Monensina sódica ou extrato de própolis na dieta de bovinos nelore terminados em confinamento : desempenho,características da carcaça e composição do músculo Longissimus

Abstract

This work was carried out to evaluate animal performance and carcass characteristics of Longissimus muscle of 33 Nellore bulls finished in feedlot in three treatments: Control - CON, Monensin - MON and Propolis - PRO. The bulls were 27 months old, their initial average weight was 401.06 kg ± 7.58 and were allocated into three groups, with 11 replications per treatment. The animals were kept in feedlot during 84 days and slaughtered with final average weight with of 484.72 kg ± 24.92. Roughage and concentrate ratio was 52% and 48%. Corn silage was used as roughage and corn, soybean meal, urea, mineral salt and limestone as concentrate. The average final weight and hot carcass weight were higher (P < 0.03) for PRO in comparison than CON and MON, respectively. Characteristics carcass: conformation, length carcass, leg carcass, cushion thickness, Longissimus muscle area, Longissimus muscle area/100 kg of live weight, fat thickness, color, texture and marbling were not influenced (P<0.05) by treatments. The average final weight (P < 0.03), final average gain (P < 0.02), feed conversion of the dry matter (P < 0.01), feed efficiency (P < 0.09) and hot carcass weight (P < 0.01) were higher for PRO treatment. The daily intake of dry matter (kg), live weight percentage and hot carcass dressing were not influenced (P > 0.10) by treatments. The treatments have not changed (P > 0.10) the subjective and quantitative characteristics (conformation, carcass length, leg length, cushion thickness, Longissimus muscle are, Longissimus muscle area per 100 kg live weight and fat thickness. The pH and myofibril fragmentation index were not influenced (P > 0.10) by treatments. The treatments have not changed (P>0.10) the chemical composition (moisture, ash, crude protein, lipids and total cholesterol) of muscle Longissimus. The fatty acids 14:0, 14:1 n-7, 15:1 n-9, 16:0, 16:1 n-5, 16:1 n-7, 18:0, 22:0, SFA and rate n-6:n-3 were not changed (P>0.10) by treatments. There were differences (P<0.10) of 15:0, 16:1 n-9, 17:0; 17:1 n-9 and 18:1 n-9, 18:1 t-11, 18:2 n-6, 18:3 n-6, 18:3 n-3, 18:2 c-9, t-11, 20:4 n-6, 20:5 n-3, 22:5 n-3, 22:6 n-3, MUFA, PUFA, total amount n-3, n-6 and rate PUFA:SFA by treatments. The addition of propolis extract may be an alternative in ruminant feed because it improves the weight gain and the dry matter conversion. The animals that received monensin in diet had better fatty acids profile in Longissimus muscle, considered more appropriate for human health.