Using Chemical and Biological Approaches to Predict Energy Values of Selected Forages Affected by Variety and Maturity Stage: Comparison of Three Approaches

J. J. McKinnon,H. W. Soita,D. A. Christensen,P. Yu

doi:10.5713/ajas.2004.228

Abstract

Two varieties of alfalfa (Medicago sativa L cv. Pioneer and Beaver) and timothy (Phleum pratense L cv. Climax and Joliette), grown at different locations in Saskatchewan (Canada), were cut at three stages (1=one week before commercial cut (early bud for alfalfa; joint for timothy); 2=at commercial cut (late bud for alfalfa; pre-bloom head for timothy); 3=one week after commercial cut (early bloom for alfalfa; full head for timothy)). The energy values of forages were determined using three approaches, including chemical (NRC 2001 formula) and biological approaches (standard in vitro and in situ assay). The objectives of this study were to determine the effects of forage variety and stage of maturity on energy values under the climate conditions of western Canada, and to investigate relationship between chemical (NRC 2001 formula) approach and biological approaches (in vitro and in situ assay) on prediction of energy values. The results showed that, in general, forage species (alfalfa vs. timothy) and cutting stage had profound impacts, but the varieties within each species (Pioneer vs. Beaver in alfalfa; Climax vs. Joliette in timothy) had minimal effects on energy values. As forage maturity increased, the energy contents behaved in a quadratic fashion, increasing at stage 2 and then significantly decreasing at stage 3. However, the prediction methods-chemical approach (NRC 2001 formula) and biological approaches (in vitro and in situ assay) had great influences on energy values. The highest predicted energy values were found by using the in situ approach, the lowest prediction value by using the NRC 2001 formula, and the intermediate values by the in vitro approach. The in situ results may be most accurate because it is closest to simulate animal condition. The energy values measured by biological approaches are not predictable by the chemical approach in this study, indicating that a refinement is needed in accurately predicting energy values. (Asian-Aust. J. Anim. Sci. 2004. Vol 17, No. 2 : 228-236)

Highlights

IntroductionAlfalfa (Medicago sativa L.) and timothy (Phleum pratense L.) are two important forages grown in western
Alfalfa (Medicago sativa L.) and timothy (Phleum pratense L.) are two important forages grown in westernCanada for export
The objectives of this study were: (1) to provide detailed information on energy values for each variety of alfalfa and timothy cut at different maturity stages for Canadian forage export industry; and (2) to investigate relationship between the chemical (NRC 2001 formula) and the biological approaches on prediction of energy values

Summary

Introduction

Alfalfa (Medicago sativa L.) and timothy (Phleum pratense L.) are two important forages grown in western. Pioneer and Beaver alfalfa and Climax and Joliette timothy are well adapted to climate and soil conditions of the region Dehydrator’s Association, 1990; Canadian Hay Association, 1999). The detailed nutritive values for these varieties affected by cutting stages are lacking. In NRC dairy (2001), there are no energy values for timothy and no effect of varieties and cutting stage on energy values for alfalfa. To produce top quality alfalfa and timothy, the need for this information is crucial. Numerous studies (Minson and McLeod, 1970; Cox et al, 1994; Lundvall et al, 1994; Jung and Allen, 1995; Mathison et al, 1996; Ayres et al, 1998; Elizalde et al., 1999; Ferdinandez and Coulman, 2001; Lyon et al, 2001)

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