HEALTHY HERBS ENHANCE GRASS
By Robert Davies
INCLUDING herbs in pasture seed mixtures could help maintain the health and fertility of dairy cows managed to optimise production from forage, with less reliance on mineral supplements.
A trial at the Institute of Grassland and Environmental Researchs Trawsgoed Farm looked at the yield, quality and mineral concentration of plant species grown in mixed swards. Researcher Richard Weller says that the plot trials results indicate scope for using herbs to replace minerals exported from a farm as milk or meat.
The concept could be particularly valuable in organic systems aiming for a high level of self-sufficiency. On these units, reducing concentrate fed cuts the quantity of minerals available to cows.
"A number of herb species, including chicory and ribgrass plantain, are proven to have a higher mineral content than grass species. However, there is little information on their influence on herbage yield or quality when introduced into legume based swards."
Plots were established using low, medium or high seed rates of perennial ryegrass or timothy, or a mixture of the two. Grasses were accompanied by 4kg/ha (1.6kg/ acre) of white clover, and 2kg/ha (0.8kg/acre) each of chicory and ribgrass plantain.
Cuts were taken on seven dates between early May and mid October. On each occasion, dry matter and proportion of each plant species were measured. Samples of each plant were analysed for nutrient detergent cellulase digestibility (NCD), neutral detergent fibre (NDF) and crude protein.
Bulked samples from the May/Jun and Jul/Oct periods were also analysed for calcium, phosphorus, magnesium, sodium and potassium.
No differences were recorded between DM yields of plots sown with perennial ryegrass, timothy or a combination of the two. However, the total contribution of herbs increased as grass seed rate was reduced. The range for chicory was between 3.5% and 15.5%.
Crude protein content of grasses and clovers increased from 9.9 to 29% during the sampling period. That of the chicory went up from 13.2 to 22.1%, while it stayed at about 14.4% for ribgrass plantain.
Calcium and magnesium content of white clover, chicory and plantain were higher than in grasses throughout the season. The highest sodium content was the 13,885mg/ kg level recorded in chicory between July and October. The lowest was 216mg/kg in timothy in May and June.
White clover plants had the lowest phosphorous and potassium concentrations and grasses contained least calcium throughout the sampling period.
"Neither chicory or ribgrass plantain increased protein content of grass/clover plots. The average digestibility was increased by inclusion of chicory and reduced by presence of ribgrass plantain.
"Analysis showed that DM of both herbs is low compared with grasses and clover. This lower DM may lead to problems of poor fermentation, effluent losses and lower feed quality when swards are conserved as silage."
Mr Weller hopes to use these results as the basis of a feeding trial to assess using multi-species swards to improve the nutrient input/output balance on a dairy farm. *
Growing herbs in grass/clover leys could reduce the need for mineral supplements,
says Richard Weller.
HERBS IN GRASS
• Can add minerals.
• Grow better with less grass.
• Silage-making concerns.