Investigation of standardized ileal amino acid digestibility of rice protein meal in sexed broilers

Rice protein meal (RPM), a byproduct of the rice industry, has emerged as a potential alternative for poultry feed, especially in rice-producing regions in the South Asia region. The aim of this study was to evaluate the standardized ileal amino acid (AA) digestibility of RPM produced from two distinct rice varieties in sexed broiler chickens, with or without the inclusion of a commercial protease enzyme. Treatments were structured in a 2 × 2 × 2 factorial arrangement, including two sources of RPM (Basmati and IRI), sex (male and female), and protease levels (0 and 500 units per ton of feed). In addition to the test diets, a reference diet based on soybean meal (SBM) and a nitrogen-free diet (NFD) were included in the experiment. Titanium dioxide was added on 0.30% of the diets as an inert marker. Experimental diets were fed to 6 replicates, each consisting of male and female chicks, from 21 to 28 days of age. The data were analyzed using General Linear Model techniques with the help of SPSS 16.0. The main effect of varieties was significant (P < 0.05), as the standardized ileal digestibility (SID) of lysine (57.8%) and threonine (50.7%) was higher for Basmati compared to IRI. The SID for arginine was lower (P = 0.02), and the SID of cysteine (14.4%), isoleucine (47.3%), leucine (46.1%), valine (45.2%), and histidine (49.6%) tended to be lower (P < 0.07) in females for RPM derived from Basmati rice. Protease had no effect on the SID of AA, nor did any of the other three- or two-way interactions.