An experiment was conducted to evaluate the effect of litter thickness on growth performance, immune status, environmental condition, and welfare quality in yellow broilers. In total, 1,800 one-day-old Suqin yellow broilers were raised for 21 d. On d 22, 1,600 birds of similar BW (404 ± 12 g) were randomly selected and placed into 20 indoor pens (8 birds/m², 10 m²/pen). These birds were assigned to a litter treatment of 4, 8, 12, and 16 cm. Each treatment was repeated in five pens. The results showed that a thicker litter was related to increased BW, daily weight gain, and daily feed intake (P < 0.001). Feed conversion ratio and mortality were unaffected by litter thickness (P = 0.320, P = 0.353, respectively). Absolute and relative liver weights showed a significant linear response to increasing litter thickness (P = 0.01, P = 0.001, respectively). The litter moisture content, air ammonia, and CO₂ content decreased, whereas the air dust content increased with increasing litter thickness (P < 0.001, P = 0.017, P = 0.033, P < 0.001, respectively). Litter thickness had no effect on gait, plumage damage, hock burn or breast skin crusting (P = 0.076, P = 0.964, P = 0.131, P = 0.401, respectively). Plumage cleanliness, foot pad dermatitis, hock swelling and breast blister varied significantly with litter thickness (P = 0.027, P = 0.011, P = 0.014, P = 0.042, respectively). The results of this study suggest that an increasing litter thickness has a beneficial effect on the growth performance, environmental condition and welfare of birds.

Original Article A deep learning model based on the attention mechanism for automatic segmentation of abdominal muscle and fat for body composition assessment Hao Shen, Pin He, Ya Ren, Zhengyong Huang, Shuluan Li, Guoshuai Wang, Minghua Cong, Dehong Luo, Dan Shao, Elaine Yuen-Phin Lee, Ruixue Cui, Li Huo, Jing Qin, Jun Liu, Zhanli Hu, Zhou Liu, Na Zhang

Chicken is a valuable model for understanding fundamental biology, vertebrate evolution and diseases, as well as a major source of nutrient-dense and lean-protein-enriched food globally. Although it is the first non-mammalian amniote genome to be sequenced, the chicken genome still lacks a systematic characterization of functional impacts of genetic variants. Here, through integrating 7,015 RNA-Seq and 2,869 whole-genome sequence data, the Chicken Genotype- Tissue Expression (ChickenGTEx) project presents the pilot reference of regulatory variants in 28 chicken tissue transcriptomes, including millions of regulatory effects on primary expression (including protein-coding genes, lncRNA and exon) and post-transcriptional modifications (alternative splicing and 3’ untranslated region alternative polyadenylation). We explored the tissue-sharing and context-specificity of these regulatory variants, their underlying molecular mechanisms of action, and their utility in interpreting adaptation and genome-wide associations of 108 chicken complex traits. Finally, we illustrated shared and lineage-specific features of gene regulation between chickens and mammals, and demonstrated how the ChickenGTEx resource can further assist with translating genetic findings across species. One-Sentence Summary: The ChickenGTEx provides a multi-tissue reference of regulatory variants for chicken genetics and genomics, functional genomics, precision breeding, veterinary medicine, vertebrate evolution and even human biomedicine.

An experiment was conducted to evaluate the effects of cyclic heat stress on phenotypic response, meat quality and muscle glycolysis of broiler. One hundred and eighty 35-day-old male Xueshan broilers with similar BW were randomly selected and exposed to either thermal neutral (TN; 23 °C, 55–60% RH, n = 6) or heat stress conditions (CHS; cyclic temperatures of 35 °C from 10:00 to 18:00, 32 °C from 18:00 to 20:00, 28 °C from 20:00 to 08:00, and 32 °C from 08:00 to 10:00 at 40–45% RH, n = 6) for 7 days. Relative to broilers under thermoneutral conditions, broilers subjected to cyclic heat stress had an overall increase in rectal temperature and respiration rate (p < .001, p < .001, respectively), and a reduced body weight, average daily gain, average feed intake and feed conversion ratio (p = .001, p < .001, p < .001, p = .002, respectively). A higher L* value was obtained from both the breast and thigh muscle of broilers under high temperatures (p = .022 and p = .009, respectively). Furthermore, the thigh muscle of broilers exposed to high temperatures showed a higher hexokinase activity than that of broilers exposed to thermal neutral conditions (p = .014). The results indicate that cyclic heat stress significantly lowers Xueshan broiler production performance and meat quality but has no significant effect on the chemical composition and glycolytic process of the meat.

