Farmers looking to maintain milk constituents while cows are out at grass, are being encouraged not to overlook the role of buffer feeding despite depleted conserved forage stocks on many farms.

While lush, fast growing grass is the perfect feedstuff and is relatively cheap to grow and is synchronised in terms of FME (fermentable metabolisable energy), and ERDP (effective rumen degradable protein), Bronwen Pihlwret – the nutritional advisor at Quality Liquid Feeds – said its low structural fibre content results in it passing through the rumen too quickly, causing milk constituents to drop.

“Structural fibre from forage is fermented in the rumen to acetate, which is the main precursor to fat production, but as a result of increased rumen throughput, we often see a drop in milk butterfat levels at this time of year,” she said.

To meet milk contract requirements, producers should be focusing on increasing butterfat levels when cows are at grass.

“This can be achieved through feeding a buffer ration, which includes structural fibre from forage such as stemmy grass silage, hay or straw,” explained Ms Pihlwret.

“The buffer feed will slow down the rumen transit rate, allowing the rumen microbes enough time to fully ferment the feedstuff and utilise the nutrients. The increase in structural fibre will also increase the proportion of acetate, helping to maximise milk butterfat production.”

She added that including a molasses-based product within buffer rations can help to increase its palatability and digestibility. “If you’re feeding a lower quality silage or straw in your buffer ration, molasses will enhance the palatability of the feed increasing intakes.

"It will also improve the digestibility of structural fibre, due to the immediately available energy in the form of six carbon sugars which improves rumen efficiency.”

Ms Pihlwret said that when this energy is combined with the available ERDP in grass the entire diet synchronicity will be greatly improved. However, she also noted that it was important to continue buffer feeding for the next few months as the nutritional value of grass continues to change.

“As we go through the grazing season, even just a month or so from now, the fibre content in the grass will increase, but sugars will reduce slightly,” she said. “The molasses in the buffer feed will at this point be needed to fill the deficit in grazed grass levels.

“By feeding a buffer feed, producers will be able to maximise the fantastic grazing opportunity this spring and produce the highest possible quality milk,” she concluded.