Glicerina bruta de baixa pureza na dieta de caprinos em confinamento

Abstract

This study aimed to evaluate the effects of the inclusion of crude glycerin (CG) on feed intake and apparent digestibility of dry matter (DM) and its components, performance, ingestive behavior, metabolic profile, carcass characteristics, components not constituents of carcase meat quality and economic analysis. Forty goats (19,70 ± 2,30 kg) with no defined racial pattern were used. The treatments consisted of inclusion of GB (63.06% glycerol) on the levels of 0; 6; 12 and 18%. The experimental design was completely randomized, with the initial PC used as a covariate, with ten repetitions. The intakes of DM, organic matter (OM), crude protein (CP), neutral detergent fiber (NDF), non fiberous carbohydrate (NFC) and total digestible nutrients (TDN) decreased linearly (P <0,05). No influence (P> 0,05) was observed for the apparent coefficients of digestibility DM, OM, CP and NDF. The levels of inclusion of GB did not affect (P> 0.05) the final body weight, total weight gain, average daily gain. The time spent by animals with food in h and in percentage % was not influenced by the inclusion of GB in the diet (P>0.05). In relation to rumination time, in h and percentage %, there was an increasing linear effect (P <0.05). The leisure time and the water intake (l/day) decreased linearly (P <0,05). In relation to blood metabolites, cholesterol presented a linear increasing effect (P <0,05), whereas beta-hydroxybutyrate reduced linearly (P <0,05). The empty body weights, hot and cold carcass, as well as pH 24 post mortem hours and loin eye area decreased linearly. It was observed that the blood was influenced quadratically, with a minimum point of 0,75 kg, at the level of 15% of CG. The inclusion of CG in diets did not interfere (P> 0,05) in the size of the liver, heart, kidneys and pancreas. In relation to the deposits of fat, there was no influence of treatments (P>0.05) on the mesentery, omentum, perirenal and internal fat. The perimeter of the leg showed a quadratic behavior, with a minimum point of 28,12 cm, at the level of 12% of CG. The chest circumference and the carcass compactness index decreased linearly. The palette, rib, serrote and leg cuts were influenced in a linearly decreasing manner. In relation to the tissue composition of the leg, it was observed that the weights of the reconstituted leg, muscle and bone decreased linearly (P <0,05). The inclusion of CG did not affect the physicochemical parameters of meat, such as color (L*, a* and b*), water retention capacity (WRC), weight loss cook (WLC), shear force (SF) and pH (P>0,05). The moisture, mineral matter (MM) and ethereal extract (EE) of the meat were influenced by the inclusion of CG in the diet (P <0,05). The crude protein (CP) of meat was not affected by the increase of CG levels (P> 0,05). The level of 18% of CG presented higher gross profit (R$ 11,24) and rate of return of feedlot (6,22%). Crude glycerin may partially replace maize and be included in up to 18% dry matter of the goat diet in feedlot.