Microbial protein synthesis and nitrogen metabolism in goats

This study aimed to estimate the microbial protein synthesis by purine derivatives method and to evaluate blood and urinary nitrogen metabolism in the semiarid region. The supplementation was based on 1% of body weight in dry matter. The treatments were: PA= free grazing without supplementation; LEU = leucaena hay (Leucaena leucocephala (Lam) from Wit.); LEU+P= leucaena hay + forage cactus (Nopalea cochenillifera - Salm Dyck); SAB= “sabiá” hay (Mimosa caesalpinifolia Benth); and SAB+P= “sabiá” hay + small forage cactus. Purine derivatives and, consequently, absorbed purines, nitrogen and microbial protein showed a significant difference (P<0.05) among treatments, also it was presented that supplementations with leucaena hay without and with small cactus had higher averages. Urea and plasma nitrogen showed significant differences (P<0.05) between treatments with higher values for the treatment with leucaena hay and “sabiá” hay. Urea and urea nitrogen did not show significant difference (P>0.05) between treatments. However, supplementation with leucaena hay for goats on pasture in the Caatinga promotes greater microbial protein synthesis between treatments. The blood and urinary nitrogen metabolism presented concentrations within the normal range in all treatments.