Chemical characteristics and in situ ruminal parameters of barley for cattle: Comparison of the malting cultivar AC Metcalfe and five feed cultivars

Abstract

The objective of this study was to compare the most widely grown barley cultivar in Canada, AC Metcalfe, a malting type barley, with five feed cultivars. Barley cultivars were grown at one location during 3 consecutive years and barley samples were milled to pass through a 1-mm screen and analysed to determine nutritive value. Additional samples were passed through a roller mill with a gap set at 1.12 mm and incubated ruminally for 0, 2, 4, 8, 12, 24, and 48 h in 3 dry Holstein cows fitted with rumen cannulae. The rate and extent of rumen digestion were estimated. AC Metcalfe had a higher (P < 0.001) concentration of NDF, and lower (P < 0.05) concentrations of non structural carbohydrates, starch, ADF, total digestible nutrients, and fermentable cell wall carbohydrates compared with the mean of the feed cultivars. The malting cultivar had a higher (P < 0.001) soluble DM fraction, lower (P < 0.05) CP and starch degradation rates, and a lower (P < 0.001) ruminally degradable starch concentration compared with the mean of the five feed cultivars. The results demonstrate that there are only small differences in terms of chemical composition and in situ degradation kinetics between the malting cultivar AC Metcalfe and the five feed cultivars of barley reported here. Key words: Barley, energy, protein, ruminants