ⅰ (P < 0.05). The triglyceride content in groups Ⅲ and Ⅳ was significantly lower than that in group Ⅰ (P < 0.01). The high-density lipoprotein–cholesterol content in group Ⅳ was significantly higher than that in group Ⅰ (P < 0.05). The total antioxidant capacity of serum and liver in group Ⅳ was significantly higher than that in group Ⅰ (P < 0.05). The malondialdehyde content in the liver in groups Ⅲ and Ⅳ was significantly lower than that in group Ⅰ (P < 0.05). Glutathione peroxidase activity in the serum in group Ⅳ was significantly higher than that in group Ⅰ (P < 0.05). Glutathione peroxidase activity in the liver in groups Ⅳ and Ⅴ was significantly higher than that in group Ⅰ (P < 0.01). The addition of pantothenic acid in the diet of one-to four-week-old Wulong geese significantly affected the growth performance, slaughter performance, lipid metabolism, and antioxidant function of the geese. In terms of economic benefits, the optimal supplemental level of pantothenic acid in one-to four-week-old geese was 15.50 mg/kg.