23 February 1996

Early turnout

diet warning

By Jessica Buss

PRODUCERS faced with forage shortages may be considering turning cows out early. That early turnout may save buying extra forage but more care of the cows diet will be needed to avoid milk loss.

This is the warning of independent consultant Dr Mike Tame, Mere, Wiltshire. He advises careful monitoring of daily milk output.

Production trends can be plotted using a graph on the dairy wall. Or for herds with cows calving, Dr Tame suggests it may be more useful to plot average daily yield for each cow in milk.

It is then important to react to any drops in yield rather than ignoring them. When milk output falls it is likely the buffer feed will need increasing.

Early turnout should be restricted. After turnout, continue feeding concentrates from winter rations but reduce forage intakes. That way the rumen adjusts to spring grass gradually.

For spring grazing the grass must be long enough 10cm (4in) for adequate intakes but should not get too far ahead of cows causing waste.

"A lift in milk output at turnout of more than 5% is a sign that cows were being under-fed in the winter. There should be little change at turnout. "If turn-out triggers a drop in milk output it may be that dry matter intakes are low due to wet grass or lack of grass."

For buffer feeding some forage must be available. Ideally save forage maize for this balances with grass well, says Dr Tame. Some straw or hay may be needed, but only feed enough to maintain diet fibre levels, milk quality and rumen function. Straw also slows down the digestion of grass so it is used more efficiently.

When buffer feeding it is difficult to assess how long forage stocks will last for use varies according to how much grass eaten, weather and the dry matter of the grass.

"Early morning dew means the grass is wet making it difficult to achieve high dry matter intakes. Last autumn we saw grass dry matter down to 15%, and a lot of milk was lost or cows became thin." Fresh weight intakes may also be restricting. In such circumstances, Dr Tame advises keeping cows in until mid-morning to let the grass dry out.

"Forage intake from wet grass could be 25-30% below that from dry grass, this is 2-3kg of dry matter or 5-6 litres worth of milk."

Spring grass has a high energy value and Dr Tame sees no reason to dilute it with poor quality straights or compounds.

Instead these should be a minimum of 12ME, for example maize gluten, sugar beet pulp, wheat, soya and rapemeal.

"Even though concentrate prices have increased the concentrate to milk price ratio is still wide, so it is still justifiable to maintain milk yields with concentrates," he claims.

"Reduce concentrates fed when yields are holding firm. Its fine to alter them weekly for cows seem to compensate to small changes readily." Cows that have yet to be served need extra care to avoid infertility caused by low energy intakes.

When milk fat content falls hay, straw or concentrates such as sugar beet pulp and citrus pellets may help increase levels. But distillers products will depress fat and to a lesser extent so will brewers grains, he warns. When milk protein drops starch and sugar levels should be increased. Cereals added as part of a balanced diet will help achieve this.

A balanced diet must be provided and for high yielding cows on grass the digestible undegradable protein (DUP) fed may need increasing. "The protein in spring grass is largely rumen degradable – ERDP – and for high yielding cows it may need balancing with DUP." But concentrates with DUP are expensive, he warns.

Fresh calvers need buffer feeding all summer for it is unlikely they will milk to potential from grass alone, he says. So these cows need to be kept separately from their lower yielding herdmates.

Mineral supply also needs monitoring – as is the case during the rest of the year for levels of each vary from farm to farm and many interactions occur. An excess of one can result in the lock-up of another. Blanket recommendations for minerals are not possible, Dr Tame claims. But he recommends magnesium supplements are added to drinking water to avoid deficiencies at turnout.


WHAT TO DO


&#8226 Monitor daily milk output.

&#8226 Restrict grazing period early on.

&#8226 Turn cows out mid-morning.

&#8226 Offer long-fibre such as straw.

&#8226 Adjust rations gradually.

&#8226 Supplement cows with cal-mag to avoid staggers.

&#8226 Use concentrates of over 12ME.

&#8226 Ensure adequate DUP.

Dr Mike Tame: Monitor daily milk output and react to any fall in yields.

Spring grass has a high energy value and nutritionist Mike Tame sees no reason to dilute it with poor-quality straights or compounds.