Blood glucose concentrations and deposition of muscular and subcutaneous fat tissues of Nellore young bulls finished in pasture supplemented with crude glycerin

Abstract Text: This trial aimed to evaluate the effects of feeding crude glycerin (CG) - 80% of glycerol - included as a substitute to corn grain in supplements of young bulls finished in pasture on rainy season on deposition of muscular and subcutaneous fat tissues and blood glucose concentration. The longissimus muscle area (LMA), rib fat thickness between the 12 and 13 ribs (RFT) and subcutaneous fat thickness in the region P8 (P8) were evaluated. Fifty Nellore young bulls with initial shrunk body weight of 427 &plusmn; 15.76 kg were randomly assigned to five treatments consisted of increasing crude glycerin concentration in the supplement: 0, 7, 14, 21 and 28% of dry matter. The CG used was derived from soybean biodiesel production. Animals were distributed in 10 paddocks of <i>Brachiaria brizantha</i> cv. Xaraés, with 1.8 hectares each (two paddocks per treatment). The animals were supplemented daily in a proportion of 300g/100kg of BW. The supplement control was constituted of corn grain, soybean meal, urea, gluten meal and mineralized salt, containing 370 g/kg DM of CG. The measurements were done in the beginning of the experiment and in each 28 days, by ultrasound (Model Aloka 500, linear carcass probe with 17.2 cm and frequency of 3.5 MHz), to evaluate the deposition of muscular and subcutaneous fat tissues. Blood was collected in vacutainer tubes from the tail vein after 16 hours withdrawal period from feed and water. Data was analyzed using the GLM procedure of SAS program and the effects of treatments (linear and quadratic) were considered significant at P&gt;0.05. There was no statistical significance (P&gt;0.05) among the treatments, and the final average values observed were: 71.5 cm² to LMA, 4.4 mm to P8 and 3.7 mm to RFT. The gain observed in the variables (initial value – final value) LMA, P8 and RFT were 13.3 cm² 1.7 mm and 1.3 mm, respectively. CG inclusion did not affect the blood glucose concentrations (P&gt;0.05), however the values showed a quadratic effect (P = 0.020), with the highest concentration (81.8 mg/dL) in the level of 14% inclusion of crude glycerin. Addition of crude glycerin in supplement (28% of DM) does not affect the deposition of muscular and subcutaneous fat tissues or blood glucose concentrations of Nellore young bulls finished in pasture on rainy season.

Keywords: beef cattle, glycerol, pasture