Chrystal M A, Seykora A J, Hansen L B, Freeman A E, Kelley D H, Healey M H
University of Minnesota, St. Paul, MN 55108, USA.
J Dairy Sci. 2001 Nov;84(11):2549-54. doi: 10.3168/jds.S0022-0302(01)74707-8.
Teat-end shapes were categorized for 1443 Holstein cows with 3582 lactations, in the Iowa State University herd at Ankeny, approximately 40 d postpartum between 1970 and 1995. Frequencies of teat-end shapes were as follows: round, 52.2%; prolapsed, 0.8%; flat, 14.2%; plate, 3.4%; funnel, 8.9%; and mixed, 20.5%. Cows were coded as mixed if all four teat-end shapes were not the same. Heritability estimates were obtained with an animal model with pedigrees traced back to registration numbers roughly conforming to birth year 1955. The heritability estimates for first, second, and third and later lactations were 34, 21, and 13%, respectively. Lactation averages for linear somatic cell scores were adjusted for days in milk, and month and age at calving, and were available for 255 cows with 431 lactations categorized from 1992 to 1995. Frequencies of teat-end shape on the 255 cows were as follows: round, 58%; prolapsed, 3%; flat, 11%; plate, 2%; funnel, 6%; and mixed, 20%. Least-squares means of somatic cell score for categories of teat-end shape were computed from a mixed model that included year, parity, and teat-end shape as fixed effects and cow as a random effect. Teat-end shape did not significantly affect somatic cell score.
对爱荷华州立大学安克尼分校牛群中1443头荷斯坦奶牛的3582次泌乳进行了乳头末端形状分类，这些奶牛在1970年至1995年间产后约40天。乳头末端形状的频率如下：圆形，52.2%；脱垂形，0.8%；扁平形，14.2%；盘形，3.4%；漏斗形，8.9%；混合形，20.5%。如果四个乳头末端形状不完全相同，则将奶牛编码为混合形。通过动物模型获得遗传力估计值，其系谱追溯到大致符合1955年出生年份的登记号码。第一胎、第二胎以及第三胎及以后胎次的遗传力估计值分别为34%、21%和13%。对线性体细胞评分的泌乳平均值进行了产奶天数、产犊月份和年龄的校正，这些数据来自1992年至1995年间分类的255头奶牛的431次泌乳。这255头奶牛的乳头末端形状频率如下：圆形，58%；脱垂形，3%；扁平形，11%；盘形，2%；漏斗形，6%；混合形，20%。乳头末端形状类别的体细胞评分的最小二乘均值由一个混合模型计算得出，该模型将年份、胎次和乳头末端形状作为固定效应，奶牛作为随机效应。乳头末端形状对体细胞评分没有显著影响。
