The effect of subclinigal infections withEimeria praecoxandEimeria tenellaon pigmentation and vitamin a absorption in broilers

Abstract

Broilers were fed for the first 5 weeks on a starter ration containing 20 g of xanthophylls/ton. They were then divided into uniform groups and fed on either a broiler finisher ration supplying 30 g xanthophylls/ton or one supplying 20 g xanthophylls/ton and supplemented with 2.5 g canthaxanthin/ton. Six groups from each dietary regime were given 10,000 sporulated oocysts of E. praecox, daily for 5 d, six with 5000 sporulated oocysts of E. tenella daily for 5 d while the remaining six groups served as uninfected controls. All birds were housed in cages with solid floors to aid in recycling the infections over the 3‐week test period. The resulting subclinical E. praecox and E. tenella infections, regardless of dietary treatment, caused slightly reduced weight gains and slightly impaired food conversions. Shank and breast skin visual scores, plasma and toe‐web carotenoids and liver vitamin A levels were not depressed as a result of either coccidial infection.