14 June 1996

Speedier grass growth calls for quality control

GRASS growth is now high and grazing management must prevent pasture getting ahead of cow demand.

Speaking at an open day at the Irish Research Centre Moorepark, Co Cork, Gearoid Stakelum urged producers to control the quality of grass on offer to secure high intakes by cows at pasture. "Offer enough high quality grass to allow cows to eat what they need to produce the milk they have the potential to produce, and leave enough to maintain quality regrowths," he said.

"The aim is to try to achieve the optimum compromise of high yields and high intakes without compromising grass quality."

Undergrazing had to be avoided for pastures would deteriorate. To maintain digestible, leafy swards grazing to 6cm (2.4in) or 1800kg dry matter a ha was still important.

Lenient grazing at this time of year would see digestibility fall as the stem, flower heads and dead material in the pasture increased, warned Dr Stakelum.

"You have the rubbish in the sward that you didnt use and then huge growth rates on top of that. It will be impossible to graze correctly the next time."

Cows wouldnt like the poor quality material on offer and intake would be low.

Failing to supply sufficient grass was a particular concern with high merit cows. These animals ate 1-2kg grass dry matter more every day than their lower merit contemporaries. Thats an increase of 0.4-0.5kg DM/day extra feed for each extra kg milk produced. "Even when underfed the high merit cows will also partition more energy to milk. Thats what their physiology is all about. If youre not feeding them enough they loose body weight and put it into milk." Fertility could suffer and they wouldnt last in the herd (see p46).

While a post-grazing height of 6cm (2.4in) is recommended from April to June to control sward quality, relaxing grazing pressure to a post-grazing height of 7-8cm (2.7-3.1in) is beneficial from July onwards, said Dr Stakelum.

&#8226 Offer enough grass.

&#8226 Maintain sward quality.

&#8226 Vigorous ryegrass pasture.

Dr Gearoid Stakelum: "Achieve high intakes at pasture by controlling the quality of sward on offer."