Effect of processing of supplemental corn on metabolizable protein of beef cows consuming low-quality forage

摘要

Supplementation is required to offset nutrient deficiencies and to ensure optimal performance of cattle consuming low-quality forages ( ). Corn is frequently supplemented at low levels to offset energy deficiencies ( ; ; ). However, forage intake and digestibility may be negatively affected by the addition of corn or other cereal grains as a result of negative associative effects ( ; ; ). The negative associative effects between corn grain and mature low-quality forage are possibly caused by exacerbating the rumen ammonia deficiency ( ) by the fast fermentation of starch. Processing grain is used to optimize starch or energy availability by maximizing the extent of carbohydrate digestion in the rumen while controlling its rate of digestibility ( ). However, the effects of processing cereal corn on forage intake, digestion function, rumen fermentation, and metabolizable protein of cattle consuming low-quality hay have not been studied. Steam-flaking corn improves starch availability as a compared to dry-rolled corn ( ). Therefore, it is hypothesized that cereal corn-processing methods that increase rate of ruminal starch fermentation will negatively impact forage intake and characteristics of digestion. Hence, steam-flaked corn ( ) may increase the negative effects of corn supplementation on forage intake and digestibility as compared to ground corn ( ). The objective of this experiment was to evaluate the effects of method of processing supplemental corn on forage intake, digestive function, metabolizable protein, and rumen fermentation.