Administration of gonadotropin-releasing hormone agonist on Day 5 increases luteal blood flow and improves pregnancy prediction accuracy on Day 14 in recipient Holstein cows

Abstract

This study assessed the effects of gonadotropin-releasing hormone (GnRH) treatment on Day 5 (Day 0 = estrus) on luteal blood flow and accuracy of pregnancy prediction in recipient cows. On Day 5, 120 lactating Holstein cows were randomly assigned to a control group (n = 63) or GnRH group treated with 100 μg of GnRH agonist (n = 57). On Days 3, 5, 7, and 14, each cow underwent ultrasound examination to measure the blood flow area (BFA) and time-averaged maximum velocity (TAMV) at the spiral arteries at the base of the corpus luteum using color Doppler ultrasonography. Cows with a corpus luteum diameter ≥ 20 mm (n = 120) received embryo transfers on Day 7. The BFA values in the GnRH group were significantly higher than those in the control group on Days 7 and 14. TAMV did not differ between these groups. According to receiver operating characteristic analyses to predict pregnancy, a BFA cutoff of 0.52 cm2 yielded the highest sensitivity (83.3%) and specificity (90.5%) on Day 7, and BFA and TAMV values of 0.94 cm2 and 44.93 cm/s, respectively, yielded the highest sensitivity (97.1%) and specificity (100%) on Day 14 in the GnRH group. The areas under the curve for the paired BFA and TAMV in the GnRH group were 0.058 higher than those in the control group (0.996 and 0.938, respectively; P < 0.05). In conclusion, GnRH treatment on Day 5 increased the luteal BFA in recipient cows on Days 7 and 14, and improved the accuracy of pregnancy prediction on Day 14.

Corpus Luteum Color Doppler Ultrasound and Pregnancy Outcome in Buffalo during the Transitional Period

“…In the present trial, TAMV values recorded on Day 8 post-TAI seem to significantly influence the likelihood of pregnancy in the buffalo species. This was supported by a recent study in which a significantly higher luteal blood flow and TAMV values were observed on Day 7 post-estrus in successfully pregnant Holstein cows, which were used as recipients for ET and treated with GnRH on Day 5, compared to nonpregnant counterparts [ 28 ]. However, according to these authors, the simultaneous evaluation of TAMV and the blood flow area may increase the accuracy of pregnancy prediction in cattle.…”

“…The influence of CL dimensions on pregnancy rate is controversial. While in some studies, pregnant buffaloes showed a higher CL area compared to nonpregnant subjects [ 10 , 27 ], no differences were observed in other studies [ 28 , 29 ]. In a recent trial [ 30 ], a difference in CL dimensions between pregnant and nonpregnant buffaloes was observed only 14 days after insemination, while no differences were recorded during the Day 5 to Day 10 period.…”

“…After ovulation, the developing CL needs blood substrates for P 4 production and several studies support a strong correlation between blood flow and P 4 levels, either in cattle [ 32 ] or in buffalo [ 10 ]. However, a significant increase of blood flow has been correlated with pregnancy in cattle only 15 days after insemination [ 33 ], although some recent studies performed in Holstein cows highlight a difference between pregnant and nonpregnant cattle from Day 7 post-estrus [ 28 ]. In the present trial, TAMV values recorded on Day 8 post-TAI seem to significantly influence the likelihood of pregnancy in the buffalo species.…”

Doppler sonography of the corpus luteum during the oestrus cycle in dairy cows

“…Lobular vessels are less evident with Doppler resolution unless managing the setting. The identification of the spiral artery is facilitated by the orientation of the probe along the longitudinal axis of the ovary, taking as a reference point the mesovary and the proper ligament of the ovary (7). The area of the CL with the maximum diameter including the apex and the base, identified by the spiral artery entry, was used in this study according to previous study (1) and it is extremely important for the standardization of the measurements.…”

Transfer of a single embryo versus drainage of subordinate follicles to prevent twin pregnancies in dairy cows. Why not both?

“…Effectively, embryo transfer (ET) is considered the most effective mechanism for maximizing fertility during heat stress, improving fresh IVP embryo pregnancy results comparable to artificial insemination (AI) under heat stress conditions [12]. Treatment with GnRH on Day 5 post-estrus increases the corpus luteum (CL) blood flow area, thus improving luteal function assessed on Day 7 at ET [13] and prompting additional corpora lutea formation [14]. This treatment improves embryonic survival in IVP embryo recipients [14].…”