Nutritional and Metabolic Characteristics of Brassica carinata Co-products from Biofuel Processing in Dairy Cows.

The increased utilization of Brassica carinata in the biofuel industry in Canada has resulted in the large-scale production of co-products that can be potentially exploited as alternative protein ingredients in dairy ration. The objectives of this study were to investigate the nutritive value of carinata presscake and meal for dairy cows in terms of (1) nutrient and antinutrient composition, (2) rumen degradation kinetics of organic matter (OM), crude protein (CP), and neutral detergent fiber, (3) hourly effective degradation ratio and potential N to energy synchronization, (4) intestinal digestion of rumen undegraded protein (RUP), and (5) total metabolizable protein (MP) supply to the small intestine. Samples (n = 3) of carinata meal, carinata presscake, and canola meal (as reference feed), collected from three consecutive batches, were evaluated. In comparison to canola meal, carinata presscake and meal had greater (p < 0.05) contents of CP [39.7 versus 48.5 and 53.5% dry matter (DM)], with a high proportion of soluble crude protein (24.0 versus 53.0 and 72.6% CP), resulting in their extensive degradation (59.2 versus 76.3 and 89.3% CP) in the rumen. As a result, carinata presscake and meal supplied smaller (p < 0.05) quantities (92 and 136 g/kg of DM) of MP compared to canola meal (153 g/kg of DM). The contents of glucosinolates were greater (p < 0.05) in carinata presscake (168.5 μmol/g) and meal (115.2 μmol/g) compared to canola meal (3.4 μmol/g), limiting its utilization as a ruminant feed. Carinata co-products can be used as an alternative feed protein source, given their nutrient composition, rumen degradation, and intestinal digestion characteristics, provided that the high glucosinolate content can be reduced.