Production of anti-PMSG antibodies and its relation to the productivity of rabbit does

Abstract

A batch of 100 female rabbits of the Hyplus breed were subjected to artificial insemination (A.I.) for a period of 9 months. With the goal of inducing the sexual receptivity of the does, half of them received systematic doses of 25 I.U .. of PMSG (Ciclogonine PROCHENA), 48 hours before A.I.. The other half were not injected (Control group). Following this experimental period (40 days after the last injection), blood samples of all the does were taken, in order to assay the anti-PMSG antibodies and to study the relationship between the production of antibodies, and the receptivity and productivity of the does observad for the previous litter. For the PMSG group, we classified the results of the does according to their level of immunity which either has a low binding rate (≤4 %) or a high one (> 4 %). 30,6% of the does from the group treated with PMSG produced anti­PMSG antibodies with a high binding rate. In no way related to the level of production of the antibodies, the PMSG treated does were found to be significantly more receptiva than the does in the control group (respectively 70.6 - 66.7 vs 42.0%, P = 0.023), while the fertility did not appear to have been either improved or decreased by the PMSG treatment. The total number of young born, born alive and weaned rabbits per litter did not vary according to the treatment or the intensity of antibody production. Likewise the weight of the litter and also the individual mean weight of the weaned young did not vary significantly according to the group. However, inside of the group treated with PMSG, the individual weight at weaning was the highest for the young from hyper- immune mothers (710 vs 639g, P = 0.035). For 29 does from the PMSG group, a second blood sample was taken 12 weeks after the previous one. Only 3 does showed a decreased level of antibodies, 4 months after the last injection. The study showed that one third of the does developed an immune reaction following injections of PMSG; however the proportion of antibodies produced did not appear related to either their sexual receptivity or productivity.