Farelo de tratado com taninos em dietas com alto teor de concentrado para bovinos de corte

Abstract

Four experiments were carried, and the first trial was conducted to evaluate the effect of different tannins on the amount and quality of RUP of different foods rich in high biological value proteins. The other 3 trials (2, 3 and 4 chapter) was conducted to evaluate the effects of replacing traditional soybean meal to soybean meal treated with tannin on intake, digestibility, performance, carcass traits, yield of commercial carcass cuts, meat quality and fatty acid composition of beef bulls finished on feedlot fed high concentrate diets (84% of DM). Bulls were fed with cracked corn, whole cottonseed and sugar-cane bagasse in natura, soybean meal treated with CT (SBMT) and traditional soybean meal (SBM). The treatments consisted of 4 levels of replacement of soybean meal whith soybean treated with CT (0, 33, 66, and 100%) and one treatment with 2.5% of SBMCT (relative to 33% of SBMT) but without SBM, which was replaced by urea and corn (with the same level of CP of soybean meal) (SBM+U). To the trial 2, It was used five Nellore bulls, with 290 ± 11.2 kg body weight, fitted with rumen and abomasum cannula. To the trial 3 and 4, Forty-two crossbred Nellore bulls were used in the study, with an average initial body weight of 242.6 ± 5.12 kg. On trial 2, the ether extract and NDFap intake were the only parameters related to food intake affected (P<0.05) by replacing the conventional soybean meal (SBM) by soybean meal treated with tannin (SBMT). Ruminal and intestinal digestibility were linear (P<0.05) only for crude protein (CP). Rumen undegraded protein intake and metabolizable protein intake showed increased linear (P<0.05) with the substitution SBM by SBMT. Rumen degradable protein intake and microbial protein (g/day) showed linear decrease (P<0.05), with the substitution SBM by SBMT. On trial 3, no significant effects (P>0.05) of treatments were observed for some of the variables evaluated: average daily gain, EBW gain, carcass daily gain and carcass yield in relation to body weight. On the other hand, dry matter intake (DMI), rib fat thickness (RFT) and flank yield decreased linearly (P<0.05). Feed conversion (FC) had a quadratic behavior (P<0.05) with better FC with 60% with the

substitution SBM by SBMT. On trial 4, no significant effects (P>0.05) of treatments were observed for the profile of fatty acids in abomasal digesta. On muscle was observed only differences (P <0.05) for stearic acid (C18: 0) and monounsaturated fatty acids. To profile of fatty acid deposited in subcutaneous fat showed increased linear (P<0.05) with the substitution SBM by SBMT. There was no interaction (P>0.05) between the treatments and days of storage of beef steaks. No difference was observed between treatments for beef color variables (P>0.05). There was an interaction between storage time and treatments for TBARS (P<0.05). Differences were observed between the shelf life only for treatments 0, 66% and SBM+U treatment. The replacement traditional soybean meal to soybean meal treated with 2.5% of tannin (85% of condensed tannin and 15% of hydrolysable tannin) in high concentrate diets implies in changes in the composition of the animals gain by increasing the rate of gain of muscle tissue in the carcass. However, at the same time causes reduction in dry matter intake, promot better feed conversion. And implies changes in fatty acid profile, especially subcutaneous fat, with no changes on meat quality.