Submitted to: Society for Range Management Meeting Abstracts
Publication Type: Abstract only
Publication Acceptance Date: 10/1/2005
Publication Date: 2/1/2006
Citation: Grings, E.E. 2006. Use of in vitro gas production techniques to evaluate associative effects of forages. Society for Range Management Meeting Abstracts #134. Interpretive Summary: same as abstract
Technical Abstract: Combinations of feedstuffs can alter ruminal fermentation patterns compared to the same feedstuffs fed individually. These associative effects can be positive or negative and alter the potential nutritive value of feedstuffs for ruminant animals. An in vitro gas production system was used to evaluate the occurrence of associative effects for native plant species common in cattle diets in the Northern Great Plains. Whole forages were clipped at various dates, ground, and weighed individually and in combination into 100 ml graduated glass syringes. A ruminal fluid-buffer mix was added, syringes placed upright in a water-bath, and gas production determined at 2, 4, 6, 8, 10, 12, 14, 24, 30, 36, 48, 54, 60, 72, and 96 hr of fermentation by manual reading of the plunger travel distance. Predicted gas production was calculated by averaging the gas production of individual species. Gas production values were converted to first derivatives (ml gas produced per 250 mg sample per hour). Residuals were calculated for these derivatives of gas production for actual combinations of forages minus the predicted values at each time point. An associative effect was determined to have occurred if the residual differed from zero (P < 0.05). Addition of Yucca glauca in combinations with Pascopyrum smithii, Bouteloua gracilis and Carex filifolia decreased gas production compared to predicted values at early hours of incubation. Addition of either Sarcobatus vermiculatus or Ceratoides lanata to combinations of grasses or sedge showed positive associative effects at early hours and negative effects at later hours of incubation. Associative effects on ruminal fermentation of native forages can be evaluated using an in vitro gas production system.