As dairy herds are turned out for spring grazing, farmers should balance rumen function and energy demands to avoid butterfat depression and fertility issues.
Dr Richard Kirkland, ruminant nutritionist for Volac Wilmar Feed Ingredients, said rumen function was under increased pressure at turnout as cows go from a controlled ration, balanced in fibre and starch, to more variable grass.
He said: “The diet transition alone is enough to cause challenges to the rumen that can have an immediate impact on milk production. Spring grass may be akin to rocket fuel and is expected to be rapidly fermentable.”
High-energy, more rapidly fermentable forage can cause disruptions in rumen pH and pass more quickly through the digestive system. This can lead to an increased risk of acidosis, which combined with the high oil loads pose a significant threat for milk fat depression.
Help meet your herd’s energy needs
Variable grazing conditions in spring make it harder to maximise energy supply, causing a drop in fertility. Dry matter and energy intakes can be significantly reduced in wet, overcast conditions.
Dr Kirkland said: “Especially for spring calvers, maximising energy intake is essential during the early part of the grazing season as cows have a greater nutrient demand to support milk production and body condition ahead of breeding.”
During early lactation, cows cannot eat enough to meet high energy demands. They begin using energy from body fat stores to support the genetic drive for milk production. Cows then enter a state of ‘negative energy balance’.
As a result, research indicates a decrease in the conception rate of around 10% for each 0.5 unit loss in condition score. But what buffer feed should you use to reverse the loss of energy? High-fibre supplements like citrus pulp and soya hulls will provide a better balance in the rumen.
Used alongside a rumen-protected fat supplement it provides the greatest response in milk fat according to research by the University of Nottingham. Supplementation with rapidly fermentable carbohydrates, like wheat or barley, can cause an increased risk of acidosis and could make the milk fat depression worse.
Dr Kirkland explained: “Rumen-protected fat supplements have around two and a half times the energy content of cereals. “This makes them ideal to help maintain energy supply through variable spring grazing conditions without the problems we see from starchy cereals through the transition from the winter to spring diet.”
Make the most of your milk contracts
Dr Kirkland said individual fatty acids impact cow performance and influence partitioning of nutrients between milk and body fat stores, impacting cow condition. Fat supplements should be based on the blend of fatty acids they contain in order to maximise returns from specific milk contracts.
The supplement you choose will depend on the stage of lactation and individual farm challenges and requirements. To support both fertility and milk production, Dr Kirkland advised feeding a rumen-protected fat supplement with a scientifically proven ratio of C16:0 (palmitic acid) and C18:1 (oleic acid), such as Mole Mega-fat Multi.
Dr Kirkland added: “Fatty acids are the building blocks of fat supplements and 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.”
During the early lactation period C18:1 is a key fatty acid, increasing partitioning of energy and nutrients to improve body condition as well as improved development of fertilised eggs. Given the challenges of early spring grass, products containing higher levels of C16:0 are effective ingredients to increase milk fat production.
Dr Kirkland concluded: “Careful choice of supplements is essential at grazing to provide those vital calories in a form that stimulates the rumen and milk fat production. “Selecting a rumen-protected fat supplement can support both fertility and milk production performance while ensuring energy demands are being met in a safe way.”
Call the Alternative Feed Office on 01566 780261 to discuss your fat requirements.