Confinamento e semiconfinamento de novilhas alimentadas com dietas contendo milho inteiro ou moído

Abstract

The objective of this study was to evaluate the processing of corn (ground or whole) and two finishing systems (grazing systems or feedlot) in the dry season, on the intake, performance, profitability and characteristics of the carcass and meat of Nellore heifers. A completely randomized experimental design was used in a 2 x 2 factorial arrangement (two grains processing and two finishing systems) with nine replications per treatment. Thirty-six heifers were used, with an average age of 17 months and initial weight of 258.66 kg ± 22.93. The experimental period was 119 days in the dry period of the year. The concentrates were formulated with whole or ground corn and a commercial pellet (Engordim ®) in a grain: pellet ratio of 850:150 g/kg in the dry matter (DM). At the end of the experiment the animals were slaughtered in a slaughterhouse located in the city of Araguaína-TO. There was no difference in the concentrate intake between the systems (3.84 kg / day). The ground corn increased (P <0.05) the concentrate intake and consequently the nutrient intake of the concentrate. The feedlot intake of silage was not altered by the corn processing (2.38 kg / day). Despite the difference in concentrate intake, there was no difference (P> 0.05) in the total dry matter intake in the feedlot (6.23 kg / day). The higher intake of concentrate with ground corn (3.94 vs 3.74 kgDM / day) reflected a higher (P <0.05) average daily gain (0.815 vs 0.695 kg / day), since the finishing systems promoted similar performances, with no difference (P> 0.05) regarding total weight gain and total carcass gain (89.97 kg, 47.97 kg). The daily cost with concentrate was similar between the systems, the difference occurred between whole and ground corn, with higher cost for ground corn. Feedlot finishing shows higher roughage cost, and consequently higher (p <0.05) total cost with feed (578.77 against 513.36 R $). There was no difference in net revenue and profitability between using whole or ground corn in the pasture (p> 0.05), however, in feedlot the ground corn reduced net revenue and profitability (p <0.05) by the pasture-like performance, but with higher food costs. The finishing system did not influence the characteristics of the carcass and meat. Animals fed with ground corn presented higher (P <0.05) slaughter weight, hot carcass weight (187.98 vs 176.04 kg), fat trimming and whole hot carcass weight. The factors tested did not change the yields of hot and cold (52.24%, 50.56%), cooling loss and subcutaneous fat thickness (4.18 mm) (P> 0.05). The feed of ground corn increased (P <0.05) the weight of the primary cuts, but did not alter the proportions and promoted an increase (P <0.05) in the percentage of carcass fat (27.32 vs 23.19%) and in the ratio edible portion/bone. Although the corn processing enhances the concentrate, it promotes higher performance and improves the characteristics of the carcass, however, in the feedlot it was impracticable to supply ground corn. By not altering the characteristics of the carcass and meat the pasture termination system can be used to produce good quality carcasses.