Subspecies and diet affect the expression of genes involved in lipid metabolism and chemical composition of muscle in beef cattle

Fourteen Nellore and 14 Angus young bulls with BW of 381±11.8kg were randomly assigned into 2 feeding groups (whole shelled corn without forage (WSC) or corn silage and ground corn (GC)) to evaluate chemical composition and expression of genes involved in lipid metabolism in the longissimus thoracis (LT). We hypothesized that bulls fed the WSC diet have greater amounts of intramuscular fat and Angus have higher expression levels of PPAR and SREBF. Meat from Angus bulls had greater ether extract compared to Nellore (P<0.05). Muscle from bulls fed the WSC diet had greater expression of PPARA (P<0.05) and lower levels of SREBF1 expression (P<0.01). The LT of Nellore fed GC had greater expression of FABP4, ACACA and SCD genes (P<0.01). In conclusion, the greater concentration of starch in the WSC diet did not increase marbling in the beef of bulls fed this diet due to the reduced expression of SREBF1.

Evaluation of carcass traits and meat characteristics of Guzerat-crossbred bulls

Our objective was to evaluate carcass and meat characteristics of Guzerat-crossbred bulls finished in feedlot. Carcasses from 18 bulls, randomly selected from a larger group of 36 bulls, consisting of F1 Guzerat×Holstein ("Guzholstein"); F1 Guzerat×Nellore ("Guzonell"); and 1/2 Simmental+1/4 Guzerat+1/4 Nellore (Three-Cross; n=6 each group) were used. Cold carcass weight was greater (P=0.01) for Three-Cross compared with "Guzonell" and "Guzholstein". Three-Cross carcasses had greater (P<0.01) rib-eye-area and 100-kg-adjusted rib-eye-area among groups. Longissimus lumborum length did not differ (P>0.05) among groups, but depth was greater (P<0.01) for Three-Cross compared with other groups. "Guzholtein" had lesser (P=0.05) shear force compared with "Guzonell", with Three-Cross being intermediate. We conclude that "Guzholstein" is an adequate option for producers willing to finish this kind of genetic group, as it is comparable or better than Bos indicus crosses and B. indicus×Bos taurus bulls.