22 March 1996


By John Burns

ONE Dorset dairy herd is showing how the benefits of maize silage in a drought-prone area can be obtained without expensive feeding equipment. The herd is the 118-cow Drayton Dairy at Winfrith New-burgh, part of the 1457ha (3600 acres) farmed in-hand by Lulworth Castle Farms which are rented from Mr and Mrs Wilfred Welds Lulworth Castle Estate.

On black, sandy loam over chalk and gravel, and in an area of very low summer rainfall, the farm suffers a drought most years. Summer grass growth is unpredictable and never plentiful and so forage maize plays a key role.

Two other herds on the estate have 280 cows each, and are on a complete diet feeding system. Each unit has three staff doing all the work except feeding. No relief labour is employed for days off and holidays.

By contrast, the 118-cow Drayton Dairy is a one-man unit with a relief milker giving the herdsman an average of a five-and-a-half day week plus annual holidays. The only equipment is a tractor with loader, automatic scrapers in the cubicle passages, and a milking parlour, where all the concentrates are fed.

There is no feed trough for forage or extra concentrates. Maize silage is self-fed and each day in winter either one big bale of grass silage and one of straw or two of grass silage, are fed in ring feeders "to keep the rumen right."

Genus consultant Quentin Straghan said if no long fibre was fed and maize silage of that quality was the only forage, they could expect a 15% to 20% incidence of displaced abomasum. "Maize silage with a very high grain content tends to sink to the bottom of the rumen and if no other forage is fed the rumen starts to swing when the cow tries to ruminate. In extreme cases it can swing right over and the result is a twisted abomasum."

Farm manager Bruce Guthrie said considerable skill was needed to operate a self-feed system with maize silage of that quality. If given complete freedom the cows would eat so much maize they would not eat their concentrates. These were an essential part of the diet, being specially formulated to correct the deficiencies of proteins and minerals in the maize.

Herdsman Mike Wilkinson had developed a system which kept the cows adequately fed but still hungry enough to eat their concentrates in the parlour. It involved a detailed knowledge of the cows and what they were eating, and moving the electric fence three or four times a day after hand forking silage off the face.

Mr Wilkinson said that despite his best endeavours a few shy feeders and heifers might not get their full share. But the alternative was a more complicated, more expensive system which would be unlikely to boost profits. The Drayton Dairys profit a litre was better than on the other units which although they had higher yields and higher margins over concentrates, also had higher operating costs (see table).

The herd calves in the December/March period and so when cows go out to grass, typically about April 7, they can respond to it. Mr Straghan emphasised that the self-feed maize system would be difficult to operate with autumn calvers – they would be over-fed in late winter – and it needed a reasonably tight calving pattern.

The cows are set-stocked on an area which increases as the year progresses. Last spring the herd was kept in at night, self-feeding maize silage, until June 16. That allowed extra grass to be big baled, though the exceptional drought meant it had to be fed during the summer along with extra concentrates. At peak yields up to 10kg of concentrates a day (in two feeds) may be fed. Cake is rationed according to yield, not stage of lactation. &#42

Drayton Dairy results

Averages for theDrayton Dairy

two 280-cow units118 cows

(Autumn calving)(Dec/Mar calving)

Milk yield

(litres a cow a year)76507100

(heading for 7200-plus)

(3 x a day milking)(2 x a day milking)

Milk from forage

(litres a cow)2.0402,992



Concentrates (kg a cow)27102050

Margin over concs

(£ a cow)15461464

*Intentionally lower fat to cut demand for leased-in quota