Seasonal variations in milk composition can affect butterfat levels

The levels of butterfat produced by cows can be affected if they are turned out early, dairy farmers are warned

Dairy cattle
Dairy cattle

Dairy producers are urged to keep a careful watch on milk composition in response to the onset of spring conditions, as cows go out to grass early.

“It’s common to see seasonal variations in milk composition,” said Andrew Howie, technical manager for Trident Feeds, “but managing butterfat levels at turnout can be an onerous task.”

As cows are being turned out up to three weeks early, the implications of changing diets can be seen.

“Butterfat levels typically drop when cows are turned out to grass. This is largely due to spring grass being typically low in structural fibre and high in soluble sugars.

“Low-fibre diets supress milk fat production,” added Mr Howie. “However, it’s often difficult to supplement a grass diet at turnout.

“Buffer feeding during spring is valuable to incorporate fibre and entices the cows to eat, the nutritional deficiencies of spring grass is then balanced with the cow’s nutritional requirements.

“Including high-fibre sources like hay and straw, as well as highly-digestible fibre such as sugar beet pulp, in buffer rations will help increase butterfat levels through the production of acetic acid in the cow’s rumen.”

He explained that increasing fibre might not lead to an instant increase in butterfat levels.

“We often find that farmers only think about milk fat levels once they’ve seen a drop; as a consequence there is not the luxury of time to increase fibre in the diet.”

Feeding high C16 rumen protected fats has been shown in some instances to increase the fat percentage of milk overnight.

“Incorporating feed such as Butterfat Extra Flakes into a buffer ration can typically result in a rise of butterfat of up to 0.3% and increases milk yield by half a litre a day.

“If producers feed this as part of a ration at turnout, it can minimise the dip in butterfat, enabling producers to effectively utilise spring grass, whilst meeting the demands of milk contracts.”

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