As a multifunctional polypeptide, epidermal growth factor (EGF) increases growth performance or enhances resistance to diseases in commercial broilers under adverse conditions. In this study, a recombinant Lactococcus lactis was established to produce the secretory form of bioactive gEGF. The results of in vitro testing showed that gEGF promoted the proliferation of chicken embryo fibroblast cells. A total of 63 5-day-old broiler chickens were evenly divided into three groups and treated with either M17 medium (the control group), supernatant of LL-pNZ8149 fermentation product (the P-LL group), or supernatant of LL-pNZ8149-gEGF fermentation product (the gEGF group). In two weeks, many measurements of growth, immunity and the intestines were significantly higher in the gEGF group than those in the control and the P-LL groups. Our study showed that the bioactive gEGF could be expressed with Lactococcus lactis expression system with the potential to enhance growth performance, immune function, and intestinal development in broiler chickens.

The effects of brewers’ spent grain (BSG) diets on the fatty liver deposition and the cecal microbial community were investigated in a total of 320 healthy 5-day-old Landes geese. These geese were randomly and evenly divided into 4 groups each containing 8 replicates and 10 geese per replicate. These four groups of geese were fed from the rearing stage (days 5–60) to the overfeeding stage (days 61–90). The Landes geese in group C (control) were fed with basal diet (days 5–90); group B fed first with basal diet in the rearing stage and then basal diet + 4% BSG in the overfeeding stage; group F first with basal diet + 4% BSG during the rearing stage and then basal diet in the overfeeding stage; and group W with basal diet + 4% BSG (days 5–90). The results showed that during the rearing stage, the body weight (BW) and the average daily gain (ADG) of Landes geese were significantly increased in groups F and W, while during the overfeeding stage, the liver weights of groups W and B were significantly higher than that of group C. The taxonomic structure of the intestinal microbiota revealed that during the overfeeding period, the relative abundance of Bacteroides in group W was increased compared to group C, while the relative abundances of Escherichia–Shigella and prevotellaceae_Ga6A1_group were decreased. Results of the transcriptomics analysis showed that addition of BSG to Landes geese diets altered the expression of genes involved in PI3K-Akt signaling pathway and sphingolipid metabolism in the liver. Our study provided novel experimental evidence based on the cecal microbiota to support the application of BSG in the regulation of fatty liver deposition by modulating the gut microbiota in Landes geese.

Bacillus amyloliquefaciens TL (B.A-TL) is well-known for its capability of promoting protein synthesis and lipid metabolism, in particular, the abdominal fat deposition in broilers. However, the underlying molecular mechanism remains unclear. In our study, the regulations of lipid metabolism of broilers by B.A-TL were explored both in vivo and in vitro. The metabolites of B.A-TL were used to simulate in vitro the effect of B.A-TL on liver metabolism based on the chicken hepatocellular carcinoma cell line (i.e., LMH cells). The effects of B.A-TL on lipid metabolism by regulating insulin/IGF signaling pathways were investigated by applying the signal pathway inhibitors in vitro. The results showed that the B.A-TL metabolites enhanced hepatic lipid synthesis and stimulated the secretion of IGF-1. The liver transcriptome analysis revealed the significantly upregulated expressions of four genes (SI, AMY2A, PCK1, and FASN) in the B.A-TL treatment group, mainly involved in carbohydrate digestion and absorption as well as biomacromolecule metabolism, with a particularly prominent effect on fatty acid synthase (FASN). Results of cellular assays showed that B.A-TL metabolites were involved in the insulin/IGF signaling pathway, regulating the expressions of lipid metabolism genes (e.g., FASN, ACCα, LPIN, and ACOX) and the FASN protein, ultimately regulating the lipid metabolism via the IGF/PI3K/FASN pathway in broilers.

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Background Epidermal growth factor (EGF) is a multifunctional polypeptide, which could be utilized to solve problems in the industry such as increasing growth performance of commercial broilers or enhancing resistance to diseases under adverse conditions. Thus far, very few studies have focused on the gallus epidermal growth factor (gEGF) despite the availability of a plethora of studies on mammalian EGF. The aim of this study was to express gallus epidermal growth factor (gEGF) using a food-grade Lactococcus lactis expression system and to investigate its biological effects on broiler chickens. Results A recombinant Lactococcus lactis, which produced the secretary form of bioactive gEGF at 2.67 μg/mL in culture supernatant, was generated. In vitro testing denoted that gEGF promoted the proliferation of UMNSAH/DF-1 cells. Sixty-three 5-day-old broiler chickens were divided into three groups and treated with either M17 medium (C, as control), supernatant of LL-pNZ8149 fermentation product (P-LL), or supernatant of LL-pNZ8149-gEGF fermentation product (gEGF-P-LL). Body weight (BW), average daily gain (ADG), and the gain:feed ratio of the gEGF-P-LL group were significantly higher than those of the other groups during the two-week study. In addition, two weeks after therapy, the indices of spleen and thymus gland, levels of serum IgA, IgG and duodenum mucosal sIgA were all significantly higher in the gEGF-P-LL group than in the other groups. Moreover, the villus height of the duodenum, jejunum and ileum and crypt depth of the jejunum of the gEGF-P-LL group were significantly higher than those of the other groups, while the crypt depth of the duodenum showed the opposite pattern during the two-week study. Conclusions The bioactive gEGF could be expressed with Lactococcus lactis expression system. Furthermore, gEGF has the potential to enhance growth performance, immune function, and intestinal development in broiler chickens.

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