Evaluation of the extent of associative effects of two groups of four feeds using an in vitro gas production procedure

P.H. Robinson, F. Getachew, J.W. Cone

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12 Citations (Scopus)


A ration formulated for ruminants is often a mixture of individual feeds, and its energetic value is generally calculated by summing the energy value of the individual feeds in it, on the assumption that the energy value of individual feeds will be the same when they are fed in combination with other feeds. In vitro gas production techniques were used to determine whether associative effects of feeds occur. Two sets of four feeds from California (alfalfa hay, AH; barley grain, BG; corn silage, CS1, soybean meal, SM) and four feeds from The Netherlands (grass silage, GS; corn silage, CS2; citrus pulp, CiP; corn gluten meal, CG) were incubated alone, and in various combinations, in buffered rumen fluid using in vitro gas techniques. Gas production (ml/g DM) at 2, 4, 6, 8, 10, 24, 30, 48 and 72 h of incubation was measured from all feed combinations. The percent increase in gas production measured on combinations of feeds, versus the gas calculated to have been produced based upon incubation of the individual feeds, was used to determine the extent of the associative effects. One-way associative effects (i.e., substitution of CS1 or CS2 by AH, BG or SM) generally occurred (P
Original languageEnglish
Pages (from-to)9-17
JournalAnimal Feed Science and Technology
Issue number1-2
Publication statusPublished - 2009


  • amino-acid digestibility
  • neutral detergent fiber
  • white-pekin ducks
  • metabolizable energy
  • rumen fermentation
  • mixed feeds
  • diets
  • hay
  • barley
  • corn

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