RELATIONSHIP BETWEEN PERIPHERAL ESTROGEN CONCENTRATIONS AT INSEMINATION AND SUBSEQUENT FETAL LOSS IN CATTLE

In a survey on pregnancy rate and embryonic losses in dairy cattle on 6 Israeli farms, cows (n=78) were divided into 3 groups on the basis o f ultrasonography at 21 d post insemination; pregnancy diagnosis at 40 to 50 d post insemination and blood progesterone (P-4) levels at 21 d . The groups were either pregnant (P-4 level >1.0 ng/mL); not pregnant (P-4 <0.5 ng/mL), or showed early embryo loss (P-4 >1.0 ng/ mt and th e presence of an embryonic vesicle on D 21 but later returned to estru s or were found not pregnant on D 40 to 50). On the day of inseminatio n, peripheral estrogen was significantly higher (P <0.05) in the early embryo loss group (15.3+/-1.1 pg/ mt, n=27). than in pregnant (9.4+/- 0.6 pg/mL, n=26) or not pregnant (9.6+/-0.7 pg/ mt, n=25) group. The c ows on 3 farms which were fed 1 to 2 kg/ d of vetch (Vicia sativa), an estrogenic legume, had higher estrogen concentrations.on the day of i nsemination than cows (2 farms)fed other legumes (13.7+/-0.64, n=58 vs 10.7+/-0.8 pg/mL, n=42; P<0.01). On one of the 3 farms, vetch was rep laced with alfalfa after the first year. Following the cessation of ve tch feeding the estrogen concentrations in the blood decreased from 32 +/-5 pg/ mt to 14+/-2 pg/ mt (n=9). These data suggest that high perip heral estrogen on the day of insemination is associated with early emb ryonic loss. These data also indicate that estrogen concentrations on the day of insemination can be influenced by diet. (C) 1998 by Elsevie r Science Inc.