The aim of this study was to determine the effect of higher light intensity on whelping interval, percentage distribution of litter sizes, and seasoality in reproduction of Polish and imported chinchillas. The analisys covered reproduction of 230 Polish (group A) and 250 chinchillas imported from Denmark and Sweden (group B). In selected part of the farm, lamps of higher powe were installed. The interiors of chinchillas cages were measured for light intensity and the chinchillas were divided into two groups: control)I) and experimental (II). Increased light intensity resulted in shorter whelping interval in both genetic groups, by 30 days on average, as well as in increased share of litters with 2 and 5 young. Elevated level of light did not eliminate seasonality in reproduction, especially in Polish chinchilles. Imported chinchilles had evenly distributed births throughout a year.

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