Effect of photoperiod on the reproductive traits of rabbit does.

The authors investigated the changes of reproductive traits when, instead of the conventional (16L: 8D, light: dark /16L/) lighting program a new method is used (8L:4D:8L:4D /8+8L/) meaning a double change of the daily light period. Pannon White rabbits at 11 weeks of age were divided into two groups and were housed in two identical rooms, which only differed in the photoperiod. Rabbits were first inseminated at the age of 16.5 weeks (16L: doe number=99, AI number=251; 8+8L: doe number=154, AI number=311); 11 days after kindling does were inseminated again. Controlled nursing was applied, does were only allowed to nurse in the morning, for half an hour (between 8:00 and 8:30). The body weight of the 16L rabbits was slightly higher at the first AI (4049 and 3982 g, NS) and at the first kindling (4264 and 4187 g, P<0.05) than that of the 8+8L group. The number of AIs for one kindling was identical in the two groups (1.18 and 1.19). The litter size was slightly higher in the 8+8L group compared to the 16L group (total: 8.50 and 8.76, NS; alive: 8.13 and 8.40, nursed: 8.17 and 8.33, P<0,05). Due to the kit mortality being slightly higher in the 8+8L group compared to the 16L (5.9 and 8.7%, NS), the litter size in the two groups at the age of 3 weeks was identical (7.69 and 7.62). No difference was found either in the litter weight (2762 and 2772 g) or individual weight at the age of 3 weeks (362 and 368 g). According to the results the 8L:4D:8L:4D photoperiod does not crucially influence the reproduction of does under controlled nursing, though the between-group difference changed according the parity order. It is still not elucidated that the production of the two groups would differ in what manner using free nursing. According to preliminary results the litter weight at the age of 3 weeks is higher in the 8+8L group, indicating the higher milk production of these does.