Soluble fiber on energy metabolism of ruminants

Abstract

Much of the energy produced by ruminant animals in a breeding environment is derived from the fermentation of soluble and structural carbohydrates, which are converted by microbial fermentation into metabolic products that can be allocated to the synthesis of meat, milk, wool and work. In this context the study´s objective is to review the importance of soluble fiber in the ruminants´ energetic metabolism and show the main differences in comparison to other fibers. The soluble fibers are pectins, beta-glucans, gums, mucilages and some hemicelluloses, and the insoluble fibers are cellulose, lignin, hemicelluloses and insoluble pectins. Pectin is the only component of the cell wall which is completely and rapidly fermentable therefore it is not in contrast to hemicelluloses one of the lignified substance of the matrix. Researchers when testing two types of corn kernels processing (flaked or coarsely grounded) and its replacement by 50% citrus pulp pelleted in Holstein cows fed with corn silage, observed that the partial inclusion of citrus pulp used in the diet did not affect the intake of DM and organic material and the digestibility of starch and crude protein. However, the apparent digestibility of NDF and ADF were higher, causing a beneficial effect on the performance of dairy cows. Where animals fed with soluble fiber showed higher weight gain and better feed conversion. In general the by-products with high pectin concentration have great potential for use in ruminant´s diets due to their high energetic density. Besides that they have a favourable type of fermentation without lactic acid production, helping maintaining a favourable rumen environment; however such introduction in the diet of ruminants must be done carefully, in order not to lose the initial economic goals and animal welfare allied to a good production.