Resumen de Diversity of repeatability between parities for litter traits and reproductive intervals in doe rabbits.
An experiment was carried out to determine the genetic variation in litter traits and reproductiva intervals between different parities in New Zealand White (NZW) and Californian (CAL) rabbits. Data on 581 litters produced by 163 does mated to 43 bucks of NZW and CAL rabbits were involved. A linear mixed model included the effects of service buck and does within service buck (as random effects) and year-season and parity (as fixed effects) was used for analysing such data. NZW breed had higher litter size, weight and gain along with a lower number of stillbirths and preweaning litter mortality relativa to CAL breed. Reproductiva intervals and number of services per conception of NZW rabbits were relatively lower than in CAL rabbits. Periods of reproductiva intervals were short in both breeds (42-43 days from a kindling to another) and they are one of the encouraging factors for the effective use of these two standard breeds on a large scale of commercial production in Egypt. Phenotypic variation in all litter traits and reproductiva intervals for both breeds was high. Year-season affected significantly most reproductiva intervals and litter traits studied. Litters kindled in spring generally had the smallest litter size and lightest litter weight and gain along with the shortest reproductiva intervals comparad to litters kindled in autumn and winter seasons. Reproductiva intervals in both breeds had a quadratic relationship with parity. Service buck had little or no effect on litter traits and reproductiva intervals. Percentage of variation attributed to the service-buck effect were generally higher in NZW breed than in CAL, while the reverse was observad for doe effect. Repeatabilities across all parities of most litter traits and reproductiva intervals in both breeds were low and ranged from O.O to 0.21 . Repeatabilities for all traits in NZW were similar to those in CAL. For both breeds, repeatabilities of doe traits for first and second parities were generally slightly higher than for second and third parities.
