Cellulolytic Interrelationships of Carbohydrates, Fat and Trace Minerals in Sheep Rations

Abstract

A series of 3 balance trials was conducted with 24 crossbred wethers fed semi-purified rations which contained ground corn cobs as the sole roughage. Observations were made on the effects of an increased corn starch intake, an increased fat (corn oil) intake, supplemental alfalfa ash and trace minerals on daily nitrogen retention and the digestibility of cellulose, organic matter and crude protein. The addition of alfalfa ash to a ration which contained 80% corn cobs did not affect the digestibility of cellulose, organic matter or crude protein. Increases in the corn starch content of the ration from 2.6 to 17.6% resulted in a significant decrease of the digestibility of cellulose. The substitution of 2% corn oil into a ration which contained 65% corn cobs significantly reduced the digestibility of cellulose, organic matter and crude protein. These depressions due to the presence of corn oil and corn starch in the rations were completely reversed by the addition of alfalfa ash to the rations. In some cases, daily nitrogen retention was significantly improved by the presence of alfalfa ash in the rations. A mixture of trace minerals patterned after the minor element composition of alfalfa was as effective as alfalfa ash in supplying the minor minerals required by the rumen microorganisms for optimum cellulolytic activity with a ration which contained 65% corn cobs and 18.6% corn starch.