Influence of Pelleting on the Utilization of Alfalfa

Abstract

Sheep were pair-fed chopped and finely ground pelleted alfalfa hay. Two feeding levels were used. Studies were made on growth, feed intake, digestibility, energy utilization and content of the hay, in vitro carbon dioxide and fatty acid production by the rumen contents at various times after feeding, and changes in the ingesta as it passes through the digestive tract. Digestibility of lignin and holocellulose was not greatly influenced by grinding and pelleting but nitrogen digestibility was higher for the pelleted hay. Eighty-nine percent of the holocellulose of both the chopped and pelleted hay was digested in the reticulo-rumen. Total digestible nutrient, digestible, metabolizable and net energy content were not significantly different between the pelleted and chopped hay. The results indicate that increased gains due to feeding the finely ground, pelleted alfalfa hay compared to chopped alfalfa hay are due to an increased feed intake. A faster passage of ingesta from the reticulorumen seemed to be responsible for this increased feed intake. This in turn was due to a faster rate of holocellulose digestion by the rumen microorganisms as indicated by the lignin-holocellulose ratios and the in vitro fatty acid production by the rumen contents. By using lignin-nitrogen ratios, calculations indicate that approximately 50% of the feed nitrogen was lost before the ingesta reached the omasum. A lowered nitrogen content persisted through the abomasum, but over a 175% increase in nitrogen was found in the small intestine. From these last observations, it is suggested that the additions of nitrogen as enzymes and other secretions which blend with the feed and microbial nitrogen in the small intestine have an important influence on the nitrogen utilization and economy of the body. Copyright © . .