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Journal of Animal Science Abstract - Ruminant Nutrition

Growth performance, rumen fermentation, bacteria composition, and gene expressions involved in intracellular pH regulation of rumen epithelium in finishing Hu lambs differing in residual feed intake phenotype1

 

This article in JAS

  1. Vol. 95 No. 4, p. 1727-1738
     
    Received: Oct 18, 2016
    Accepted: Feb 12, 2017
    Published: April 13, 2017


    2 Corresponding author(s): lfei@lzu.edu.cn
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doi:10.2527/jas2016.1134
  1. Y. S. Liang*,
  2. G. Z. Li*,
  3. X. Y. Li*,
  4. J. Y. Lü*,
  5. F. D. Li*†,
  6. D. F. Tang,
  7. F. Li 2*,
  8. Y. Deng*,
  9. H. Zhang*,
  10. Z. L. Wang* and
  11. X. X. Weng*
  1. * State Key Laboratory of Pastoral Agricultural Ecosystem, College of Pastoral Agriculture Science and Technology, Lanzhou University, Lanzhou 730000, P. R. China
     Engineering Laboratory of Sheep Breeding and Reproduction Biotechnology in Gansu Province, Minqin 733300, P. R. China
     College of Animal Science and Technology, Gansu Agriculture University, Lanzhou 730000, P. R. China

Abstract

The objective of this study was to evaluate the effect of residual feed intake (RFI) on rumen function in finishing lambs. A total of 60 male Hu lambs (average initial BW = 25.2 ± 2.5kg) were used and were offered a pelleted high-concentrate diet, of which the forage to concentrate ratio was 25:75. Individual feed intake was recorded over a period of 42 d, then 10 lambs with the lowest RFI and the highest RFI were selected, respectively. The rumen fluid used for fermentation variables and relative abundance of bacteria measurement was obtained on d 10 and 20 after RFI measurement. At the end of this experiment, the selected lambs were slaughtered and rumen epithelium and liver tissues were collected for RNA extraction. Low-RFI lambs had lower (P < 0.01) DMI and greater (P < 0.05) G:F than the high-RFI ones, while the RFI groups did not differ in ADG and BW (P > 0.05). Additionally, RFI was positively (r = 0.57; P < 0.01) correlated with DMI and negatively (r = −0.53; P < 0.05) correlated with G:F. Total VFA and individual VFA decreased (P < 0.05) over time. The concentrations of total VFA, acetate, valerate, isobutyrate, isovalerate, and rumen pH (P > 0.05) were not affected by RFI classification. Nonetheless, low-RFI group lambs had a greater (P < 0.05) concentration of propionate, a lower (P < 0.05) concentration of butyrate, and a lower (P < 0.05) acetate to propionate ratio compared with the high-RFI group. There was a significant (P < 0.05) effect of RFI on the relative abundance of Butyrivibrio fibrisolvens and Escherichia coli. The relative abundance of Ruminococcus albus, Ruminococcus flavefaciens, and Prevotella bryantii decreased (P < 0.05) over time in high-RFI group. And the relative abundance of B. fibrisolvens in high-RFI group was greater (P < 0.05) than its low-RFI counterpart. Furthermore, RFI had no effect (P > 0.05) on gene expression associated with intracellular pH regulation (PAT1, AE2, DRA, NHE2, NHE3, MCT1, MCT4, and ATPase) in rumen epithelium and β-hydroxybutyrate metabolism (HMGCS2) in both rumen epithelium and liver tissues. In conclusion, even though low-RFI lambs had lower DMI, however, the number of B. fibrisolvens was lower. Additionally, there was no difference in gene expressions level associated with intracellular pH regulation in rumen epithelium between RFI groups.

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