ABSTRACT: The effects of three doses of vitamin C (100, 200 and 300 mg/kg) added to the feed of reproductive pheasants on egg production, egg fertility and parameters of hatchability were investigated. In experiments I (1999) and II (2000) birds were kept in outdoor aviaries. In 2000, air temperatures recorded on the farm during the experiment were high (25–30^oC), differing considerably from those recorded in the preceding years. In experiment I no statistically significant differences were shown between the control pheasants and those supplemented with 100 and 200 mg/kg vitamin C in terms of egg production, egg fertility and parameters of hatchability. The poorest results were found in the group of birds receiving a feed supplemented with 300 mg/kg vitamin C. In experiment II, statistically higher egg production and egg fertility were noted, compared to the control group, in the groups supplemented with 100 and 200 mg/kg vitamin C. Compared to the control group, pheasants from these groups were also characterized by higher hatchability from set eggs (by approx. 15 percentage units) and fertilized eggs (by approx. 9 percentage units) and smaller number of unhatched chicks and dead embryos after day 10 of incubation. In experiment II, the beneficial effect of 100 and 200 mg supplements of vitamin C on the studied parameters could result from the soothing action of the vitamin on the effects of heat stress. The present results justify the prophylactic use of vitamin C supplement at 100 mg/kg feed in the nutrition of reproductive pheasants reared in aviaries. Under heat stress (high air temperatures) increasing the dose of this vitamin to 200 mg/kg feed seems beneficial.

Keywords: vitamin C; pheasant; reproduction; laying; hatchability; stress