مقايسه جنسيت گوساله و بره متولد شده از شاخ راست و چپ رحم در گاو و گوسفند

Sex determination in cattle and ewes according to site of ovulation on left or right ovaries.

Occasionally claims are made that certain specific and intentional procedures will influence the sex ratio. One of these claims which received wide public was the alteration of the PH of the vagina before service. Widespread use of artificial insemination bring about many further experiments to be conducted to separate the y - bearing spermatozoa from x-bearing spermatozoa with electrophoresis, centrifugation,sedimentation and other techniques such as flow cytometry. In fact that the rate of ovulation on the right ovary of many species were compared with the left ovary, the sex ratio has not been compared as yet. In order to determine the likelihood of changing sex ratio with selective breeding on the basis of the right or left ovarian ovulations, 56 slaughtered pregnant ewes (in Sarhang slaughterhouses in Tehran) and 76 pregnant cattle (Pakdam Farm, Robatkarim) were randomly selected. Gender of fetuses in the right and left uterine horns of slaughtered ewes and the site of corpus luteum on right or left ovaries were recorded. In cattle at the time of pregnancy diagnosis (55 days after breeding), the site of corpus luteum on the right or left ovaries were recorded as an indicator of ovulation site. Gender of the fetuses was determined after parturition. Chi-Square test was used to compare sex ratio (the rate of male fetuses at parturition) between right and left uterine horns iu cattle and ewes. Results of this stud)ʹ indicated that in cattle, from 44 cases of pregnancy producing ovulations in right ovaries, 26 cases (54.6 %) were male and 18 cases (40.9 %) were female, however from 32 cases of pregnancy producing ovulations in left ovaries, 10 cases (31.25%) were male and 22 cases ( 64.75 % ) were female (P <0.05). From 76 cases of pregnant cattle, 4 cases were twines but only in right ovaries (2 cases male X male, I cases male X female and I cases female X female). Altogether, from 76 cases of pregnancy producing ovulation, 44 cases (57.81 %) were from the right and 32 cases (42.2 0/0) were form the left ovaries. In ewes, from 28 cases of pregnancy producing ovulations in right ovaries, 15 cases (53.6 0/0) were male and 13 cases (46.6 0/0) were female, whereas from 22 cases of pregnancy producing ovulations in the left ovaries,8 cases (36.4 % ) male and 14 cases ( 63.6 %) were female (P>0.05). Altogether, from 50 cases of pregnancy, 28 cases (56 %) were in the right horn and 22 cases (44 %) were in the left horn. It is concluded that insemination of cattle with left ovarian ovulation may increase the rate of female fetuses at pregnancy and parturition. However, this effect has not been observed in sheep. Key words: Sex ratio, Sexing, Left and right utrine horn pregnancy.