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The present study investigated the effect of Bacillus subtilis DSM 29784 (Ba) and enzymes (xylanase and β-glucanases; Enz), alone or in combination (BE) as antibiotic replacements, on the growth performance, digestive enzyme activity, immune response and the intestinal barrier of broiler chickens. In total, 1200 1-d-old broilers were randomly assigned to five dietary treatments, each with six replicate pens of forty birds for 63 d as follows: (a) basal diet (control), supplemented with (b) 1 × 109 colony-forming units (cfu)/kg Ba, (c) 300 mg/kg Enz, (d) 1 × 109 cfu/kg Ba and 300 mg/kg Enz and (e) 250 mg/kg enramycin (ER). Ba, Enz and BE, similar to ER, decreased the feed conversion rate, maintained intestinal integrity with a higher villus height:crypt depth ratio and increased the numbers of goblet cells. The BE group exhibited higher expression of claudin-1 and mucin 2 than the other four groups. BE supplementation significantly increased the α-diversity and β-diversity of the intestinal microbiota and markedly enhanced lipase activity in the duodenal mucosa. Serum endotoxin was significantly decreased in the BE group. Compared with those in the control group, increased superoxide dismutase and glutathione peroxidase activities were observed in the jejunal mucosa of the Ba and BE groups, respectively. In conclusion, the results suggested that dietary treatment with Ba, Enz or BE has beneficial effects on growth performance and anti-oxidative capacity, and BE had better effects than Ba or Enz alone on digestive enzyme activity and the intestinal microbiota. Ba or Enz could be used as an alternative to antibiotics for broiler chickens.

In the present study, we evaluated the effects of various stocking densities on the tracheal barrier and plasma metabolic profiles of finishing broilers. We randomly assigned 1,440 Lingnan Yellow feathered broilers (age 22 d) to 5 different stocking density groups (8 m -2 , 10 m -2 , 12 m -2 , 14 m -2 , and 16 m -2 ). Each of these consisted of 3 replicates. The interleukin (IL)-1β and IL-10 concentrations were substantially higher in the 16 m -2 treatment group than they were in the 8 m -2 and 10 m -2 treatment groups (P < 0.05). Nevertheless, IL-4 did not significantly differ among the 5 treatments (P > 0.05). The tracheal mucosae of the birds in the 16 m -2 group (high stocking density, HSD) were considerably thicker than those for the birds in the 10 m -2 group (control, CSD). Relative to CSD, the claudin1 expression level was lower, and the muc2 and caspase3 expression levels were higher for HSD. Compared with CSD, 10 metabolites were significantly upregulated (P < 0.05), and 7 were significantly downregulated (P < 0.05) in HSD. Most of these putative diagnostic biomarkers were implicated in matter biosynthesis and energy metabolism. A metabolic pathway analysis revealed that the most relevant and critical biomarkers were pentose and glucuronate interconversions and the pentose phosphate pathway. Activation of the aforementioned pathways may partially counteract the adverse effects of the stress induced by high stocking density. This work helped improve our understanding of the harmful effects of high stocking density on the tracheal barrier and identified 2 metabolic pathways that might be associated with high stocking density-induced metabolic disorders in broilers., (Copyright © 2020. Published by Elsevier Inc.)

There is no information regarding the influence of heat stress (HS) on host metabolic profile. In this study, we investigated the effects of different environmental temperatures on oxidative status, hormone levels, HS indicators, and plasma metabolites in broilers. A total of 1,680 yellow-feather broilers (28 D old) were randomly allotted to 4 groups with 6 replicates. The broilers (29-57 D old) were maintained in thermostatic rooms (20°C, 25°C, 28°C, and 30°C) for 28 consecutive days. The results showed that the plasma cortisol and adrenocorticotropic hormone levels and creatine kinase and lactate dehydrogenase activities gradually increased when the temperature increased from 20°C to 30°C. However, the insulin-like growth factor-І level decreased gradually. Furthermore, heat shock protein 70 expression significantly increased in the liver and breast muscle (P < 0.01). As the temperature increased, the total anti-oxidant capacity in the plasma and liver gradually decreased, whereas the malondialdehyde level increased. The activity of plasma glutathione peroxidase and total superoxide dismutase in the liver showed a similar increasing trend (P < 0.01). In addition, 15 metabolites were identified at higher (P < 0.05) levels, whereas 2 metabolites were identified at lower (P < 0.05) levels in the 30°C treatment group than those in the 25°C treatment group. Most of these potentially diagnostic biomarkers are involved in carbohydrate, amino acid, lipid, or gut microbiome-derived metabolism, indicating that HS affected the metabolic pathways in broilers. Six candidate metabolites (tartronic acid, l-bethreine, tartaric acid, allose, glutaric acid, and neohesperidin) were selected as biomarkers, as they showed high sensitivity, specificity, and accuracy in diagnosing broilers under HS (P < 0.01). In conclusion, in the final stage of growth, we identified 6 plasma differential metabolites as potential biomarkers of HS-induced metabolic disorders in yellow-feathered broilers. This work offers new insights into the metabolic alterations of broilers exposed to HS and provides a new perspective for further study., (Copyright © 2020 The Authors. Published by Elsevier Inc. All rights reserved.)

This study was conducted to investigate the effects of different selenomethionine (SM) forms and levels on productive performance and antioxidant status of broiler breeders and its offspring. Four hundred eighty 48-week-old Lingnan Yellow broiler breeders were randomly divided into four groups, provided basal diet with 0.15 or 0.30 mg/kg Se coming from two SM forms of DL-SM and L-SM. The experiment included a 4-week pretreatment period and an 8-week trial period. During the trial period, eggs were incubated once a week under standard conditions. The broiler breeders were slaughtered after the trial period. At the same time, 15 1-day-old chicks were selected at random per replicate and killed. The results showed that different SM forms and levels had no significant differences in average egg weight, feed intake, and feed-to-egg ration. The DL-SM group in contrast to the L-SM group induced a notable elevation of glutathione peroxidase (GPx) activity in serum (P < 0.01) and liver (P < 0.05), and the 0.15 mg/kg group had higher GPx activity than 0.30 mg/kg in serum (P < 0.01) and pancreas (P < 0.05). Different SM forms showed no significant differences in total antioxidant capability (T-AOC). Diets with 0.15 mg/kg Se exhibited a higher level of T-AOC in serum (P < 0.01) and some tissues. Besides, malondialdehyde (MDA) concentrations in serum, liver, and kidney significantly decreased due to the supplementation of DL-SM. Supplemental 0.15 mg/kg Se reduced MDA concentrations in kidney and muscle. The offspring of broiler breeders fed on DL-SM had higher GPx activity in liver and kidney than L-SM treatment. Supplemental 0.15 mg/kg Se also improved GPx activity in kidney and muscle and T-AOC in kidney of 1-day-old chicks. In summary, our study demonstrated that compared with L-SM, DL-SM was more effective for enhancing the antioxidant status of broiler breeders and its offspring. Moreover, the recommended level of Se supplementation was 0.15 mg/kg Se in Lingnan Yellow broiler breeder diets.