Rapeseed meal in complete feeds for dairy cows.

Three complete feeds containing low glucosinolate, low erucic acid rapeseed meal (Cultivar "1788"), high glucosinolate, low erucic acid rapeseed meal (Cultivar "Span"), or soybean meal as protein supplement were evaluated with lactating Holstein cows in a double 3 X 3 Latin square design. Lactation performance, hematology, blood chemistry, serum-free amino acids, rumen volatile fatty acid concentrations, and milk fatty acid composition were measured. The 1788 ration tended to increase yield of milk and of total solids. Hematology, blood chemistry, and serum-free amino acid data showed no differencein utilization of nitrogen. Concentrations of volatile fatty acids were not different. Feeding of the high glucosinolate Span ration did not reduce feed intake. However, there were indications that Span-fed cows may have experienced hypothyroidism. No differences were in erucic acid content of milk fat, and concentrations were low. Rapeseed meals 1788 and Span and soybean meal were equal as protein supplements.