Impact of exogenous enzymes on micronutrient digestibility, tissue protein contents and internal enzyme activities of broilers fed on all-vegetable diets

The study was conducted to investigate the effects of diets, amino acid and mineral digestibility, tissue protein contents, and endogenous enzyme activities of broilers fed diets based on all-vegetable ingredients with or without supplementation of microbial enzymes. Ross 308 one-day old male broiler chicks (n=160) were assigned to four dietary treatments, each replicated five times, eight chicks per replicate, in a (2 x 2) factorial design. Two basal diets were formulated with soybean (SBM) and canola (CM) meals at a ratio of 75:25, respectively along with basal grains, and fed the birds 'ad libitum' as such or supplemented with enzymes from day 1-35 days. Results showed that tissue protein contents and endogenous enzyme activities (except for maltase) were unaffected by dietary sources and microbial enzyme supplementation. Only the activities of maltase increased (P<0.05) on CM diet compared to SBM diets, but this effect was not shown when enzyme supplementation to diets was mae. The digestibility of threonine, lysine, valine, isoleucine, and leucine was increased (P<0.05; P<0.01) on SBM diet compared to CM diet. The addition of enzymes to diets improved (P,0.05) the digestibility of histidine, threonine, lysine, and isoleucine on day 35. Enzymes had no (P.0.05) effect on mineral digestibility of broilers during this period. The digestibility of Cu, Zn, and Mg was increased (P<0.05) on CM diet, whereas Ca digestibility was higher on SBM diet at 35 days.