Factors affecting the voluntary feed intakes of sheep grazing Pennisetum clandestinum (kikuyu) pastures: observations in the animal

Abstract

Two experiments designed to establish possible reasons for the often-observed low voluntary feed intake of animals grazing kikuyu pastures were conducted at two widely differing locations. Low digestibility and low rate of digestion limited feed intake only when sheep were grazing dry, wilted kikuyu. At other times, rumen contents were relatively low, and voluntary intakes appeared to have been controlled by other factors. The foaminess of the rumen under circumstances of a low rumen fill seems to suggest that a high saponin content could have limited intake. However, the fact that a high rumen fill coincided with a high in vitro foam production in one instance may imply that a high saponin content was not instrumental in limiting intake. Only the rumen ammonia concentration and the total nitrogen content of the leaves showed a consistent relationship with voluntary intake.

Keywords: ammonia; ammonium; digestibility; digestion; foam; grazing; intake; irene animal production institute; kikuyu; kikuyu pastures; leaves; microbial protein; nitrogen; nitrogen content; pasture; pasture science; pastures; pennisetum clandestinum; production; saponin; sheep; sheep grazing; south africa; ukulinga research station

African Journal of Range & Forage Science, 10(3): pp. 145-150