Even at temperatures as low as 20°C, heat stress can reduce feed intake, drop butterfats and cut milk yields by up to 20%, warns KW nutritionist Dr Anna Sutcliffe.
“When cows are in direct sunlight or high humidity, even modest ambient temperatures will cause milking and transition cows to start suffering the negative effects of heat stress,” she warns.
“So watch closely for cows that are panting, lethargic, standing rather than lying or with a respiratory rate higher than the normal is 26-50 breaths/minute. Reductions in feed intake or milk yield of 10% or more – as well as Increased ration sorting – can also indicate that heat stress is a problem.”
Good access to clean drinking water is essential, as are changes to herd management to reduce exposure to direct sunlight, lower stocking rates, boost ventilation and increase access to shade. Rations will also need to be adjusted to account for the lower feed intakes.
“Increase ration energy density by feeding high quality forage – or using energy-rich moist feeds like Traffordgold – and boost digestible fibre intakes to reduce acidosis risk by including sugar beet feed, British wheat distillers’ feed or soya hulls. Rumen-protected fat supplements such as Goldenflake and Butterfat Extra can also help, as will adding a liquid feeds like Rouxminate, Molale or Lactoboost to increase palatability, encourage intakes and reduce sorting.”
