Profit from grass update - 22 June 2010

Published 22 June 10

Grass growth has put on a spurt in parts of the country in the past two weeks, as the highest rate from our 'Profit from grass' trial has reached 120kg DM/ha/day.

"This rate occurred in Somerset where a big jump in growth followed a much-needed dose of rain, although areas which missed out on the rain fared less well, leading to variable growth across the country," says Adam Clay, extension officer with DairyCo.

"A rate of 120kg would far more normally be seen at the end of May, so this in itself is a sign that the season is still around two weeks later than usual."

The slower early season growth appears to be reflected in lower quantities of first cut silage with yields widely thought to be down by 20 to 30 per cent.

"But there's definitely no need to panic," says Mr Clay, "as dry matters have generally been high, so the amount of feed value in the clamp should be high as a result.

"There's also ample evidence that a light first cut is likely to be followed by a heavier second cut, which - with sufficient rain - should bring overall silage stocks up to what we would normally see."

Where weather has continued to be dry and temperatures high, grass has tended to go to seed, which has led to the first drop in metabolisable energy that has so far been seen in the trial.

"ME has dropped to an average of 11.8 MJ/kg DM amongst the group, although half of the farms are still over 12, which shows that with good management, even if conditions are tough, quality can be maintained at an acceptable level."

However, in the face of declining MEs, it's more important than ever that dry matter intake is maintained, and a close watch should be kept on milk yield which will quickly decline if DMI goes down.

"To achieve a DMI of 12kg/day, a cow will need to eat 60kg fresh weight of a 20 per cent dry matter grass," says Mr Clay. "But if dry matter drops to 16 per cent, she'll need to eat 75kg fresh weight, which is close to the limit of what she can feasibly eat.

"So, in the face of variable conditions and variable dry matters, I'd recommend keeping a close eye on milk yields and reacting quickly after wet weather when intakes could be compromised and supplementation required."