Effect of dietary mannan oligosaccharide with or without oregano essential oil and hop extract supplementation on the performance and slaughter characteristics of male broilers

The effects of some alternative feed additives for antibiotic growth promoters on performance and some slaughter characteristics were examined in broilers fed wheat-soya based basal starter and finisher diets. A total of 2160 one-day-old male broiler chicks were randomly allocated to six groups with six replicate pens per treatment. The treatments were the basal diet (Control), and the basal diet supplemented with an antibiotic growth promoter (AGP); a prebiotic, mannan oligosaccharide (Bio-Mos, MOS); an essential oil of oregano (Herb-Mos Oregano, HMO); a plant extract of hop (Herb-Mos Hops, HMH) or a mixture of Herb-Mos Oregano and Herb-Mos Hops (HMOH). There were significant effects of dietary treatments on body weight and feed conversion ratio in the 0 21 d period, and on body weight and feed consumption in the 0 42 d period. The addition of all experimental additives to the diet resulted in significantly higher body weights as compared to the control treatment at both 21 and 42 days of age. Feed intakes were significantly different between the treatments at 0 21 d and 22 42 d periods, but not during the 0 42 d period. However, during the 0 21 d period the broiler chickens that received diets supplemented with AGP, MOS, HMO, HMH and HMOH had significantly better feed conversion ratios than the control group, but this pattern was not sustained during the finisher period (22 42 d). Mortality rate, hot carcass yield and relative weights of the small intestines, pancreas, abdominal fat and bursa of fabricius were not affected by experimental treatments. The HMH supplementation increased relative liver weight. These results showed that AGP, MOS and herbal feed additive (HMO, HMH, HMOH) supplementation to a diet provided significant advantages on broiler growth performance through a 42-d growth period. However, the combined supplementation of HMO and HMH did not exert either synergistic or additive benefits on the live performance of the broilers. These results also proved that MOS, HMO, HMH and HMOH improved broiler live performance as well as an AGP in both the starter and through the grower period. Furthermore, outstanding advantages were evidenced for the HMH treatment in particular. Therefore, the MOS, HMO, HMH and HMOH performance enhancer feed additives of natural origin may be considered as potential substitutes for AGP in broiler diets. ________________________________________________________________________________