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Journal of Animal Science Abstract -

Effects of Dietary Fiber of Young Adult Genetically Lean, Obese and Contemporary Pigs: Rate of Passage, Digestibility and Microbiological Data1


This article in JAS

  1. Vol. 66 No. 3, p. 707-712
    Received: Apr 27, 1987
    Accepted: Oct 20, 1987


  1. V. H. Varel,
  2. H. G. Jung2 and
  3. W. G. Pond
  1. U.S. Department of Agriculture, Clay Center, NE 689333



Twenty-one genetically lean, obese or contemporary slaughter weight castrated male pigs (6 mo old; seven of each genotype) were assigned to individual tether stalls and fed either a control diet (low fiber) or a diet containing 80% alfalfa meal (high fiber) at 1.50% of initial body weight for 71 d (1.75% for d 1 to 4). Apparent dry matter digestibility of the diets was estimated by determining acid insoluble ash in fecal samples. Fecal cellulolytic bacteria and total viable bacteria were enumerated at d 0, 14, 35, 49 and 70. Fecal inocula were used to determine 48-h in vitro digestibility of alfalfa meal fractions on the same days. Digesta rate of passage was determined by feeding a pulse dose of chromium-mordanted alfalfa fiber to the pigs fed the high-fiber diet. In vivo digestibility of both diets was less for the obese pigs than for the lean or contemporary genotypes. In vitro digestibility of alfalfa fiber fractions was not different between the genotypes fed either diet. When the high-fiber diet was fed, in vitro digestibility increased for all genotypes from d 0 to d 14, but not thereafter. The numbers of cellulolytic bacteria for all three genotypes were greater when pigs were fed the high-fiber diet (23.0 × 105, 51.6 × 108, 37.2 × 108 per gram fecal dry weight; obese, lean and contemporary, respectively) compared to the low-fiber diet (3.0 × 108 , 3.2 × 108 , 3.4 × 108, respectively). There was a trend for lower numbers of cellulolytic bacteria in the fecal samples of obese pigs fed the high-fiber diet than of the lean or contemporary pigs. Digesta rate of passage was faster for the obese pigs. The fact that the rate of passage is faster explains the lower in vivo fiber digestibility by the obese pigs compared with that by the other genotypes.

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Copyright © 1988. American Society of Animal ScienceCopyright 1988 by American Society of Animal Science