Efeitos da divergência fenotípica para eficiência alimentar no desempenho, termografia e metabólitos sanguíneos e ruminais em bezerras Gir após o desaleitamento

Abstract

The objectives of this study were: 1) to identify and rank phenotypically divergent animals for residual feed intake (RFI) regarding their efficiency (high – HE or low – LE); 2) to evaluate their relationships with infrared thermography, performance, ingestive behavior, and ruminal and blood parameters in Gyr heifers; 3) to determine if such measurements can be used as feed efficiency markers during rearing heifer. Thirty-eight heifers, 143 d ± 4 (Mean ± SD) of age and 108.7 kg ± 17.9 of body weight were used. The animals were fed with a total mixed ration during 91 d of a trial. A variation between -0.358 kg/d (HE) and 0.337 kg/d (LE) was observed. Dry matter intake (DMI) was lower in the HE: 2.5 kg DMI/d vs. 3.1 kg DMI/d, as well as the number of visits to the feed bin with consumption (59 vs. 71). Along with water intake, these were the measures that best functioned as markers of divergence in RFI. The ruminal fermentation variables, blood metabolites, blood hormones, such as the other ingestive behavior variables, and infrared thermography were not able to accurately predict HE or LE animals.