Heat stress has a profound effect on poultry health and productivity. The present study evaluated whether feeding betaine could ameliorate long-term heat stress-induced impairment of productive performance in indigenous yellow-feathered broilers. A total of 240 five-week-old male broilers were randomly allocated to five treatments with six replicates of eight broilers each. The five treatments included a thermoneutral zone control group (TN, fed basal diet), a heat stress control group (HS, fed basal diet), and an HS control group supplemented 500, 1000, 2000 mg/kg betaine, respectively. The TN group was raised at 26 ± 1 °C during the whole study, HS groups exposed to 32 ± 1 °C for 8 h/day from 9:00 am to 17:00 pm. The results showed that heat stress decreased the body weight gain (BWG) and feed intake of broilers during 1–5, 6–10, and 1–10 weeks (p < 0.05). Dietary betaine tended to improve the BWG and feed intake of broilers under 5 weeks of heat stress (linear, p < 0.10), and betaine supplementation linearly increased the BWG and feed intake during 6–10 and 1–10 weeks (p < 0.05). Additionally, nitrogen retention was reduced by 5 weeks and 10 weeks of heat stress (p < 0.05), whereas dietary betaine could improve nitrogen retention in heat stressed broilers after both 5 and 10 weeks of heat stress (linear, p < 0.05). Moreover, this study observed that the trypsin activity of jejunum was decreased by 5 weeks of heat stress (p < 0.05), whereas betaine supplementation had quadratic effects on trypsin activity of jejunum in heat stressed broilers (p < 0.05). Furthermore, 10 weeks of heat stress induced a reduction of villus height of the duodenum and jejunum (p < 0.05), and decreased the villus height to crypt depth ratio of the jejunum (p < 0.05). Supplementation with betaine ameliorated the adverse effects of heat stress on these parameters (p < 0.05). Compared with the TN group, 10 weeks of heat stress reduced carcass and breast yield (p < 0.05) and betaine supplementation improved carcass and breast yield of heat stressed broilers (linear, p < 0.05). In conclusion, dietary supplementation of betaine could reduce the detrimental effects of long-term heat stress on growth performance, digestive function, and carcass traits in indigenous yellow-feathered broilers.

This study aimed to investigate the protective effects of dietary algae-derived polysaccharides (ADP) from Enteromorpha prolifera against heat stress (HS)-induced bursa of Fabricius injure in broilers, and to elucidate the molecular mechanisms underlying the protective effect. A total of 144 8-week-old male yellow-feathered broilers were randomly allocated into 3 treatments of 6 replicates each (8 broilers per replicate): thermoneutral zone group (TN, fed basal diet); heat stress group (HS, fed basal diet); heat stress + ADP group (HSA, basal diet supplemented with 1,000 mg/kg ADP). Broilers in TN group were raised at 23.6 ± 1.8°C during the whole study. Broilers in HS and HSA groups were exposed to 33.2 ± 1.5°C for 10 h/day. The experimental period lasted for four weeks. The results showed that HS and dietary ADP had no significant effects on bursa of Fabricius index (P > 0.05). HS exposure increased the apoptosis rate of bursa of Fabricius (P < 0.05), and the apoptosis rate was reduced by dietary ADP (P < 0.05). Besides, broilers in HS and HSA groups had a lower glutathione-S transferase (GST) activity and total anti-oxidation capacity (T-AOC), whereas had a higher malondialdehyde (MDA) levels of bursa of Fabricius than those in TN group (P < 0.05). HS exposure elevated the concentration of tumor necrosis factor-α (TNF-α), interleukin (IL)-1β, IL-4, and IL-6, while decreased the concentration of interferon-γ (INF-γ) and IL-2 (P < 0.05), and dietary inclusion of ADP reduced the IL-1β level and increased the IL-2 level of bursa of Fabricius (P < 0.05). Compared with TN group, broilers in HS and HSA groups had lower relative mRNA expression of nuclear factor erythroid 2-related factor 2 (Nrf2), heme oxygenase-1 (HO-1) and GSTT1 in bursa of Fabricius (P < 0.05). Additionally, HS exposure down-regulated the mRNA expression of inhibitor kappa B alpha (IκBα), IFN-γ, and IL-2, while up-regulated the mRNA expression of nuclear factor-kappa B (NF-κB) p65, TNF-α, IL-1β, and IL-6 in bursa of Fabricius (P < 0.05). However, dietary inclusion of ADP up-regulated the mRNA expression of IκBα and down-regulated the mRNA expression of NF-κB p65, TNF-α, and IL-6 in bursa of Fabricius (P < 0.05). Furthermore, HS exposure increased the relative protein expression levels of total and nuclear NF-κB p65 (P < 0.05), but dietary ADP supplementation reduced the relative protein expression levels of total and nuclear NF-κB p65 in bursa of Fabricius (P < 0.05). Collectively, dietary ADP ameliorated the impairment of histology, cell apoptosis and immune balance in bursa of Fabricius of heat stressed broilers, which is involved in modulation of NF-κB signaling pathway.

