Protein quality of linseed for growing broiler chicks

The protein quality of linseed was assessed and compared to that of soybean meal (SBM) in two experiments using growing broiler chicks. In the first e xperiment, the protein efficiency ratio (PER) and net protein ratio (NPR) w ere calculated for diets (90 g crude protein kg(-1)) containing the followi ng sources of protein: SBM and SBM diet modified to contain 10, 30 and 100% of the total protein from linseed, There was a significant (P<0.001) relat ionship between performance data or PER and NPR values and inclusion rate o f linseed in the diet. When fed as the sole source of protein, linseed caus ed a drastic reduction in weight gain (97.6 versus 6.9 g) and PER (3.38 ver sus 0.40) and NPR (4.29 versus 1.96) values compared to those for SBM. In t he second experiment, apparent and true total tract retentions (ATTR and TT TR) for nitrogen and amino acids were determined for diets (150 g crude pro tein kg(-1)) containing SBM as reference protein or SBM protein replaced 10 and 30% by linseed protein. The ATTR values were 15.3 and 24.8% lower for nitrogen and 4.6 and 15.5% lower for total amino acids for diets containing Linseed to compared to SBM diet. The response of individual amino acids to inclusion level of linseed was Linear (P<0.001). The TTTR values followed a similar trend than that found for apparent retention. In conclusion, util ization of linseed protein by broiler chicks was worse than that from SBM a nd it attributable in all probability to the presence in linseed of antinut ritional factors, such as mucilage, which can depress the retention of prot ein in chicks. (C) 2000 Elsevier Science B.V. All rights reserved.