Desempenho de vacas girolando F1 em pastejo rotativo de Panicum maximum cv. Mombaça suplementadas com diferentes fontes de proteínas não degradáveis no rúmen e de carboidratos

Aiming to evaluate the dry matter intake (DMI), milk production and composition, production of derivatives of purine and kinetics of digestion of cows girolando F1, were supplied with two sources and two levels of rumen undegradable protein (RUP) associated with corn or citrus pulp. The experiment was a 4 x 4 Latin square with three replications in a factorial 2 x 2, ie two energy sources (corn or citrus pulp) and two amounts of RUP (40% or 33% CP) . Diets were Amido40 (A40), Pectina40 (P40), Amido33 (A33) and Pectina33 (P33). Diets were formulated to be isonitrogenous and isocaloric, differing in RUP content. Cows on diets P33 and P40 had higher DMI compared with the A33 and A40 diets, with (p = 0.02 and p = 0.08), respectively. Milk production corrected for fat and 3.5% (LCG3, 5) was higher in the P33 diet (p = 0.08) compared with the A33, with yields of 31.32 and 29.60 kg / day, respectively . The percentage of milk fat was different (p = 0.03) among the treatments of low RUP, P33 and A33, (3.74 and 3.43% respectively). The percentage of protein was higher (p = 0.001) for treatments of corn, regardless of level of RUP, and the amounts of 2.93, 2.77, 2.93 and 2.80, for A40, P40, A33 and P33 respectively. The treatment with citrus pulp (P40 and P33 vs. A40 and A33) had lower (p = 0.003) values of milk urea nitrogen (MUN), 17.13 and 18.42; vs. 20.66 and 21.80 mg / dl, respectively. When comparing the treatments of citrus pulp between them (P40 vs. P33), with values of 17.13 and 18.42 NUL, respectively, the P40 was lower (p = 0.01) than the P33. The concentrations of uric acid, creatinine, allantoin and allantoin ratio to creatinine were not influenced by different treatments (p> 0.05). The passage rate of solid and liquid phases were high above 5.52% / h, reaching values of 6.36% / h and ranged from 10.09 to 13.24% / h for the solid and liquid states, respectively . Increasing the RUP does not increase milk protein. The passage rate of dairy cows in rotational grazing Panicum maximum cv. Mombasa were high when compared to those found in the literature.