Determinação do consumo alimentar residual de bezerros Nelore na pré e pós desmama

Abstract

In Brazil, the cattle corresponds to approximately 213 million head, being the largest productive herd in the word. As the most of the operacional costs of this production are focused on food, strategies to select more efficent animals for food use are being used. Residual feed intake (RFI) proposed by Koch et al., (1963) is an important tool for evaluating food efficiency. This mensure is defined by the difference between observed and estimated intake as a function of metabolic weight (BW0,75) and average daily gain (ADG). Thus, the objective of this study is to determine residual feed intake (RFI) in pre and post weaning of Nellore calves. Fifty-three calves were evaluated in pre-weaning phase and 25 male calves in post-weaning phase. Individual feed intake was recorded by the GrowSafe automatic feed system. Pre weaning calf milk consumption was estimated by cow milk production at 63±5, 84±5 and 152±5 after calving, by mechanical milking, and daily dry matter intanke (DMI, kg DM/day) was obtained from 35 to 190±13 days of age. The daily metabolizable energy intake of the calf at weaning (Mcons, Mcal/day) was estimated by summing the metabolizable energy intake of the diet (Mcal/day). At weaning, residual metabolizable energy consumption (RFI pre) was estimated as the residue of the Mcons regression equation on mean daily gain (ADG) and metabolic mean body weight (BW0,75) obtained at weaning. After weaning, the calf RFI was estimated by the residual of dry matter consumption (DMI) regression equation on ADG and BW0.75 obtained after weaning. The average of Mcons (pre-weaning) and DMI (post-weaning) was 9.90±2.10 Mcal/day and 7.63±0.77 kg/day, respectively. RFI ranged from 3.30 to 3.24 Mcal/day and from -0.920 to 0.910 kg/day, respectively in pre and post weaning period. Correlation between Mcons and DMI (pre and post weaning) was significant (0.468), however correlations between ADG and between RFI obtained in pre and post weaning were low and non significant (0.191 and 0.150). The results showed the feed efficiency of Nellore calves in pre and post weaning may be not the same trait. RFI is not consistent and repeatable in these two growth periods.