Bussiman F O, Perez B C, Ventura R V, Peixoto M G C D, Curi R A, Balieiro J C C
1Department of Animal Science, College of Animal Science and Food Engineering,University of São Paulo (FZEA/USP),Av. Duque de Caxias Norte,225, Campus Fernando Costa,Pirassununga, São Paulo, 13.635-900,Brazil.
4National Centre of Research on Dairy Cattle, Brazilian Agricultural Research Corporation (CNPGL/EMBRAPA), Rua Eugênio do Nascimento,610, Dom Bosco, Juiz de Fora, Minas Gerais, 36.038-330,Brazil.
Animal. 2018;12(11):2246-2255. doi: 10.1017/S175173111800023X. Epub 2018 Feb 22.
Genetic improvement, without control of inbreeding, can go to loss of genetic variability, reducing the potential for genetic gains in the domestic populations. The aim of this study was to analyze the population structure and the inbreeding depression in Campolina horses. Phenotype information from 43 465 individuals was analyzed, data provided by the Campolina Breeders Association. A pedigree file containing 107 951 horses was used to connected the phenotyped individuals. The inbreeding coefficient was performed by use of the diagonal of the relationship matrix and the genealogical parameters were computed using proper softwares. The effective population size was estimated based on the rate of inbreeding and census information, and the stratification of the population was verified by the average relationship coefficient between animals born in different regions of Brazil. The effects of inbreeding on morphological traits were made by the use of inbreeding coefficient as a covariate in the model of random regression. The inbreeding coefficient increased from 1990 on, impacting effective population size and, consequently, shrinking genetic variability. The paternal inbreeding was greater than maternal, which may be attributed to the preference for inbred animals in reproduction. The average genetic relationship coefficient of animals born in different states was lower than individuals born within the same state. The increase in the inbreeding coefficient was negatively associated with all studied traits, showing the importance to avoid genetic losses in the long term. Although results do not indicate a severe narrowing of the population until the present date, the average relationship coefficient shows signs of increase, which could cause a drastic reduction in genetic variability if inbred mating is not successfully controlled in the Campolina horse population.
在不控制近亲繁殖的情况下进行遗传改良，可能会导致遗传变异性丧失，降低家养群体的遗传增益潜力。本研究的目的是分析坎波拉马的种群结构和近亲繁殖衰退情况。分析了来自坎波拉饲养者协会提供的43465个个体的表型信息。使用包含107951匹马的系谱文件将表型个体联系起来。通过关系矩阵的对角线计算近亲繁殖系数，并使用适当的软件计算系谱参数。根据近亲繁殖率和普查信息估计有效种群大小，并通过巴西不同地区出生的动物之间的平均亲缘系数验证种群分层。在随机回归模型中，通过将近亲繁殖系数作为协变量来分析近亲繁殖对形态性状的影响。近亲繁殖系数自1990年起上升，影响了有效种群大小，从而导致遗传变异性缩小。父系近亲繁殖大于母系近亲繁殖，这可能归因于繁殖中对近亲动物的偏好。不同州出生的动物的平均遗传亲缘系数低于同一州内出生的个体。近亲繁殖系数的增加与所有研究性状呈负相关，表明从长远来看避免遗传损失的重要性。尽管结果表明到目前为止种群没有严重缩小，但平均亲缘系数显示出增加的迹象，如果坎波拉马种群中近亲交配不能得到有效控制，可能会导致遗传变异性急剧下降。
