Guanidinoacetic Acid and Its Impact on the Performance, Carcass and Meat Quality of Growing and Finishing Nellore Cattle.

This study evaluated the effects of guanidinoacetic acid (GAA) supplementation during the growing and finishing phases on Nellore bulls' performance, carcass traits, and meat quality. Fifty-two Nellore bulls were randomly assigned to four treatments: control (CON, without GAA) and three GAA levels (3, 6, and 9 g/kg dry matter [DM] in the growing supplement; 0.3, 0.6, and 0.9 g/kg DM in the finishing diet). During the 280-day growing phase, bulls were kept in paddocks, while in the 74-day feedlot finishing phase, they were housed in collective pens. Body weight, average daily gain, and carcass ultrasound measurements were recorded in both phases. Feed intake was recorded daily during finishing, and carcass traits were evaluated post-slaughter. GAA supplementation during the growing phase did not affect performance or ultrasound carcass traits ≥ 0.12). In the finishing phase, increasing GAA doses linearly reduced body weight gain ( = 0.03) without affecting carcass traits assessed by ultrasound or post-slaughter ( ≥ 0.10). GAA supplementation linearly reduced cooking loss ( = 0.02) without influencing other meat quality parameters ( ≥ 0.11). It is concluded that, under the conditions of this study, GAA supplementation did not affect performance or carcass traits, except for reduced weight gain at the highest dose, but reduced water loss from cooked meat.