This study was conducted to investigate the effects of supplementation with nicotinamide (NAM) and sodium butyrate (BA) on meat quality and expression of muscle development genes in broilers reared at a high stocking density. A total of 567, 21-day-old AA broilers were randomly assigned to 5 treatment groups and 2 control groups, with 7 replicates of each group. The control groups included a low stocking density (LD; 12.9 birds/m2) and were fed a basal diet. The treatment groups were kept at a high stocking density (HD; 18.6 birds/m2) and received either a low dose of NAM (50 mg/kg; treatment LN), a high dose of NAM (100 mg/kg; treatment HN), a low dose of BA (500 mg/kg; treatment LB), a high dose of BA (1,000 mg/kg; treatment HB), or a compound supplement (50 mg/kg NAM+500 mg/kg BA; treatment COMB); broilers were reared till 42 D of age. The control groups were kept at HD or at LD (12.9 birds/m2) and were fed a basal diet. The heterophil-to-lymphocyte ratio was significantly higher in the HD control group than that in the LD group; this ratio was significantly lower in treatments LN, HN, HB, and COMB than that in the HD control group. The lightness of breast muscles at 45 min and 24 h after slaughter was significantly higher in the HD group than that in the LD group, and the HD group showed the highest drip loss at 24 h and 48 h. Lightness and drip loss were lower in the HN, LB, and COMB treatments than those in the HD group. HD rearing significantly reduced gene expression of myogenic regulatory factor 5 (MYF5) while significantly increased expression of the protein ubiquitin degradation genes FBXO9, FBXO22, and FBXO32. All treatments significantly reduced FBXO9 and FBXO32 expression. Our results suggest dietary supplementation with NAM and BA can improve meat quality of broilers under high stocking density by upregulating the expression of myogenic genes, and inhibiting protein ubiquitination.

Background: Polyunsaturated fatty acids (PUFA), particularly n-3, have beneficial effects on human health, and for this reason foodstuffs with increased content of n-3 PUFA are now very common and widely available. Design: This study was conducted to investigate the effect of the duration of a flaxseed diet on Peking duck’s growth performance, antioxidant status, gene expression, and fatty acid profile of the meat. A total of 792 12-day-old white Peking ducks were divided into four groups. In the control group, animals were provided with a basal diet. In the three experimental groups, animals were fed a 10% flax seed diet with vitamin E at 13, 23, and 33 days of age for 30, 20, and 10 days, respectively. Results: The growth performance of the ducks decreased with flaxseed diet’s duration. Both body weight and body weight gain decreased linearly while Feed conversion ratios (FCR) increased in the group of ducks fed flaxseed compared to control ducks. Serum triglycerides (TG), very low density lipoprotein (VLDL), low density lipoprotein cholesterol (LDL-C), and aspartate aminotransferase (AST) linearly decreased while high density lipoprotein cholesterol (HDL-C) and lipopolysaccharide (LPS) levels increased by feeding flaxseed up to 30 days. The expression of lipin-1 gene (LPIN-1) and fatty acid desaturase 2 (FADS2) linearly increased in ducks fed flaxseed for 30 days. Linolenic acid (n-3) and its long-chain metabolites like eicosatetraenoic acid (ETA), eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), and total n-3 fatty acids (FA) linearly increased while the ratio of n-6 to n-3 was reduced with increased duration of flaxseed supplementation. Conclusion: Overall, we found that increasing the duration of flaxseed diet with vitamin E for more than 10 days had a mild adverse effect on duck’s growth performance but enrichedits meat with long-chain PUFA and decreased the n-6 to n-3 ratio, providing quality meat for health-conscious consumers. A period of 20 days is good for producing n-3 enriched Peking duck meat and skin.

This study was conducted to investigate the effects of stocking density and dietary nicotinamide (NAM) and butyrate sodium (BA) supplementation on the growth performance, liver mitochondrial function and gut microbiota of broilers at high stocking density. A total of 342, 26-d-old Cobb500 broilers were divided into 5 groups with 6 replicates. Treatments were as follows: (a) Low stocking density (L, 9 birds per cage); (b) High stocking density (H, 12 birds per cage); (c) H + 50 ppm NAM; (d) H + 500 ppm BA; (e) H + 50 ppm NAM + 500 ppm BA (COMB). The results showed that high stocking density significantly reduced the feed intake and body weight gain of broilers, while COMB improved the growth performance at high stocking density. High stocking density significantly reduced the liver metallothionein content, liver mitochondrial membrane potential and the activities of Na⁺K⁺-ATPase and Ca²⁺Mg²⁺-ATPase. In contrast, the liver metallothionein contents in the NAM, BA and COMB fed group were higher than those in the H group. COMB increased the activity of ATPase as well, but it failed to enhance the mitochondrial membrane potential. Stocking density also affected gut microbiota of broilers. The high-density group increased the relative abundance of Blautia. Supplementation of BA and NAM increased the abundance of Lactobacillus and Bifidobacteria, respectively. In conclusion, a combination of NAM and BA can improve the performance, antioxidant capacity, mitochondrial function and intestinal microbiota of broilers at high stocking density.

This study aimed to determine the impact of stocking density on the liver proteome and cecal microbiota of Peking ducks. A total of 1,200 21-day-old ducks were randomly assigned to 5 stocking density groups of 5, 6, 7, 8 and 9 ducks/m², with 6 replicates for each group. At 40 days of age, duck serum and pectorals were collected for biochemical tests; liver and cecal contents of ducks were gathered for proteome and microbiota analysis, respectively. Serum MDA increased while pectorals T-AOC reduced linearly with enhancing stocking density. Duck lipid metabolism was altered under different stocking density as well. Serum LDL-C increased linearly with increasing stocking density. Proteome analysis revealed fatty acid biosynthesis proteins such as acyl-CoA synthetase family member 2 and fatty acid oxidation related proteins including acyl-CoA dehydrogenase long chain and acyl-coenzyme A oxidase were enriched in high stocking density group. Additionally, high stocking density increased oxidative response associated proteins such as DDRGK domain containing 1. Furthermore, increasing stocking density diminished proteins of anti-oxidant capacity including regucalcin and catalase. 16S rDNA analysis revealed that higher stocking density was accompanied with decreased microbial diversity, as well as depletion of anti-inflammatory bacterial taxa, including Bacteroidales, Butyricimonas and Alistipe. Besides, reduced bile acid metabolism-associated bacteria such as Ruminococcaceae, Clostridiales and Desulfovibrionaceae were found in the high-density group. Both proteome and 16S rDNA results showed inflammation and chronic liver disease trend in the high-density group, which suggests the involvement of the liver-gut axis in oxidative stress.