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Quality traits of Longissimus muscle of two genetic groups fed with crude glycerin
Quality traits of Longissimus muscle of two genetic groups: Nellore (NE) and F1 Red Angus x Nellore (NA), with 18 months of age, fed diets containing 5% and 15% of crude glycerin for 84 days, were evaluated. Higher concentration of blood glucose was observed in NE (P = 0.0097) than in F1 cross, and it was not affected by diet (P = 0.9573). No effects of genetic group (P = 0.0908) and crude glycerin (P = 0.0733) were observed on serum insulin, carcass pH and final temperature, frequency of muscle fiber type and size of type IIB fiber, beef color, shear-force, myofibrillar fragmentation index, purge loss, ether extract, ashes, and moisture content. The size of type I muscle fiber did not differ (P = 0.0521) among genetic groups and was larger in muscle from animals fed 15% of crude glycerin (P = 0.0244). The size of type IIA muscle fibers was greater in Longissimus muscle of F1 cross (P = 0.0002) than NE cattle, and in Longissimus muscle from animals fed 15% crude glycerin (P = 0.0068) compared to those fed diets with other levels evaluated. Collagen solubility was greater in meat of F1 cross (P < 0.0001) compared to NE cattle and was not affected by diet (P = 0.1146). There was interaction among genetic group and diet on total collagen amount (P = 0.0002) in beef. Greater crude protein level was observed on beef from animals fed 15% of crude glycerin (P = 0.0468). However, crude protein was not affected (P = 0.2197) by genetic group. The inclusion of crude glycerin in diets does not affect beef quality traits. These data show that it is possible to produce beef with desirable quality traits by using F1 Red Angus x Nellore and Nellore cattle.
Keywords: Collagen, fiber, insulin