18 August 1995

Nutritions vital to fertility when grazing is poor

Feeding to maintain fertility of summer-calving stock is important in a season when grass growth is poor. Jessica Buss and Jonathan Riley report

TO safeguard fertility of summer calving cows feed them carefully as grazing runs short.

So says Oxon-based dairy vet Eddie Friend, of the Larkmead Surgery, Wallingford. Mr Friend claims fewer cows are seen bulling in summer. Although this could be because they are less active in hot weather, or just down to poor heat detection, he suggests poor summer fertility is triggered when cows lose weight.

This is reflected by the fact that condition scores of cows inspected for fertility problems often drop between fortnightly visits, he says.

Best progress improving cow fertility was made when there was a good working relationship between herdsman, vet and nutritionist.

Mr Friend prefers to work with a herds nutritionist because as a vet he sees the tricky cows and usually visits the farm more often. One nutritionist he is in regular contact with is Geoff Homewood of Lyst Mill, Watlington.

Mr Homewood says high summer milk prices have encouraged more June calvings, so cows are higher yielding when summer grazing runs short. This grazing shortage has been compounded by higher maize acreages, so cows have tended to start the winter ration sooner.

He advises saving some maize for feeding in the summer and autumn. By-products such as brewers grains or citrus pulp are useful forage replacers, he says, but their use needed planning to ensure a consistent ration.

"With high yielders the fewer changes to the diet the better to avoid harming cow performance," says Mr Homewood.

The increase in maize and unmineralised straights and blends in cow rations meant the reduced parlour concentrate could not provide adequate minerals. Maize was low in all minerals and this needed to be corrected in the diet. But according to Mr Homewood free-access minerals were not the answer, as the mineral specification needed to be accurate.

"Minerals should be mixed in the ration or fed out along the trough with forage," he says.

Mr Friend agrees it is essential to get the mineral levels right, especially in the dry period.

"Where a mineral deficiency such as selenium is identified it can be treated by the vet with a long-acting injection but it is better to include the mineral in the diet," he says. "General purpose minerals are not a cost-effective solution. They provide too little of some minerals and too much of others."

To ensure the vet sees cows which fail to conceive, adequate records were needed. Mr Friend recommends on-farm packages, such as DAISY from the University of Reading, to help record herd fertility performance.

It was useful that most herds now had regular vet visits. "With quick handling facilities a lot of cows can be seen for post-calving checks at low cost," he says.

Careful monitoring

DIY AId herds needed careful monitoring. "When two people share AI the results between operators can be compared," he says. This would identify whether poor fertility was due to poor insemination skills.

Mr Friend is called out to few cases of retained cleansings. He says a herdsmen capable of AI can also cleanse a cow without the cost of calling out the vet. "A cow with a retained cleansing and a high temperature needs antibiotics quickly," he says. "Treat the cow and discuss difficulties over the phone with the vet."

As for cystic cows, Mr Friend claims greater incidence in cubicle-housed cows. "Cysts may be due to feeding or due to the stresses of cubicle life," he says.

He also reckons herds suffering poor fertility and low conception rates could benefit from pregnancy scanning at 30 days after service, for a high proportion of cows are identified empty 30 days. The cow was then at the correct stage in her cycle to inject with prostaglandin.