Administration of a single dose of 300 IU of human chorionic gonadotropin seven days after the onset of estrus improves pregnancy rate in dairy goats by an unknown mechanism

This study examined the effects of exogenous hCG administration on ovarian function and pregnancy rates in estrous-induced dairy goats during the transition into the breeding season. Eighty-six Toggenburg does received 60 mg of medroxyprogesterone acetate intravaginal sponge for 6 d plus 200 IU of equine chorionic gonadotropin and 30 μg of d-cloprostenol i.m. 24 h before sponge removal, and were then bred for 96 h. Seven days (D7) after first mating the does received either 1 mL of saline (the control group, n = 43) or 300 IU of hCG (the hCG-treated group, n = 43) i.m. Transrectal ovarian ultrasonography (B-mode and color Doppler) was performed on D7, D13, D17, and D21 and ultrasonographic pregnancy detection on D30. Pregnancy rate was higher (P < 0.05) in hCG-treated goats (90.7%; 39/43) than that in control animals (74.4%; 32/43). Accessory luteal structures (ALSs) were detected in 46.5% (20/43) of hCG-treated does. All hCG-treated does that had ALSs and 82.6% of goats without ALS post-treatment remained pregnant. The total luteal area increased (P < 0.05) from D7 to D13 in pregnant animals of both groups, whereas mean vascular area declined (P < 0.05) by D21 in all nonpregnant does. Serum progesterone concentrations increased (P < 0.05) on D21 in pregnant goats of both groups, but they were related to changes in luteal tissue content only in control does throughout the present study. Mean daily numbers of small- and medium-sized antral follicles decreased (P < 0.05) only in pregnant animals of both groups with a decline in medium follicle numbers occurring earlier in hCG-treated (D13) compared with control does (D17). To summarize, a single dose of hCG given on D7 after estrus was followed by a decrease in the number of medium-sized antral follicles in gestating hCG-treated does, induced the formation of ALSs in ~47% of all hCG-treated does, and significantly increased the pregnancy rate in estrous-induced Toggenburg goats in the transition to the breeding season.

Transrectal ultrasound evaluation in tropical dairy goats: an indispensable tool for the diagnosis of reproductive disorders

In Brazil, great milk productivity was achieved after the implementation of a genetic improvement program. However, reproductive efficiency is still far from optimal, possibly due to the high number of undiagnosed disorders that may affect fertility. The aim of this study was to evaluate occurrences of the main reproductive disorders in dairy goats in southeastern Brazil. Data were collected between January 2015 and May 2017 from 23 commercial herds of different breeds, with goats ranging from 8 months to 12 years of age. Transrectal ultrasound exams were performed in 2680 goats. A total of 14.8% of the does showed a disorder in the reproductive tract: hydrometra (10.0%), ovarian follicular cysts (2.3%), gestational loss (1.5%), and hydrosalpinx (1.1%). This was the first study evaluating reproductive disorders in live animals that used a high number of Brazilian dairy goats. Considering that all these diseases affect fertility to different degrees, the performance of transrectal ultrasonography exams twice a year is strongly suggested, in order to guide precocious treatment or discard the animal as soon as possible, thus reducing economic losses in dairy goat farming.