FEEDING OF BRONOWSKI, SPAN AND COMMERCIAL RAPESEED MEALS WITH OR WITHOUT ADDITION OF MOLASSES OR FLAVOR IN RATIONS OF LACTATING COWS

Abstract

Lactating Holstein dairy cows were used in two experiments to determine if using Bronowski (low glucosinolate) rapeseed meal (RSM) in place of commercial RSM (high glucosinolate) would allow greater quantities of RSM to be used in dairy rations without adversely affecting animal performance. A third experiment was carried out to determine the effect of pelleting and adding either molasses or "feed flavor" on consumption of a dairy ration containing 19% commercial RSM or 19% Span RSM with no additives. When commercial RSM made up 14% of the grain mixture (11.9% including hay), grain consumption was reduced (P < 0.05) compared to Bronowski-containing mixture; however, there was no effect (P > 0.05) on level of milk production. When Bronowski made up 10, 17 or 24% of the grain mixture in place of soybean meal (SBM), feed intake, milk composition, digestibility of the ration and nitrogen retention were not different (P > 0.05). The addition of 19% commercial or Span RSM in place of SBM reduced ad libitum grain consumption but not significantly (P > 0.05). Pelleting or addition of molasses or "feed flavor" did not (P > 0.05) improve ad libitum intake of rations containing commercial RSM. However, the trend was for greater consumption. Daily milk yield was higher (P < 0.05) for SBM, flavored feed and Span RSM treatments compared to the commercial RSM treatment. The low fat test (P < 0.05) observed for the SBM and pelleted RSM rations could be due to lower fibre level in the first case and a pelleting effect in the second case.