Wind chill and rain may reduce a cow’s effective temperature to below its critical level, resulting in a decrease in weight gain and milk yield and increases in milk fat.
For high risk animals the outcome may even be death.
Cattle at highest risk of cold stress include:
- Newly born calves and calving cows.
- Cattle in low body condition.
- Sick cattle.
Appetite is stimulated by cold temperatures, and cold stress increases an animal’s requirement for energy to maintain body temperature and functions.
Studies suggest that a yearling’s energy requirement may increase during an extreme winter event.
Where cold stress is likely, providing shelter and increasing the availability of highly digestible and palatable feed will assist cattle to maintain normal body temperature and production — minimising the effects of cold stress.
Shelter for calving cows
Special shelter management may be necessary for calving cows and their calves.
If required, small paddocks within a sheltered area along the edge of shelterbelts are useful.
Close regular observation should be carried out, and any cow found down and unable to stand should receive appropriate treatment and be provided with shelter or be moved carefully to a sheltered area.
Extra feed may be required to help the cow meet her own metabolic needs as well as the nutritional needs of the calf.
Calves in cold weather
Calves are most at risk during cold weather due to their small size. They need to have good shelter provided, as even strong and healthy calves can die if exposed to adverse weather.
Decreasing temperature and increasing precipitation on the day of calving increases mortality, and calves born to heifers are particularly susceptible to adverse weather conditions.
Additionally, cold stress has been shown to decrease the rate of absorption of colostrum in newborn calves — compromising their immune system and contributing potentially to morbidity and mortality.
Pens used for rearing calves should have a draught-free covered area to protect calves from the elements, and paddocks should have shelter accessible to all calves.
Shelter suitable for extreme cold
The following forms of shelter are suitable for cattle:
- Constructed wind breaks.
- Natural undulating paddocks and gullies.
- Shelterbelts.
- Trees planted in a north-south direction to protect from north and south-westerly winds.
- Sheds (open on one side) constructed in paddocks can afford protection from wind.
Temporary shelter can be provided in the form of shade cloths or plastic tarpaulins if other shelter is not available.
– Agriculture Victoria