Milk producers are being urged to monitor cows closely for signs of acidosis throughout the grazing season, with research showing that one in ten animals could be suffering from sub-acute ruminal acidosis (SARA).
A study in Ireland investigating the rumen pH of grazing cows supplemented with less than 2kg/day of concentrate showed that 11% of cows were suffering from SARA, 42% were at high risk and only 47% had a rumen pH within the normal range (pH>5.8). A study of 100 grazing herds in Australia produced similar results.
“It appears that modern ryegrass swards pose a significant acidosis risk whenever cows are grazing, not just in the spring” states Dr Nicola Walker, AB Vista’s Ruminant Product Development Manager. “Even a small meal of starchy concentrates can then push cows over the limit.”
Dr Walker is advising milk producers to be on the lookout for any unexpected reduction in feed intakes, milk yields or butterfat level, as well as undigested feed or mucin tags in the manure. Where levels of supplementary concentrate are higher than in the studies, the incidence and risk of SARA will potentially be even greater, she warns.
“Any time the rumen drops below pH5.8, its ability to function will be impaired, and under pH5.5 cows are considered to be suffering from SARA. With significant negative effects on milk output and cow health issues like laminitis, it’s important to avoid SARA whenever possible.
“Limit in-parlour feeding to 2kg/cow/day, switch to a compound high in digestible fibre and consider feeding an efficient rumen conditioner like Acid Buf or Vistacell live yeast to help stabilise pH,” she adds. “With a typically yield increase of up to 2 litres/cow/day, even before signs of SARA are evident, the returns will far outweigh the additional cost.”
