Dr. Evans et al., FORAGE YIELD AND QUALITY INTERACTIONS BETWEEN WHITE CLOVER AND CONTRASTING RYEGRASS VARIETIES IN GRAZED SWARDS, Journal of Agricultural Science, 126, 1996, pp. 295-299
The impact of white clover on seasonal yield and nutritive value trait
s in perennial ryegrass was investigated using six ryegrass varieties
which expressed contrasting levels of water soluble carbohydrate (WSC)
. These were sown in an upland environment at Syfydrin, near Aberystwy
th, in mixtures with white clover and in monocultures. Plots were graz
ed by sheep and sampled during 1991-93. Grass yields in mixtures and m
onocultures were similar except during mid to late summer when clover
contents were high. White clover had a considerably lower WSC content
but a much higher crude protein (CP) content than the ryegrasses. The
WSC content of grasses in mixed swards was consistently lower than in
monocultures and markedly so during mid to late summer. Use of ryegras
s varieties with a relatively high WSC content can compensate for this
depletion. Consequently high WSC grasses may reduce the amounts of ni
trogen excreted by ruminants grazing mixed swards by increasing the ef
ficiency of protein use from clover.