Qualitative traits of the meat of Nellore steers supplemented with energy and protein in an integrated crop–livestock system

Abstract

Context Santa Fe is a model of integrated crop–livestock system in which grain crops and grasses are grown intercropped. After crop harvest, the pastures are grazed in the dry season and, after that, accumulate straw for no-till systems. In this way, protein and energy supplementation can contribute to finish steers on pastures, attending to the increasing demand from internal and external markets for sustainable high-quality red meat. Aim The present study evaluated physical and chemical composition of the Longissimus dorsi meat of Nellore steers fed with increasing levels of energy and protein supplementation on Brachiaria ruziziensis pasture in Santa Fe integrated crop–livestock system. Methods Forty chemically castrated steers were randomly assigned into four groups under a completely randomised design. Each group was supplemented one of four levels of a concentrate containing 17% crude protein and 75% of total digestible nutrients, at 0.98, 1.45, 1.86 and 2.02 kg/animal.day, representing 0.23%, 0.34%, 0.44% and 0.47% of bodyweight respectively. The experiment lasted 105 days, with trough supplementation once a day. Key results As energy and protein increased in the diet, cooking loss decreased (P = 0.01) linearly and shearing force decreased quadratically (P = 0.02), with a strong correlation between them (r = 0.93). Subcutaneous fat thickness showed a quadratic increase (P = 0.03), with its maximum point at the concentrate supplementation level of 1.55 kg/animal.day, with a thickness of 3.36 cm and a high Pearson’s correlation with the loin eye area (r = 0.94). There was a quadratic increase in C18:2n6 (P = 0.05) and a linear increase in C22:6n3 (P = 0.04) polyunsaturated fatty acids. The fatty acids of the ω3 series increased indifferently to the total fat and saturated fatty acids. Conclusions Supplementing Nellore steers with energy and protein in this integrated crop–livestock system improved meat quality, as indicated by tenderness and marbling, and changed the fatty acid profile in a way that would be more attractive to consumers. Implications The results of the experiment will guide ruminant nutritionists to define a supplement plan for finishing steers in Santa Fe integrated crop-livestock systems targeting healthier, high-quality, and sustainable meat markets.