Abstract 272

Butterworth,MH; Mosi,-A

International Livestock Centre for Africa, PO Box 5689, Addis Ababa, Ethiopia.

Animal-Feed-Science-and-Technology. 1986, 16: 1/2, 99-107; 12 ref.

In 2 experiments, noug meal was given to groups of 5 wether sheep to provide 14, 26 and 40% of diets based on maize stover and 18, 34 and 45% of diets based on oat straw, both roughages being given ad lib. Two periods, each of 7 days, were used for the determination of total DM intake and digestibility by total collection. Nitrogen balance and rumen NH3 concentration were also estimated. The cereal straws were each given without supplement to one group of sheep. The intake of the roughages when given alone was similar but the apparent digestibility of cell-wall constituents was higher for the maize stover than for the oat straw. The apparent digestibility of N was negative for both straws. The addition of noug meal caused an increase in total DM intake of the complete diet but this was accompanied by a decrease in the intake of the cereal straw. The intake of NDF was similar in all the diets studied but there was a small but significant decrease in intake of both diets containing high levels of noug meal. With both roughages the addition of noug meal significantly increased the digestibility of DM, organic matter (OM) and most cell-wall constituents. The return attributable to noug meal diminished as its rate of inclusion increased and the relation could best be described by an equation of the form y = a + blogx. There was strong evidence of a positive associative effect of the noug meal on the digestibility of the cereal straws. The digestibility of the various components of noug meal was calculated by difference and the high values obtained provided further evidence of an associative effect. Nitrogen digestibility, rumen NH3 and N balance were all increased by the addition of noug meal. Maintenance requirements for N calculated by regression of N balance on N intake were lower than recent recommendations. The addition of 15-30% of noug meal to the cereal straws studied would be expected to provide a production ration for ruminants.