Techniques developed for improvement of reproductive performance in holstein dairy cattle

• Main Authors: Chih-Hua Wang, 王治華
• Other Authors: Yan-Nian Jiang
• Format: Others
• Language: zh-TW
• Published: 1999
• Online Access: http://ndltd.ncl.edu.tw/handle/87862871683233278585

博士 === 國立臺灣大學 === 畜產學研究所 === 87 === The purpose of this study includes (1) setting up an automatic estrus detection system to resolve the problem of poor estrus detection rate and improper breeding time and to improve the conception rate and furthermore the reproductive performance in Holstein dairy cattle; (2) using the technique of sexing bovine embryos with a pair of sex-specific primers, which are designed with the same origin of X and Y chromosomes, to allow the amplification of different length of gene fragment from X and Y chromosomes, and to determine the unimplantation gender of early stage embryos, and enhance the genetic improvement. Experimental results show that the estrus detection rate acquired from the thin & full-lengthed sensor and thick & half-lengthed sensor is 80% and 93.7%, respectively, and the pregnancy rate is 57.1% and 72.7%, respectively. All reveal that the thick & half-lengthed sensor is better than thin & full-lengthed type. However, environmental temperature would also have effect on estrus detection and pregnancy rate. Duration of estrus in hot season (>23℃) was shorter than that in cool season (<23℃) (9.3 vs. 12.7 h), as well as the pregnancy rate (49.9 vs. 76.9%). A pair of pbAML5XY(+) and pbAML5XY(-) primers, used for sexing cow embryos, are characterized by such features as significant sensitivity, successful application of a single blastomere isolated from cow embryos by direct cell lysis and PCR, and correct dealing with sex-determination of over hundred embryos within 4 hours. The number of blastomeres aspirated from embryos (X) could accurately predict the successful rate of sex identification (Y) with an equation of Y = 49.8 + 4.21 X (R2 = 0.87). There is no significant difference between the sex ratio of male and female embryos. The developmental rate in vitro (92.5 vs. 93.3%) and pregnancy rate following embryo transfer (44.3 vs. 41.8%) between micromanipulated and control group have no significant difference either. The accuracy of female calves following sex identification and embryo transfer is 90%, and 100% for that of male calves. In addition, the incidence of identical twin calves is 21.4%. In conclusion, that using the automatic estrus detection system and the technique of sexing bovine embryos can get the acceptable pregnancy rate and desired sex of calves, and can improve the reproductive performance of Holstein dairy cattle and promote the development of dairy industry furthermore.