SUBSTITUIÇÃO DE IONÓFOROS POR UM BLEND DE ÓLEOS FUNCIONAIS NA ALIMENTAÇÃO DE NOVILHAS NELORE EM TERMINAÇÃO INTENSIVA A PASTO

Abstract

The objectives were: Chapter 1 – Write a literature review on the benefits, challenges and opportunities of intensive finishing on pasture and the use of ionophore antibiotics and functional oils as additives in ruminant nutrition; Chapter 2 – Evaluate the replacement of the ionophore antibiotics Monensina and Narasin by a blend of functional oils based on cashew and castor oil on the performance of heifers (Bos indicus) fed a diet with high concentrate content in intensive finishing on pasture; Chapter 3 – Evaluate the replacement of the ionophore antibiotics Monensin and Narasin by a blend of functional oils based on cashew and castor oil on the diurnal behavior of heifers (Bos indicus) fed a diet with high concentrated content in intensive finishing on pasture. Material and Methods: Chapters 2 and 3 - Twenty-seven Nelore heifers were used, with a mean age of 18 months and initial body weight (BW) 294.2 ± 16.5 kg. Three food additives were evaluated, namely: two ionophore antibiotics - Monensin (with inclusion of 25 mg/kg of DM concentrate) and Narasin (with inclusion of 13 mg/kg of DM concentrate); and a blend of functional oils (OF) based on cashew and castor oil (including 500 mg/kg of concentrate DM); Chapter 2 - Concentrate intake, performance, body development, fat finish, yield and carcass weight were analyzed; Chapter 3 – The following behavioral activities were analyzed: standing time (ST), lying time (LT), walking time (WT), grazing time (GT), time eating in the trough (TT), time drinking water (TW) , number of visits in the trough (NVT) and total time eating (TEtot), total time in activity (TAtot) were calculated. Results: Chapter 2 - No significant effect was observed in the analyzed variables, presenting similar results. Chapter 3 - The animals that received Monensin spent longer in the trough (P<0.05), followed by the OF and for less (P<0.05) time in the trough the animals that received Narasin. This shorter time in the trough observed with Narasin resulted in the longest (P<0.05) grazing time. The OF had a higher (P<0.05) number of visits in the trough compared to the other treatments. Conclusion: The blend of functional oils based on cashew and castor oils can be used to replace the ionophore antibiotics Monensin and Narasin. In the diurnal behavior, Narasina led the animals to start grazing at dawn and for a longer period of daytime grazing.