Ahealthy cow comes bulling regularly. 'Bulling expression' is the best indication of happiness a cow can show. Not bulling means she is not happy."

This was how Dr Dirk Zaaijer, acknowledged veterinary specialist in herd health management and cattle reproduction, whose advice is sought by leading dairy farmers here and across the Continent, opened his talk to a big assembly of members of Worcestershire Grassland Society.

They had crowded into a marquee at Ditchford Bank Farm, Hanbury, where Gordon Few and his sons have a herd of 350 cows, with 300 in milk.

"We have to become more diligent in observing our cows much more closely, so that we have the whole cow in perspective and look for signs indicating how we can make things better for her. Observation is the key. Keep thinking", urged Dr Zaaijer.

"Most of the problems we are confronted with come from management inadequacies. With the right management you can prevent most diseases. It does demand your time and attention - a lot of work, but it is rewarding.

"If cows are fed in the right way so their metabolism is not stressed they are more capable of fighting disease. Healthy cows will have high immuno-activity to ward off disease."

Turning to fertility problems, Dr Zaaijer said: "It is a fundamental mistake to blame genetics. We have to alter our attitude and approach to fertility problems in aiming to put things right by injections (of prostaglandins, hormones, antibiotics) which do not cure the cause of the problems.

"What we should do is improve environmental conditions like housing, ventilation and light, and especially nutrition, which is the most important factor. When a cow is not able to eat enough after calving she has a negative energy balance and this lowers her resistance. She should have a position balance restored as soon as possible."

John Few led us to look at dry cows and those in milk, so that Dr Zaaijer could demonstrate how close observation of the left side of the cow's body can give a reliable indication of how well her rumen is filled. He explained how to score the rumen fill. A deep hollow behind the ribs and in front of the hipbone shows much too empty a rumen....score one.

"At the other extreme, with a heavily-filled rumen the abdominal skin is tightly stretched with no depression behind the ribs... score five. Stages between are given intermediate scores.

"Palatability must be good to promote appetite. Silage quality is very important. The cow's natural food is grass," said Dr Zaaijer.

"I am happy with 50 per cent maize silage and 50 per cent grass silage, but would prefer not to have the maize higher than 50 per cent as the maize stem is not so digestible.

"Consistency in the ration is all important. Grass silage can vary considerably and a sample should be taken every month. Thorough mixing of a complete feed ration is vital. It is all too easy to assume that all is well, but sample checks can often show wide variations which will affect appetite and performance.

"Disappointing performance can all too often result from lack of even mixing. Grains should be kibbled rather than ground too fine, which would make them pass too rapidly through the digestive tract. Not more than one kilogram of rape should be fed.

"The ration in front of the cows should be checked every day for any signs of heating. You should make sure the cows are getting sufficient dry matter intake every day by checking their rumen fill and the consistency of and undigested fraction of their faeces."

Dr Zaaijer then demonstrated how to score the fresh cow pats by handling them after putting on a long plastic glove. Score one feels like creamy emulsion, homogenous and with no undigested particles.

To scores three and four undigested particles have increased and at five it is clear that the feed is largely undigested. He also showed a boot test by treading on the pats and assessing their consistency. Score one is watery thin, three like a thick pudding, while score five looks like dry horse manure.

These are tests I have never seen before, but clearly show how meticulous Dr Zaaijer is in his thoroughness in ensuring that the dairy cows are being properly fed. Experienced stock workers may well be taking a mental note of these signs, but it must be a helpful guide to make regular conscious checks using the scoring system.

These regular checks will not only ensure that the cows are being properly fed, but will also avoid expensive wastage through inadequate preparation and mixing of the cows' rations.

He also reminded us that water troughs must be cleaned every day and ample water must always be readily available. High yielders drink 100 litres or more a day and 70 per cent is consumed immediately after milking, half a.m. and half p.m.

In winter it should be warmed to 15 to 20 degrees Celsius.

Dr Zaaijer, with his profound knowledge of what makes a high-yielding cow tick and how best she can express her potential, set an example by going down to the most basic practical checks which few of us would have thought of in showing how they will help to improve the cow's well-being and hence her more profitable performance to the benefit of the farmer.