A total of 800 1-day-old Ross 308 male broiler chicks were used in a 5-wk feeding trial to evaluate the effects of commercial feed additive that is composed of blends of essential oil (EO; CRINA Poultry, DSM) and vitamin D-3. The birds were randomly assigned to 5 treatments with 10 replicate cages; each stocked with 16 birds and was fed corn-soybean-meal-based basal diet. Dietary treatments included: CON, unvaccinated birds fed basal diet/control; CCO, CON + coccidian oocysts vaccinated birds; EOD1, CCO + Essential oil blends and vitamin D/Prototype 1 (50 mu g 25-OH-D3/kg diet, 15 mg CRINA Poultry/kg diet); EOD2, CCO + Prototype 2 (69 mu g 25-OH-D3/kg diet, 30 mg CRINA Poultry/kg diet); and EOD3, CCO + Prototype 3 (138 mu g 25-OH-D3/kg diet, 50 mg CRINA Poultry/kg diet). On day 7, all birds, except CON, were inoculated with 300 to 500 purified sporulated viable oocysts from Eimeria tenella and Eimeria maxima. As a result of this study, the supplementation of EO blends with vitamin D-3 showed trends in improvement (P = 0.075) body weight gain (BWG) compared with CON and CCO during the grower phase (day 7 to 21). An increase (P < 0.05) in BWG and reduction (P < 0.05) in feed conversion ratio (FCR) were observed in birds fed EOD2 diet during day 21 to 35 compared with vaccinated birds without feed additive. The cumulative performance during overall period (day 1 to 35) also showed that BWG was increased and FCR was reduced in EOD2 and EOD3 compared with CON, CCO, and EOD1. Furthermore, the apparent total tract digestibility of dry matter tended (P = 0.06) to increase in EOD2 and EOD3 compared with CON and other treatments. The EOD2 and EOD3 treatments showed increased (P < 0.05) excreta Lactobacillus counts than EOD1. The intestinal lesion score induced by E. tennela in gastro-intestinal tract was lower (P < 0.05) in EOD1, EOD2, and EOD3 treatments compared with CCO. In conclusion, blends of EO and vitamin D3 could be used as anti-coccidial feed additive in broilers with coccidian infection.
