Effect of different photoperiods and melatonin treatment on rabbit reproductive performance.

Abstract

Rabbit production in Egypt exhibits a seasonal pattern with much higher yields from September to May. This variation might be explained by reproductive performance as controlled by annual photoperiodicity.
The aim of this study was to investigate whether the reproductive performance of rabbits can be improved by either increasing the photoperiod or by administering melatonin supplement.
In total 78 White New Zealand rabbits (60 does and 18 bucks) were used during September and October reared in a private Rabbitary in Menuofia Governorate, Egypt. The animals were randomly assigned to six treatment groups of 10 does and three bucks each (8, 10, 12, 14, and 16 h light and melatonin (1 mg/kg BW/day orally for two weeks). Ejaculate traits, sexual activity of bucks, sexual receptivity and reproductive performance of does were recorded.
The results revealed that exposure of rabbits to long photoperiods (14 and 16 h light) or treatment with melatonin improved the quantity and quality of ejaculate traits and buck sexual activity as well as doe's sexual receptivity, feed intake, litter size, weight at birth and time-to-weaning. On the other hand, gestation period and pre-weaning mortality percentage decreased.
Application of long photoperiods is beneficial to rabbit producers and 14 h light combined with 10 h dark is optimal for satisfying the physiological requirements of the rabbits. Finally, from an economic point of view, the light schedules are cheap and easy to apply and can be used as biostimulation instead of melatonin.