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A Comparison of Several Laboratory Techniques to Predict Digestibility and Intake of Forages^{1, 2,}

Ohio Agricultural Research and Development Center, Wooster

Abstract

A total of 77 forages were used to compare the relationships between several in vitro analyses and in vivo dry matter and energy digestibilities (DMD and ED), relative intake (RI) and nutritive value index (NVI). RI and NVI were predicted most accurately by IVCD x DMS or CED x DMS, followed by cell wall constituents (CWC). When RI was estimated with IVCD x DMS or CWC, the R² values were significantly increased by using a quadratic equation, indicating curvilinearity. Standard errors of the estimate were all high when RI was estimated from in vitro measurements, the lowest being 10.8 using IVCD x DMS.

DMD and ED were most accurately predicted by a two-stage digestion procedure. DMD was related to the in vitro two-stage digestion values by the following linear regression: Y=7.1+0.83 X; SEE=2.1. No improvement was obtained when a quadratic equation was developed. The next best estimate for DMD was CED x DMS using a quadratic equation, SEE=2.8.

¹ Approved for publication as Journal Article No. 40–67 by the Associate Director of the Ohio Agricultural Research and Development Center, Wooster.

² Supported in part by regional research funds in support of N.C. Regional Project NC-64, The Development and Application of Laboratory Methods for Determining Forage Quality.

³ Department of Animal Science. The authors acknowledge C. R. Weaver for assistance in the statistical analysis.