How cold is too cold for your calves? For animals under four weeks of age, the low end of their thermoneutral zone is 10° C. By a month of age, this low end has dropped to 0° C.
Research studies (Nordlund, University of Wisconsin) have shown that calves, on milk, in an environment where the ambient temp is less than 10° C (or 0° C once a month old) will burn energy to maintain body heat. This decreases the total energy available to the calf and therefore decreases energy that could be used for calf growth and immune system function. These colder conditions can result in a slower growing, weaker calf.
There is also plenty of evidence showing that early heifer growth translates into increased productivity when these heifers calve out. By ensuring calves gain similarly in cold weather as in the spring and summer, we can help heifers reach their genetic potential at all times of the year.
What should we do when the temperature is below 10° C for calves less than 4 weeks of age, and below 0° C for calves over 4 weeks old?
1.) Before birth – having good dry cow nutrition ensures calves are born with adequate fat stores.
2.) At birth – dry calves off and get them standing as soon as possible (increases body temperature), as well as feeding 4L of clean, quality colostrum right away!
3.) Calories – work with your nutritionist and veterinarian to ensure your milk-fed calves are getting adequate nutrition, and are maximizing their growth potential.
4.) Bedding – dry straw bedding they can nest into is best. Adequate nesting is achieved when you can’t see the calves’ legs when they are lying down.
5.) *Calf coats – help hold body heat in and keep them dry. A North Dakota study found 0.2 lbs. more daily gain in hutch housed calves with coats vs. calves without.
Your herd health veterinarian would be happy to discuss your current calf management program with you and see if there are any opportunities to increase productivity and keep your calves healthy and gaining well in the winter months!
*Calf coats can be purchased through the clinic.