China Animal Husbandry and Veterinary Medicine ›› 2021, Vol. 48 ›› Issue (5): 1593-1602.doi: 10.16431/j.cnki.1671-7236.2021.05.010

• Animal Nutrition and Feed Science • Previous Articles     Next Articles

Effects of Different Levels and Ratios of Two Fat Sources on Ruminal Fermentation and Purine Derivatives in Holstein Steers

CAO Mingyu1, YANG Zhiling1, TAN Yanan1,2, WANG Yaru1, XU Peng1, DUAN Zengliang1, ZHANG Shuanlin1, LIU Qiang1, GUO Gang1   

  1. 1. College of Animal Science and Veterinary Medicine, Shanxi Agricultural University, Taigu 030801, China;
    2. Bureau of Rural and Agriculture of Wenshui County, Shanxi Province, Wenshui 032101, China
  • Received:2020-09-23 Online:2021-05-20 Published:2021-05-20

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Abstract: The purpose of this experiment was to screen the appropriate level and proportion of rumen protected unsaturated fat (RPUF) and flaxseed in the diet of Holstein steers.Four Holstein steers (average body weight 580 kg±50 kg,2.5 years old) with rumen fistula were added with 2 sources of fat (RPUF and flaxseed) at 3 supplementation levels (4%,5% and 6%) interacted with 4 different ratios (100:0,85:15,70:30 and 55:45) per kg diet were used in 3×4 two-factorial design.Fat additional level/ratio in the twelve groups were 4/100,4/85,4/70,4/55,5/100,5/85,5/70,5/55,6/100,6/85,6/70 and 6/55,respectively.The effects of rumen protected unsaturated fat and whole flaxseed with different levels and ratio on rumen fermentation,nutrients degradability and purine derivatives were studied.The experiment was divided into 12 stages.The first 14 d of each stage was an adjustment period and the following 5 d was for sample collection.The results showed that:①Ruminal pH,concentrations of acetate,propionate and total volatile fatty acids were not affected by lipid supplement levels interacted with different ratios (P>0.05),ammonia nitrogen concentration and the ratio of acetate to propionate of 6% fat groups were significantly increased compared to 4% groups (P<0.05).②For the dry matter effective degradability,4% fat groups were significantly higher than 5% and 6% fat groups (P<0.05),4/85,4/70 and 4/55 groups were significantly higher than 5/55 (P<0.05).For the crude protein effective degradability,70:30 group was significantly higher than 100:0 group (P<0.05),5/70 group was significantly higher than 6/100 group (P<0.05).③The content of allantoin and purine derivatives in 4% fat groups were significantly higher than 5% and 6% fat groups (P<0.05).In conclusion,from the perspective of rumen fermentation,nutrients degradability and urine purine derivatives yield,the optimum of lipid addition level was 4%,and the optimum of ratio (RPUF:flaxseed) was 70:30.

Key words: rumen protected unsaturated fat; flaxseed; Holstein steers; ruminal fermentation; nutrients degradability in rumen; purine derivative

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