Kidd K K, Stone W H, Crimella C, Carenzi C, Casati M, Rognoni G
Anim Blood Groups Biochem Genet. 1980;11(1):21-38. doi: 10.1111/j.1365-2052.1980.tb01489.x.
Blood samples were collected from more than 100 animals in each of 2 Spanish cattle breeds (Retinto and De Lidia), 2 Portuguese breeds (Alentejana and Mertolenga), and American Longhorn cattle. All samples for the 4 Iberian breeds were tested for 20 polymorphic systems; American Longhorn were tested for 19 of the 20. For each breed an average inbreeding coefficient was estimated by a comparison of the observed and expected heterozygosity at 7 or 8 codominant systems tested. All breeds had positive values but only 3 breeds had estimates of inbreeding that were statistically significantly different from 0: De Lidia with f = 0.17, Retinto with f = 0.08 and Mertolenga with f = 0.05. The De Lidia breed especially may be suffering from inbreeding depression since this high value is greater than expected if all of the animals were progeny of half-sib matings. Genetic distances were calculated from the gene frequency data on these 5 breeds plus 9 other European breeds. Analyses of these distances show a closely related group of the 4 Iberian breeds and American Longhorn, confirming the close relationships among the Iberian breeds and the Iberian, probably Portuguese, origin of American Longhorn cattle.
从西班牙的两个牛品种（雷廷托牛和德利迪亚牛）、葡萄牙的两个品种（阿连特茹纳牛和梅尔托伦加牛）以及美国长角牛中各选取了100多头动物采集血样。对4个伊比利亚品种的所有样本进行了20个多态系统的检测；美国长角牛检测了其中19个系统。通过比较在7个或8个共显性系统中观察到的杂合度和预期杂合度，估算了每个品种的平均近交系数。所有品种的近交系数均为正值，但只有3个品种的近交系数估计值与0有统计学显著差异：德利迪亚牛，f = 0.17；雷廷托牛，f = 0.08；梅尔托伦加牛，f = 0.05。德利迪亚品种尤其可能正遭受近交衰退的影响，因为如果所有动物都是半同胞交配的后代，这个高值会高于预期。根据这5个品种以及另外9个欧洲品种的基因频率数据计算了遗传距离。对这些距离的分析表明，4个伊比利亚品种和美国长角牛构成了一个密切相关的群体，证实了伊比利亚品种之间的密切关系以及美国长角牛的伊比利亚（可能是葡萄牙）起源。
