OVER-RELIANCE ON AUTUMN GRASS HITTING SOME HERDS HARD

OVER-RELIANCE ON AUTUMN GRASS HITTING SOME HERDS HARD

While some herds are performing exceptionally well this winter, for others it is proving difficult to get cows settled into lactation and milking as expected. NWF Technical Manager Tom Hough suggests there may be a straightforward explanation for the difference.

"It is noticeable that there is a wide variation in how herds are performing this winter," Mr Hough comments. "Undoubtedly a considerable part of the difference can be put down to silage quality as the harvest season and resulting analysis varied greatly from region to region. However the biggest single reason for the way some cows are performing has been the overestimation of the value of grass during the late extended grazing season."

According to Mr Hough the combination of better than average late season grass growth and exceptional grazing conditions meant that many farmers keep late lactation and dry cows out at grass for longer than usual and this has affected early lactation performance.

"While the grass might have looked nutritious, the truth is that it was low feed value and many farmers over-estimated its value. The ramifications of this are being felt now and will potentially continue to do so for several weeks to come."

To minimise the impact of late season grazing on herd performance, Mr Hough recommends farmers start by taking a close look at late lactation and dry cows.

Where late lactation cows were grazed later than usual and have now gone dry, Mr Hough stresses the need for an effective transition diet. "Good transition management over the three weeks pre- and three weeks immediately post-calving is the key to minimising the extent and duration of post-calving negative energy balance, encouraging higher intakes and a more effective rumen.

"Provided transition management is of the highest order, the impact of prolonged grazing and over-reliance on autumn grass can be reduced and cows should settle into lactation well."

Where late lactation cows were fed high levels of autumn grass but are still milking, he advises monitoring condition score and ensuring they cows dry off around condition score 3.0.

"If these animals have not been gaining condition, or worse have been losing weight it is absolutely vital the situation is reversed before they go dry. Getting these cows in optimum condition followed by careful transition management should mean they will perform to their potential when they enter the herd.

Where dry cows had to rely on grazing and have since calved down, the consequence is that the rumen was not fully prepared and fresh calvers have struggled to achieve high dry matter intakes, leading to a longer and more severe period of negative energy balance resulting in poor milk yields and the risk of reduced fertility and milk proteins.

"There is no magic bullet to get these cows milking properly. Over time the rumen will compensate, appetite will recover and yields will stabilise and possibly improve. In the interim it is important to do all you can to encourage a healthy rumen and to get cows to eat more."

He advises farmers to ensure the ration is balanced and that palatable silages are on offer. The physical composition of the diet should be evaluated by a trained advisor using a Penn State Separator to ensure this is not contributing to the risk of acidosis which will suppress intakes.

"Farmers should ensure they are feeding a good balance of rapidly and slowly fermented energy and protein sources to promote rumen synchrony and I would recommend adding a rumen buffer to help compensate for any fluctuations in rumen pH.

"These cows should be monitored closely with particular attention paid to areas such as cudding rate, dung consistency and rumen fill. A meeting between the nutritionist and vet may identify areas where management can be adjusted to improve the rate at which these cows improve.

 "While the impact of over-reliance of grazing with fresh calved cows will take a while to work out of the system, prompt action can help reduce the problem in cows yet to calve down," Mr Hough concludes.