We hear a lot over the winter months about the impact of cold weather on calf health and growth performance, but how does cold weather affect the milking herd? Cows are much less susceptible to cold stress, being comfortable within the temperature range between -4 to 18°C. However, it is thought that cold stress can occur at temperatures between 0 to -7°C depending on draughts and coat condition. During periods of colder weather, more energy will be required to maintain body temperature, diverting energy away from milk production.
Available water supply is essential for milk production, so it is important to ensure that the water supply is not frozen and that cows have access 24 hours a day. Excessively cold water can limit intake; cows prefer to drink water between 5 to 18°C.
Ensuring plenty of clean dry bedding will help protect against cold weather, both in straw yards and cubicle bedding. A good depth of bedding will help keep cows warmer and reduce the risk of chapping/damage to teat skin and hyperkeratosis. This is where a pre-dip with a high emollient content is of benefit. Keep cows clean and dry, as wet skin will increase the rate of heat loss and lead to chilling. This is where cow brushes can help.
As temperatures drop to freezing and below, maintenance requirements can increase by around 10% as more energy is required to maintain body temperature. In draughty sheds the wind chill factor will increase maintenance requirements further. Below freezing, dry matter intake will increase in the region of 5 to 10% as the cow tries to consume more energy. Combined with lower water intakes with cold water, milk yield can decline. However, the drop in yield is likely to go unnoticed, even down to temperatures of -6°C, but body condition will start to be lost to maintain milk output and core body temperature. The following table shows the relative changes in daily requirements of milking cows at various environmental temperatures compared to temperate environmental conditions set at 100%:
It is worth observing the amount of refusals and whether they reduce with colder weather. If so, increase the number of portions fed to reduce the risk of running out of feed, especially for transition cow groups.
If there is a prolonged spell of cold weather and milk output is being sustained, keep an eye on body condition and milk protein percentage. A decline in either or both is an indication that cows are lacking in energy, and it will be newly calved cows that are most susceptible to extended periods of cold weather.
In countries where below freezing temperatures are common for long periods of time, some farmers change their feeding time. By providing fresh feed mid-afternoon, this means the cow will spend a significant proportion of the evening hours ruminating, which is when the rumen is producing heat, and when temperatures are most likely falling.
While concerns around prolonged spells of cold weather are not so relevant to typical Scottish winters, what we should be mindful of is slippery walking surfaces if ice forms in passageways and in the collecting yard. Putting down salt or sand/grit on the main walkways that are most susceptible to freezing will help prevent injuries from slipping.
From a production point of view, prolonged cold temperatures in Scotland are unlikely to significantly impact the milking herd in terms of milk output. However, from a health point of view some diseases are more likely to occur during the winter months and should be looked out for:
- Pneumonia (both viral and bacterial causes): any cows that appear listless and depressed should be carefully monitored. An increase in respiration rate and loss of appetite are indicative of more advanced pneumonia and require prompt treatment.
- Winter dysentery: caused by a coronavirus and causes significant and sudden milk drop along with extremely loose faeces, which can have a blackish-greenish colour (sometimes blood may be present). While there is no treatment for this disease, electrolytes and proper nutrition will help improve recovery time.
- Abortions: these can be more common from bacterial sources over the winter.
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