Spineless cactus-based diets associated with various nitrogen sources in sheep diets

This study evaluated the effects of various nitrogen (N) sources augmenting spineless cactus-based diets on intake, digestibility, rumen kinetics and N balance in sheep. Eight rumen-fistulated sheep with an average initial bodyweight of 62 ± 6.83 kg were allotted to one of two 4 x 4 Latin squares. The diets consisted of spineless cactus (Nopalea cochenillifera), Tifton hay, corn grain, vegetable oil and a mineral mixture augmented with either soybean meal (SBM), cottonseed meal (CSM), whole cottonseed (WCS) or urea (U) to provide additional nitrogen. Dry matter (DM), crude protein (CP), and neutral detergent fibre (NDF) intakes were similar (P >0.05) for sheep fed the diets with SBM, CSM, and WCS. The digestibility coefficients of DM and CP were similar (P >0.05) for SM, CM, and U diets. The rate of DM disappearance from the rumen did not differ (P >0.05) between treatments. However, the rumen ammonia, pH and N balance was higher (P <0.05) for sheep fed the WCS and U diets. The N absorbed and N retained did not differ (P >0.05) between the diets. Soybean meal and CSM are similar in their effects and can be used for sheep in diets based on spineless cactus. Whole cottonseed and U are interesting sources of N but should be used with caution owing to their effects on digestibility and nutrient intake in sheep.