FARMERS looking to maintain milk constituents this spring, 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.

Lush, fast growing grass is the perfect feed-stuff, being relatively cheap to grow and perfectly synchronised in terms of FME (fermentable metabolisable energy) and ERDP (effective rumen degradable protein), said Bronwen Pihlwret, nutritional advisor at Quality Liquid Feeds.

But its low structural fibre content results in it passing through the rumen too quickly to be fully utilised by the cow, causing milk constituents to drop.

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

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,” she said.

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

Including a molasses-based product within buffer rations could help to increase its palatability and digestibility. Bronwen said: “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.”

When this energy combined with the available ERDP in grass, the entire diet synchronicity was greatly improved.