Ration Characteristics Influencing Rumen Protozoal Populations

Abstract

A series of trials was conducted in studying the influence of level of feed intake, rate of passage of ingesta, physical form of ration and feeding diethylstilbestrol upon rumen protozoal populations in lambs. Full feeding a pelleted high-concentrate ration resulted in very small rumen protozoal numbers, whereas two-thirds of a full feed resulted in relatively large numbers of rumen protozoa. Lambs consuming high-concentrate pelleted rations with high rate of passage indices, had very few protozoa. In contrast, lambs receiving a long hay-corn ration and having a lower rate of passage index had a larger rumen protozoal population. As the particle size of the ration decreased, the number of rumen protozoa decreased. Lambs consuming rations with some unground hay harbored relatively large protozoal numbers, while the feeding of pelleted or finely ground mixed rations resulted in small numbers of rumen protozoa. Protozoal population changes were observed to take place within 2 to 4 weeks after lambs were placed on a given ration treatment. Diethylstilbestrol not only prevented the disappearance of rumen protozoa from lambs fed high-concentrate pelleted ration, but it also increased protozoal numbers in all rations studied. These increases were accompanied by improved liveweight gain and feed conversion. Copyright © 1964. American Society of Animal Science . Copyright 1964 by American Society of Animal Science