By Shirley Macmillan

GETTING COWS to graze seed-heads before they develop into poor quality long stems could maintain sward quality and yields this summer.

Australian extension officer Frank Tyndall says only a few paddocks get this timely grazing. “Most do not, so the alternative is to mow.”

Ryegrass produces seed-heads when temperatures remain below 10C for at least a week and the plant turns into a reproductive state, explains Mr Tyndall. Increasing day length triggers seed-heads to appear.

Mowing to prevent them developing is logical theory, but hard to prove in practice, says Grassland Challenge extension officer Tim Martyn, based at North Wyke, Devon.

“When grass puts its energy into reproductive growth, vegetative growth drops off and when a tiller produces a seed-head, it dies off. This leads to thinning pastures, encroaching weeds and a sward less resistant to poaching,” he says.

“Getting cows to graze low enough to eat seed-heads is a problem. It is also hard to prove a yield difference.

“However, producers in Cornwall have mown in front of cows in June – after two grazing rounds – and seen few seed-heads afterwards. Because cows eat everything, there is no build up of rejected patches and it certainly evens the sward up.”

With a range of ryegrass heading dates from May 7 to June 19, getting the right date to mow is tricky, says IGER”s Aberystwyth-based extension officer Chris Duller.

Traditional topping at the end of June is mostly cosmetic and too late, he adds. “It doesn”t do much for grass growth and should really be done in May at peak grass growing time.”

shirley.macmillan@rbi.co.uk

Seed-heads unpalatable June topping cosmetic May mowing prevents quality decline