The Screening Of Low-methane Emission Dietfor Yak And Its Mechanism

Influenced by various factors such as climate change,person disturbance et al.,native pasture of Qinghai-Tibet Plateau(QTP)gradually was degenerated,so that the conflict of nutrition supply from native grassland and nutriton requirement of grazing livestock was severe.In order to ensured yaks’ safety and production in winter,appropriate supplementary for grazing yaks was the better alternative.Meanwhile,the methane emission from yaks was major factor influencing on environment.So the screening of low-methane emission supplemanry diet and researching on its mechanism was essential for developing eco-livestock-husbandry in QTP.Based on yak diet nutrition,different diet for mulations of concentrate to roughage ratio(20:80,30:70,40:60,50:50,60:40,70:30,80:20)and concentrate energy level(low energy 8.63 MJ/kg,middle energy 11.15 MJ/kg,high energy13.58 MJ/kg)were designed.IVGPT,SF6 tracer technology and 16 S r DNA Metagenomics were used and determined the feed associated effects,methane emissions from yak rumen,rumen fermentation conditions,body weight gain,and rumen microbe.The results demonstrated that the dry matter digestibility of diet 70:30 for concentrate to roughage ratio was higher(62.25%).Meanwhile,rumen environment wasno influenced and methane emission was the lowest.When the concentrate to roughage ratio was 70:30,methane emission in middle energy levelof diet was the least.High energy level concentrate could decrease the diversity of rumen bacteria and archaea.Methanobrevibacter was the dominating methanogens genus in yak rumen and its amount was minimum in group 70:30H,maximum in group 70:30L.The Prevotella quantity in group 70:30M was the highest,as a result to improve the feed degradability,yak weight gain in this group was the best(523.61g/kg·d),thus,methane emission of per body weight gain in group 70:30M was the lowest.To sum up,the diet of 70:30M was better than other diets for indoor feeding yak at low methane emissions.