Publication Date

1993

Description

The intake and rate of live-weight gain of 500 growing steer calves fed experimental forage diets in 7 trials were compared with corresponding values predicted using the Na1ional Research Council (NRC) model (1984). The cattle were predominantly weaned calves and most of the experimental diets were alfalfa-grass silage, either unsupplemented or supplemented with various protein sources, but some diets were based on maize silage or maize grain. The feeding period evaluated in this study ranged between the first 84 and 147 days when protein accretion rate in the cattle would be relatively high. Dry matter intakes were overpredicted by the NRC model but mean differences were less than 5% of the actual values. In contrast, the model predicted live-weight gains that were only 53.7% and 43.0% of actual gain for cattle fed unsupplemented and protein­supplemented diets, respectively. Most of these differences in predicting live-weight gain were attributed lo bias. The model predicted gains of cattle fed maize grain diets within 13% of the actual gains.

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An Analysis of the Dry Matter Intake and Rate of Live-Weight Gain of Growing Cattle Fed Forage Diets

The intake and rate of live-weight gain of 500 growing steer calves fed experimental forage diets in 7 trials were compared with corresponding values predicted using the Na1ional Research Council (NRC) model (1984). The cattle were predominantly weaned calves and most of the experimental diets were alfalfa-grass silage, either unsupplemented or supplemented with various protein sources, but some diets were based on maize silage or maize grain. The feeding period evaluated in this study ranged between the first 84 and 147 days when protein accretion rate in the cattle would be relatively high. Dry matter intakes were overpredicted by the NRC model but mean differences were less than 5% of the actual values. In contrast, the model predicted live-weight gains that were only 53.7% and 43.0% of actual gain for cattle fed unsupplemented and protein­supplemented diets, respectively. Most of these differences in predicting live-weight gain were attributed lo bias. The model predicted gains of cattle fed maize grain diets within 13% of the actual gains.