Effect of eCG dose on ovarian haemodynamics, hormonal profiles and prolificacy rate when oestrus was induced during low‐breeding season in Beetal goats

Abstract

The objectives of the experiment were to determine the effect of two doses of equine chorionic gonadotropin (eCG) in a standard synchronization protocol based on a short‐term progesterone (P4) priming on ovarian structures and haemodynamics, concentrations of steroid hormones and prolificacy rate when oestrus was induced during low‐breeding season (LBS) in Beetal dairy goats. We hypothesized that inclusion of eCG in a short‐term P4 priming‐based synchronization protocol would increase the blood perfusion to ovarian structures leading to enhance oestrous and ovulatory responses and prolificacy rate in goats. Forty‐two multiparous acyclic goats were blocked by body condition and, within block, assigned randomly to receive saline as control (CON), low eCG (L‐eCG; 300 IU) or high eCG (H‐eCG; 600 IU) dose. Initially, a controlled internal drug release (CIDR) device was placed in the anterior vagina on d −8, followed by removal of CIDR on d −3, concurrent with the administration of PGF2α and eCG according to their respective treatments. Goats were monitored for oestrous response. B‐mode and Doppler ultrasonography was performed with 12‐h interval, starting from day −3 until natural breeding (day 0), and then on days 5, 10, 15 and 20 post‐breeding to monitor follicular and luteal dynamics and blood flow, respectively. Blood was sampled at 0, 12, 24, 36 and 60 h after CIDR removal to quantify plasma concentrations of estradiol‐17β (E2), whereas plasma concentrations of P4 were assayed at days 5, 10, 15 and 20 after breeding. Pregnancy and prolificacy rates were determined at day 30 and 150 after breeding, respectively. Data were analysed with mixed‐effects models, and orthogonal contrasts were used to evaluate the effect of treatment [Con vs. (½ L‐eCG + ½ H‐eCG)] and dose of eCG (L‐eCG vs. H‐eCG). Data are presented in sequence as CON, L‐eCG, H‐eCG (LSM ± SEM). The oestrous intensity score (152.9 vs. 182.7 vs. 186.5 ± 15.1; p = .02) was greater in eCG‐treated goats as compared to CON. Administration of eCG reduced the intervals to standing oestrus (66.2 vs. 41.8 vs. 48.9 h ± 5.5; p = .05), breeding (70.2 vs. 44.4 vs. 45.4 h ± 4.5; p = .03) and ovulation (84.5 vs. 61.2 vs. 63.4 h ± 6.2; p = .05) compared with CON goats. The mean growth rate of pre‐ovulatory follicle was greater (1.11 vs. 1.49 vs. 1.45 mm ± 0.08; p = .01) in eCG‐treated goats resulting in an increased diameter of pre‐ovulatory follicle (6.27 vs. 7.20 vs. 7.31 mm ± 0.07; p < .01) and corpora lutea (6.75 vs. 8.26 vs. 8.07 mm ± 0.42; p = .04) than CON. The mean follicular blood flow did not differ among treatments; however, the mean luteal blood flow was greater in L‐eCG‐treated goats (0.81 vs. 1.61 vs. 1.07 cm2 ± 0.12; p = .001). The mean concentrations of E2 (4.03 vs. 5.21 vs. 4.78 pg/ml ± 0.42; p = .04) and P4 (4.85 vs. 6.39 vs. 6.22 ng/ml ± 0.34; p = .04) were greater in eCG‐treated goats. The twinning rate did not differ between treatments; nevertheless, prolificacy rate was greater (p = .04) in L‐eCG‐treated goats. Collectively, our data sugges...

Influence of repeated estrus synchronization treatment on hormone secretion, growth, and development of dairy goats

“…PMSG, with physiological activities similar to those of FSH and LH, influences follicle development and hormone secretion and is often used with P4 for the ES of dairy goats ( 3 , 34 ). Further, anti-PMSG forms a macromolecular antigen–antibody complex in vivo , neutralising PMSG and reducing its biological titre ( 14 , 15 ).…”

“…Following the protocol from previous research ( 3 ), ES treatment in each group involved using a CIDR device impregnated with 300 mg P4 [Pharmacia&Ujohn Company, New York, NY, United States (United States of America)], which was introduced into and maintained in the vagina of each goat for 10 d. Additionally, PMSG was intramuscularly injected in each goat at a dose of 300 IU (Sansheng Corporation, Ningbo, China) 48 h before the withdrawal of the CIDR device ( Figure 1B ).…”

“…The predominant hormones for ES are pregnant mare serum gonadotropin (PMSG) and progesterone (P4) ( 2 ). The combination of intramuscular PMSG injection and vaginal P4 suppositories is widely employed to enhance ES efficiency in dairy goats ( 3 , 4 ).…”

“…Notably, PMSG and CIDR containing P4 are often combined in ES treatment for does ( 3 , 5 ). However, the impact of vaginal P4 devices during repeated ES treatments on P4 antibody levels and reduced fecundity remains poorly understood.…”

“…The predominant hormones for ES are pregnant mare serum gonadotropin (PMSG) and progesterone (P4) (2). The combination of intramuscular PMSG injection and (3,4). PMSG is a gonadotropin produced in the chorionic membrane of a pregnant mare, acts as both follicle-stimulating (FSH) and luteinising hormone (LH) (5).…”