Goats fed with non-protein nitrogen: ruminal bacterial community and ruminal fermentation, intake, digestibility and nitrogen balance

The current study assessed ruminal fermentation parameters and bacterial community, nutrient intake, nutrient digestibility and nitrogen balance of goats fed diets containing buffel grass hay and ruminal ammonia nitrogen (N-NH3). Five rumen-cannulated mixed-breed castrated adult goats (45 ± 2.3 kg) were used in a 5 × 5 Latin square design represented by five N-NH3 levels (3.43, 9.95, 17.2, 23.0 and 33.7 mg/dl). Control animals were fed hay exclusively. Other treatments were represented by ruminal infusion composed of a mixture containing urea, ammonium sulphate and casein. The increasing N-NH3 concentrations did not affect rumen fluid pH, which averaged 6.43. Rumen ammoniacal nitrogen increased linearly in response to N-NH3. Volatile fatty acids were not affected by increasing N-NH3 concentrations. A higher abundance of Ruminococcaceae (Ruminococcus 1, Ruminococcaceae UCG-014 and Ruminococcaceae NK4A214 group) was observed in the rumen of goats infused with higher concentrations of N-NH3 (17.2 and 33.7 mg/dl N-NH3). There was a quadratic effect (P < 0.050) of N-NH3 levels on neutral detergent fibre intake with maximum values estimated at 13.7 mg/dl N-NH3. Nutrient intake, nitrogen excretion and nitrogen balance presented a positive linear effect (P < 0.050). In conclusion, 3.43 mg/dl of N-NH3 is the minimum level to maintain microbial activity, whereas the recommended level to optimize the microbial community is 14.5 mg/dl of N-NH3 in the rumen of goats fed buffel grass.