VALEUR ALIMENTAIRE DES FOINS CONDENSÉS. II. — INFLUENCE DU BROYAGE ET DE LA MISE EN AGGLOMÉRÉS SUR LA DIGESTION DU FOIN DE LUZERNE DANS LE RUMEN

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Abstract
Digestibility of lucerne hay decreased little when given in pelleted form despite large increases of intake and rate of passage through the digestive tract. This seems to be due to the increased rate of fermentation in the rumen, as judged by the rate of gas production during fermentation of rumen fluid in vitro and the concentrations of volatile fatty acids and ammonia. The microbial activity was little affected; cellulolytic activity was slightly less, unchanged or slightly more according to the trial and the methods of estimation in vivo or in vitro. Condition of the medium, pH and volatile fatty acid composition of rumen fluid also were little changed. Consequently it seems that the increase in rate of fermentation is due to the reduced resistance of the hay to microbial attack resulting from the division into fine particles. The digestive processes which limit intake of pelleted hay do not seem to be of the same origin as they are in the case of long hay. With pelleted hay the effect of degree of fill of the parts of the digestive tract posterior to the rumen must be superimposed on that of the rumen itself, if the difference in amount of contents between the 2 diets is considered: the dry contents of the whole digestive tract is greater by about a half with pelleted hay than with long hay while that of the rumen remains unchanged.