Resumen

PORDOMINGO, Anibal J. et al. Substitución de harina de girasol por poroto de soja en la dieta de novillos alimentados a corral sobre la respuesta productiva y características de la res. RIA. Rev. investig. agropecu. [online]. 2021, vol.47, n.2, pp.293-301.  Epub 22-Sep-2021. ISSN 1669-2314.

Two experiments were conducted to determine the effects of inclusion (Level: 0, 8, 16 and 24% on DM basis), processing (Grnd: whole or ground) and thermal treatment (Roast: raw vs roasted) of soybeans substituting for sunflower meal, on performance and carcass traits of pen-fed steers. Experiment 1 explored responses to Level and Grnd. Experiment 2 explored responses to Level and Roast. For Experiment 1, 96 Angus steers (210 ± 14.50 kg) were distributed randomly in 24 pens with 4 per pen. For Experiment 2, 96 Angus steers (280 ± 18.50 kg) were distributed into 32 pens with 3 per pen. Diets were based on corn grain, sunflower meal, urea, hay and a mineral/vitamin premix, with soybeans added according to Level. Variables determined were: live weight (LW), LW gain (LWG), dry matter intake (DMI), DMI relative to LW (DMILW), feed efficiency (FE), hot carcass yield (HCY), rib eye area (REA) of the longissimus thoracis section and back fat thickness (BFT). Data of each experiment were analyzed in a 4 x 2 factorial completely randomized design. Pens were the experimental units. Effects of Level were separated by Tukey; effects of Grnd and Roast by significance of F test. For both experiments, inclusion of 24% raw soybeans depressed (P < 0,05) final LW, LWG, DMI, DMILW and worsened FE, compared with the other levels. Level 24 also reduced (P < 0,05) RRes and BFT in experiment 1. No interactions (P ≥ 0,37) between Level and Grnd and no effects (P ≥ 0.39) of Grnd were detected. Level interacted with Roast (P < 0.01). Roasting removed the depressing effects of Level 24 on animal performance. Substituting sunflower meal for raw soybeans up to 16% of the diet, or roasted across at levels, did not (P > 0,05) affect performance and carcass variables.

Palabras clave : soybeans; raw soybeans; heat-treated soybean; growth variables; carcass characteristics.

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