Nutritive value of diets composed by starch and nitrogen sources with high and low ruminal degradability

The objective of this study was to evaluate the intake, apparent digestibility coefficient (ADC), nitrogen balance, pH and nitrogen ammonia concentration (N-NH3) in the ruminal fluid of sheep. The animals were fed diets composed by concentrates with different ruminal degradability of the fractions starch and protein from the used sources: starch with high (triticale) and low (corn) ruminal degradability combined with nitrogen (N) sources of high (canola meal plus urea) and low (cottonseed meal plus meat and bone meal) ruminal degradability. Sixteen Suffolk sheep, castrated, weighing 37 kg LW were used to estimate the ADC by means of the total collection of feces and urine method. A completely randomized experimental design, with a 2 x 2 factorial arrangement, with four replicates per treatment, was used. In the evaluation of pH and N-NH3, a split plot design was used, being the treatment the whole plot and the time of sampling as the split plot. Higher intakes of dry matter (DM), crude protein (CP) and neutral detergent fiber (NDF) were observed in the animals fed N diets of low ruminal degradability. Higher DM, CP and gross energy ADC were observed for N diets with high ruminal degradability, and for starch, diets with high ruminal degradability of starch and N. The N diets with low ruminal degradability showed the highest values of pH and the lowest concentration of the ruminal ammonia.