Using clover/grass silage as a protein feed for dairy bull calves

摘要

Soybean meal (SBM) is globally used as a protein feed of good nutritional quality, e.g. for calves. However, the environmental impact of soybean cultivation is often questioned and SBM can therefore of ethical reasons be replaced by nitrogen-fixing forage and grain legumes and rapeseed products. In two experiments (exp.), we examined whether feeding dairy bull calves forages with a high inclusion of red clover together with cold-pressed rapeseed cake (CRC; exps. 1 and 2) and field bean (FB; exp. 2) met their protein requirement for proper growth, and calculated the profitability of using these diets. The calves were allocated to one of three protein feed treatments per experiment and studied from 97 to 275 kg live weight. In exp. 1, red clover/grasssilage was combined with either smaller or greater amounts of CRC, which was compared with SBM. In exp. 2, red clover/grass silage, CRC and FB were combined with silage constituting 40, 50 or 60 % of DM in the total diet, to find the best combination. The profitability was calculated as value of calf gain minus feed costs. Soybean meal gave the highest live weight gain (LWG) and profitability in exp. 1, closely followed by the diet with greater amount of CRC together with clover/ grass silage. In exp.2, the diets with 40 or 50 % silage resulted in similar DM intake and LWG,both higher than with 60 % silage. At conventional prices, the 40 % silage diet had the highest profitability, whereas at organic prices, the 50 % silage diet was more profitable.