PSV-38 Fatty acids profile of subcutaneous fat deposition in Nellore bulls classified by feed efficiency

Abstract

Abstract Microbial population and ruminal fermentation patterns differ according residual feed intake (RFI) classes, with possible alterations in biohydrogenation and consequently in fatty acids (FA) profile of subcutaneous fat deposition. This study aimed to evaluate FA profile of subcutaneous fat deposition in Nellore bulls classified by RFI. Data from four different trials, totaling 106 Nellore bulls (475.5 ± 77 kg of slaughter BW and 623 ± 97 d of age at slaughter), previously classified by RFI as positive (PRFI) or negative (NRFI), were used. Fatty acids profile was determined in Longissimus muscle with fat cover samples, collected immediately after boning, vacuum packed and frozen until analysis. Data were analyzed using SAS MIXED procedure, including in the model as fixed effects RFI class and age at slaughter as covariate and as random effects feeding type within trial and year of trial. Least square means were compared by the t-test, being significance determined at P ≤ 0.05 and trends at 0.05 < P ≤ 0.10. Significant difference between RFI classes was only detected for cis-vaccenic FA (C8:1 n7) (2.45 vs 2.29 g/100g; P = 0.049) and tendency for oleic FA (C18:1 n9) (34.9 vs 36.3 g/100g; P = 0.092), for PRFI and NRFI respectively. The sum of total saturated (43.4 g/ 100g), monounsaturated, and polyunsaturated (12.8 g/100g) FA, revealed a significant difference between RFI classes only for total monounsaturated FA (43.2 vs 44.8 g/100g; P = 0.046) for PRFI and NRFI respectively. This difference can be due the tendency detected between RFI classes for oleic FA, which is the monounsaturated FA in the highest concentration in the profile. Monounsaturated FA are essential in human diet because they can contribute to reduced blood cholesterol and triglyceride levels, exerting cardiovascular protection. In conclusion, NRFI Nellore animals have a better FA profile of subcutaneous fat deposition.