Effect of supplementation of beef XXXX with different protein levels and degradation rates during transition from the dry to rainy season.

@entity1131 @entity291
UNASSIGNED: The objective of this study was to evaluate the effect of increasing the supply of protein with different degradation rates on the performance and metabolism of growing Nellore @entity291 reared on Brachiaria brizantha cv. Marandu pasture during the transition period from the dry to rainy season. The experiment was installed on an area of 34  ha, divided into 12 paddocks with an average area of 2.85  ha. In the performance evaluation were utilized 72 recently weaned, non-castrated Nellore @entity291 with an initial body weight (BW) of 199  kg (SEM   =   16). The following supplements were used: energy protein supplement containing 25  % @entity1131 ( @entity1131 ) (C-25) and energy protein supplements containing 40  % @entity1131 with one third highly degradable @entity1131 and two thirds poorly degradable @entity1131 (40-1/3NPN), one half highly degradable @entity1131 and one half poorly degradable @entity1131 (40-1/2NPN), and two thirds highly degradable @entity1131 and one third poorly degradable @entity1131 (40-2/3NPN). Higher protein degradation rates reduced supplement intake (P   <   0.01). In the first period, animals consuming supplement 40-1/3NPN exhibited higher average daily gain (ADG) (0.30  kg/day), similar to that of animals receiving supplement 40-1/2NPN (P   =   0.04). In the second period, supplement 40-2/3NPN resulted in lower ADG (0.19  kg/day less than the other supplements). There was no effect of supplement on animal performance in the third period (P   >   0.10), when ADG was 0.56  kg/day. In conclusion, the response to supplementation is associated with interactions with characteristics of the forage canopy. Supplementation with a true protein source will be beneficial only during the early stage of the dry-rainy season transition period.
