Abstract 168

Kabaija,-E; Smith,-OB

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

Animal-Feed-Science-and-Technology. 1988, 20: 2, 171-176; 15 ref.

Six- and 12-week regrowth samples of 2 legumes (Gliricidia sepium and Leucaena leucocephala) and 2 grasses Panicum maximum (Guinea grass) and Cynodon nlemfuensis (giant star grass) were analysed for Mn, Fe, Zn and Cu content. The change in content of Mn, Fe and Zn in the forages due to age of regrowth was inconsistent but Cu content decreased with age of regrowth in all the forages. The Cu content in all the forages and the Zn content in all except giant star grass were marginal to deficient for cattle requirements. The disappearance of Fe, Zn and Cu from forages in nylon bags suspended for 48 h in the rumen of sheep was highest in 6-weeks regrowth for all the forages, while that of Mn was highest in 12-weeks regrowth of legumes. The percentage release of Zn and Cu from the forages was on average less than 30%. Because of their low concentration in the forages, as well as low percentage release in the rumen, it would be advisable to offer supplemental Zn and Cu to cattle in cases where these 4 forages are the sole feed.