Resumen de Grouping of rabbit reproduction management by means of artificial insemination

Pilar García Rebollar, José Mario Rodríguez Alvariño, E. Ubilla

• One hundred and thirty does of the Californian x New Zealand breed were artificially inseminated on a fixed day of the week, during a thirteen months long study. AII insemination were performed on Monday, using 1 mi diluted semen. Does with less than 8 youngs/litter (M1) were inseminated on day 3 or 4 post-partum (PP.), and rabbits with than 8 or more youngs/litter (M2) on day 1 O or 11 PP. AII does found non pregnant were considered pseudopregnant and inseminated on day 24 PP. (M3). The first artificial insemination (A.I.) in nulliparous rabbits was performed at 4 months of age. 1679 A.I. were carried out during this experiment. Ovulation was induced with 20 µg of GnAH (Fertagyl, lntervet Lab.) in all rabbits, without considering their sexual receptivity. The overall conception rate (C.A.) obtained was 58.5 %. The lactation significatively influenced conception rate in animals inseminated in the post-partum period (P<0.001). Higher conception rate was observed in does inseminated after a first non-fertile insemination (type M3), (P<0.05). No difference between does M1 vs M2 was detected. C.R. in nulliparous does was higher compared to rabbits M2, and lower than rabbits M3 (P<0.05). Although rabbits were inseminated on a fixed day of the week, as a consequence of the pregnancy period variations, A.I. was finally performed between day 1 to 12 PP. Nevertheless, most of the inseminations were carried out on days 3, 4 and 10, 11 PP. Lower C.A. were obtained when comparing A.I. on days 3 to 5 and 9 to 12 PP., versus females inseminated on days 1 to 2 and 6 to 8 PP. (50.3 % and 48.9 % vs 69.5 % and 66.6 % respectively), (P<0.001). A significative interaction type of rabbit*lactation was detected when comparing non lactating rabbits inseminated on days 3 or 4, 1 O or 11, 24 or after PP., versus lactating does inseminated on the same days (71. 78 %, 68.9 %, 71.5 % vs 53.6 %, 48.7 %, 62.2 %, respectively, P<0.001). No influence on prolificacy was detected. The overall means obtained were: No. of youngs born/litter: 7.1 ± 0.1; No of youngs born dead/litter: 0.6 ± 0.05.Our results suggest a better reproductive management when A.I. was performed on one fixed day of the week. Practically all pregnancy diagnosis by abdominal palpation were carried out on Fridays (day 11 after A.1.), nest settings on Tuesdays (day 29 after A.1.), and parturition occurred on Thursdays and Fridays (day 31-32 after A.I.) of the same week. Nevertheless, the better C.A. observed in does A.I. on days 1 or 2 and 6 to 8 suggests that reproductive management could be organized on two fixed day of the week.