Evaluation of treatments with hCG and carprofen at embryo transfer in a demi-embryo and recipient virgin heifer model

Abstract

An in vivo model, combining a low developmental competence embryo (demi-embryo) and a high-fertility recipient (virgin dairy heifer) was used to evaluate the effects of treatment with human chorionic gonadotropin (hCG) and carprofen at embryo transfer (ET) on plasma progesterone (P 4 ) concentrations of recipients and on embryonic growth and survival. Embryos were bisected and each demi-embryo was transferred to a recipient on Day 7 of the estrous cycle. At ET, heifers (n 5 163) were randomly allocated to treatment with hCG (2500 IU im), carprofen (500 mg iv), hCG plus carprofen or to untreated controls. Plasma P 4 concentrations were measured on Days 0, 7, 14 and 21 of all recipients plus on Days 28, 42 and 63 of pregnant recipients. Pregnancy was presumed to be present in recipients with luteal plasma P 4 concentrations until Day 21 and confirmed by using transrectal ultrasonography on Days 28, 42 and 63. Embryonic measurements (crown-rump length and width) were obtained on Day 42. Treatment with hCG induced formation of secondary corpora lutea (CL) in 97% of heifers and increased ( P , 0.01) mean plasma P 4 concentrations of non-pregnant recipients on Day 14 and of pregnant heifers on Days 14 to 63. This was associated to a significant decrease in early embryonic mortality. In contrast, subsequent embryonic losses resulted in a non-significant numerical increase by 8% of pregnancies maintained to Day 63. Therefore, treatment with hCG significantly rescued embryos through the maternal recognition of pregnancy window but was not able to support development thereafter. Treatment with carprofen at ET had no significant effects on plasma P 4 concentrations and rate of embryo mortality. Treatment with hCG plus carprofen at ET induced formation of secondary CL in 90% of heifers but decreased the luteotrophic effect of hCG, resulting in no effect on embryo survival. Low developmental competence embryos showed an intrinsic deficiency in overcoming the maternal recognition of pregnancy challenge and in proceeding to further development until Day 28 of pregnancy, whereas mortality beyond this point was residual. Results on pregnancy rates should be confirmed in further experiments involving a larger sample size. Keywords: demi-embryo, hCG, carprofen, progesterone, bovine Implications Embryonic mortality is a major source of economic loss in the cattle industry, and may occur because of intrinsic embryonic, maternal and management factors. These factors may interact, which makes difficult to study their mechanisms of action and the design of appropriate therapeutic approaches. Herein, we used an in vivo model, considering a compromised embryo and a high-fertility recipient, to evaluate therapeutic strategies designed to enhance embryonic survival. Preliminary results showed that treatment with hCG at embryo transfer may be of interest to decrease embryonic mortality, whereas carprofen had no apparent effect on embryo survival. IntroductionPregnancy loss is a major cause of reproductive failure and of economic waste in...

Effect of treatment with human chorionic gonadotropin 7 days after artificial insemination or at the time of embryo transfer on reproductive outcomes in nulliparous Holstein heifers

“…The homology in β-subunits between hCG and bovine LH is ~80% (Pierce and Parsons, 1981); thus, treatment with hCG has an LH-like effect in cattle, resulting in an increase in serum P4 concentration either by stimulating an increase in P4 production from the existing corpus luteum (Stevenson et al, 2007), by inducing ovulation of a dominant follicle to form an accessory corpus luteum (Schmitt et al, 1996;Santos et al, 2001;Thatcher et al, 2001;Nascimento et al, 2013), or via both mechanisms. In other experiments, treatment with hCG during the early (d 4 to 7) luteal phase when a dominant follicle of the first follicular wave is present caused formation of an accessory corpus luteum in 83 (Price and Webb, 1989), 97 (Torres et al, 2013b), and 100% (Diaz et al, 1998) of nulliparous Holstein heifers.…”

“…Differences in P4 due to pregnancy status before luteolysis in the present study are in agreement with others. When heifers were inseminated to a detected estrus, P4 concentrations did not differ between pregnant and nonpregnant cows and heifers 7 d after AI (Santos et al, 2001; Chagas e Silva and Lopes da Costa, 2005) or ET (Niemann et al, 1985;Stubbings and Walton, 1986;Chagas e Silva et al, 2002; Chagas e Silva and Lopes da Costa, 2005;Torres et al, 2013b).…”

“…In cows, treatment with hCG on d 5 (Schmitt et al, 1996;Santos et al, 2001;Nascimento et al, 2013), 7 (Sianangama and Rajamahendran, 1992;Dahlen et al, 2010;Wallace et al, 2011;Torres et al, 2013a), and 14 (Sianangama and Rajamahendran, 1992) increased P4 concentrations; however, effects on pregnancy outcomes and pregnancy loss varied. Pregnancy outcomes for heifers treated with hCG have varied even more; P/ AI increased after treatment with hCG on d 4 (Breuel et al, 1989) and 7 (Chagas e Silva and Lopes da Costa, 2005;Torres et al, 2013b), whereas no difference was reported in other studies when beef heifers were treated with hCG on d 4 (Breuel et al, 1990), 5 (Funston et al, 2005), or 6 (Funston et al, 2005).…”

Pregnancy rates and serum 13,14-dihydro-15-keto-PGF2α concentrations in recipient Nelore heifers treated with meloxicam after the transfer of in vitro–produced embryos

“…Torres et al [15] evaluated the effects of treatment with hCG and carprofen at embryo transfer in a demi-embryo and recipient virgin heifer model on plasma progesterone concentrations of recipients and on embryonic growth and survival. Females were divided into untreated or treated animals with carprofen, hCG, or carprofen plus hCG.…”

“…Only grade I COCs were in vitro matured (10 per 100-mL drop) on Day 0 in a Petri dish (Ingámed, Maringá, Paraná, Brazil) containing 100 mL of tissue culture medium 199 and minimum essential medium (Gibco, New York, NY, USA) supplemented with BSA, pyruvate, cysteine, streptomycin and penicillin (Gibco), FSH (Folltropin V; Bioniche Animal Health, Athens, GA, USA), LH (Lutropin V; Bioniche Animal Health), and EGF under mineral oil for 24 hours at 38 C in a humidified environment of 5% O 2 . After 24 hours, COCs were fertilized with frozen-thawed semen from a Nelore bull in Fert TALP (Tyrode's albumin, lactate and pyruvate solution), sperm TALP, and Fert HEPES medium supplemented with BSA, pyruvate, streptomycin, and PHE (penicillamine, hypotaurine, and epinephrine) [15]. Eighteen hours later, the presumptive zygotes were denuded; the percentage of cleavage was determined; and every 10 zygotes were transferred to 100-mL drops of culture medium for 3 days of culture.…”