Effect of threonine and potassium carbonate on broiler chicken performance, immunity, carcass traits, and small intestine morphology.

This study aimed to investigate the interactive effect of dietary threonine (i.e., 100, 110, and 120%) and low and high dietary potassium (i.e., 0.85 and 0.94% of diet) on the performance, immune response, blood metabolites, carcass traits, and jejunum morphology of broiler chickens in Iran. In a completely randomized design, 300 1-day-old broiler chicks (Ross 308) were assigned to one of six dietary treatments with a 3 × 2 factorial arrangement. Broiler chicken growth performance, blood metabolite concentration, jejunum morphology, and antibody titter against Newcastle disease and influenza viruses were not affected by dietary treatments (P > 0.05). High level of dietary potassium led to lower toe web thickness index at 4 h post injection while compared to control group, threonine supplementation significantly decreased toe web thickness of broiler chickens at 24 and 48 h post injection (P < 0.05). Dietary treatments had no significant effects on carcass, abdominal fat, and breast and thigh percentages while higher dietary potassium increased serum glucose concentration (P < 0.05). Broilers fed diet supplemented with 20% supplemented threonine and higher potassium level had lower breast meat fat percentage while those fed diet supplemented with 20% threonine and low potassium had higher thigh meat protein percentage (P < 0.05). It can be concluded that although threonine supplementation improved toe web thickness index as cell-mediated immune response and lowered breast meat fat percentage in broiler chickens, there was no interaction between potassium with threonine in broiler chicken nutrition.