Wei, H. - State Key Laboratory of Grassland Agro-ecosystem, Engineering Research Center of Arid Agriculture and Ecological Remediation of Ministry of Education, School of Life Sciences, Lanzhou University, Lanzhou, China.
Ding, L. - State Key Laboratory of Grassland Agro-ecosystem, Engineering Research Center of Arid Agriculture and Ecological Remediation of Ministry of Education, School of Life Sciences, Lanzhou University, Lanzhou, China; Qinghai Provincial Key Laboratory of Adaptive Management on Alpine Grassland, Qinghai University, Xining, China.
Wang, X. - State Key Laboratory of Grassland Agro-ecosystem, Engineering Research Center of Arid Agriculture and Ecological Remediation of Ministry of Education, School of Life Sciences, Lanzhou University, Lanzhou, China.
Yan, Q. - State Key Laboratory of Grassland Agro-ecosystem, Engineering Research Center of Arid Agriculture and Ecological Remediation of Ministry of Education, School of Life Sciences, Lanzhou University, Lanzhou, China.
Jiang, C. - State Key Laboratory of Grassland Agro-ecosystem, Engineering Research Center of Arid Agriculture and Ecological Remediation of Ministry of Education, School of Life Sciences, Lanzhou University, Lanzhou, China.
Hu, C. - State Key Laboratory of Grassland Agro-ecosystem, Engineering Research Center of Arid Agriculture and Ecological Remediation of Ministry of Education, School of Life Sciences, Lanzhou University, Lanzhou, China.
Wang, G. - Key Laboratory of Adaptation and Evolution of Plateau Biota, Northwest Institute of Plateau Biology, Chinese Academy of Science, Xining, China.
Zhou, Y. - Haibei Comprehensive Experimental Station of National Beef Cattle & Yak Industrial Technology System, Haibei, China.
Degen, A.A. - Desert Animal Adaptations and Husbandry, Wyler Department of Dryland Agriculture, Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Beer Sheva, Israel
BACKGROUND: Early weaning in yak calves is being attempted to improve yak reproduction rate. However, this has to be done with caution because of the high mortality rate of calves due to the lack of nutrients and the harsh environmental conditions. Twenty-four weaned male yak calves were used in a 60 day feeding trial in which astragalus root extract (ARE) was supplemented. They were assigned randomly to one of four dietary treatments (n = six per treatment) that differed in ARE level: 0 g kg−1 (control), ARE0; 20 g kg−1, ARE20; 50 g kg−1, ARE50; and 80 g kg−1 dry matter intake (DMI), ARE80. RESULTS: Final bodyweight and average daily gain (ADG) were significantly higher and the DMI/ADG ratio was significantly lower in calves with ARE supplementation than control (ARE0) calves. Ruminal concentrations of acetate and propionate and serum concentration of superoxide dismutase in ARE80 calves were higher than in the other groups and serum concentration of insulin was higher in ARE80 calves than in ARE20 calves. Serum immunoglobulin G (IgG) and interleukin-2 (IL-2) concentrations in ARE-fed calves were higher than in controls. Serum tumor necrosis factor (TNF-α) concentration was higher in ARE50 and ARE80 groups than ARE0 calves and serum interleukin-6 (IL-6) concentration was higher in ARE80 than in ARE0 calves. Serum immunoglobulin A (IgA), IgG and immunoglobulin M (IgM) concentrations increased with age in ARE-fed calves. ARE supplementation increased the abundance of fiber degrading bacteria. CONCLUSION: ARE at a dosage of 5% to 8% DMI can be supplemented to early weaned yak calves to improve growth performance, antioxidant capacity and immunity. © 2020 Society of Chemical Industry.
