title: Small intestine histomorphometry of beef cattle with divergent feed efficiency.
abstract: BACKGROUND
  The provision of feed is a major cost in beef production. Therefore, the improvement of feed efficiency is warranted. The direct assessment of feed efficiency has limitations and alternatives are needed. Small intestine micro-architecture is associated with function and may be related to feed efficiency. The objective was to verify the potential histomorphological differences in the small intestine of animals with divergent feed efficiency.
  
  
  METHODS
  From a population of 45 feedlot steers, 12 were selected with low-RFI (superior feed efficiency) and 12 with high-RFI (inferior feed efficiency) at the end of the finishing period. The animals were processed at 13.79 ± 1.21 months of age. Within 1.5 h of slaughter the gastrointestinal tract was collected and segments from duodenum and ileum were harvested. Tissue fragments were processed, sectioned and stained with hematoxylin and eosin. Photomicroscopy images were taken under 1000x magnification. For each animal 100 intestinal crypts were imaged, in a cross section view, from each of the two intestinal segments. Images were analyzed using the software ImageJ(®). The measurements taken were: crypt area, crypt perimeter, crypt lumen area, nuclei number and the cell size was indirectly calculated. Data were analyzed using general linear model and correlation procedures of SAS(®).
  
  
  RESULTS
  Efficient beef steers (low-RFI) have a greater cellularity (indicated by nuclei number) in the small intestinal crypts, both in duodenum and ileum, than less efficient beef steers (high-RFI) (P < 0.05). The mean values for the nuclei number of the low-RFI and high-RFI groups were 33.16 and 30.30 in the duodenum and 37.21 and 33.65 in the ileum, respectively. The average size of the cells did not differ between feed efficiency groups in both segments (P ≥ 0.10). A trend was observed (P ≤ 0.10) for greater crypt area and crypt perimeter in the ileum for cattle with improved feed efficiency.
  
  
  CONCLUSIONS
  Improved feed efficiency is associated with greater cellularity and no differences on average cell size in the crypts of the small intestine in the bovine. These observations are likely to lead to an increase in the energy demand by the small intestine regardless of the more desirable feed efficiency.
authors: Department of Animal and Poultry Science, University of Guelph, 70-50 Stone Road East, Guelph N1G 2W1, ON, Canada. ymontanh@uoguelph.ca
authors: Yuri
authors: Y
authors: Montanholi
authors: Ananda
authors: A
authors: Fontoura
authors: Kendall
authors: K
authors: Swanson
authors: Brenda
authors: B
authors: Coomber
authors: Shigeto
authors: S
authors: Yamashiro
authors: Stephen
authors: S
authors: Miller
mesh_terms: D000818:Animals; D002417:Cattle / Q000502:physiology*; D004734:Energy Metabolism / Q000502:physiology*; D007421:Intestine, Small / Q000033:anatomy & histology* / Q000502:physiology*; D015430:Weight Gain / Q000502:physiology*
references: J Anim Sci. 1990 Sep;68(9):2997-3010
references: 2170320
references: J Anim Sci. 1996 Oct;74(10):2541-53
references: 8904723
references: Nat Rev Genet. 2006 May;7(5):349-59
references: 16619050
references: Br J Nutr. 1990 Sep;64(2):439-48
references: 2223745
references: Comp Biochem Physiol A Mol Integr Physiol. 2005 Jul;141(3):280-91
references: 16002308
references: J Anim Sci. 2011 Nov;89(11):3362-71
references: 21642494
references: J Anim Sci. 1986 Nov;63(5):1634-48
references: 3539905
references: Br Poult Sci. 2001 Sep;42(4):505-13
references: 11572627
references: J Nutr. 2001 Apr;131(4):1256-63
references: 11285335
references: J Anim Sci. 1997 Mar;75(3):852-67
references: 9078506
references: Anim Genet. 2011 Oct;42(5):475-90
references: 21906099
references: J Anim Sci. 2009 Apr;87(4):1548-57
references: 18952722
references: J Anim Sci. 2007 Jun;85(6):1479-86
references: 17296777
references: Br J Nutr. 1985 May;53(3):605-14
references: 2998448
references: J Exp Biol. 2001 Jan;204(Pt 2):325-35
references: 11136618
references: J Dairy Sci. 1993 Jul;76(7):2125-31
references: 8345135
references: Dig Dis Sci. 2003 Apr;48(4):765-9
references: 12741469
references: J Anim Sci. 1992 Apr;70(4):1137-45
references: 1374754
references: J Anim Sci. 2009 Apr;87(14 Suppl):E64-71
references: 19028857
references: Adv Exp Med Biol. 1998;445:325-43
references: 9781399
references: Am J Anat. 1974 Dec;141(4):461-79
references: 4440632
references: J Anim Sci. 1998 Mar;76(3):758-65
references: 9535335
references: Comp Biochem Physiol A Mol Integr Physiol. 2001 Jul;129(4):933-47
references: 11440878
references: Cell Tissue Kinet. 1989 Nov;22(6):425-50
references: 2611855
references: Trends Ecol Evol. 1997 Apr;12(4):134-8
references: 21238009
references: Anim Genet. 2012 Oct;43(5):599-603
references: 22497335
references: Animal. 2010 May;4(5):692-701
references: 22444121
references: J Nutr. 1990 Jun;120(6):649-55
references: 2191096
references: J Anim Sci. 2009 Aug;87(8):2685-9
references: 19395511
references: J Anim Sci. 2006 Jan;84(1):145-53
references: 16361501
references: J Anim Sci. 2006 Jul;84(7):1761-6
references: 16775060
references: J Anim Sci. 2012 Sep;90(9):2963-9
references: 22585812
references: J Cell Sci. 1994 Dec;107 ( Pt 12):3569-77
references: 7706406
references: J Anim Sci. 1997 Aug;75(8):2024-32
references: 9263047
references: J Anim Sci. 2006 Apr;84(4):938-45
references: 16543572