Supplementing to support fertility and milk production at grass
Feeding digestible fibre and rumen protected fats to spring calving cows in early lactation can help support production and body
condition while protecting fertility.
While the nutrition focus for spring calving cows is often on transitioning from the winter TMR to a grass-based diet without succumbing to post-turnout milk fat depression, protecting fertility must be 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. As a result, they lose condition.
“Research indicates a fall-off in conception rate of around 10% for each 0.5 unit loss in condition through this period,” he says.
Varied intakes from grass
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 Richard.
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.
He adds: “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.”
Strategic use of rumen protected fat supplementation
According to Richard, 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. This makes 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, Richard 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 Richard.
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,” Richard concludes.
“Selecting a rumen protected fat supplement such as Mega-Fat Multi, farmers can support both fertility and milk production performance while helping ensure energy demands are being met.”
