Avaliação bioeconômica da cultura do milho (Zea mays L.) utilizada sob diferentes formas na alimentação de novilhos em confinamento

Abstract

The times of low remuneration for corn discourage its cultivation and marketing, and cause losses to producers, being necessary to look for alternatives to aggregate value to the product. In this sense, three hypotheses were formulated for the producer who works with feedlot cattle: 1) Harvest as a forage and supply of diet with silage for feedlot cattle; 2) Harvest of grains and supply of diet independent of roughage for feedlot cattle; 3) Harvest and sale of the grain; The objective was to promote the bioeconomic evaluation of maize harvest for production of silage or grain, for use in feedlot steers. Specifically, was intended to evaluate the export of macronutrients from the soil by the harvest of forage or grains; subsequently were used diets for feedlot steers, being: T1 - 100% concentrate: whole corn grains (80%) + protein core (20%) and T2 - corn silage (45%) + concentrate (55%), for evaluation of performance, intake behavior, carcass characteristics and its non-member components, measure the return of macronutrients to the soil through manure and perform the economic analysis of the systems. manure and perform the economic analysis of the systems. The harvest of forage resulted in the largest export macronutrients in the order of 56% N, 74% P, 384% K, 228% of Ca and 322% Mg more than export only the grain. The mineral fertilization of the crop was performed according to the recommendation for grain production, and it was enough when harvested only grains, although, generated deficits to the soil of 93 kg ha?¹ N and 84 kg ha?¹ K when the corn was harvested as forage. The diets showed no difference in weight gain (1.513 kg day-1), T1 showed better feed conversion (4.57 vs 6.67 kg kg?¹) and digestibility (79 vs 68%), decreased dry matter intake (6.54 vs 9.45 kg day-1) and consumption in relation to the weight (1.52% vs 2.20%), decreased 60% by volume of manure, 36% of the time consuming and 82% of the rumination time. There was no difference in carcass yield (53.6%); T1 showed lower fat thickness (3.13 vs 4.13 mm), increased by 30% the proportion of 79% of heart and spleen. Considering the fertilization with manure, the systems were capable of enriching the soil nutrient balance, only the K on the foraging system showed deficit of 25 kg ha?¹. The 100% concentrate diet had net income per animal over 65% than silage diet. Although, the highest remuneration per area were generated on the foraging (R$ 5765 ha?¹), followed by grain harvest to 100% concentrate diet (R$ 4395 ha?¹), and lowest net income was the sale of grains (R$ 1021 ha?¹)