5 June 1998

Calve at right time to optimise use

Is autumn or spring calving

most profitable on a drought

prone farm? Jessica Buss

follows the debate at a BGS

dicussion group meeting in

West Sussex

MAKING the most of grazing to lower feeding costs means calving at the right time of year – with mid-January deemed too early to profit fully from spring calving.

That was the conclusion of a BGS grazing discussion group which met at Stuart Harrisons Broadbridge Farm, Ashington, Pulborough. They decided that to make more use of grass, ease his workload, and improve profits, he should begin calving in early to mid-February.

Mr Harrison calves his 80 cows from Jan 20 to the end of March. Cows are fed between 6kg and 7kg of maize gluten and grass silage until turnout usually in early April, although this year cows went out on Mar 15.

"Silage and concentrate feeding usually stops in mid-April, but by July in three of the past five years cows have had to be fed straw and maize gluten," says his consultant Kay Carslaw.

"Last summer with no drought, there was no need to feed maize gluten in summer, and concentrate use that year fell to 450kg a cow compared with up to 1360kg in a dry year." Cows average 4500 litres a year and are dried off in November to save on quota and silage stocks.

Mr Carslaw says purchased feed costs in a good year are just 1p/litre but in a dry year the cost increases to 3p/litre. Mr Harrison makes about 550t of silage a year using grass surplus to grazing. Because this is only enough for 1.5t of DM a cow, he must buy straw for dry cow feed in winter and milkers in summer.

Because the farm is drought-prone, increasing feed costs in a dry year, Mr Carslaw believes that autumn calving would be more profitable. Cows could be dried off in summer and more silage could be made in spring to be rationed out in winter.

An autumn calving herd can produce milk for a feed cost of 2p/litre with an extra 1000 litres produced from 1250kg of concentrate a cow, helping to spread fixed costs making it more profitable, adds Mr Carslaw.

The discussion group also felt a switch in the calving pattern would lift profits. But argued that calving later, in early to mid-February would be most profitable and easiest for Mr Harrison to manage.

But at the moment, the group thought Mr Harrisons grazing management was too similar to that for autumn calving herds, because he feeds cows silage and concentrates from calving until turnout.

To profit from spring calving he should calve cows so their peak demand meets peak grass growth rates. True spring calving would maximise use of grass, to reduce costs and should be more profitable than autumn calving, they felt. Spring grazing management at the farm was good, with cows averaging 21 litres off high quality swards. BGS grazing consultant Paul Bird considered the quality of grass available could support cows averaging 25 litres.

"Cows strip graze until mid-June and then graze each field for about two days," says Mr Harrison. He does not back fence unless cows are in a field for more than two days.

One field of 8ha (20 acres) has not been grazed and is awaiting a contractor to cut it for silage and another 16ha (40 acres) has been grazed and will be silaged in early June.

The rest of the 45ha (112 acres) farm is available for grazing by milkers and followers.

But to maximise profit – by feeding less silage and concentrate – with spring calvers, grazing management must provide grass through the whole season, which has proved difficult at Broadbridge Farm, which is drought-prone in summer.

Mr Harrison admits he has been optimistic about a drought not lasting in the past and has delayed supplementing cows with straw and concentrates, grazing larger areas each day instead. But by shortening his grazing round in this way, cows are left with no grass to graze after a couple of weeks.

Although shortening the grazing round and grazing the farm bare is acceptable with autumn calvers which can be dried off in a drought, a grass wedge should be built up in front of spring calvers so that the rotation can be slowed down when it gets dry, says Mr Bird. &#42

When should I calve cows to maximise profits without increasing the workload? Stuart Harrison (left) asked a BGS discussion group.


&#8226 Calve cows so peak intake matches peak grass growth.

&#8226 Keep a grass wedge to graze into a drought.

&#8226 Calving later in spring can ease management.


Plan to keep a grazing wedge in front of cows into a drought, increasing the length of grazing round to 30-40 days. By allocating less area more grass will grow from the longer grass in dry weather. There will also be a grazing wedge after rain. If Mr Harrison follows this management, he will be able to graze for two weeks into a drought and reduce concentrate use in most summers, says BGS consultant Paul Bird. This year, with ample high quality grass in front of cows, Mr Harrison is in an ideal situation to start a drought management strategy.