The experiment was conducted to investigate the effects of bilberry extract on growth performance, meat quality, antioxidant status, and immune function of yellow-feathered chickens. A total of 360 female hatchling Lingnan chickens were randomly allocated to three treatments with 6 replicates of 20 chickens per replicate. Birds were fed a basal diet supplemented with 0 (the control group), 100 (B100), and 400 (B400) mg/kg of bilberry extract for 63 d. Compared with the controls, (1) dietary supplementation with bilberry extract did not affect the growth performance of chickens from 1 to 63 d. (2) At 21 d, the relative weight of the bursa of Fabricius was increased (p < 0.05) by dietary supplementation with 400 mg/kg bilberry extract. Bilberry extract decreased the concentrations of IgY and IgM in blood plasma of 63-d chickens (p < 0.05). (3) For 21-d chickens, dietary supplementation with 400 mg/kg bilberry extract increased (p < 0.05) the activity of GSH-Px in blood plasma and jejunal mucosa (p < 0.05). Supplementation with 100 mg/kg bilberry extract increased (p < 0.05) the activities of T-SOD in jejunal mucosa and GSH-Px in the liver and decreased (p < 0.05) the MDA concentration in the liver. For chickens at the age of 63 d, both levels of bilberry extract increased activity of T-SOD in blood plasma (p < 0.05) and reduced MDA concentration in the jejunum (p < 0.05). (4) Supplementation with bilberry extract in the diet decreased the MDA concentration (B100) in muscle of 63-d chickens at 45 min postmortem and increased (p < 0.05) the activity of T-SOD (B400) at 4 d postmortem. (5) In breast muscle at 63 d, birds supplemented with bilberry extract (B400) had increased pH and drip loss while drip loss was reduced in the B100 treatment (p < 0.05); treatments did not affect inosinic acid or intramuscular fat contents. In conclusion, dietary supplementation of yellow-feathered chickens with bilberry extract enhanced the relative weight of the bursa of Fabricius, and broadly increased activities of antioxidant enzymes; indices of meat quality were improved without impact on growth performance. Considering the results in the current research, 100 mg/kg bilberry extract was recommended when supplemented in chickens.

This experiment investigated the effects of L-Methionine (L-Met) on growth performance, Met-metabolizing enzyme activity, feather traits, and small intestinal morphological characteristics, and compared these with DL-Methionine (DL-Met) for medium-growing, yellow-feathered broilers during the starter phase. Furthermore, the aim was to provide recommendations for the appropriate dietary Met levels in feed. A total of 1584 1-d broilers were randomly divided into 11 treatment groups with six replicates of 24 birds each: basal diet (CON, Met 0.28%), basal diet + L-Met (0.04%, 0.08%, 0.12%, 0.16%, 0.20%), and basal diet + DL-Met (0.04%, 0.08%, 0.12%, 0.16%, 0.20%). The total trial period was 30 days. Compared with broilers fed the basal diet, those fed 0.04 to 0.20% supplemental Met had higher final body weight (FBW), average daily feed intake (ADFI), average daily gain (ADG), and lower feed-to-gain ratio (F: G) (p < 0.05). Compared with DL-Met groups, the L-Met group had higher FBW and ADG (p < 0.05). The relative bioavailability (RBV) of L-Met in ADG of 1–30 d was 142.5%. Chicks fed diets supplemented with L-Met had longer fourth primary feather lengths compared to birds fed the control and diets supplemented with DL-Met (p < 0.05). Compared to the control, birds supplemented with DL-Met or L-Met had an increased moulting score (p ≤ 0.05). Chicks fed diets supplemented with L-Met had lower activities of methionine adenosyl transferase (MAT) compared to those fed the basal diet or supplemented with DL-Met (p < 0.05). Chicks supplemented with either DL-Met or L-Met had higher activities of cystathionine β-synthase (CBS) than those fed the basal diet (p < 0.05). Compared with the control, chicks fed diets supplemented with either DL-Met or L-Met had an enhanced level of albumin in plasma (p < 0.05). There were no obvious differences in the plasma content of uric acid and total protein among the treatments (p > 0.05). Chicks fed diets supplemented with either DL-Met or L-Met had higher villus height and V/C in the duodenal than chicks fed the basal diet (p < 0.05). The jejunum morphology was not affected by either L-Met or DL-Met supplementation (p > 0.05). Therefore, dietary supplementation with DL-Met or L-Met improved the growth performance, feather traits, and intestinal morphological characteristics of medium-growing, yellow-feathered broiler chickens aged 1 to 30 d by decreasing the enzyme activities of Met methylation (MAT) and increasing the enzyme activities of the sulfur transfer pathway (CBS), and supplementation with L-Met showed a better improvement compared with DL-Met. The relative efficacy of L-Met to DL-Met was 142.5% for ADG of yellow-feathered broilers. The appropriate Met levels for medium-growing, yellow-feathered broilers are between 0.36~0.38% (supplementation with DL-Met) or 0.32~0.33% (supplementation with L-Met) when based on ADG and feed-to-gain ratio.

