5 April 2002

High yields in summer without condition loss

By Richard Allison

FINE tuning buffer feeding is helping one Sussex-based producer to maximise summer milk yields, without increasing body condition loss in heifers.

The 150-cow, 8200-litre herd at Great Trippetts Dairy, Liphook, now calves in summer to take advantage of seasonality payments, says farm manager, Jonathan Powell.

"We have a contract to supply milk to Marks & Spencer, produced using only GM-free feeds. Our 12-month rolling milk price is 20.7p/litre, helped by the GM-free premium and seasonality payments."

With this incentive, the policy over recent years has been to maximise summer milk production by pushing back calving dates by two months. But summer calving has not suited heifers due to limited feed intakes. They produce milk to the detriment of body condition.

Fertility then suffers making it more difficult to get heifers in calf. In a block calving herd, any reduction in fertility and a delay in conception is the last thing you want, says Mr Powell.

Having only one herdsman means heifers and cows have to be managed in a single group until September, when they are separated for winter housing. The solution to this problem was to increase ration energy concentration by including a rumen-protected fat.

"This was the only way to increase ration energy content as high energy forages were already being fed, including maize silage, crimped peas, crimped wheat and whole-crop peas. They all had metabolisable energy contents of more than 12MJ/kg."

But milk protein content remained low at 3% last summer. Following the advice of Countrywide field manager Danny Mosely, protected methionine was added to the ration as Megalac Plus. "Checking the ration with the formulation programme indicated a methionine deficiency, which explained a low milk protein," says Mr Mosely.

After including methionine, milk protein immediately increased by 0.3% and cows yielded an extra 2 litres a day. This equates to an additional 39p a day in milk sales for an extra 3.5p a day in feed costs.

Mr Powell believes it helped heifers to cope with the system last summer by improving the use of nutrients. Fertility is good with conception rates to first service at 57% and cows are visually in excellent condition.

Responses to methionine will not be seen on all units, stresses Volac product manager Mike Rogers. "Mixed forage rations which promote excellent rumen function are less likely to be lysine limiting. This is crucial as lysine can limit milk production, therefore, feeding more methionine will have little benefit."

Producers and their advisers must be sure that dietary methionine supply is limiting milk production before using the product, he stresses.

"Cows dont necessarily have to be yielding more than 40kg a day of milk to benefit. Mr Powells herd was averaging 35kg a day when methionine was introduced."

While feeding fat has minimised body condition loss, a longer-term solution has been to breed larger heifers, says herdsman Steve Bell. "Heifers have traditionally been small at calving, weighing about 500kg and were expected to finish growing and get in calf while under stress of milk production."

Bulls have been selected to increase capacity to eat feed and produce milk. Heifers at 18-months are already larger than this years batch, he adds.

Heifers are also being bred for increased production and Mr Powell believes this together with improved nutrition will allow the herd to increase average yield to more than 10,000 litres. &#42