MONENSINA SÓDICA E ÓLEO ESSENCIAL DE CAPIM LIMÃO (Cymbopogum flexuosus) EM DIETAS PARA CORDEIROS

Abstract

The objective of this study was to evaluate the effect of the inclusion of two levels of monensin and essential oil (EO) of lemon grass on nutrient intake and digestibility, ruminal fermentation and ingestive behavior of lambs receiving high concentrate diet. Four uncastrated lambs were used (44.0 kg of BW and approximately 4 months old), cannulated in the rumen. The animals were distributed in a 4 x 4 Latin square experimental design, with four animals, four treatments and four experimental periods. The treatments were defined by the addition of two levels of monensin or lemon grass essential oil to a base diet containing 85% concentrate and 15% forage (white oat hay, Avena sativa), as follows: CONT - diet without addition of monensin or essential oil; 12.5MON - diet containing 12.5 mg/kg of monensin; 25MON - diet containing 25 mg/kg of monensin and EO - diet added with 1 ml/kg of essential oil of lemongrass (Cymbopogum flexuosus). There was no effect of the treatments on the nutrient intake and digestibility. The animals that received the diet containing EO presented ruminal pH superior to those that received the control diet, however they did not differ from those that received monensin. There was a quadratic effect of the monensin on the ruminal pH, being the highest value observed in the animals fed diet with 12.5 MON. The animals that received the OE diet had a higher ruminal concentration of acetate compared to that receiving monensin. There was a quadratic effect of the monensin on ruminal concentration of acetate, being the lowest value observed for the diet containing 12.5 MON. The acetate:propionate ratio was lower in animals receiving the diet with 12.5 MON. Compared to the CONT, EO decreased the ruminal concentration of butyrate; however, its concentration was higher in animals receiving monensin than those receiving essential oil. The ruminal concentration of valerate was higher in animals receiving essential oil. The EO supply decreased the ruminal concentration of isobutyrate and isovalerate. A lower concentration of total SCFA was observed in animals fed the diet containing 12.5 MON. The ALT blood concentration was higher in the animals that received the diet containing EO compared to the control diet. EO increased rumen concentration of blood glucose compared to diets containing monensin. OE decreased the number of eggs per gram of feces (EGF) in relation to diets containing monensin. In addition, there was a quadratic effect of monensin on the EGF, with a higher value in the animals fed diets containing 12.5 MON. In conclusion, the use of only 12.5 MON was shown to be an efficient alternative in ruminal modulation of lambs fed high concentrate diet. In turn, lemon grass EO had an effect on ruminal characteristics that enabled it as a potential additive for use in high concentrate diet for lambs.