Carnosic acid (CA), a natural phenolic terpenoid compound, is widely distributed in plants such as sage and rosemary, and exhibits a strong antioxidant capacity. The aim of this study was to investigate the effects of different levels of CA on growth performance, antioxidant capacity, and intestinal health of yellow-feathered broilers, and then to determine the optimal dose of CA to promote sustainable broiler production. A total of 384 1-day-old yellow-feathered broilers were randomly allocated into six treatment groups with eight replicates per group and eight birds per replicate pen. The control group (CON) was fed a basal diet and the CA treated groups (CA5, CA10, CA20, CA40, and CA80) were fed diets given different doses of CA (5, 10, 20, 40, and 80 mg/kg), respectively, for 53 days (1~21 d and 22~53 d). The results showed that, in the later stages of the experiment, supplementation with 10, 20, and 40 mg/kg of CA increased (p < 0.05) the final body weight and average daily gain. Morphometric analyses of the jejunum showed that supplementation of CA increased (p < 0.05) the ratio of villus height to crypt depth (V/C). Antioxidant indices revealed that CA significantly reduced MDA levels in plasma, liver, and jejunum, while enhancing activities of GSH-Px, T-SOD, and T-AOC (p < 0.05). Moreover, CA upregulated hepatic Nrf2, HO-1, GSH-Px, and GSR expression via downregulated Keap1. The analysis of intestinal microbiota showed that CA increased (p < 0.05) microbial α diversity (Ace, Chao, and Sobs indices) and increased (p < 0.05) beneficial bacteria, such as Streptococcus, Enterococcus, and Phascolarctobacterium. In conclusion, CA improves growth performance, antioxidant capacity, intestinal health, and gut microbial diversity in broilers. Under the conditions of this experiment, quadratic regressions for different variables showed that the optimal range for supplemental CA in chicken’s diet was 19.11~76.85 mg/kg. Combined with experimental observation and regression analysis, the optimal level of supplementation was 40 mg/kg.

Background: The study objective was to investigate the protective effects of bilberry anthocyanin (AC) on growth performance, intestinal mucosal barrier and cecal microbes of chickens challenged with Salmonella.Methods: A total of 240 male hatchling chickens were randomly allocated to 4 treatments, each with 6 replicates. Birds were fed a basal diet supplemented with 0 (CON, and ST), 100 (ACL) and 400 (ACH) mg/kg of AC for 60 d, and orally challenged with 10⁹ CFU/bird (ST, ACL, ACH) Salmonella typhimurium at 14 and 16 d, birds in CON were given the same volume of PBS.Results: (1) Dietary supplementation of AC significantly increased d 18 BW, and ADG from d 1 to 18, and significantly decreased the F/G from d 1 to 18, d 1 to 28, d 1 to 60 (P<0.05); (2) At d 18, AC increased (P<0.05) the number of Salmonella in the liver and spleen of chickens; (3) AC decreased (P<0.05) plasma NO and ileal IL-1β, IL-6, IL-8, TNF-α, IFN-β, and IFN-γ; (4) AC also significantly increased ileal villus height (ACL, ACH), the ratio of villus height to crypt depth (ACH) and significantly decreased crypt depth (ACH). AC increased (P<0.05) the expression of Claudin-1 and Muc2 (ACL), ZO-1 and Occludin (ACH) as well; (5) Analysis of cecal microbes indicated that AC had a significant effect on principal co-ordinates and increased the alpha-diversity indexes (Chao, Pd, Shannon and Sobs) (P < 0.05). At the phylum level, the relative abundance of Firmicutes (ACL, ACH) was increased (P<0.05), and the relative abundance of Proteobacteria (ACL, ACH) and Bacteroidota (ACL) was decreased (P<0.05). At the genus level, AC decreased (P<0.05) the relative abundances of Bacteroides and Escherichia-Shigella, and increased (P<0.05) the relative abundances of Lactobacillus, Clostridia_UCG-014, Lachnospiraceae, and Shuttleworthia. Conclusion: Dietary AC prevented Salmonella infection in chicken via inhibiting the Salmonella colonization in liver and spleen, suppressing secretion of inflammatory factors, up-regulating the expression of ileal mucosal tight junction and mucin proteins, and ameliorating the composition of cecal microbes. Under the circumstance of this experiment, 100 mg/kg bilberry anthocyanin was recommended for chickens.