Relationship between non-protein nitrogen and true protein in supplements during the post-weaning phase of Nellore steers in the dry-wet season transition

Abstract Text: The objective of this study was to evaluate the effect of different levels and rates of protein degradation , on the performance of Nellore , recreated on Brachiaria brizantha . Marandu during the transition period dry water . 72 bulls were used with 412.45 kg body weight (BW ) initial, non-castrated Nelore , daily receiving 3 g / kg BW of supplement , these were divided into 12 paddocks. The treatments were : energy protein supplement ( SPE ) with 25 % CP (control ) , energy protein supplement with 40 % CP , 1 /3 of the PB of vegetable and 2/3 of chemical origin , Supplement energy protein with 40 % CP , with two thirds of the PB of vegetable and 1/3 of chemical origin , energy protein supplement with 40 % CP , 1 /2 PB of plant origin and half of chemical origin . The animals were weighed every 28 days after 16 hours of fasting and liquid in order to obtain the average daily gain (ADG ) . The experiment took place from September to December 2013, totaling 84 day evaluation . The experimental unit used was the picket, which is composed of six testeres animals . The experimental design was a randomized block experimental areas and the blocking factor , there were three paddocks per treatment. Data were analyzed using mixed model using the MIXED procedure of SAS software, version 9.2 ( SAS , 2008) , the 10% level of significance by t test. The increase in NNP ( 40-2/3NNP ) depressed ADG ( P = 0.07 ) 0.265 kg / day in compared to other treatments with averaged 0.366 kg , 0.419 kg and 0.399 kg for C - 25 , 40-1 / 2NNP and 40-1/3NNP respectively. The final body weight was greater ( P = 0.08)in animals that received 40-1/2 NNP ( 416.7 kg ) compared to those who received C - 25 ( 408.5 kg ) or 40-2/3 NNP ( 404.4 kg ) . The 40-1/3NNP treatment with intermediate weight (413.1 kg) did not differ from treatments 40-1/2 NNP (P = 0.40) and C - 25 (P = 0.30) . It is concluded that supplementation with 40 % CP and ½ NNP is able to generate heavier animals in the transition dry - waters.  Supported by CNPq and Bellman.

Keywords: average daily gain, brachiaria brizantha, supplementation