Calves are much less able to deal with variation in temperature than older animals. The highly variable temperatures, such as those we experience through our autumn and winter months, leads a young calf to expend more energy dealing with it than an older animal, when in fact it should be using this energy for growth and fighting disease.
It is unsurprising then that statistically calves are more likely to die in the winter months than the summer. What this article aims to do is look at the contributing factors and how we can reduce the risks.
While it is beyond the scope of this article to go into much detail about colostrum management, it would be wrong to leave it out. When calves are likely to face more adverse conditions in their first few weeks of life, giving them the right start with good colostrum management is of upmost importance (3-4 litres of 22% or higher on a Brix Refractometer within 6 hours of birth).
Newborn calves require temperatures of 15C. As a very rough guide, but easy to remember rule, this temperature decreases by about 0.5C every day, meaning that by a month old calves can tolerate temperatures of zero degrees Celsius. It also means that in its first two weeks of life a calf will be cold stressed between 15C and 7C, so we need to ameliorate this to allow colosturm to do what it needs to do. The average UK temperature doesn’t reach 15C until June! The temperature inside and outside calf housing is likely to be the same because, unlike cows, calves don’t produce enough energy to change it. So, what can we do? The two easiest options are calf jackets and/or increasing a calf’s ability to nest by providing a deep straw bed. With the cost of straw at the moment the latter may be less appealing but consider using cheaper material to lift the calf off the cold ground such as sand or woodchip, before providing a top layer of straw for nesting, The benefit of nesting is that it gives the calf the ability to manage its own environment. A simple max/min thermometer is a great way to track temperatures within calf sheds.
A calf in a damp environment at 5C is physiologically colder and therefore requires more energy to maintain its body temperature than a calf in a dry environment at 5C. Moist conditions also encourage the survival and spread of harmful bacteria and viruses. How well does your calf housing drain? Signs that moisture levels are too high include wet floors, sweat and dirt on coats and condensation on the underside of the roof. If you are seeing some of these things is it due to poor drainage or moisture entering the building? Are there hot spots where drains can be dug in? Along the same lines it is essential that calves are dried thoroughly before having a calf jacket put on or being moved to an individual pen.
It also goes without saying that a dirty, wet environment will lead to cold sick calves. A recent AHDB study carried out by Dr Robert Hyde at the University of Nottingham looking at calf rearing on 60 farms throughout the UK found that there was a correlation between cleaning out calf pens and DLWG, with cleaning out at least once a month being associated with higher growth rates.
4. Fresh air
Fresh air is a fantastic biocide, and a lack of fresh air will increase viral survival times. However, a draught will do the most damage the quickest, so we need to remember that we want fresh air – not wind. When thinking about this it’s really important to get down to calf level to experience what they’re experiencing – the target is fresh air delivery to all parts of the floor at calf height. Do calves huddle together on windy days? Is there a smell of ammonia? Does your calf housing have/need the ability to be adaptable with the changing weather conditions? If it can’t, it may be worth considering positive pressure tube ventilation. Another option would be to provide protected areas for young calves, again so they have some ability to manage their environment.
We generally don’t feed calves enough for most of the year and this is even more true during the winter months. Calves will eat 10l-12l from their dam each day and we should be aiming to feed at least 6-8l of a good quality powder at 150g/l, or whole milk, to provide somewhere near the same level of nutrition. For every degree drop in temperature below 10C we should feed an extra 2% in VOLUME, not concentration. If this becomes too much to feed at 2 feeds, then this should be split over 3 feeds. Generally this is an unpopular suggestion, but it really is best practice. If you are getting poor growth rates despite a high level of nutrition, then it would suggest the calf’s environment is not optimal.
There are various vaccinations available to help prevent pneumonia in young animals. Vaccinations can be given from as young as 9 days of age and working with your vet to find out what pathogens are present on your farm so vaccination programmes can be targeted and effective is essential.
7. Join the Club!
Join the Torch youngstock club so our team can help you optimise your calf rearing and minimise losses, especially during these challenging months. Speak to your vet to find out more.