Correlations between feed efficiency and ingestive behavior of Nellore breed bulls housed in collective pens equipped with electronic feed bunks The evaluation of ingestive behavior in beef cattle allow a better understanding of the mechanisms that involve the variations in the efficiency of food utilization, based on the energy expenditure of the animals, making it possible to identify the feeding patterns of more efficient and less efficient animals. Thus, the aim of this study was to evaluate the associations between feed efficiency and ingestive behavior of 603 Nellore bulls housed in collective pens equipped with electronic feed bunks. The animals received a total mixed ration containing 70 % of total digestible nutrients and 14 % of crude protein for 56 days to obtain dry matter intake (DMI) and average daily gain (ADG) data to calculate the residual feed intake (RFI), feed conversion ratio (FCR) and gross feed efficiency (GFE). The behavioral variables were obtained by the electronic monitoring system of the automatic feed bunks, being evaluated the total time in trough (TT), feeding time (FT), total visits (TV), visits with and without feed intake (VI and VwI) and feed rates per hour and per visit. Pearson simple correlations were estimated through CORR procedure of SAS and were considered significant when P<0.05. The final live weight (FLW), metabolic live weight (MLW0.75) and ADG presented weak positive phenotypic correlations with feed rates per hour (0.36, 0.34 and 0.13, respectively) and per visit (0.23, 0.22 and 0.10, respectively). Weak positive correlations were observed between observed dry matter intake (DMIobs) and TT (0.09), FT (0.09), TV (0.24), VI (0.23) VwI (0.17) and feed rate per hour (0.45). The DMI calculated on the basis of live weight (DMI %LW) was positively correlated to TT (0.13), FT (0.14), TV (0.31), VI (0.32), VwI (0.17), feed rate per hour (0.15) and it was negatively associated with the feed rate per visit (-0.21). The RFI presented weak positive correlations with TV (0.14), VI (0.14), VwI (0.11) and feeding rate per hour (0.26). The FCR showed weak positive correlation with feed rate per hour (0.09), while the GFE was negatively associated with TV (-0.14), VI (-0.14), VwI (-0.08) and feeding rate per hour (-0.13). Feed efficiency measures such as residual feed intake and gross feed efficiency presents significant correlations with ingestive behavior characteristics of Nellore bulls in feedlot, being possible to observe a pattern of behavior of the more efficient animals for these measures. Keywords: Bos indicus, dry matter intake, feeding rates, residual feed intake, weight gain

Luiz Otavio C SILVA, Ricardo Favero, Vinicius Okamura, Marcus Vinicius L Junior, Andrea Gondo, Roberto Augusto A Junior, Gilberto Romeiro O Menezes, Rodrigo C Gomes

Proceedings of the World Congress on Genetics Applied to Livestock Production, Volume Electronic Poster Session - Biology - Feed Intake and Efficiency 1, , 782, 2018
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