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Acta Prataculturae Sinica ›› 2022, Vol. 31 ›› Issue (8): 99-110.DOI: 10.11686/cyxb2021432

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Comparison of nutritional value of oat hay, oat silage and Sichuan pasture for yaks

Yin-jie YOU(), Hao-zhen ZHOU, Yao LIU, Chen-xi WANG, Zhong-li PENG()   

  1. College of Animal Husbandry & Veterinary Science,Southwest Minzu University,Chengdu 610041,China
  • Received:2021-11-25 Revised:2022-01-28 Online:2022-08-20 Published:2022-07-01
  • Contact: Zhong-li PENG

Abstract:

This experiment compared the nutritional value of forages conventionally fed to yaks in Sichuan. Oat (Avena sativa) hay, oat silage and Sichuan pasture were analyzed for their nutritional value and in vitro gas production. An in vivo digestion experiment was conducted in Hongyuan, Sichuan Province. Maiwa male yaks (n=9) with an initial body weight of 150±10 kg were randomly divided into 3 treatment groups with 3 yaks in each group. It was found that: 1) The crude protein (CP) content of pasture was significantly higher than that in oat silage and oat hay (P<0.05). The neutral detergent fiber (NDF) and acid detergent fiber (ADF) content of pasture was significantly lower than that in oat silage (P<0.05). 2) The non-protein nitrogen content in oat silage was significantly higher than that in oat hay and pasture (P<0.05). The rapidly degraded protein, moderately degraded protein and slowly degraded protein contents in pasture were the highest and the unavailable protein content was the lowest. The unavailable fiber content in oat silage was significantly higher than that in pasture and oat hay (P<0.05), while the slowly degraded fiber and non-structural carbohydrate contents were significantly lower than those in pasture and oat hay (P<0.05). 3) The NDF and CP digestibility of pasture were significantly higher than those of oat hay and oat silage (P<0.05). The ADF digestibility of pasture was significantly higher than that of oat silage (P<0.05), but did not differ significantly from that of oat hay (P>0.05). 4) The NH3-N concentration in the rumen fluid of yaks in the pasture treatment group was significantly higher than in animals fed oat silage and oat hay (P<0.05), and the micro crude protein yield was significantly higher in the pasture diet than that in the oat hay diet but did not differ significantly from that in the oat silage diet. Oat hay had the highest total volatile fatty acid yield. 5) The gas production of animals fed pasture was significantly higher than that of animals fed oat silage (P<0.05). Overall, rumen fermentation results reflected the predictions from diet component analysis using the cornell net carbohydrate and protein system (CNCPS) and in vitro gas production results were basically consistent with the results of nutrient digestibility and rumen metabolites determined by the yak in vivo digestion test. These results indicate that it is feasible to evaluate the nutritional value of yak roughage using the CNCPS and in vitro gas production methods. The nutritional values of the three forages were: pasture>oat hay>oat silage.

Key words: cornell net carbohydrate and protein system, in vitro gas production, yak nutrition