Feeding behavior, microbial efficiency, and nitrogen balance of Nellore heifers supplemented with crude glycerin

Abstract

This study aimed to evaluate the inclusion of crude glycerin in diets for Nellore heifers grazing on a Brachiaria brizantha pasture, during the dry season, on urine and plasma urea concentrations, feeding behavior, and microbial protein synthesis. Sixty Nellore heifers with an average initial weight of 285.89 ± 18.74 kg, at approximately 19 ± 2 months of age, were distributed, in a completely randomized design, into the following five treatments with twelve replicates: 0.00, 4.00, 8.00, 12.00, and 16.00% inclusion of crude glycerin in the diet they were fed. Grazing time decreased linearly (P < 0.05) by 7.44 min with every percent of crude glycerin included in the diet. Microbial efficiency was not affected (P > 0.05), averaging 113.73g CP per kg TDN ingested. Plasma nitrogen concentration did not show any effects (P > 0.05), averaging 13.11 mg dL?1. Supplementing heifers during the dry season, at 0.7% BW, using up to 16% crude glycerin in the diet composition, did not elicit positive responses from feeding behavior and had little influence on microbial synthesis.