the effect of branched-chain amino acids (l-valine, l-leucine and l-isoleucine) on intestinal morphology and igf-1 gene expression in broiler chickens

Background: insulin-like growth factor 1 (igf-1) is an important regulator of growth, amino acid (aa) elongation, glucose metabolism, dna synthesis, protein synthesis, and the proliferation and differentiation of various cell types. therefore, igf-1 may affect intestinal morphology by increasing nutrient uptake into intestinal enterocytes and promoting cell proliferation. objectives: the present study aimed to evaluate the effects of different levels of branched-chain amino acids (bcaas) (l-valine, l-leucine, and l-isoleucine) in low crude protein (cp) diets on intestinal morphology and igf-1 gene expression in broiler chickens. methods: a total of 480 one-day-old male and female broilers of the ross 308 strain, with an average weight of 42.75 ± 0.47 g, were used. this experiment was carried out as a 3 × 2 factorial in the form of a completely randomized design with 6 treatments and 4 replications. the experimental diets included three levels of bcaa (0%, 10%, and 20% higher than the standard) and two levels of cp (standard or 10% lower than the standard). results: using 20% bcaa in the diet increased the villus height to crypt depth (vh/cd) ratio in the duodenum, jejunum, and ileum compared to the standard level of bcaa (p < 0.05). reducing cp by 10% significantly lowered the vh/cd ratio in the duodenum, jejunum, and ileum (p < 0.05). the expression of igf-1 mrna in liver tissue was higher in the groups containing 10% bcaa than in the standard bcaa groups, regardless of the cp level. conclusions: in general, bcaa supplementation could be beneficial for improving intestinal morphology and igf-1 gene expression in broiler chickens on low cp diets.