Effect of a 48h delayed insemination with or without a 48h doe-litter separation on performance of non-receptive rabbit does
The effectiveness of delayed artificial insemination (DAI) of non-receptive (R-) does, with or without oestrus synchronisation by doe-litter separation (MLS), was studied and compared with receptive (R+) does. During 10 months, 105 NZW does, in three homogeneous groups (A, B, C), were artificially inseminated (Al) according to a 42-day reproduction rhythm in two batches. Every 21 days, two Al were effected, the second 48 hours alter the first. The R+ does of ali groups were inseminated al the first Al, while the R- does were treated, in relation to their group, as follows: inseminated at the first Al (A); 48-hour DAI (B); 48-hour MLS by closing the nestbox before Al, when lactating, and 48- hour DAI (C). The lactating does were subjected to systematic controlled nursing from littering until Al. The R+ does had a significantly higher fertility rate than the R- does of all groups. Receptivity was improved by DAI, especially on the non-lactating does (+60.6%), while an important increase was caused by MLS in the lactating does (+ 15.7%, P<0.05). A different effect on fertility was seen according to the lactation order of the does. A DAI improved fertility of does of lactation order ≥5 in comparison with the A group (+ 18.2%, P<0.05) and MLS improved fertility of the R- of lactation order 1-4 (+25.0%, P<0.01). MLS did not affect either rabbit loss or the incidence of mastitis, but reduced the weaning weight of rabbits (-52 g equal to -7.7%, P<0.01), especially when their dams were of lactation order≥5 (-76 g, P<0.01). The weight recorded on day 74, at the end of the fattening period, was significantly lower in rabbits separated from their dams (-75 g, P<0.01), although the relative difference was reduced (-3.3%: 2270 g vs 2345 g).
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