Supplements containing different crude glycerin concentration does not affect the intake and digestibility of Nellore grass-fed beef

Abstract Text: The aim of this work was to evaluate the effect of crude glycerin (CG) - 80% of glycerol - inclusion as a substitute to corn grain in the intake and digestibility (DM, OM, CP, NDF and TDN) of Nellore steers on pasture, supplemented in the dry season. Ten rumen-cannulated Nellore steers, with average body weight of 427 ± 15.76 kg were randomly assigned in double Latin square 5 x 5. The animals were distributed in five paddocks, of 0.4 hectares each (two animals per paddocks). Treatments were constituted by five concentrations of CG in the supplement: 0, 70, 140, 210 and 280 g / kg dry matter of CG. Animals were supplemented individually, daily in a proportion of 300 g / 100 kg of BW. The supplement was constituted of corn grain, soybean meal, urea, gluten meal and commercial premix, containing 300 g / kg DM of crude protein. Each experimental period lasted 14 days, so the first ten days were for animal’s adaptation and the remaining days to collect samples. Intake and nutrient digestibility were estimated using two markers: isolated, purified and enriched lignin (LIPE^®) and indigestible neutral detergent fiber (iNDF), used for estimation of fecal excretion and forage intake, respectively. Fecal samples were collected directly from the rectum, two times a day for three days, totaling six samples, with an interval of two hours between collections. Data were analyzed in two simultaneous 5 x 5 latin squares by MIXED procedure of SAS (version 9.1), the effects of treatments were considered significant at P<0.05. There was no statistical significance among the treatments, for intake of DM (P = 0.239), OM (P = 0.183), CP (P = 0.076), NDF (P=0.179) and TDN (P=0.218) with mean values of 7.59, 7.05, 1.24, 3.9 and 3.88, respectively. The inclusion of glycerin had no effect in the digestibility for DM (P = 0.286), OM (0.315), CP (P=0.339) and NDF (0.270), with mean values of 44.26, 51.50, 57.20 and 43.04, respectively. The inclusion of crude glycerin until the level of 280 g / kg DM in the supplement did not affect the intake and digestibility of Nellore steers fed on tropical pasture in the dry season.

Keywords: pasture, co-product, biodiesel, glycerol