Growth performance, liver and kidney functions, blood hormonal profile and economic efficiency of broilers fed different levels of threonine supplementation during feed restriction

The objective of the existing investigation was to determine the effect of dietary inclusion of threonine amino acid at different levels during feed restriction on growth indices, liver and kidney function parameters, and some hormonal profiles along with economic indicators in broiler chickens. A total of 1600 from two different breeds (800 Ross 308 and 800 Indian River) at 21 old age were incorporated. Chicks were randomly assigned into two main groups, control and feed restricted (8 hours/day), during the 4th week of age. Each main group was subdivided into four groups. The first group was fed a basal diet without adding extra threonine (100 %), the 2nd, 3rd and 4th groups were fed a basal diet with extra threonine levels of 110, 120 and 130 %, respectively. Each subgroup consisted of ten replicates of ten birds. We noticed that the dietary inclusion of threonine at extra levels in the basal diets significantly enhanced final body weight, body weight gain and better feed conversion ratio. This was mainly due to the enhanced levels of growth hormone (GH), insulin-like growth factor (IGF1), triiodothyronine (T3) and thyroxine (T4). Moreover, the lowest feed cost per kilogram body weight gain and improved return parameters were reported in control and feed-restricted birds fed higher levels of threonine than other groups. Also, a significant increase in ALT (Alanine Aminotransferase), AST (Aspartate Aminotransferase) and urea levels was observed in feed-restricted birds supplemented with 120 and 130 % levels of threonine. Hence, we recommend supplementing threonine at levels of 120 % and 130 % in the diet of broilers to promote growth and profitability.