Effect of reproductive methods and GnRH administration on long-term protocol in Santa Ines ewes

Abstract

This study aimed to determine whether reproductive performance of ewes submitted to laparoscopic timed artificial insemination (TAI) would be similar to ante meridiem (AM)/post meridiem (PM) rule and assisted natural mating (NM), and whether GnRH may enhance the pregnancy rate in TAI. In experiment I, 191 non-lactating ewes were synchronized, then TAI was performed either 48 h after progesterone (P4) removal (TAI-48 h) or 12 h after estrus detection (AM/PM); moreover, some ewes were submitted to NM (NM) as control treatment. In experiment II, 247 non-lactating ewes were allocated in five treatments, a control (no-GnRH on protocol) and four treatments arranged in a factorial design 2 × 2. The factors were time and dose of GnRH: ewes that received either 10 μg (TAI-10 μg-36 h) or 25 μg of GnRH (TAI-25 μg-36 h) 36 h after P4 removal and ewes that received either 10 μg (TAI-10 μg-48 h) or 25 μg of GnRH (TAI-25 μg-48 h) at time of insemination, 48 h after P4 removal. In experiment I, pregnancy rate in TAI-48 h was lower (P = 0.03) than AM/PM and NM. Moreover, the probability of pregnancy in TAI-48 h was higher (P = 0.06) in ewes detected in estrus early. In experiment II, the use of GnRH in TAI protocols increased (P < 0.01) pregnancy rate at synchronization, and TAI-25 μ-48 h and TAI-10 μg-36 h treatments increased (P = 0.02) pregnancy rate compered to TAI-10 μg-48 h. We conclude that TAI decreased pregnancy rate compered to NM and AM/PM, which may be improved by GnRH use in TAI to synchronize ovulation.

Evaluación del protocolo corto y largo de sincronización de celo en borregas inseminadas con semen congelado

“…Several ES techniques have been developed to induce estrus in sheep 3 . Long-term progestogen treatments (12 to 14 days) are commonly applied in sheep [4][5][6][7][8][9][10][11][12][13] , with a percentage of animals showing acceptable estrus and fertility rates 12 , but with lower fertility than natural estrus [14][15][16] . This low fertility rate is due to different causes such as, deficiencies in detection and ES, slow follicular turnover that generates a persistent follicle 4,17,18 on the other hand the traditional synchronization system brings vaginal infections 15,19 , with bacterial proliferation 20 has also been associated with accumulation of offensive vaginal mucus, bad odor 21 , vaginal adhesions, vaginitis 22 , which result in low fertility rates, after AI with fresh semen.…”

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 ).…”

A comparative transcriptome and proteomics study of post‐partum ovarian cycle arrest in yaks (Bos grunniens)

“…The level of gonadotrophin‐releasing hormone receptor (GnRHR) mRNA in the hypothalamus is higher than that in the pineal gland, pituitary gland and ovary during oestrus of yak (Huo et al., 2018). This GnRH leads to accessory corpus luteum formation, but neither the plasma progesterone concentration nor the pregnancy rate is affected by having an accessory corpus luteum (Abalos et al., 2018; Biehl et al., 2017; Desaulniers et al., 2017; Kaim et al., 2003). The follicle‐stimulating hormone receptor ( FSHR ) mRNA expression level is higher in the pituitary gland tissue compared with luteinizing hormone receptor ( LHR ) during oestrus of yak, whereas there is low expression of FSHR and LHR mRNA in the pineal gland and hypothalamus.…”