Evaluation of reliability of solubility in potassium hydroxide solution as an in vitro method for predicting organic matter digestibility of ruminant feeds
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Department of Animal Nutrition and Physiology, Research Institute of Animal Production, Sarego 2, 31-047 Kraków, Poland
National Institute for Animal Nutrition, Scheldeweg 68, B-9090 Melle-Gontrode, Belgium
Department of Feed Science and Animal Products, Research Institute of Animal Production, 32-083 Balice, Poland
Research Institute of Animal Production, Experimental Station Pawłowice, 64-122 Pawłowice, Poland
Publication date: 1996-01-12
J. Anim. Feed Sci. 1996;5(1):83–92
The applicability of the alkaline extraction method using a 5% potassium hydroxide (KOH) solution to predict organic matter digestibility (DOM) of ruminant feeds was examined. The predictive value of the assay was estimated using 110 feeds including dried grass (70), grass silages (33) and compounds (7) of known DOM determined on sheep (DOMv). A fairly close linear relationships for all samples and forages between the in vitro organic matter digestibility (DOMk, X, %) and DOMv (Y, %) estimates were found. The regression equation for all samples (n= 110) was Y = 0.934 X + 5.74, R2 = 0.75 (P<0.001), residual standard deviation RSD 3.65, for all forages (n= 103) Y = 0.903 X + 7.67, R2 = 0.67 (P<0.001), RSD 3.62. The regression of DOMv on DOMk for compounds (n = 7) was insignificant (R2 = 0.30, RSD 3.74). The relationship between DOMv (determined values) and DOMvk (predicted from the equation for all samples) was linear. The predicted values could account for 75% of the variance in determined DOMv; RSD = 2.52. The residuals (DOMv - DOMvk) were correlated with DOMv (r = 0.51, P<0.001). DOMvk tended to be overestimated for samples of DOM ranging 50-60% (negative residuals only) and underestimated for that of DOM exceeding 80% (positive residuals only). The most even distribution of the residuals was in the DOM range of 70-80%.