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Strategic use of rumen-protected fat supplements help meet energy requirements and support milk quality.  

As grass growth takes off in the early part of the grazing season, nutrition focus tends to be on completing the transition from the winter TMR to a grass-based diet without succumbing to post-turnout milk fat depression. While this remains important, fertility also needs to be made a priority, says Dr Richard Kirkland, ruminant nutritionist for Volac Wilmar Feed Ingredients.

“For spring calvers, there’s a short window to support a cow’s body condition to help secure her getting back in calf. During early lactation, cows cannot eat enough to meet the high energy demands of milk production and enter a state of ‘negative energy balance’, using energy from body fat stores to support the genetic drive for milk production, and lose condition. Research indicates a fall-off in conception rate of around 10% for each 0.5-unit loss in condition through this period,” explains Dr Kirkland.

Early spring grass can support reasonably high levels of production though intakes can vary considerably depending on weather conditions, putting pressure on energy intakes.

“Perfect grazing conditions may support 25+ litres of milk per day, but dry matter and energy intakes can be significantly reduced in wet, overcast conditions. We can see similar effects in the peak of summer where grass availability and heat stress will reduce intakes,” says Dr Kirkland.

Milk fat is also a challenge to maintain in this period as the low fibre, high sugar, high unsaturated oil levels disrupt rumen activity and lead to conditions where milk fat production is not favoured.

“While early grass growth may be akin to rocket fuel, it is more rapidly fermentable which will cause disruptions in rumen pH and pass more quickly through the digestive system. These conditions lead to an increased risk of acidosis and along with the high oil loads a significant milk fat depression,” says Dr Kirkland.

Strategic use of rumen-protected fat supplementation in buffer rations

According to Dr Kirkland, using a combination of digestible fibre sources and rumen-protected fat supplements in buffer rations will help protect milk production and support fertility in early lactation.

“Rumen-protected fat supplements have around 2.5-times the energy content of cereals, making them ideal to help maintain energy supply through variable springtime grazing conditions while reducing undesirable rumen effects through the transition from the winter diet to the spring grazing scenario,” he says.

To support both fertility and milk production during this time, Dr Kirkland advises feeding a rumen-protected fat supplement with a research-proven ratio of C16:0 (palmitic acid) and C18:1 (oleic acid) to strategically influence the partitioning of nutrients between milk and body condition.

“Fatty acids, the building blocks of fat supplements, influence the partitioning of nutrients to specific areas of cow performance, enabling producers to choose supplements according to milk contract requirements at particular stages in the lactation cycle,” explains Dr Kirkland.

During the early lactation period C18:1 (oleic acid) is a key fatty acid, increasing partitioning of energy and nutrients to improve body condition as well as improved development of fertilised eggs. However, given the challenges of early spring grass, products containing higher levels of C16:0 (palmitic acid) can be considered as effective ingredients to increase milk fat production.

“Careful choice of supplements is essential at grazing to provide those vital megajoules of energy in a form that stimulates the rumen and milk fat production,” Dr Kirkland concludes. “Selecting a rumen-protected fat supplement such as Mega-Max, farmers can support both fertility and milk production performance while helping ensure energy demands are being met.”