PSIX-25 Meat quality of young cattle fed with different nutritional plans on growing phase and finished in pasture or feedlot.

This trial aimed to evaluate the meat quality of three cattle breeds, supplemented in two nutritional plans (NP) during the growing phase and finished in Express® (high concentrate in pasture) or conventional feedlot. 119 bulls from three genetic groups: Nellore (268.8 ± 11.63 kg), ½ Angus x ½ Nellore (287 ± 17.38 kg) and ½ Senepol x ½ Nellore (231.1 ± 18.50 kg), were randomly assigned in two NP on growing phase (140 d in wet season): mineral or supplement (energy protein 0.3% BW). Animals from each NP were splitted in two finishing systems (110 d in dry season): Express Feedlot (EF, n=59) and conventional feedlot (CF, n=60). Bulls were supplemented daily with 2% BW of concentrate (16% CP and 78% TDN). Bulls were slaughtered and the carcasses were refrigerated (0oC–24h). Steaks from Longissimus muscle (2.5 cm) and subcutaneous fat were removed between 11st to 13rd ribs. Myofibrillar fragmentation index (MFI) and malonaldehyde (MDA) were analyzed in 1, 7 and 14 days of aging. Sarcomere length (SL) and percentage of lipids (L) were analyzed on day 1. The results were analyzed by ANOVA using PROC MIXED procedures in SAS 9.4, with a 3 × 2×2 factorial arrangement, using 5% of significance level. The MFI and MDA was influenced by aging time (21.99, 29.69 and 31.98; P<0.001, 0.30, 0.43 and 0.48 mg/ kg of meat; P<0.001, 1, 7 and 14 days respectively). The finishing systems influenced the SL (1.42 and 1.60μm, P<0.001, PA and FE), L (1.82 and 2.34%, P<0.001, PA and FE). The genetic groups influenced the L (2.32 Nellore, 2.21 Angus and 1.96% Senepol; P=0.01). In this study, the meat quality parameters were more affected by finished systems (FE was better) and genetic group (Nellore and Angus x ½ Nellore were better than Senepol) than feeding in the growing phase.