Effect of slow release urea in sheep feed on intake, nutrient digestibility, and ruminal parameters

Abstract

This study aimed to evaluate the inclusion of 0.0%, 0.4%, 0.8%, and 1.2% slow release urea (SRU) in sheep feed on the intake and total digestibility coefficient (DC) of nutrients and ruminal parameters of sheep living in tropical regions. Four sheep with a body weight (BW) average of 30.8 ± 1.7 kg were assigned to a Latin square design. The animals were placed in metabolic cages and received two meals a day. Intake data and DC of nutrients of the sheep were subjected to analysis of variance and differences were tested using a regression equation to 5% probability. The inclusion of 0.0%, 0.4%, 0.8%, and 1.2% SRU in sheep feed did not change (p > 0.05) the intake of dry matter (DM), organic matter (OM), crude protein (CP), ether extract (EE), neutral or acid detergent fiber (NDF, ADF), total carbohydrates (TC), and non-fibrous carbohydrate (NFC) expressed in g animal-1 day-1, g (kg0.75)-1, and % BW. The mean values of 3.04%, 2.82%, 0.41%, 0.07%, 1.36%, 0.87%, 2.31%, and 1.00% of BW were obtained for the intake of DM, OM, CP, EE, ANF, ADF, TC, and NFC, respectively. The inclusion of 0.0%, 0.4%, 0.8%, and 1.2% of SRU in sheep rations had a quadratic manner (p < 0.05) the DC of DM and CP, with maximum values of 69.67% and 63.59%, respectively, for 0.51% and 0.66% levels of SRU inclusion in the experimental diets. The pH of the rumen fluid did not vary (p > 0.05) for different levels of inclusion of SRU in the feed. However, the pH of the rumen fluid did differ (p < 0.05) in relation to time (T) after feeding for all experimental diets. The inclusion levels of SRU in sheep feed did not affect (p > 0.05) the concentration of ammonia nitrogen (NH3-N) of the rumen fluid, but there was a quadratic effect (p < 0.05) with relation to T for all experimental diets. Thus, we conclude that the inclusion of 0.66% SRU provides the best digestibility value of CP and is the appropriate value for the digestion of DM. The inclusion of up to 1.2% of SRU in sheep rations did not change the intake of nutrients and ruminal parameters.