Ruminal Nitrogen Degradability and Escape of Wet and Dry Distillers Grains and Wet and Dry Corn Gluten Feeds

Solubility and rate and extent of ruminal digestion of nitrogen in wet distillers grains, dry distillers grains, wet corn gluten feed, and dry corn gluten feed were evaluated in the laboratory, in situ, and in vivo. Distillers grains protein was the most insoluble in modified Burrough's mineral mix, corn gluten feed protein the least insoluble, and soybean meal protein intermediate. In the in situ trial (trial 1), nitrogen of wet and dry distillers grains and nitrogen of wet and dry corn gluten feed disappeared at similar rates, respectively. However, nitrogen disappearance rates were greater for wet and dry distillers grains. In the rumen escape trial (trial 2), wet distillers grains, dry distillers grains, wet corn gluten feed, and dry corn gluten feed were fed as supplemental protein sources and a urea control served to estimate endogenous nitrogen flow. Non-ammonia-nonbacterial nitrogen reaching the duodenum was lowest for steers fed the urea treatment (20.9 g/day). Rates were higher for wet distillers grains (64.1 g/day) and dried distillers grains (74.7 g/day) treatments compared to wet corn gluten feed (41.3 g/day) and dry corn gluten feed (32.7 g/day) treatments. Percentage protein apparently escaping rumen fermentation was greater for steers fed wet distillers grains (47%) or dried distillers grains (54%) than for those fed wet corn gluten feed (26%) or dry corn gluten feed (14%).