Metabolic profile in grazing suckling male calves supplemented with different protein regimens.

Background: the use of creep-feeding combined with the correct management of pastures has been one of the main tools of nutritional management in cattle. Objective: to evaluate the effects of supplementation with different protein regimes on the metabolic profile in grazing suckling male calves. Methods: fifty suckling Nellore male calves with average initial body weight (BW) of 114 ± 2.4 kg and 105 ± 3.0 days age were used and distributed in a completely randomized design in two treatments and 25 replicates. The protein regimens evaluated were low protein (LOW)-supplement with 150 g CP/kg DM and; High protein (HIGH) - supplement with 300 g CP/kg DM. The supplements were composed of soybean meal‚ cornmeal‚ wheat meal‚ mineral mixture‚ and molasses‚ and provided in amounts of 6 g/kg BW. The animals were subjected to 78 experimental days and kept in eight 5 hectares paddocks each‚ formed by Brachiaria decumbens and equipped with drinkers and feeders. All animals had unrestricted access to water. Blood samples were collected to quantify levels of urea‚ albumin‚ globulins‚ total protein‚ glucose‚ triglycerides‚ and insulinlike growth factor 1 (IGF-1). Globulin concentrations were calculated by the difference between total protein and albumin concentration. Results: no treatment effect was observed (p > 0.10) on concentrations of glucose (77.6 vs 81.6 mg/mL)‚ triglycerides (32.8 vs 39.2 mg/mL)‚ total proteins (6.52 vs 6.67 g/dL)‚ globulin (3.28 vs 3.25 g/dL) and IGF-1 (424 vs 441 nm/ mL); while the albumin (3.24 vs 3.42 g/dL) and SUN (10.2 vs 15.7 mg/dL) concentrations did show significant differences (p < 0.05)‚ being higher in the calves supplemented with higher level of crude protein. Conclusions: supplementation with 150 g CP/kg DM in the amount of 6 g/kg PC is recommended for lactating beef calves during the rainy season and rainy-dry transition. [ABSTRACT FROM AUTHOR]