COMPARISON OF LIGNOSULFONATE-TREATED CANOLA-MEAL AND SOYBEAN-MEAL AS RUMEN UNDEGRADABLE PROTEIN SUPPLEMENTS FOR LAMBS

An experiment was undertaken to determine the effect of lignosulfonate (LSO(3)) treatment on the rumen-undegradable protein (RUDP) value of canola meal (CM) and soybean meal (SM). Canola meal and SM were treated with 7% LSO(3) and heated (95 degrees C) for 1 h. Treated and untreated meals were compared in vitro, in situ and in digestibility and growth experiments using Romanov x Suffolk and Romanov x Dorset lambs. Lambs were fed four barley-based diets [13.5% crude protein (CP)] with one of CM, SM, LSO(3)-treated CM (LSO(3)-CM) or LSO(3)-treated SM (LSO(3)-SM) as protein supplements. Lignosulfonate treatment increased acid detergent insoluble nitrogen (ADIN) five-fold in SM and threefold in CM. After 6 h incubation with ruminal fluid, ammonia production from LSO(3)-treated meals was one-half that from untreated meals. Lignosulfonate treatment reduced (P < 0.01) in situ rates of dry matter (DM) and protein disappearance and the soluble DM and protein fractions for both SM and CM, but not the potentially digestible fractions. No differences in feed conversion or average daily gain (P > 0.05) were found among the treatments. Although LSO(3) treatment did not improve the ADG of lambs fed barley-based diets, it increased the RUDP value of SM and CM without adverse effects on digestibility.