Induction of accessory corpus luteum in cows by gonadotropin-releasing hormone administrated after insemination

Abstract

Sufficiency of progesterone limits conception rate in dairy cows. This study evaluates the effect of gonadotropin-releasing hormone on induction of accessory corpus luteum, progesterone concentrations and pregnancy in dairy cows. The hormone (0.05 mg) was administrated intramuscularly to cows with one corpus luteum on day 5-7 (Group E1, n = 57) or 11-13 (Group E2, n = 40) after insemination; control groups C1 (n = 54) and C2 (n = 41) were not treated. Detection of pregnancy by ultrasound examination and measurement of serum progesterone concentration was performed on day 25-39 and around day 90 after insemination. The occurrences of two corpora lutea in groups E1 and E2 versus C1 and C2 were 43.9% and 33.5% vs. 3.7% and 9.8% (P < 0.001). Progesterone concentrations were 5.9 ± 2.92 ng/ml and 7.8 ± 2.35 ng/ml in untreated and treated cows (P = 0.016), respectively. Conception rates in groups E1 and E2 were 100% and 86.7% in cows bearing two corpora lutea, and only 16.7% and 38.9% in cows bearing one corpus luteum (P < 0.01); similarly as in groups E1 and E2 compared to groups C1 and C2 (49.1% and 50% vs. 50% and 31.7%). Pregnancy rates around day 90 in groups E1 and E2 compared to groups C1 and C2 were 45.6% and 45% vs. 42.6% and 26.8%, respectively. Administration of gonadotropin-releasing hormone on day 5-7 or 11-13 after insemination was efficient to induce accessory corpus luteum and increase the concentration of serum progesterone but had no effect on the conception rate.

Induction of accessory corpus luteum by gonadorelin in relation to the time of treatment and the follicle size in inseminated cows

“…The occurrence of 2 CL was 15% in cows treated on days 0 and 12 (Lopez-Gatius et al 2006) or 17.7% in cows treated on days 28-34 (Bech-Sabat et al 2009) after insemination. Occurrences of 2 CL in cows treated on day 7 or on days 5-7 vs cows treated on day 13 or on days 11-13 after insemination were 54.2 or 43.9% vs 24.7 or 33.5% in our previous studies Musilova et al 2014). In this study we found a similar occurrence of 2 CL (42.2%) in the same period after treatment (day 28).…”

“…Usual rates of early embryo doi: 10.17221/46/2016-CJAS mortality, late embryo/early fetal mortality, and late abortion in cows are 20-45%, 8-17.7%, and 1-4%, respectively (Humblot 2001). Insignificant lower late embryo/early fetal mortalities in the presence of accessory CL have been described by Bartolome et al (2006), Bech-Sabat et al (2009), andMusilova et al (2014). We did not find significant differences in pregnancy loss between treated cows bearing 1 or 2 CL in this trial either.…”

“…We considered a small follicle (≤ 9 mm in diameter) to be a follicle in the growth or selection phase of the follicular wave while medium (10-14 mm) and large (15-20 mm) follicles were considered to be follicles in the early and late (preovulatory) dominant phases of the follicular wave. The occurrence of 2 CL after GnRH treatment was significantly higher in inseminated cows bearing follicles 10-14 mm or 15-20 mm in diameter compared to cows bearing follicles ≤ 9 mm in diameter in our previous study (48.2 or 55.6% vs 6.7%; Musilova et al 2014). We did not confirm the same relation in this trial.…”

Plasma progesterone profile and conception rate following exogenous supplementation of gonadotropin-releasing hormone, human chorionic gonadotropin, and progesterone releasing intra-vaginal device in repeat-breeder crossbred cows

“…This is also in agreement with the findings of Musilová et al . [ 18 ], who reported that administration of GnRH on day 5-7 or 11-13 after insemination was efficient to induce accessory CL and increase the concentration of serum progesterone. Several studies have reported a positive effect of GnRH administration on pregnancy rates [ 19 - 21 ], but in few other studies, GnRH administration failed to exhibit a positive impact on pregnancy rate [ 22 , 23 ].…”

An Approach Study for Reducing the Early Embryonic Loss in Egyptian Buffalo-cows

“…Similar to buffalo-cows treated with GnRH in our study, [46] showed that GnRH administered 12 days post insemination significantly increased serum P4 on day 18 post-insemination in dairy cattle. Also, administration of GnRH injection in cows at 11-13 day post-AI have been reported to cause ovulation of second follicular wave follicle, induce accessory CL formation, stimulate CL function, induce increase plasma P4, reduce estrogen production and have a positive effect on embryo survival and ultimately improving fertility responses [45].…”