Twelve 7/8 Holstein-Zebu steers were used in three 4 x 4 latin square design, consisted of three body weight groups (250, 350 e 450 kg), individualy housed in covered pens, during 60 days (four periods of 15 days). Each group of four animals were fed during four periods, with "Napier" grass (Pennisetum purpureum) and supplements constituted of four types of poultry litter (wood shavings, chopped corn cobs, coffee hulls and chopped and dry elephant grass "Cameroon"), urea and concentrate based on corn and soybean meal (70:30%), in levels of 75%, 12.5% and 12.5%, respectively. The forage and supplements were fed separatelly once per day in the morning and mineral mixture and water were furnished always ad libitum. It was observed that the association of high levels of poultry litters and urea showed elevated inhibitory effect in supplement intake, ranging from 174 to 405 g of dry matter/animal/day, for the supplements containing poultry litter constituted of chopped and dry elephant grass and wood shavings, respectively. However, the supplements supplied the nutritional requirements of the animals with 350 kg of live weight and gain of 370 g/day up to 32%, 29% and 40%, for CP, Ca and P, respectively, although the consumption of them were only 2.8 to 6.3% of the total dry matter intake. Despite the lack of supplement effects in ruminal and serum parameters, it was verified positive correlations among intakes of dry matter and crude protein of supplements and ruminal ammonia levels.
ammonia; minerals; pH; rumen; serum urea; steers
