Effect of cat seminal plasma and purified llama ovulation-inducing factor (β-NGF) on ovarian function in queens

The present study aimed to determine the effect of cat seminal plasma and purified llama ovulation-inducing factor (β-NGF) on ovarian activity in queens. Queens (n = 6) were used for all the treatments in a crossover design with an interval time between treatments of three interestrus intervals. Forty-eight hours after the detection of an estrus vaginal cytology, queens were given cat seminal plasma (subcutaneous or intramuscular), purified llama ovulation-inducing factor (15 or 35 μg), hCG (75 UI), saline, or were mated with a male. A total of 192 estrous cycles were observed. Estrus length and serum estradiol concentration were 6 ± 1 days (range 2-10 d) and 38 pg/mL (range 10-75 pg/mL), respectively. Queens mated and given hCG showed higher serum progesterone concentration and longer interestrus interval (47 ± 5 d) than that of controls (10 ± 3 d). Sixty-seven percent of queens (4/6) treated with subcutaneous cat seminal plasma, and 17% of those treated with purified llama β-NGF showed high serum progesterone concentrations along with prolonged interestrus. However, intramuscular administration of cat seminal plasma produced interestrus intervals similar to controls (15 ± 5 d) and basal serum progesterone concentration (<0.50 ng/mL). This study demonstrates that the subcutaneous administration of cat seminal plasma induced ovulation in queens. Therefore, molecules present in cat seminal plasma, contribute to the induction of ovulation in queens. Identifying those molecules will improve the knowledge of queen's reproductive physiology. Also, it could offer a physiologic alternative to induce ovulation in queens when reproductive biotechnologies are used.