Ruminal and Post-ruminal Digestion of Alfalfa Fed as Pellets or Long Hay

Abstract

The extent of ruminal and total digestion of the carbohydrate portion of long alfalfa and dehydrated, pelleted alfalfa was compared using the lignin-ratio method with four rumen fistulated steers.The apparent digestibility of the fibrous portion (crude fiber, acid detergent fiber, cellulose, and holocellulose) of pelleted alfalfa was only about 70% that observed for long hay. The apparent digestibility of the nitrogen-free extract did not differ significantly. The extent of the nitrogen-free extract digested in the reticulo-rumen was lower on the pelleted alfalfa ration than on the long alfalfa ration. While feeding pelleted alfalfa, less than 60% of the digestible fibrous portion was digested in the reticulo-rumen; whereas, more than 90% was digested in the reticulo-rumen when long alfalfa was fed.The proportion of ruminal acetic acid was lower, and the propionic and butyric acids were higher when feeding pellets compared to hay. Total volatile fatty acids and ruminal fill were depressed by the pellet ration.