1Department of Veterinary Medicine - Sportive Horse Research Center,University of Perugia,via S. Costanzo 4,06123 Perugia,Italy.
2Department of Agricultural,Food and Environmental Sciences,University of Perugia,Borgo XX Giugno,74, 06121 Perugia,Italy.
Animal. 2019 Jan;13(1):15-24. doi: 10.1017/S1751731118001180. Epub 2018 May 29.
The Maremmano is an autochthonous Italian horse breed, which probably descended from the native horses of the Etruscans (VI century B.C.); the Studbook was acknowledged in 1980, and it includes 12 368 horses born from that year up to 2015. The aim of this study was to evaluate the effect of the selection program on the genetic variability of the Maremmano population; the analysis was performed using both the 'Endog v 4.8' program available at http://webs.ucm.es/info/prodanim/html/JP_Web.htm and in-house software on official pedigree data. Four Reference Populations were considered, and the most important one was the population of the 12 368 Maremmano horses officially registered in the National Studbook. The pedigree completeness of this population was very good because it was more than 90% at the third parental generation and more than 70% at the fifth generation; the pedigree traced back to a maximum of 10.50 generations with an average of 3.30 complete generations and 5.70 equivalent complete generations. The average generation interval was 10.65±4.72 years, with stallions used for longer periods than mares. The intervals ranged from 10.15±4.45 (mother-daughter) to 10.99±4.93 (father-daughter). The effective number of founders (f e) was 74 and the effective number of ancestors (f a) was 30 so that the ratio f e/f a was 2.47. The founder genome equivalents (f g) was 13.72 with a ratio f g/f e equal to 0.18. The mean of the genetic conservation index was 5.55±3.37, and it ranged from 0.81 to 21.32. The average inbreeding coefficient was 2.94%, with an increase of 0.1%/year, and the average relatedness coefficient was 5.52%. The effective population size (N e) computed by an individual increase in inbreeding was 68.1±13.00; the N e on equivalent generations was 42.00, and this value slightly increased to 42.20 when computed by Log regression on equivalent generations. The analysis confirmed the presence of seven traditional male lines. The percentage of Thoroughbred blood in the foals born in 2015 was 20.30% and has increased 0.21%/year since 1980; in particular, it increased more than twice (0.51%/year) until 1993 and afterwards slightly fluctuated. The pedigree analysis confirmed the completeness of genealogical information and the traditional importance that breeders gave to the male lines; although the genetic diversity of Maremmano seemed to be not endangered by the selection program, some effects on the population structure were found and a more scientific approach to genetic conservation should be incorporated in the selection plans.
马雷马诺马是一种原产于意大利的马种，可能源自伊特鲁里亚人（公元前六世纪）的本地马；该品种的血统登记册于 1980 年得到认可，其中包括自该年起至 2015 年出生的 12368 匹马。本研究旨在评估选择计划对马雷马诺马种群遗传多样性的影响；分析使用了可在 http://webs.ucm.es/info/prodanim/html/JP_Web.htm 上访问的“Endog v 4.8”程序和内部软件进行官方血统数据。考虑了四个参考群体，其中最重要的是在国家血统登记册中正式登记的 12368 匹马的群体。该群体的血统完整性非常好，因为在第三代以上的完整程度超过 90%，在第五代以上的完整程度超过 70%；血统可追溯到最多 10.50 代，平均有 3.30 代完整血统和 5.70 代等效完整血统。平均世代间隔为 10.65±4.72 年，公马的使用时间长于母马。间隔范围从 10.15±4.45（母子）到 10.99±4.93（父女）。有效创始人数量（f e）为 74，有效祖先数量（f a）为 30，因此 f e/f a 的比值为 2.47。创始人基因组当量（f g）为 13.72，f g/f e 的比值为 0.18。遗传保护指数的平均值为 5.55±3.37，范围为 0.81 至 21.32。平均近交系数为 2.94%，每年增加 0.1%，平均亲缘系数为 5.52%。通过个体近交增加计算的有效种群大小（N e）为 68.1±13.00；在等效世代上的 N e 为 42.00，当通过等效世代的对数回归计算时，该值略微增加到 42.20。分析证实存在七个传统的雄性系。2015 年出生的幼驹中纯血马的比例为 20.30%，自 1980 年以来每年增加 0.21%；特别是，在 1993 年之前，它的增长率超过两倍（0.51%/年），此后略有波动。系谱分析证实了系谱信息的完整性和饲养者对雄性系的传统重视；尽管马雷马诺马的遗传多样性似乎没有因选择计划而受到威胁，但发现了一些对种群结构的影响，应该在选择计划中纳入更科学的遗传保护方法。