The present study evaluated the effects of 3 supplemental levels of dietary genistein ingested during the late laying period (66-73 wk) of laying hens. A total of 384 Hy-Line brown hens (66 wk old) were randomly divided into 4 groups (6 replicates of 16 hens in each group), the basal diet group (CON), and groups for the basal diet supplemented with 80, 120, and 400 mg/kg of genistein, G1, G2, and G3, respectively. The results of the present study showed an increased laying rate in groups G2 and G3 (linear, P < 0.01), and decreased feed-egg ratios (linear, P < 0.05) and broken egg rate (P < 0.01) in all genistein-treated groups compared with the CON group. Moreover, the G2 group showed an increase in eggshell strength and ratio (linear, P < 0.05), whereas all genistein-treated groups saw a decrease in the L* value (linear, P < 0.01) and an increase in the a* value (linear, P < 0.05) compared with the CON group. Additionally, all genistein-treated groups had an increase in the total antioxidant capacity of plasma (linear, P < 0.05), along with reduced plasma, ovarian, and yolk malondialdehyde levels (linear, P < 0.05), compared with the CON group. The G2 group had an increase in both the superoxide dismutase activity of plasma (P < 0.01) and the total antioxidant capacity of the ovaries (linear, P < 0.05), compared with the CON group. The G3 group had an increase in both the glutathione peroxidase concentration of plasma (linear, P < 0.05) and the total antioxidant capacity of the ovaries (linear, P < 0.01), compared with the CON group. The transcript levels of nuclear factor erythroid 2-related factor 2, superoxide dismutase 1, and catalase were increased in all of the genistein-treated groups (P < 0.05) compared with the CON group, whereas heme oxygenase 1 and glutamate-cysteine ligase modifier subunit were increased only in the G2 group (P < 0.05). In conclusion, supplementation with 120 mg/kg dietary genistein had the best effect on improving the laying rate, eggshell quality, and antioxidant capacity in Hy-Line brown hens during the late laying period.

This study aimed to determine the effects of feeding patterns and dietary available phosphorus levels on laying performance, eggshell quality, calcium, and phosphorus metabolism in aged laying hens. The experiment followed a 3 × 2 factorial arrangement of three feeding patterns (feeding twice a day, 1/2 daily feeding at 8:00, and 1/2 daily feeding at 14:00; disequilibrium feeding twice a day, 1/3 daily feeding at 8:00, and 2/3 daily feeding at 14:00; feeding thrice a day, 1/3 daily feeding at 8:00, 1/3 daily feeding at 14:00, and 1/3 daily feeding at 18:00) and two available phosphorus levels (0.32 %, 0.27 %) was carried out with a total of 528 Hy-Line Brown laying hens aged 62-74 weeks. Each group had 8 replicates of 11 hens. The results revealed that feeding patterns and phosphorus levels significantly interacted with egg production ratios, soft shell and broken egg ratios in weeks 9-12 (P < 0.05). Feeding thrice a day and disequilibrium feeding twice a day significantly improved the equatorial and average eggshell thickness (P < 0.05), and had a trend of increasing eggshell strength at week 12 (P= 0.068). They also significantly increased the effective layer thickness and the calcified layer thickness of the eggshell (P < 0.05). Additionally, feeding thrice a day significantly increased serum calcium content compared with feeding twice a day (P < 0.05), and feeding thrice a day significantly increased the calcium content of the eggshell, mRNA expression level of CaBP-D28k in the uterine compared with the other two feeding patterns (P < 0.05). While disequilibrium feeding twice a day resulted in higher phosphorus content in the excreta compared with the other two feeding patterns (P < 0.05). These results indicated that feeding hens thrice a day with 0.27 % dietary available phosphorus level might improve in laying performance and eggshell quality of aged laying hens.