Grass growth has seen a slow start this year, particularly in Scotland, according to SAC’s Dairy Select manager Jimmy Goldie. And before grass stocks are adequate to sustain cows fully, buffer feeding will be required to even diets up.
“Grass is high in both protein and energy, so should ideally be balanced by a high energy, low protein buffer to balance digestion,” he says. “The key factor is measuring grass growth accurately and thinking ahead in terms of how long it will take for grass to regrow, which can be anything from 16-24 days for a 1ha field being grazed by 100 cows, calculated at a grazing allocation of 15kg/day/cow.”
Feeding a suitable buffer is essential for most herds, Mr Goldie explains. “Although a wedge has built up over winter and growing conditions are currently good, grass growth needs to be kept in front of cows, otherwise stocks will be depleted quickly. While cows should, theoretically, be able to yield 25-30 litres/day from grass, early grass growth is insufficient for high yielding cows to maintain 30-35 litres/day, at a sufficient yield and level of quality.”
And with many milk producers depending on quality contracts requiring butterfat levels to be continually higher than 3.5%, if fats fall below this level, the penalties can be harsh. Not only this, but rumen function also suffers, explains Mr Goldie. “Even if producers are not on such a contract, maintaining quality and yields are essential in producing milk efficiently.
“There are three primary ways to minimise the drop in butterfat percentages at turnout. The first is restricting grass, which is infeasible for producers trying to maximise returns the second is to introduce a high fibre fraction into the diet such as hay, big bale silage or straw. Whole-crop silage works well as a buffer, as it is relatively low in protein.”
Adding 0.4kg protected fats to the ration can help arrest the drop in butterfats by as much as 0.3%, says Mr Goldie. “However, producers have to bear in mind the cost implications of including this expensive supplement and whether continuing to sustain the butterfat percentage is cost effective.”
Furthermore, including protected fats may mask a problem with the underlying diet, believes Kite’s dairy business consultant Ben Watts.
“By grazing two to three hours a day at turnout and increasing gradually to half days over seven to 10 days, introducing new season grass over a period of time helps the rumen adjust to the change slowly and more sustainably,” he adds.
Including nutritionally improved straw pellets or 0.25kg-1kg chopped straw to the ration helps maintain quality, he says. “Stemmy, long fibre, forage and sources of high quality protein should be included to balance the ration. Problems associated with not including enough fibre in diets include displaced abomasums, something that can be prevented with careful diet management.”
“Be aware that as grass continues to grow at different rates, rations will need to be continually adjusted and the buffer itself may need countering with an acid buffer or sodium bicarbonate.”