26 November 1999

KEEPDRY COWSINTRIM

By Marianne Curtis

METABOLIC disease incidence will increase when dry cows are allowed to fall below condition score 3-3.5 this winter. Even when cows are fat at drying off, they should not lose condition before calving.

That is the warning of Somerset-based Axient nutritionist Diana Allen. "The worst thing you can do with dry cows is to let them lose weight. It leads to an increase in metabolic disease incidence."

All cows should be housed full time by now, as remaining grass is wet and of poor nutritional value, according to Mrs Allen. They should be split into two groups; early dry cows more than three weeks from calving, and late dry cows with less than three weeks before calving.

"Early dry cows should be fed at maintenance, plus enough to allow for calf growth. This means feeding poorer quality big bale silage and straw. Late dry cows should be moved on to whatever the silage mix will be post calving to allow the rumen time to adapt."

There is conflicting evidence on whether concentrates should be included in late dry rations, explains Mrs Allen. "Work done at Aberystwyth University showed no yield response in concentrate-fed dry cows. But work at ADAS Bridgets showed a yield response in cows fed concentrates of low energy density.

"It is prudent to offer up to 2kg of concentrates with dry cow minerals which are low in calcium. Cows in poorer condition can enter the late group and be fed concentrates a couple of weeks sooner."

Yield losses through mastitis can also be avoided by improved dry cow management, according to independent mastitis consultant John Hughes. "Now that most cows receive dry cow therapy, the organisms causing mastitis have changed.

"Dry cow therapy also removes the natural barrier of udder organisms which help protect it against environmental bacteria such as Strep uberis or E coli. When sufficient numbers of these bacteria enter udders during the six weeks before calving, they can cause clinical mastitis in lactation."

Where dry cows are outside in autumn, Mr Hughes advises inspecting paddocks and housing when they become wet.

"Areas around water troughs and trees can become wet and dirty, presenting a mastitis risk when cows lie on them."

Cubicles bedded with 15cm (6in) of sand are ideal for dry cows, he says. "Sand is an inert material which minimises growth of environmental mastitis bacteria."

On units where dry cows are housed on straw, it must be deep, clean and dry to reduce exposure of udders to bacteria, he stresses. "Dry cows need to be in clean, well ventilated accommodation with plenty of dry straw. Too often they are housed on dirty beds."

For calving areas he recommends using 15cm (6in) of sand with straw over the top. "After a fortnight, the calving area should be mucked out as adding straw over sand for a longer period than this reduces its effectiveness." &#42

DRY COW MANAGEMENT

&#8226 Keep at condition score 3-3.5.

&#8226 Up to 2kg concentrates in late dry period.

&#8226 Sand or clean, dry straw.

Deep clean, dry straw is just as important for dry cows as for milkers to reduce mastitis. Dont let dry cows fall below condition score 3-3.5, says Axient nutritionist Diana Allen (left).