DeJarnette J M, Nebel R L, Marshall C E
Select Sires Inc., Plain City, OH 43064, USA.
Theriogenology. 2009 Jan 1;71(1):49-58. doi: 10.1016/j.theriogenology.2008.09.042. Epub 2008 Nov 8.
These data summarize on-farm records of dairy herds (n=211) using sexed semen. Sexed semen was predominantly used at first and second service in virgin heifers, which is reflected in younger ages at AI and at calving. Conception rates at first service averaged 47% for Holstein heifers and 53% for Jersey heifers, which were approximately 80% of that achieved with conventional semen. Analysis of inter-estrus intervals provides no evidence that cycle lengths are extended by use of sexed semen. Among singleton births, 89% were reported as female offspring and this rises to 90% for gestation lengths within a normal 265-295 d range. Age at calving appeared to interact with calf sex and semen type to influence the incidence of stillbirths. Semen type had no effect on the incidence of stillbirths among heifers delivering female calves. However, the incidence of stillbirths among heifers delivering male calves was greater for those conceived from sexed semen and was only partially explained by age at calving. Because the incidence of male calves from sexed semen is only 10%, the total incidence of stillbirths was not affected by semen type. In conclusion, failure to differentiate sexed from conventional semen in data recording and preferential bias in use of sexed semen in younger, more fertile females makes legitimate comparisons of sexed and conventional semen in the commercial setting difficult. When used in Holstein heifers, the average first service conception rate achieved with sex-sorted semen was 47%, which appeared to approximately 80% of that achieved with conventional semen in the same herds. The percentage of female calves (89%) was consistent with expectations. After adjusting for age at calving, sexed semen had no affect on the total incidence of stillbirths, however the source for an apparent increased incidence of stillbirth among male calves born from X-sorted sperm populations requires further investigation.
这些数据总结了使用性别分选精液的奶牛群（n = 211）的农场记录。性别分选精液主要用于初产小母牛的首次和第二次输精，这反映在人工授精和产犊时的年龄较小。荷斯坦小母牛首次输精的受胎率平均为47%，泽西小母牛为53%，约为使用常规精液时受胎率的80%。对发情间隔的分析没有提供证据表明使用性别分选精液会延长周期长度。在单胎分娩中，89%被报告为雌性后代，在正常的265 - 295天范围内，这一比例在妊娠期内上升到90%。产犊年龄似乎与犊牛性别和精液类型相互作用，影响死产发生率。精液类型对产下雌性犊牛的小母牛的死产发生率没有影响。然而，对于产下雄性犊牛的小母牛，使用性别分选精液受孕的死产发生率更高，且仅部分由产犊年龄来解释。由于性别分选精液产生雄性犊牛的发生率仅为10%，死产的总发生率不受精液类型的影响。总之，在数据记录中未能区分性别分选精液和常规精液，以及在更年轻、繁殖力更强的雌性中优先偏向使用性别分选精液，使得在商业环境中对性别分选精液和常规精液进行合理比较变得困难。当用于荷斯坦小母牛时，性别分选精液的首次输精平均受胎率为47%，似乎约为同一牛群中使用常规精液时受胎率的80%。雌性犊牛的比例（89%）与预期一致。在调整产犊年龄后，性别分选精液对死产的总发生率没有影响，然而，来自X分选精子群体出生的雄性犊牛中明显增加的死产发生率的原因需要进一步调查。
