The Effect of Exogenous Protease in Broiler Diets on the Apparent Ileal Digestibility of Amino Acids and on Protease Activity in Jejunum

The objective of this study was to evaluate the effect of a mono-component commercial serine protease supplement in broiler diets on apparent ileal amino acid digestibility and protease activity. A total of 150 male (28 d old) ROSS 308 were randomly placed into 30 battery pens and divided into 5 treatment groups with 6 replicates each. The experiment was performed for 7 days. Five dietary treatments were used: 2 standard protein diets without (SP) and with protease (SP + P) formulated 20.7 % CP, 2 lower-protein diets (19.9 % CP) without (LP) and with protease (LP + P) and one lower-protein diet with protease and with doubled rapeseed meal (RSM) content (SP-RSM + P) compared with the other treatments. Lower-protein diets were formulated with a 4 % decrease in the relative CP value compared with the standard protein diet. Enzyme protease was added to the diets at a concentration of 200 ppm (15,000 PROT units per kg). The diets contained 0.3 % Cr2O3 to facilitate the estimation of apparent AA digestibility and overall apparent ileal crude protein digestibility. Mono-component protease had no effect on apparent ileal AA digestibility or jejunum protease activity if diets contained the same level of RSM. The supplement of exogenous protease did not affect (P > 0.05) the apparent ileal AA digestibility coefficients if a higher RSM level was used. The CP level influenced (P < 0.05) only the coefficients of the apparent ileal AA digestibility of Pro and Arg. The RSM level (P < 0.01) had significant effects on protease activity in the jejunum.