When cows are turned out, farmers often breathe a sigh of relief, as the general consensus is that grazed grass is the cheapest feed available on the farm, but Charlotte Ward, nutritionist from KW Alternative Feeds warns it can soon become expensive if nutrient intake is not balanced.
Nutrient supply can change dramatically when cows begin to graze in the spring and result in an increased incidence of sub-acute rumen acidosis (SARA). SARA is caused by an accumulation of volatile fatty acids and insufficient rumen buffering, causing a drop in rumen pH. Increases in mastitis and poor fertility can be seen in sufferers of SARA.
According to Ms Ward, failing to address the change in nutrient balance could cut feed intakes by five per cent or more, leading to a loss of up to 2.5kg of milk per cow per day. Butterfats can also be hit hard when fibre digestion in the rumen is compromised, impacting the value of milk.
“Inadequate or poorly formulated buffer rations will disrupt rumen fermentation, undermine feed conversion efficiency and reduce milk from forage, the net result is a reduction in income over feed costs (IOFC) rather than an increase, even when feed costs are cut.” says Ms Ward.
Ms Ward explains including high value buffer feeds that contain the structural and digestible fibre needed for good rumen function is essential. “Good silages, sugar beet feed, soya hulls and moist feeds will reduce the risk of SARA and support butterfats.”
Switching to slower release starch feeds like sodawheat and ground maize will also support milk butterfats. If a further boost is still needed, Ms Ward advises adding a high-C16 rumen-protected fat and balancing the predominantly rumen degradable protein in spring grass with feeds high in rumen-bypass protein like soyabean meal.