Effects of Dietary Concentration of Polyunsaturated Fatty Acids on the Carcass Traits of Feedlot B. Indicus and Cross-Bred B. Taurus x B. Indicus Cattle

Inclusion of vegetable oils in diets formulation of finishing beef cattle increases the availability of polyunsaturated fatty acids (PUFA) in the diet, which may modulate the carcass traits of lean meat producing animals. This study was carried out to evaluate the effects of PUFA dietary concentration in animals from different genetic predispositions for fat deposition on carcass traits. Thirty Nellore and thirty crossbred Angus x Nellore (368 ± 28 kg bodyweight; 24 mo old) were weighed, tagged and allocated in individual pens according to the initial BW (block) in a block design with a 2 x 2 factorial arrangement (genetic group x diet) and 15 replications per treatment. Animals were fed for 133 d from one of two high concentration diets: control diet (CON; TDN = 78.9%; EE = 3.11%) and soybean oil diet (SBO; TDN = 82.3%; EE = 6.45%), containing corn silage (10%), sugarcane bagasse (5%), corn grain (58% for CON and 54.5% for SBO), citrus pulp (16%), soybean meal (9%), urea (1.2%), mineral salt (0.8%) and soybean oil (3.5% for SBO). Hot carcass weight (HCW), dressing percent (DP), kidney, pelvic and inguinal (KPI) fat weight as a percentage of HCW, and liver weight were evaluated. There was no genetic group x diet interaction for any trait evaluated. No difference was observed between B. indicus and cross-bred animals for HCW (316 x 330 kg; P = 0.1311), DP (59.1 x 58.8%; P = 0.7098), KPI fat (3.0 x 3.1 % HCW; P = 0.3905), and liver weight (6.6 x 7.0 kg; P = 0.1075), respectively. Although no difference was observed between diets for HCW (P = 0.2469) and DP (P = 0.6350), animals fed SBO diet had a higher KPI fat (3.3 x 2.7 % HCW; P = 0.0066) besides tending to have a higher liver weight (7.0 x 5.6 kg; P = 0.0722) than animals fed CON diet, respectively. Animals with different genetic predispositions for fat deposition had similar carcass traits, in these study conditions. Higher dietary concentration of PUFA did not change HCW and DP due to the increase of the internal fat deposition and viscera weight.