Desempenho produtivo e econômico de bovinos terminados com diferentes alimentos energéticos e aditivos em dietas sem forragem

Abstract

The objectives of this study were to evaluate the performance, carcass and meat characteristics, as well as the economic feasibility of finishing cattle fed without forage diets. The animals were of the Nellore breed, uncastrated males, aged between 24 to 30 months and with a body weight of 415 (± 32 kg). Blood samples were collected to evaluate D-Lactate. After evisceration, entire surface of the rumen was evaluated and sampled. After cooling, subcutaneous fat thickness (SFT) and lein muscle area (LM) in the Longissimus thoracis muscle were measured. Muscle samples were analyzed to determine: pH, color, cooking weight loss (CWL), shear force, chemical composition, collagen and fatty acid (FA) profile. The research was divided into two experiments, the first being an evaluation of different energy sources; and the second an evaluation of additive associations. Experiment 1: 96 steers were used, with meat from 60 animals being sampled. Experiment 1: 96 steers were used, sampling meat from 60 animals. The DIC was used, with four treatments and 24 repetitions, which received one of the rations: RM - ground corn; RMP1 - ground corn and citrus pulp (2:1); RMP2 - ground corn and citrus pulp (1:1); RS - ground sorghum. In the economic feasibility analysis, the effective operating cost (EOC) and the profitability indicator gross margin (GM) were estimated, as well as the economic benefits (EB). There were differences for final body weight, average daily gain (ADG), dry matter intake (DMI) and feed efficiency (FE). In the evaluation of carcasses and meat, the indicators dressing percentage (DP), gain yeld (GY), SFT, pH, CWL, crude protein, mineral matter and moisture differed between treatments. The FA differed for palmitic, myristoleic, palmitoleic, elaidic and ecosatrienoic, in addition to the sum of monounsaturated FA. The EOC components that had the greatest representation were the animals acquisition and feed. RMP1 and RMP2 had the highest values for GM and EB indicators, respectively. The partial replacement of ground corn by citrus pulp or total by ground sorghum showed to be viable alternatives for the maintenance of ADG in carcass, which are zootechnical performance indicators with a direct relation to profitability in feedlot systems. Experiment 2: 92 steers were used, and meat from 40 animals was sampled. The DIC was used, with two treatments and 46 repetitions, which received: MOE - ration with monensin and a blend of essential oils (32mg and 150mg/kg DM, respectively); MVM - ration with monensin and virginiamycin (32mg and 27mg/kg DM, respectively). MOE showed higher DP and GY. DMI did not differ; however, FE was better for MVM. D-lactate was lower for MOE only at the end of adaptation. Lower ruminits scores and number of papillae were observed in MVM, although the absorptive surface area did not differ. MVM showed higher LM area and lower CWL. The use of a blend of essential oils proved to be efficient in replacing virginiamycin and an alternative to the use of antibiotics in a bovine finishing system without forage.