Comparison of the rumen passage rate of different forages using rare-earth markers
Abstract: The passage rate of nine different forages (diploid perennial ryegrass, tetraploid perennial ryegrass, Italian ryegrass, hybrid ryegrass, meadow fescue, tall fescue, timothy, cocksfoot and white clover) was evaluated with help of two markers (Yb and Dy) in a small-scale study at IGER, Aberystwyth, UK. Five dry Holstein-Friesian cows were used in a 4-period incomplete changeover design experiment. Cows received a mix of 30 kg maize silage (30% DM), 1 kg barley straw, 1 kg soyabean meal and dry cow mineral. At the beginning of each measurement period the cows were offered small amounts of two marker-labelled feeds which were randomly assigned to them, one Yb-labelled and one Dy-labelled. Grab samples of faeces were taken twice-daily over the next nine days. Faeces were dried, ground and analysed for concentration of markers. The concentrations were plotted against time and an equation was fitted and analysed statistically. There were no significant differences between passage rate of the different forages or markers. The highest passage rates were for dipolid perennial ryegrass (Dy-labelled) and white clover (Yb-labelled).
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