The intake, digestibility, nitrogen balance and energetic balance were evaluated in sheep diets consisting of hay from Tifton 85 grass at two ages of regrowth (28 and 42 days) and hay from leucaena at 40 days of regrowth, in the proportions of 20 and 40%. Twenty Santa Inês sheep, kept in metabolic cages, were used in a randomised block design according to body weight. The hay from the Tifton 85 grass, processed at 28 days of regrowth, resulted in a higher CP intake than when processed at 42 days of regrowth. There was higher protein intake for the 40% proportion of leucaena hay in relation to that of 20%, regardless of the regrowth age of the grass. Diets containing Tifton 85 grass processed at 28 days resulted in greater values for both DE and ME. There was greater intake, absorption and urinary excretion of N, and a lower Nfaecal to Nurinary ratio, with diets containing Tifton 85 grass processed at 28 days, as well as with those diets containing 40% leucaena hay. When formulating sheep diets containing hay from Tifton 85 grass processed at 28 days of regrowth and combined with 20% hay from leucaena, the grass, despite showing good energetic value, is not enough to provide full use of the nitrogen available to the ruminant, making it necessary need to find combinations with concentrated food sources which are able to optimise the use of nitrogen, reduce environmental impact and maximise sheep production.
Nutrient balance; Voluntary intake; Cynodon spp. Digestibility; Leucaena leucocephala
