Natural additives in the diet of bulls (Angus vs. Nellore) finished in feedlot: fatty acids composition

Abstract Text: Natural extracts could be an alternative for the use of antibiotics as growth promoters in animal feed. The objective of this study was to evaluate the effects of the inclusion of natural additives in the diet of bulls finished in feedlots on Longissimus muscle fatty acids composition. Forty eight bulls (Angus vs. Nellore) finished in feedlot during 94 days were used. The experiment was completely randomized and animals were distributed into four treatments: control (CON); essential oils (EOL – addition of 4 g/animal/day of a mix of essential oils from castor bean - Ricinus communis - and cashew - Anacardium occidentale); Confimax (MAX – addition of 10 g/animal/day of mix of essential oils from oregano - Origanum vulgare, castor bean and cashew, and yeast); and yeast (YST – addition of 5 g/animal/day of yeast - Saccharomyces cerevisiae). Bulls had an average of 22 months old and 318 ± 30 kg at the beginning of the trial and were slaughtered with an average of 468 ± 45kg. Roughage:concentrate ratio was 50:50. A variance analysis was performed and a comparison of means was performed using Tukey test at 10% of significance. Most fatty acids in the Longissimus muscle were not altered by the inclusion of additives. The myristic acid was higher (P < 0.10) in the CON (3.27%) treatment compared to the EOL (2.83%). Palmitic acid was lower (P < 0.10) for the YST. Oleic acid was higher (P < 0.10) for the YST (41.4%) and lower for MAX (39.0%) treatment. Natural additives had no effect on SFA, MUFA, PUFA, n-3, n-6, and the ratio between PUFA/SFA and n-6/n-3. When fatty acids were analysed individually, some differences were found for YST, indicating a healthier meat fatty acid composition profile for this treatment. The used natural additives had mild effects on fatty acid composition of bulls finished in feedlot.

Keywords: animal nutrition, essential oils, meat quality