Relationship between the sire and the sex of day-7 transferable embryos after insemination in superovulated japanese black cattle

摘要

This experiment was undertaken to examine the relationships between the sex and the developmental stage and/or the quality grade of bovine Day-7 transferable embryos.Twenty two Japanese Black cattle were superovulated 38 separate times with FSH-Prostaglandin-analog, and the embryos recovered 7 days after artificial insemination were classified by 4 morphological criteria; transferable (stages of late morula, early blastocyst, blastocyst and expanded blastocyst).Then the transferable embryos were ranked by 4 morphological quality grades; excellent, good, fair and poor *. The sex of 281 transferable embryos was determined by polymerase chain reaction (PCR) method. As a result, 150 male and 132 female embryos were identified. The rate of male embryos (male embryos/male+ female embryos X 100) was 53.2 percent and no skewed.In tested 3 sires, the male ratio of sire Y was significantly lower than that of sire N and sire U (Y 41.4 percent, N 60.4 percent, U 54.5 percent; P<0.05). Moreover, from analysis based on the embryo donor cows, the male ratio of sire Y was also lower than that of sire N and sire U (Y 34.2 percent, N 56.4 percent, U 52.3 percent; Y:N, P<0.05, Y:U, P=0.055).In the developmental stage, the percentage of male embryos classified as excellent rade of sire Y was significantly lower than that of sire U and sire N (Y: 42.1 percent, N: 76.7 percent and U: 71.4 percent; P<0.05), and as poor was significantly lower than sire U (Y:8.3 percent, U: 52.4 percent; P<0.05). The percentages of male embryos at the stages of early blastocyst and late morula of sire Y were significant lower than those of sire N (early blastocyst stage Y:55.6 percent; N: 77.3 percent; late morula stage Y:30.0 percent, N:55.3 percent; P<0.05).In the quality grade, the percentages of male embryos at the early blastocyst and the late morula stages of sire Y were significant lower than those of sire N (early blastocyst stage Y:55.6 percent, N:77.3 percent, late morula stage Y:30.0 percent, N:55.3 percent; P<0.05).Therefore, it was found that the rate of male embryos recovered 7 days after insemination from superovulated Japanese Black cattle is different between sires.*Linder, G. M. & R. W. Wright (1983), Theriogenology, 20(4): 407-414