EVALUATION OF SOLVENT AND EXPELLER LINSEED MEALS AS PROTEIN-SOURCES FOR DAIRY-CATTLE

The objectives of the present study were to evaluate the nutritive value of expeller linseed meal (ELM) and solvent linseed meal (SLM) as protein supplements for lactating dairy cows utilizing analytical and in situ procedures, and determine the in vivo nutritive value of the most promising linseed meal in diets containing either barley of corn-based concentrate. Canola meal (CM) and soybean meal (SBM) were included in the evaluative stage for comparative purposes. Linseed meals contained 37.8 and 35.4% crude protein (CP); 22.6 and 25.9% neutral detergent fibre (NDF); and 12.9 and 7.1% crude fat for ELM and SLM, respectively. Rate and extent of dry matter, NDF, and CP digestion, as determined by the rumen in situ technique, indicated that ruminal digestibility of SLM was similar to that observed for CM, but ruminal escape of ELM protein was higher than for CM. The proportion of ruminal escape protein was similar for SLM, CM and SBM. Total tract CP digestibilities of SLM and CM were similar to and lower than those observed for ELM and SBM. Soybean meal had the highest total tract CP digestibility. Based on results of the analytical and in situ procedures, SLM was selected for evaluation in the in vivo experiment. Results indicated that SLM did not have any deleterious effect on digestion of other components of the diet, and parameters of rumen fermentation indicated similar digestion patterns for cows fed SLM and CM. Overall, results indicate that SLM has potential as a replacement for CM or SBM in diets of dairy cattle. It was also concluded that replacement of barley with corn does not influence the nutritive value of SLM for dairy cows.