Effects of doe-litter separation on endocrinological and productivity variables in lactating rabbits

The objective of this study was to explore the effects of a doe-litter sepa ration for 48 h before artificial insemination (AI) on various endocrinolog ical and productivity variables determined in 24 doe rabbits. The control g roup (C) (n = 12) had free access to nursing and the separated group (S) (n = 12) were kept apart form their litters for 48 h prior to AI on day 11 of the lactation period. Lower plasma prolactin (PRL) concentrations were obs erved 24 h after the doe-litter separation (P < 0.04). The S does had incre ased plasma oestradiol (E-2) concentrations 48 h after the doe-litter separ ation, compared with preseparation values of the same group and with C does (P < 0.0001). A higher proportion of does showing high sexual receptivity was observed among the S group compared with the C group (P < 0.05). The su ckling episode ranged from 3 to 5 min in S does. Teal stimulation by suckli ng caused an immediate increase in PRL in S does (P < 0.0001). PRL remained high until 7 h after suckling in S does, compared with C does IP ( 0.04). The doe-litter separation resulted in a mean (+/-S.E.M.) reduction in litte r weight of 217 (+/-22.1) g (P < 0.02). No kits died in either group during the separation period. The litter weight on day 21 after parturition and m ilk production/doe were not affected by treatment. When analysing the subse quent litters, no differences were observed between 8 and C does in kindlin g rate, litter size at birth, number of dead kits/litter, litter size at we aning and number of kits dead from birth to weaning. The results suggest th at a transient doe-litter separation causes an increase in the proportion o f does showing signs of oestrus and may have a major influence on fertility . These effects may be induced by the absence of suckling episodes together with the higher plasma E-2 and lower PRL concentrations seen in the S does prior to AI. (C) 2000 Elsevier Science B.V. All rights reserved.