Swapping traditional mixed swards for separate grass and clover leys and changing grazing times can improve dairy herd welfare and increase milk yields by as much as 10%.
Researchers at Harper Adams University found giving dairy cows in a once-a-day rotation system a fresh allocation of herbage following afternoon milking boosted yields and increased milk fats.
When given the option, cows consumed 40% of the 19kg of daily dry matter they needed in the evening, when plant sugars were highest and grass was sweeter.
Allowing cattle to graze later in the day led to increased consumption, which resulted in a 5% increase in milk production and a rise in milk fat of 0.5%, the Dairy Co-funded research found.
Further studies to determine cow preference and selection of food discovered yields could be further boosted by giving cattle a clearer choice between grass and clover when grazing.
According to researchers, cows’ diets consist of about 70% clover to 30% grass, with grazing preferences changing throughout the day.
In traditional mixed swards, cows were found to spend nearly three-quarters of their time while out at pasture selecting food rather than grazing.
But in swards where grass and clover was separated, cows spent more time grazing, resulting in a 3kg/day increase in consumption and an increase in milk yields of up to 10%.
“Traditional mixed swards creates a constraint on cows’ ability to graze,” Mark Rutter of the Harper Adams research team told delegates at the Dairy Technology 2012 event at the Shropshire agricultural college on 2 May.
“They are spending 70% of their day searching, not grazing, which means we are suppressing their intake.”
Dr Rutter said it could be difficult for farmers to manage monocultures, but tests had shown that strips of grass and clover in 12-36cm intervals produced benefits.
“You can achieve those intervals naturally if you select varieties of clover that grow in patches,” he added.
“Our research has shown that dairy cattle – and sheep as well – have a preference for clover and you can improve production if you can find ways to reduce selection and give a degree of separation. It improves welfare, as it allows them to eat a mixed diet.”