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Acta Prataculturae Sinica ›› 2023, Vol. 32 ›› Issue (11): 119-129.DOI: 10.11686/cyxb2022494

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Effect of feed level of oat hay on average daily gain, blood physiological and biochemical indexes, and rumen fermentation parameters in yaks

Dao zhi cai rang WU1(), Cheng-fang PEI2, Zhi-yuan MA3, Hong-shan LIU1, Xu-liang CAO1, Hu LIU1, Jian-wei ZHOU1()   

  1. 1.College of Pastoral Agriculture Science and Technology,Lanzhou University,State Key Laboratory of Herbage Improvement and Grassland Agro-Ecosystems,Lanzhou 730000,China
    2.Animal Husbandry Technology Promotion Station of Tianzhu Tibetan Autonomous County,Wuwei 733200,China
    3.College of Ecology,Lanzhou University,Lanzhou 730000,China
  • Received:2022-12-22 Revised:2023-03-14 Online:2023-11-20 Published:2023-09-27
  • Contact: Jian-wei ZHOU

Abstract:

This study was conducted to investigate the response of average daily gain, blood physiological, biochemical indexes and rumen fermentation parameters to different feeding levels of pelleted oat hay in yaks, in order to provide technical data for scientifically informed yak farming on the Qinghai-Tibetan Plateau. Six healthy castrated yaks [(203.0±6.0) kg], aged 3.5 years old, were selected for the experiment which used a 4×4 Latin square design. The two additional animals were considered as biological replicates for one of the Latin square sequences. Voluntary intake of each animal was determined in a 14-day pretrial test, then oat hay feeding levels were set at 0.45, 0.60, 0.75 and 0.90 VI (voluntary intake). It was found that: 1) The average daily gain (ADG) of the yaks increased linearly (P<0.001) with increase in oat hay feeding level. A regression equation ADG (g·day-1)=973 X-513 (R2=0.727) was determined where X denotes metabolic energy allowance [MJ·kg-1·BW-0.75·d-1] established based on the ADG (Y) and metabolic energy (ME, X) intakes in yaks, and the estimated body maintenance ME requirement was 0.527 MJ·kg-1·BW-0.75·d-1. 2) As the feed level of oat hay increased, the population of red blood cells was decreased linearly (P<0.05), while the population of platelets was increased linearly (P=0.05), and the other blood physiological indexes were not affected by feeding level treatments (P≥0.10). 3) With increase in the feed level of oat hay, serum concentrations of urea nitrogen and growth hormone increased linearly (P<0.05) while glucose concentration decreased linearly (P<0.05). Meanwhile, serum insulin concentration tended to increase (P=0.091) with feed intakes whereas β-hydroxybutyric acid level tended to decrease (P=0.063). 4) The concentrations of ruminal total volatile fatty acid, acetate and butyrate increased linearly (P<0.05) with increased oat hay feeding level in yaks, and propionate concentration tended to increase (P=0.093), accompanied with a decrease of ruminal pH (P<0.05). The above results showed that both blood physiological and biochemical indexes and rumen fermentation parameters in yaks were somewhat affected by the feeding level of forages, which in turn ultimately determined the growth performance. According to the maintenance ME requirement of yaks estimated in present study, the dry matter intake of oat hay should be greater than 50.7 g·kg-1·BW-0.75·d-1 in order for the animals to maintain their body weight or gain weight.

Key words: yak, feed level, blood indexes, average daily gain, rumen fermentation