Immunocastration of goats using anti-gonadotrophin releasing hormone vaccine.

The aim of this study was to evaluate the immuno-sterilizing action of anti-gonadotrophin-releasing hormone (anti-GnRH) vaccine in goats. Eighteen male goats were randomly distributed to receive three treatments: T1 (control) - whole animals, and T2 and T3 - application of 0.5 and 1.0 mL of anti-GnRH vaccine, respectively, with six replicates and one goat per experimental unit. Vaccine was administered at 8 months of age and 30 days after the first immunization. Testicular biometry was evaluated monthly, along with seminal collections, for the physical and morphological evaluation of semen. At the time of slaughter, the testicle were collected, and fragments were measured and removed for histological evaluation. The data were evaluated for normality by the Shapiro-Wilk test, followed by appropriate statistical tests for each variable. A reduction in width and length of the right and left testicles was observed and, consequently, the scrotal circumference of the immunized animals reduced after the second vaccine application (P < 0.05). Thirty-days after the first vaccine application, there was a negative effect on seminal production and quality; and 60 days after the second application, a pronounced reduction was observed in all seminal parameters in the vaccinated animals, including azoospermia (83.33% of animals; P < 0.05). Vaccine application reduced testicular weight, seminiferous tubule diameter, and gonadosomatic and tubulosomatic index (P < 0.05), but did not influence the proportion of testicular parenchyma components (P > 0.05). Two applications of the anti-GnRH conjugate are effective for the immunological castration of goats, and the 0.5 mL dose is recommended for use in crossbred goats.

Follicular response and oocyte production following variations in ovarian stimulation in goats.

In this study, goats were subjected to ovarian stimulation protocols to evaluate possible differences in ovarian follicular responses and oocyte production. Two experiments were conducted to assess the effects of hormonal protocol duration (seven or twelve days) and number of follicle stimulating hormone (FSH) applications (one or five doses). All animals received intravaginal sponges saturated with 60 mg medroxyprogesterone acetate and an application of 125 µg cloprostenol 72 h before the sponges were removed. For ovarian stimulation, 120 mg FSH was applied in a single dose 36 h before laparoscopic follicular aspiration (LOPU) or in five doses (30, 30, 20, 20, and 20 mg) at 12 h intervals, with the last dose applied 36 h before LOPU. In the first experimental phase, ultrasonography was performed to monitor follicular number and diameter, and in the second phase, the animals received LOPU to count the follicles and cumulus-oocyte complexes (COCs) and for morphological classification. There was no significant effect (P > 0.05) of any variable or combination of variables on follicle number on Day (D) 0 or D3/D8 (day of LOPU). However, evaluation at D6/D11 revealed an effect (P < 0.05) from the protocol duration with the highest number of small follicles resulting from the short protocol. There was also an effect (P < 0.05) of FSH dose number on the resulting number of medium and large follicles, with more medium follicles recovered after a single dose and more large follicles after multiple doses. There was no effect of any variable (P > 0.05) on the diameters of the large, medium, and small follicles, except for the D4/D9 evaluation, which showed a combination effect for large follicles (P < 0.05). In the second phase, no variable had an effect on the number of follicles visualized or aspirated, number of COCs recovered, recovery rate, morphological quality of COCs in grades 1, 2, 3, and 4, or rate of viable COCs. Thus, all four protocols efficiently stimulated the ovarian response and oocyte production of goats, although the short protocol (7 days) with a single dose of FSH was most efficacious based upon the greater number of medium-sized follicles available for aspiration, the shorter time, and greater practicality of execution.