Microbial protein synthesis in goats grazing supplemented with concentrates containing mesquite pod meal

This study aimed to evaluate the effect of concentrate supplementation levels to crossbred goats under deferred grazing grass Urochloa mosambicensis (Hack) Daudy on microbial protein synthesis. We used 35 Boer crossbreed goats, not castrated, and weaned with initial body weight (BW) 24.03 ? 2.91 kg and approximately 120 days of age. The experimental design was completely randomized with five treatments and seven replications. Data were submitted to analysis of variance and realized the orthogonal contrast between the control treatment versus levels of supplementation and study of levels of the supplementation was done by regression analysis and polynomial contrast adopting 5% probability. After a 15-day adaptation period was initiated the experimental period, which was 90 days. The treatments were the control (protein salt supplement) and levels of supplementation with concentrate containing mesquite pod meal (0.5, 1.0, 1.5 and 2.0% BW).The samples of spot urine of each animal were obtained on the 22nd day of each experimental sub-period, after 4 hours of supplement intake during spontaneous urination. Aliquots of 10 ml were diluted with 40 ml of 0.036 N H₂SO₄and then stored at -20 ?C for subsequent analysis of creatinine and purine derivatives.The level of supplementation 1.5% PC showed maximum microbial protein synthesis, however, the higher microbial efficiency was not obtained for this level of supplementation, which was 0.5% BW, due to less intake of TDN.