The purpose of this study was to evaluate the effects of chitosan oligosaccharides (COS) on intestinal permeability, morphology, antioxidant status, and inflammatory response in heat-stressed broilers. A total of 108 thirty-five-day-old Chinese yellow-feather broilers (body weight 470.31 ± 13.15 g) were randomly allocated to 3 dietary treatments as follows: CON group, basal diet and raised under normal temperature (24°C); HS group, basal diet and raised under cycle heat stress (34°C from 10:00-18:00 and 24°C for the rest time); HSC group, basal diet with 200 mg/kg COS supplementation and raised under cycle heat stress. Each treatment had 6 replication pens and 6 broilers per pen. Compared with the CON group, heat stress decreased (P < 0.05) the relative weight of duodenum and jejunum; the relative length and villus height (VH) of duodenum, jejunum, and ileum; the ileum VH to crypt depth ratio; duodenum mucosal catalase (CAT) activity; and jejunum mucosal glutathione peroxidase (GSH-Px) and CAT activity, whereas it increased (P < 0.05) serum diamine oxidase (DAO) activity and D-lactate acid (D-LA) content, duodenum and jejunum mucosal malondialdehyde (MDA) and interleukin-1β (IL-1β) content, and ileum mucosal tumor necrosis factor-α content. Compared to the HS group, dietary COS supplementation increased (P < 0.05) the relative length of duodenum, jejunum, and ileum; the VH of jejunum and ileum; and duodenum and jejunum mucosal GSH-Px activity, whereas it decreased (P < 0.05) serum DAO activity and D-LA concentration and duodenum and jejunum mucosal MDA and IL-1β content. These results suggested that dietary COS supplementation had beneficial effects on intestinal morphology by increasing jejunum and ileum VH; permeability by decreasing serum DAO activity and D-LA content; antioxidant capacity by decreasing duodenum and jejunum mucosal MDA content and by increasing duodenum and jejunum GSH-Px activity; and inflammatory response by decreasing duodenum and jejunum mucosal IL-1β content.

To evaluate the ameliorative effect of algae-derived polysaccharide (ADP) supplementation on duodenal injury caused by heat stress (HS) in broilers, a total of 144 male yellow-feathered broilers (56-day-old) were randomly allocated into three groups: The TN group (thermoneutral zone, broilers were raised at 23.6 ± 1.8 °C); HS group (heat stress, broilers were exposed to 33.2 ± 1.5 °C 10 h/day, 8:00 a.m.–18:00 p.m., the temperature in the remaining period was consistent with the TN group); HSA group (heat-stressed broilers were fed with ADP supplemented diet at 1000 mg/kg). There were six replications in each treatment, and eight broilers in each replication. The feeding trial lasted four weeks. The results showed that dietary ADP supplementation tended to increase the villus height (p = 0.077) and villus width (p = 0.062), and decrease the apoptosis rate (p = 0.081) in the duodenum of broilers under HS. Furthermore, dietary ADP increased the relative mRNA and protein (based on immunofluorescence) expression levels of occludin and zonula occludens-1 (ZO-1) in the duodenum of broilers under HS (p < 0.05). In addition, dietary ADP enhanced the total antioxidation capacity (T-AOC) and activity of glutathione-S transferase (GST), while reducing the malondialdehyde (MDA) concentration of the duodenum in broilers under HS (p < 0.05). Moreover, dietary ADP supplementation upregulated the duodenal nuclear factor erythroid 2-related factor 2 (Nrf2), heme oxygenase-1 (HO-1), glutathione peroxidase 1 (GPx1) and glutathione S-transferase theta 1 (GSTT1) mRNA expression levels in heat-stressed broilers (p < 0.05). Furthermore, compared with the HS group, broilers fed with an ADP supplemented diet had a higher relative mRNA expression of inhibitor kappa B alpha (IκBα) (p < 0.05) and a lower relative mRNA expression of tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) in the duodenum (p < 0.05). In summary, dietary ADP supplementation had an ameliorative effect on HS-induced impairment of tight junctions, antioxidant capacity and the immune response of the duodenum in broilers. These beneficial effects might be related to the modulation of Nrf2 and NF-κB signaling pathways.

Milk fat is a key factor affecting milk quality and is also a major trait targeted in dairy cow breeding. To determine how the synthesis and the metabolism of lipids in bovine milk is regulated at the miRNA level, primary mammary epithelial cells (pMEC) derived from two Chinese Holstein dairy cows that produced extreme differences in milk fat percentage were cultured by the method of tissue nubbles culture. Small RNA libraries were constructed from each of the two pMEC groups, and Solexa sequencing and bioinformatics analysis were then used to determine the abundance of miRNAs and their differential expression pattern between pMECs. Target genes and functional prediction of differentially expressed miRNAs by Gene Ontology and the Kyoto Encyclopedia of Genes and Genomes analysis illustrated their roles in milk fat metabolism. Results show that a total of 292 known miRNAs and 116 novel miRNAs were detected in both pMECs. Identification of known and novel miRNA candidates demonstrated the feasibility and sensitivity of sequencing at the cellular level. Additionally, 97 miRNAs were significantly differentially expressed between the pMECs. Finally, three miRNAs including bta-miR-33a, bta-miR-152 and bta-miR-224 whose predicted target genes were annotated to the pathway of lipid metabolism were screened and verified by real-time qPCR and Western-blotting experiments. This study is the first comparative profiling of the miRNA transcriptome in pMECs that produce different milk fat content.