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U. P. College of Agriculture, Los Banos, Laguna, Philippines and Comell University, Ithaca, New York 14850
Abstract
Factors affecting digestibility such as dry matter intake, metabolic loss and ability of cattle and buffaloes to select the Napier grass were studied at the University of the Philippines, College of Agriculture.
Napier grass was lower in dry matter, fibrous components and gross energy, but higher in crude protein and ash content at 45 than at 60 days of age. Buffaloes digested 2% to 4% more of most nutrients than cattle during the wet season; but species effects were not different during the dry season. Metabolic losses were lower for buffaloes than for cattle during the wet season and slightly higher during the dry season. Variation in metabolic losses affected differences in digestibility. Negative digestion coefficients for silica could have been due in part to slow erosion and passage of soil and rocks that settled to the bottom of the rumen and reticulum.
Dry matter intake was significantly lower for buffaloes in all trials. Lower dry matter intakes contributed to higher digestibilities by buffaloes in the wet season. Less metabolic loss by cattle was probably responsible for lack of animal species differences in digestibility during the dry season. In the dry season buffaloes selected the leafier portions of the Napier grass; but this was not reflected in higher digestion coefficients. The 2% to 4% higher digestibilities observed for the buffaloes over cattle on wet season grass would probably not be biologically significant. The fact that the cattle had higher intakes of dry matter would be more significant in increasing production, i.e., milk or weight gain, than the higher digestion coefficients of the buffaloes while eating less.
During the wet season, chopping the Napier grass significantly increased the digestibility of dry matter, with the reverse in the dry season. It is not readily apparent why chopping the feed increased digestibility in one instance and not in another. Wilting markedly increased intake and digestibility of the Napier grass, and significantly lowered the metabolic losses. Apparently, some chemical or enzymatic change within the plant during the wilting period caused an increase in digestibility of the cell wall.
1 Submitted from Ph.D. thesis of major author.
4 Research was funded by the Ford Foundation in connection with the University of the Philippines Cornell Graduate Education Program. Appreciation is expressed for the technical assistance given by Dr. L.S. Castillo, Dr. A.L. Ordoveza, Mr. Alberto Y. Robles and Mrs. L. P. Palo.
2 Present Address: Hoechst Pharmaceuticals, Inc., Animal Health Department, Somerville, New Jersey 08876.
3 Present Address: U.P. College of Agriculture, Department of Animal Husbandry College, Laguna, Philippines.
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