Low-temperature conditions influence cattle productivity and survivability. Understanding the metabolic regulations of specific cattle breeds and identifying potential biomarkers related to cold challenges are important for cattle management and optimization of genetic improvement programs. In this study, 28 Inner-Mongolia Sanhe and 22 Holstein heifers were exposed to -25°C for 1 h to evaluate the differences in metabolic mechanisms of thermoregulation. In response to this acute cold challenge, altered rectal temperature was only observed in Holstein cattle. Further metabolome analyses showed a greater baseline of glycolytic activity and mobilization of AA in Sanhe cattle during normal conditions. Both breeds responded to the acute cold challenge by altering their metabolism of volatile fatty acids and AA for gluconeogenesis, which resulted in increased glucose levels. Furthermore, Sanhe cattle mobilized the citric acid cycle activity, and creatine and creatine phosphate metabolism to supply energy, whereas Holstein cattle used greater AA metabolism for this purpose. Altogether, we found that propionate and methanol are potential biomarkers of acute cold challenge response in cattle. Our findings provide novel insights into the biological mechanisms of acute cold response and climatic resilience, and will be used as the basis when developing breeding tools for genetically selecting for improved cold adaptation in cattle.

三河牛具有适应当地气候、生态条件并且生产性能高的特点,2009年已进入国家良种补贴计划,对当地牛群的遗传改良发挥了重要作用.但由于受客观条件的限制,人工授精技术在呼伦贝尔边远地区尚未普及,为此特为不具备冷配条件的地区特培了用于本交的三河牛公牛,以期为边远牧区提供优良种畜,提高当地牛群遗传水平.经2014～2017年的推广应用,杂种一代犊牛增重速度比当地犊牛高20％以上,而且杂交后代具有与当地牛同样的耐粗饲、耐寒、适应性强的特性,同时母牛的配种受胎率高,大大增加了当地牧民的养殖效益.

Sanhe Cattle in Inner Mongolia is a local dual purpose breed formed and approved in China with more than 100 years developing history in Hulunbuir pasture.Sanhe cattle is famous for its durability,disease resistance,high quality in both milk and meat production,and suitability for grazing.Since it was approved as a breed in 1986,this breed was preserved adopting selection within family lines in the nucleolus herd,both its performance and reproduction efficiency was preserved under the harsh condition in Hulunbuir pasture.Although Sanhe cattle was challenged by high yield breeds during the past 20 years,such as Holstein,it remained as a major breed because it was highly adapted for the local environment and had excellent performance in meat and milk production.Since the beginning of the 11th five-year plan,state government paid more attention to the genetic improvement of Sanhe from the basis of existing system for breed registration and performance testing.National standard for Sanhe cattle breed was revised and re-published,breeding information database for Sanhe cattle was established and DHI testing system used for dairy cattle was introduced,the dual purpose breeding goal was re-emphasized through introducing elite stock of international recognized similar type of breed,progresses were achieved through this open nucleus breeding system philosophy.This paper first reviewed the breeding history and then summarized the recent progresses in the breeding system to share our experience.