8 December 1995

Design your ideal diet, then make sure it is eaten

By Jessica Buss

ONCE you have designed the ideal cow diet the rest is down to ensuring that the cows eat enough of it to achieve set performance targets.

Cows eating 5% less dry matter than predicted in ration formulations will be under-performing by two litres a cow a day. When this happens in early lactation it could amount to a yield loss of 500 litres a cow a year.

This is the message of midlands ADAS dairy consultant Mark Roach. He stresses that you are not just feeding cows for today but for the rest of their lactation and the next lactation.

"When formulating a cow diet decide firstly how much she can be expected to eat. Then balance the ration for energy; then in turn for protein, fibre, oil, major minerals, trace minerals and vitamins."

Mr Roach fails to see any reason for restricting dry matter intakes. "Feed should be ad-lib," he says. "When the cows are getting too fat lower the energy density of the diet." This can be achieved using chopped straw to secure an energy density of 11MJ/kg DM.

"Underfeeding results in low milk yields, poor milk quality, body condition loss, infertility and even health problems.

"Look to maximise intakes in early lactation – for a high yielding cow this means up to 25kg DM a day and for lower yielders 19-20kg DM. For this the ration needs to be available 24 hours a day. When there are empty spaces in troughs each morning the diet is not being fed ad-lib."

Mr Roach says it is acceptable to put feed out once a day but it should be pushed towards the cows frequently to keep them interested, standing and eating.

To maximise intakes on self-feed systems, silage from high clamps needs pulling down and the face loose enough for cows to pull the silage out. Also keep the wire close to the feed face, he advises.

However, cow intakes can be increased by 10-15% by taking feed from the face and putting it in ring feeders, particularly for shy feeders. But ring feeders must be kept clean.

He recommends cows on these systems are fed a maximum of 4kg of concentrate at a time. So to provide high yielding cows enough concentrate to prevent loss of condition a third feed may be needed.

"When using wet feeds, storage is important. Brewers grains must be stacked and sheeted well. Use within a fortnight of delivery to prevent aerobic spoilage."

To ensure the ration is working monitor cow condition, milk yields and check the milk quality.

"Cow condition determines whether the ration needs altering no matter what the computer diet says," he adds. "Ideally condition score the herd once a month.

"Also watch out for daily variations in milk yield for these nearly always indicate differences in dry matter intakes. When yields dip find out why – firstly by checking troughs were filled properly the day before. Monitoring against targets for production using lactation curves is also useful. Yields of each monthly calving group are plotted against a prediction to show whether they are failing to reach target peak yields.

or when yields drop too quickly. This is simple to do and tells how much milk is lost."

&#8226 Design a good diet.

&#8226 Dont restrict intakes.

&#8226 Push up feed frequently.

&#8226 Offer 24-hour access to feed.

&#8226 Watch for daily variations in milk yield.

&#8226 Monitor cow condition, yields and milk quality.

&#8226 Avoid deterioration of stored feeds.

&#8226 Plan use of forage stocks well ahead.

&#8226 Sell off surplus animals when forage stocks are tight.

&#8226 Ensure adequate water supplies, especially when dry diets are being fed.

&#8226 Provide salt blocks to encourage saliva production to naturally buffer acid diets.

ADASconsultant, Mark Roach:"Look to maximise intakes in early lactation – for high yielders, up to 25kg DM a day."