The effect of dietary protein on reproduction in the mare. I. The composition and evaluation of the digestibility of dietary protein from different sources.

Four rations that differed in their crude protein and essential amino-acid content were compiled. Digestibility of the crude protein and essential amino-acid contents were determined biologically in a feeding trial using 4 Anglo-Arab stallions. Their respective daily diets were: Diet 1:2 kg cubes, 5 kg tef hay (Eragrostis tef); Diet 2:2 kg cubes, 5 kg lucerne hay (Medicago sativa); Diet 3:2 kg cubes, 5 kg tef hay, 200 g fishmeal; Diet 4:2 kg cubes, 5 kg lucerne hay, 200 g fishmeal. The concentrations of the amino-acids threonine, iso-leucine, leucine and arginine were increased in the total ration when lucerne hay replaced the tef hay while fishmeal supplementation increased the methionine and lysine contents, which provided a wide-range of concentrations of digestible amino-acids in each of the 4 rations.