Artificial insemination of Cashmere goats: effects on fertility and fecundity of intravaginal treatment, method and time of insemination, semen freezing process, number of motile spermatozoa and age of females

Abstract

The experiments, using a total of 1833 Cashmere does, were conducted to examine the effects on fertility and fecundity of intravaginal treatment for control of ovulation, time of insemination by cervical and laparoscopic methods, semen processing in pellets and straws, and number of frozen-thawed motile spermatozoa. Adult does (greater than or equal to 2.5 years) that had previously kidded were inseminated into the cervix, and maiden (kid: 6-8 months; hogget: 18 months) and adult does were inseminated laparoscopically. The rates of pregnancy determined by ultrasonic scanning (75-80 days after insemination) for cervical (Experiment 1) and laparoscopic (Experiments 2 and 3) insemination were 39.1%, 63.6% and 52.1%. The number of motile spermatozoa did not affect fertility after cervical (80, 120 and 160 x 10(6) or laparoscopic (Experiment 2: 15, 30 and 60 x 10(6); Experiment 3:5, 10 and 20 x 10(6) insemination. The method of insemination or number of motile spermatozoa did not affect fecundity. With cervical insemination, fertility and fecundity improved with increasing depth of insemination into the reproductive tract. Intravaginal sponges containing fluorogestone acetate and controlled internal drug release (CIDR) devices containing progesterone were equally effective for control of ovulation when combined with an injection of pregnant mare's serum gonadotrophin (PMSG; 200 i.u.) before insemination. Fertility was higher when does were inseminated before than after ovulation. After laparoscopic insemination, results were similar for semen frozen as pellets and in straws, and for 3-, 6- and 24-fold pre-freezing dilution of semen. For kid, hogget and adult does in Experiment 3, pregnancy rates were 34.0%, 55.4% and 63.9% and rates of fecundity were 1.17, 1.22 and 1.27 fetuses/pregnant doe.