7 June 1996

Keep cattle topped up, or risk health

EXCESSIVE loss of condition during the dry period can reduce fertility, claims Dynamic Nutrition Services consultant Mike Tame.

"Fertility is at risk because ova shed in the next lactation begin developing during the dry period," he says.

"And, with more maize and whole-crop silage being fed during lactation, intake of some minerals and vitamins is lower than on an all-grass system. Cow reserves may need replenishing, therefore, before the next lactation.

"Condition at drying off should be about 2.5 to 3 and this should be held throughout the dry period. Clean, bright and palatable straw, supplemented with just sufficient forage to maintain an adequate energy intake, should form the basis of the feeding regime."

Dr Tame suggests that the forage supplement should not exceed 2kg to 3kg of dry matter a day. Milk fever could be a risk when any extra forage is offered, especially if grass silage is used as the supplement.

Stocking rates for dry cows at grass must also be high enough to ensure intakes are restricted to no more than 2kg to 3kg dry matter (10kg to 15kg fresh weight).

"To supply sufficient vitamins and minerals feed a specially formulated dry cow roll throughout the period," he says.

This should comprise under 2% to 3% calcium, high phosphorus and magnesium levels and a very high trace mineral and vitamins content.

If grass silage was the sole forage source offered during lactation, then he suggests feeding about 1kg a cow of dry cow rolls for the first half of the dry period. "When the maize inclusion in the diet was low to moderate during lactation, feed 1.5kg a cow and if maize silage was high then 2kg a cow," he says.

Where there is a problem of milk fever when grazing, or grass silage is used to supplement straw, reduce forage intake and increase the rolls to 2kg a day. In all cases 2kg should be fed during the second half of the dry period, says Dr Tame.

For the last 10 days of the dry period cows should be given 10kg to 15kg of the milking ration depending on dry matter to enable the rumen bugs to acclimatise to the post-calving ration and reduce digestive disorders. &#42