Effect of Sperm Immunization of Male Rabbits on Sperm Quality, Conception Rate and Litter Size

Five Adult male rabbits (7months old) were used in this study. Among these, three were immunized intramuscularly with washed, sonicated rabbit sperm cells in Freund’s adjuvant and two were given intramuscular injection of phosphate buffered saline (PBS) at weeks 0 and 2. Semen and blood samples were collected from each rabbit weekly for 14 weeks, examined for sperm motility and tested for sperm antibodies. Serum sperm antibody titer was inversely correlated with sperm motility in the immunized rabbits (r = -0.93, p<0.001) and there was no significant difference in response between rabbits (p>0.05). The 3 rabbits were reimmunized and the two control rabbits also given PBS as before at week 16. Each of the 5 rabbits was used to breed 4 randomly selected 7-8.month old fertile females. Conception rate (16.67%) and litter size (0.42/female) in females bred by immunized males were significantly lower than in those bred by control males (87.5%, p<0.02 and 7.5/female, p<0.001). Subsequent breeding of normal females with the previously immunized males at week 22 significantly improved the conception rate (55.56%, p<0.02) and litter size (3.05/female, p<0.001) compared to the breeding at week 16. It can be concluded that immunization of male rabbits with homologus sperm might reduce fertility and thus