Environmental and physiological factors influencing kindling rates and litter size at birth in artificially inseminated doe rabbits

Abstract

A total of 713 inseminations and 431 kindling records were used for statistical analysis to determine the fixed effects of season, sexual receptivity and physiological status on kindling rates (KR) and total born per litter (TB). Rabbits were reared in México under a moderate climate located at 2240m above sea level with an average yearly temperature of 15ºC. Eighty four New Zealand White rabbits two months of age were reared in a 64-cage replacement system and bred throughout a one-year reproduction cycle. Does kept in 32 cages were inseminated regularly 4-8 days after parturition while does maintained in the other 32 cages were under a 9-13 days reproductive rhythm. Season had no influence on reproductive performance (P>0.05). Kindling rates for spring, summer, autumn and winter were 0.67, 0.67, 0.66, and 0.65 respectively, with TB values of 8.35 ± 0.26, 8.06 ± 0.25, 8.03 ± 0.27 and 7.86 ± 0.40 respectively. Does that were sexually receptive at insemination had significantly (P<0.0001) greater KR (0.87) than non-receptive (0.46) does. TB in the first category (8.23 ± 0.22) was higher (P<0.01) than in the second (7.92 ± 0.20). There was an important effect of physiological status on reproductive performance (P<0.0001). KR in non-lactating nulliparous (0.86) was higher than non-lactating multiparous does (0.68), lactating does under 4-8 days reproductive rhythm (0.53) and lactating does under 9-13 days rhythm (0.59). Nulliparous does had significantly lower TB (6.79 ± 0.14) than the other physiological statuses (8.64 ± 0.25, 8.50 ± 0.26 and 8.37 ± 0.26 respectively). Kindling rate was influenced by the interaction between receptivity and physiological status (P<0.05). The effects of the number of suckling rabbits at insemination on reproductive performance of next litter are discussed.