Abstract
Fatty acid (FA) composition in beef is related to beef quality and human health. It was recently reported that feeding active dried yeast (ADY) in finishing bull altered some FA of longissimus muscle. The objective was to evaluate the effects of adding ruminally protected versus non-protected ADY on FA profiles of the pars costalis diaphragmatis (PCD) muscle of beef cattle. Seventy-five Angus steers (initial BW 448 kg) were assigned to a randomized complete block design with five treatments: control (no additives), antibiotics (ANT, 330 mg monensin + 110 mg tylosin/d), ADY (1.5 g/d), encapsulated ADY (EDY, 3 g/d) and combination of ADY and EDY (MDY). The encapsulated ADY consisted of 1.5 g ADY and 2 g capsule. Antibiotics, ADY and EDY were top-dressed to a diet containing 10% barley silage and 90% barley concentrate (DM basis). The PCD samples were collected from cattle at slaughter. Intakes (g/d) of total FA (144), saturated FA (SFA; 41), monounsaturated FA (MUFA, 16) and polyunsaturated FA (PUFA, 87) were not different among treatments. Proportion of SFA (49.0%) and MUFA (48.2%) in PCD did not differ among treatments, whereas the proportion of PUFA was greater (P < 0.05) with EDY (3.0%) and MDY (3.0%) than control (2.4%). The proportion of n-3 FA also tended (P < 0.06) to be greater with EDY (0.49%) and MDY (0.50%) than control (0.41%) and ADY (0.41%). Steers fed EDY and MDY enhanced (P < 0.05) the proportion of linoleic acid (LA n-6) and decosapentaenoic acid (DPA n-3) compared with control. These results indicated that feeding EDY and MDY increased amounts of PUFA, FA n-3, LA n-6 and DPA n-3. Inclusion of encapsulated yeasts to diet might increase the amount of bioactive yeasts reached intestines and result in better utilization of PUFA from the digesta and increase the accumulation in the intramuscular fat.
Keywords: encapsulated active dried yeast, beef, fatty acid profiles