Effects of hCG administration on accessory corpus luteum formation and progesterone production in estrous-induced nulliparous Santa Inês ewes

Abstract

The effect of hCG administration on accessory corpus luteum (ACL) formation, CL area, and plasma progesterone (P4) concentration (ng/mL) seven days after breeding was studied in nulliparous Santa Inês sheep. Intravaginal 60 mg MAP sponges were inserted into ewes for six days and 300 IU eCG i.m. and 30 µg d-cloprostenol latero-vulvar were administered 24 h before sponge removal. Ewes were naturally bred and, seven days after first mating (Day 0; D0), were treated with either 250 IU hCG (hCG group; n = 7) or 1 mL saline solution (control group; n = 7). Blood was collected to determine plasma P4 concentrations and sonograms were performed on Days 7, 10, 13, 16, 19, and 22. Number of CL on D7 was similar (P > 0.05) between hCG (1.3 ± 0.5) and control (1.3 ± 0.5) groups; however, on D13, it was greater (P < 0.05) in the hCG group (2.3 ± 0.5) than in the control group (1.3 ± 0.5). A greater (P < 0.05) luteal tissue area was detected in hCG-treated ewes (n = 4) on Days 16 to 22 than in the animals in the control group (n = 7). Plasma P4 concentration on D13 to D22 was higher (P < 0.05) in hCG-treated animals than in control ewes. Administration of hCG seven days after estrus onset efficiently induced accessory CL formation in ewes, increasing luteal tissue area and plasma P4 concentration.

Technologies Used in Production Systems for Santa Inês Sheep: A Systematic Review

“…As well as progesterone, other ovulation inducers have been used in protocols, such as human chorionic gonadotropin (eCG) ( 47 ), gonadotropin-releasing hormone (GnRH) ( 48 ), and pFSH in combination with eCG ( 49 ) or successive administration ( 50 ).…”

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

“…Our findings are in line with Echternkamp et al (2009) who showed that the size of the CL influenced the plasma concentrations of P 4 in cattle, and similar observations have been reported elsewhere (Perry et al, 2005). In sheep, eCG treatment increased the number of CL, luteal tissue area and plasma P 4 concentrations (da Fonseca et al, 2018), suggesting that eCG might play a role in luteal cell differentiation. The potential role of eCG on luteal cell differentiation could be partially explained because of increased blood prefusion to the CL as observed in the present experiment.…”

Effect of hCG administration on Day 7 post-mating on accessory corpus luteum development and progesterone concentration in llamas

“…Moreover, some authors have reported an improvement in pregnancy rates after this treatment [15,16,17]. Similarly, in sheep, the administration of hCG some days post-mating induced the development of an accessory CL accompanied by an increase in plasma P4 concentration [18,19,20]. In llamas, the development of an accessory CL has been achieved by the administration of a GnRH analog on day 7 post-mating [21].…”