Diagnóstico de la gestación en la oveja según su reacción etológica a los estrógenos y capacidad abortiva del D.D.E. y del B.E.

Abstract

Ewes of three breed groups (rasas, 41 kg; gallegas, 21 kg; cross bred fleischschaf x Rasa, 52 kg average live weight), previously exposed to fertile rams were used in three experiments designed to test the possibility of detecting pregnancy in sheep injected with estrogens and joined thereafter with raddled sexual active rams, whose reactions were recorded for three consecutive days after treatments, twice a day, for half an hour each day. Later parturition or abortion were the criteria considered for testing the efficiency of the proposed method. Experiments 1 and 2 were performed In february and september, 1972, respectively, on ewes previously exposed to fertile rams for 40 days. The animals were divided into 4 groups; three of them were dosed subcutane ously with 0.5, 1.0 and 1.5 mg/head of oil solution of dioxi-dietil-stilboestrol (D. D. E.), remaining a fourth group as con¬trol. At estrogens treatment time condition of ewes as far as pregnancy concerns was unknown. In both experiments heats were not detected at all by the raddle drams in 56 pregnant ewes, but 5 of these aborted in groups 2 and 3, one abortion being recorded among the 15 ewes in control group. From 45 open ewes in experimental groups exhibited oestrus 53.2, 35.7 and 417 p. 100 respectively vs. 33.3 p. 100 in a control group with 9 control animals. Only one from 13 young open ewes dosed with D. D. E. in three similar dosification groups to adult ones exhibited heats. Experiment 3 was perfomed in january-February, 1973, in 71 adult eves of same breed groups as those in experiments 1 and 2, previously exposed to fertile rams for 43 days and dosed intramuscularly with 0.015, 0.030 and 0.060 mg/head of estradiol benzoate (E. B.) From 23 pregnant ewes in experimental group and 7 in control group only one exhibited behaviour changes that could be alike normal heat. No abortion was recorded at all, being 99 days average gestation period for ewes in the four groups injected with E. B. From 30 open ewes in experimental groups exhibited oestrus 40,0 60.0 and 40.0 p. 100 vs. 18.2 p. 100 in a control group with 11 ewes. In all three experiments lambs were normal both in weight and vita¬lity at birth for sex, breed and litter size. Evaluation of the experiments reported suggests that pregnancy de¬tection in ewes recording ethologic reaction to estrogens applied in the gestation interval from 60 to 90 days depends widely upon proportion of pregnant and open ewes in the problem flock, ranging from 45 p. 100 efficiency for a flock with 100 p. 100 open ewes to a 1C0 p. 100 efficiency for a flock with 100 p. 100 pregnant ewes (because no pregnant ewes shows oestrus if injected with estrogens as general rule). The risk of abortion seems to be low for the dosis and the estrogens tested. The method seems to be not useful whith young ewes. More research is needed concerning its aplicability in non breeding season and for finding compounds more active and less potencially dangerous. For pregnancy diagnosis is suggested intramuscular dosing with 1,0 mg of D. D, E. or 0,030 mg. of E. B. for 45-55 kg. ewes and half these doses for mature ewes weighting 30-40 kg. between 70-90 days after ram exposure. Abortion risk seems to be low if ewes are gently restricted. Some raddled or vasectomised rams are better detectors than others.

Tres grupos de ovejas adultas previamente expuestas a moruecos fértiles fueron inyectadas subcutáneamente con soluciones oleosas de D. D. E. (0,5, 1,0 y 1,5 mg por cabeza) en febrero y septiembre 1972 y con solución oleosa de B. E. (0,015, 0,030 y 0,060 mg por cabeza) en enero, febrero 1973. Al efectuar los ensayos, las gestaciones de los tres grupos habían avanzado hasta periodos medios de 61,1, 92,6 y 99,0 días, respectivamente. Los celos fueron detectados utilizando moruecos provistos de mandiles durante tres días tras los tratamientos. Solamente se observaron 6 abortos de un total de 133 ovejas inyectadas vs. una en uno de los grupos de control. De un total de 45 ovejas no gestantes en el 1.° y 2.° grupos, los celos registrados fueron 52,2, 35,7 y 43,7 p. 100 vs. 33,0 p. 100 en 9 ovejas del grupo testigo. De un total de 53 ovejas no gestantes del 3.° grupo (B. E.) los porcentajes fueron 40,0, 60,0 y 40,0 p. 100 vs. 18,2 p. 100 en un grupo control de 18 ovejas. El D. D. E. no promovió manifestaciones de celo en 13 primalas vacías.