Dietary supplementation with avilamycin and Lactobacillus acidophilus effects growth performance and the expression of growth-related genes in broilers

Context The use of antibiotics in poultry production is appropriate; however, it brings a high risk of dissemination of antibiotic-resistant strains of pathogenic and non-pathogenic bacteria and their further transmission to humans via the food chain. Aims The effects of supplementation with Lactobacillus acidophilus (a probiotic) or avilamycin (an in-feed antibiotic growth promoter), on growth performance, digestibility, plasma lipid levels, and the expression of certain growth-related genes were investigated. Methods In total, 135 15-day-old broiler chicks were divided into three groups (n = 45): a control group and two treatment groups. Each treatment group was then further divided into three replicates (15 birds each). The control group was fed a basal diet; the second group received basal diet supplemented with avilamycin (0.1 g/kg); the third group received basal diet plus L. acidophilus (0.1 g/kg). Growth performance (bodyweight, feed intake and feed-conversion ratio) was measured. Digestibility and gene expression were measured at the end of the experiment. Key results Greatest bodyweight gain was achieved in the L. acidophilus-fed chicks, which were significantly (P < 0.05) heavier than the control chicks and the avilamycin-fed chicks. Addition of avilamycin or L. acidophilus to the diet also significantly improved feed efficiency (P < 0.05) compared with the control. Although the digestibility of dry matter, crude protein and crude fibre significantly improved in the two experimental groups compared with the control, ether extract was not affected. In addition, plasma total cholesterol, triglyceride and low-density-lipoprotein cholesterol levels were significantly (P < 0.05) decreased whereas plasma high-density-lipoprotein cholesterol was significantly (P < 0.05) increased in the L. acidophilus group compared with the control. Expression of the genes for growth hormone secretagogue receptor (GHSR), insulin-like growth factor 1 (IGF-1) and insulin-like growth factor 1 receptor (IGF1R) was remarkably upregulated in the skeletal muscles of the two experimental groups. Conclusions Supplementation with L. acidophilus (0.1 g/kg) in the broiler diet had positive effects on growth, feed intake, feed efficiency, digestibility, and plasma lipid levels of the broilers. Implications Lactobacillus acidophilus might be a more useful additive in broiler feed than antibiotic growth promoters such as avilamycin.