ACTA VETERINARIA ET ZOOTECHNICA SINICA ›› 2014, Vol. 45 ›› Issue (8): 1295-1301.doi: 10.11843/j.issn.0366-6964.2014.08.013

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Study on Dietary Protein Metabolic Rule of Chinese Holstein Heifer during 300-350 kg Body Weight

GAO Yan-xia1,2,3，YU Zhi1， CAO Yu-feng1,2,3，LI Qiu-feng1,2,3，LI Jian-guo1,2,3*   

  1. (1.College of Animal Science and Technology，Agricultural University of Hebei，Baoding 071001，China；2.Research Center of Embryo Engineering Technology in Cattle and Sheep of Hebei，Baoding 071001，China；3.Cattle Science Institute，Agricultural University of Hebei，Baoding 071001，China)
  • Received:2014-01-20 Online:2014-08-23 Published:2014-08-23

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Abstract:

The experiment was conducted to study the metabolic rule of the dietary protein of Chinese Holstein heifer with 300-350 kg body weight，and quantify the dietary protein requirement of heifers at this stage.Twenty one 10-month-old healthy heifers with similar initial body weight ((307.67±2.99)kg) were divided into 3 groups (A，B and C) in a randomized experiment design.The heifers in group A，B and C were fed diets with the same ratio of concentrate to forage and different nutritional levels (DM basis).The DE and crude protein content of experimental diet were 10.98 MJ•kg-1 and 10.06%，11.43 MJ•kg-1 and 11.04%，11.90 MJ•kg-1 and 12.04% (dry matter basis)，respectively.The ADG of heifers in experiment groups were 620.09，820.30 and 887.30 g•d-1，respectively.The average apparent digestibility of dietary DM，OM，NDF and ADF were 70.70%，72.51%，68.70% and 68.29% for heifer at this stage.The digestibility and deposition rate of dietary CP were 69.77% and 41.37%.The estimated requirement model of crude protein (CP)，digestible crude protein (RDCP)，rumen degraded protein (RDP) and the small intestine digestible protein (IDCP) of heifers were:CP（g•d-1）=5.62W0.75+595.31△W；RDCP（g•d-1）=3.90W0.75+418.04△W；RDP（g•d-1）=2.50 W0.75+266.19△W；IDCP（g•d-1）=3.60 W0.75+384.94△W(W was BW of heifers，kg；△W was ADG，kg•d-1).

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