RUMINAL METABOLISM AND DIGESTIBILITY OF HIGH CONCENTRATE DIETS WITH VARYING PROTEIN LEVELS FOR RAM LAMBS.

Abstract

Differences among dietary protein levels suggested in the literature indicate the need for better evaluation of protein requirements of growing lambs raised in drylot and fed a high concentrate diet. Five Santa Inês ram lambs (43 kg body weigh) fitted with ruminal cannulas were used in a 5x5 latin square design. Diets contained 80% concentrate and 20% sugarcane bagasse with 12, 14, 16, 18 and 20% CP. There were no differences (P> 0.05) in dry matter, organic matter, neutral detergent fiber and acid detergent fiber apparent digestibilities in the total digestive tract. Crude protein apparent digestibility in the total digestive tract and N retention (g/day) were greater (P < 0.05) for diets with 16, 18 and 20% CP than for the diets with 12 and 14% CP. Ruminal ammonia-N concentration increased (P < 0.05) with increasing levels of dietary CP, and no differences (P > 0.05) were observed on pH and ruminal volatile fatty acids concentrations. KEY-WORDS: Ram lambs. Protein levels. Digestibility. Ruminal metabolism. High grain diet.