Managing in the heat
Hot season strategies
Summer nutrition program
Good nutrition is always important, but it is particularly important during hot weather. Remember, hot weather reduces cows’ appetites and less feed means less production. Hot weather also alters the way nutrients are processed and used by the cow.
Feeding management strategies during the hot season are generally aimed at helping the cow do one or more of the following:
- Maintain daily intakes of metabolisable energy and other nutrients;
- Maintain digestibility of feed in the gut;
- Free up more energy for milk production by maintaining normal heat balance; and
- Provide energy in the form that best suits the cows in their challeged state.
Consult your nutrition adviser to develop a summer nutrition program to ensure the cows get what they need to stay healthy and productive despite the challenges presented by hot weather.
Some points to keep in mind when looking at your summer nutrition program are:
- Cows will eat less overall, so increase the energy density of your diet where possible. More starch or added fat can be useful tools.
- The risk of ruminal acidosis is increased during hot weather by several factors:
- Cows prefer to eat in “blocks” in the cooler times of the morning and evening each day in hot weather;
- Cows tend to select against low quality forage/fibre; and
- The natural buffering system the cow relies on to combat ruminal acidosis does not work as well in hot weather.
- Feeding of a high quality fibre source in the diet that helps maintain a stable rumen, but still contributes energy rather then just gut fill, is therefore essential in hot weather. For high-producing herds already being fed plenty of starch via grain / concentrates, this is particularly crucial.
- Recent research work in Arizona (where they know a bit about heat!) suggests that heat stressed cows switch metabolism and have an increased need for glucose within their bodies. Feedstuffs and feeding strategies that either provide the cow with more glucose or spare the amount she uses in her normal body processes may therefore be useful in hot weather.
When looking to support cows during the hot season, it is useful to distinguish between nutrition strategies for herds with lower and higher levels of milk production per cow:
