COMPARISON OF TOWER RAPESEED MEAL AND SOYBEAN MEAL AS SOURCES OF PROTEIN IN PELLETED CALF STARTER RATIONS

Forty Holstein calves (20 male, 20 female) were used in an experiment to compare Tower rapeseed meal (RSM) with soybean meal (SBM) as the sole or partial source of supplemental protein in calf starter rations. Four pelleted calf starter rations were fed to calves on a free choice basis from 2 days until 12 wk of age. Calves were weaned from a limited milk feeding program at 5 wk of age. Rations were 16% crude protein formulations with supplemental protein from (1) SBM, (2) 50% SBM + 50% RSM and (3) RSM or (4) a 14% crude protein formulation with RSM as the supplemental protein. A 50/50 isonitrogenous combination of SBM + RSM (ration (2) or complete substitution of SBM by RSM (ration 3) resulted in feed intake, daily gain and feed/gain ratios similar to those in calves fed rations containing SBM (ration 1) as the protein source. The 16% crude protein rations were similar in the preweaning and postweaning periods and with respect to overall performance. Calves fed the 14% crude protein ration with RSM exhibited similar feed intakes and daily gains but required more feed per unit gain than calves fed the 16% rations containing SBM, RSM and SBM + RSM. Tower RSM can provide 100% of the supplementary protein or up to 17.3% of calf starter rations without resulting in impaired calf performance.