Effect of Particle Size of Soybean Meal on Protein Utilization in Steers and Lactating Cows

Open Access
Publisher Website
Google Scholar
Abstract
The effect of particle size of soybean meal on protein utilization was examined in 2 trials. In trial 1 4 steers with ruminal and abomasal fistulas were in a 3 .times. 3 Latin square design with a column added to estimate the effect of particle size on degradation of protein in the rumen. Rations of prairie hay and ground corn were supplemented with 3.2% urea or 22.3% soybean meal finely ground or of a coarser particle size. Abomasal nonammonia N passages were 170, 236 and 217 g/day for steers fed rations containing urea and fine and coarse soybean meal. Calculated by difference, bypass of N was 61.4 and 44.7% for fine and coarse soybean meal. Neither rumen ammonia concentration nor digestibility of ration components was changed by particle size. In trial 2, 24 Holstein cows were fed fine and coarse soybean meal at 14.5 and 32.8% of the concentrate mixture. Milk yield, rumen ammonia and blood urea were higher for cows consuming the higher protein rations but particle size had no effect on these criteria of response.