26 May 1995

Ketosis is halved by redesigned ration

By Rebecca Austin

RADICALLY altering the dry cow ration has halved ketosis incidence post-calving at CWS Agricultures Weston Hall Estate, Crewe, Cheshire.

The effect was seen in all five herds milked on the 1295ha (3200-acre) estate. Previously the policy was to dry off cows in straw yards where they were offered ad-lib silage and minerals. Six weeks into lactation ketosis (caused by a negative energy balance) struck those cows which were fattest when dry.

"In a mild form, ketosis plays havoc with the breeding cycle," explains Bruce Johnston, the estate manager. Milk fever was also running at an average 2% across the herds.

So, as the milkers were receiving a complete diet feed already, Mr Johnston decided it was high time a ration was designed for the dry cows.

He approached Trouw Nutritions John Twigge, who suggested a special dry cow ration. This diet, which is fed to appetite once a day from a Keenan feeder for five weeks before calving, contains dry cow minerals, so guaranteeing each cow receives what she needs. "Before we were just sprinkling the minerals on the silage by hand which was very unsatisfactory," says Mr Johnston.

Sopralin, at 46.5% protein, is extracted soyabean meal treated to ensure 90% of the protein content is undegradeable in the rumen, says technical manager Dr Twigge.

Dry cows are introduced to the low-yielding milkers ration four to five days before they calve, so as to avoid sudden changes to the diet.

Since feeding the new dry cow ration from July last year, there have been only five cases of milk fever out of the 700 calvings on the estate between September and April.

"The first thing we noticed was how sharp the calves were," says Mr Johnston. "They were easier to rear and good at drinking. Birth weights were steady between 46kg and 51kg, and coats were bright. Soon it became apparent there were less retained placentas."

Cows were also keen to get on and dry matter intakes were 2kg higher than normal at about 26kg/day.

Milk proteins also improved on all the farms for about six weeks after calving, to 3.3% compared with 3.18%-3.20% recorded in the previous year. However, Mr Johnston stresses that after Christmas this increase was not sustained.

As yet it is too early to tell whether fertility has been enhanced, as Mr Johnston believes a full breeding season needs to be completed before passing judgement. But two farms have shown a marked improvement in conception rates.

The new ration is no more expensive in terms of nutrition, says Mr Johnston. Sopralin is bought in at £260/t, but when the dry cows moved on to the new ration there was a 600t saving in silage fed. "That left more for the milkers, as well as leaving some over for buffer feeding. Without that we would have been in trouble," says Mr Johnston.

"There were doubts initially with the new system. When the cows were due to calve they were not so full in the udder, which panicked some of the herdsmen. But they came into their milk in time," he says.

Chopping straw has proved expensive and time-consuming. The estate grows its own and is a net seller. "It does tend to blow around the yard and I would think twice about the ration if we had to buy in straw," says Mr Johnston.

But he believes using the ration across five herds under the same management, but with different herdsmen, has been a fair trial. "The results are more realistic and believable that way," he adds.

&#8226 10kg-15kg DM silage (11.5 ME).

&#8226 6kg-7kg DM chopped wheat straw.

&#8226 600g Sopralin.

&#8226 125g dry cow minerals*.

&#8226 300g crushed barley.

*High in magnesium, low in calcium

Left: Bruce Johnston, CWS Agricultures Weston Hall Estate manager, with the dry cow ration which contains Sopralin, an extracted soyabean meal. Above: This second-calver is in peak condition. Only a few days off calving and she is neither too fat, nor too lean, says Mr Johnston.