Using rumen-protected fats to protect milk production as grass quality
Using rumen-protected fats to protect milk production as grass quality declines
As grass quality declines through late summer and autumn, maintaining energy supply without disrupting rumen balance becomes one of the biggest nutritional challenges facing grazing dairy herds.
While mature pasture generally contains more structural fiber, supporting butterfat production, declining grass quality, lower dry matter intakes and reduced energy density can steadily erode milk yield if rations are not adjusted. However, seasonal changes in grass composition can create further nutritional challenges.
According to Dr Richard Kirkland, Global Technical Manager for Volac Wilmar Feed Ingredients, flushes of leafy regrowth later in the grazing season can trigger similar rumen responses resulting in butterfat depression as seen in early turnout periods.
"Throughout the end of the summer, the oil concentration in grass begins to increase as it comes out of the reproductive heading phase. The result is a leafier, higher-oil grass that can trigger a similar rumen response to early-season pasture," says Dr Kirkland. "Being prepared with an appropriate feeding strategy helps minimise the impact on milk quality."
Protecting rumen function should remain the priority when supplementing grazing cows.
"Late-season grazing isn't simply about adding more energy," says Dr Kirkland. "It's about delivering enough energy to maintain milk production without compromising rumen health. Once rumen function is disrupted, feed efficiency falls and performance quickly follows."
As pasture digestibility declines, many herds require buffer feeding to maintain energy intake. However, Dr Kirkland warns that increasing cereal inclusion too far can create further nutritional challenges.
"High-starch feeds ferment rapidly, increasing acid production in the rumen and lowering rumen pH," he explains. "That can reduce fiber digestion, increase the risk of subacute acidosis and ultimately compromise both milk yield and milk fat production."
To maintain balance, Dr Kirkland recommends increasing dietary energy density with rumen-protected fat supplements, which are not fermented in the rumen and deliver concentrated energy directly to the small intestine.
"Rumen-protected fats provide around 2.5-times the energy density of cereals without adding to the rumen acid load," says Dr Kirkland. "They allow producers to increase energy supply while maintaining fiber digestion and rumen stability."
Research also demonstrates the benefits of strategic supplementation. In grazing trials at the Tasmanian Institute of Agriculture's Dairy Research Centre, cows supplemented with 250 g/day of Megalac rumen-protected fat produced up to 2.1 kg of additional milk at peak lactation and maintained up to 1.5 kg/day additional response at 200-days in milk, while maintaining high fertility.
With energy supply becoming increasingly limiting as grazing conditions deteriorate, he believes rumen-protected fat should form a key part of late-season buffer feeding strategies.
"As grass quality and availability decline, buffer feeding with rumen-protected fat supplements helps meet energy demands without compromising rumen function. Combined with good grazing management, they allow producers to maintain milk production, protect milk quality and support herd performance right through to housing."
Dr Richard Kirkland, Global Technical Manager for Volac Wilmar Feed Ingredients.