Most people are familiar with the concept that some animal species grow a longer, thicker coat in the winter. Some of our livestock species also partake in this physiologic thermostat. But how do their bodies know it’s time to grow the equivalent of an extra sweater? You may be surprised at the answer.
Let’s debunk a myth right at the start. Ambient temperature does not determine when an animal starts to grow its winter coat. Instead, the trigger is the shortening of daylight.
Here’s how: Hair growth is controlled by a small gland at the back of the brain called the pineal gland. This gland secretes the hormone melatonin. Occasionally known as the “light of night”, melatonin is produced by the brain when it is dark outside.
What does this have to do with hair growth, you may ask? Hair follicles have melatonin receptors, which stimulate hair growth. As the days grow darker, more melatonin is produced, which stimulates hair growth.
The end result: a thicker coat for winter.
This is a wonderful method to help keep livestock self-sufficiently warm in the depths of winter. But sometimes mother nature can’t do it all, and we have to step in and help. You’ve probably seen horses donning jackets when the weather is poor.
So when are you supposed to provide a winter coat for your livestock animals? Do cattle, sheep or goats need jackets, too?
Let’s start with horses. There are a handful of reasons to put a blanket (coat and rug are also synonymous) on a horse.
Many horses are clipped in the fall and winter to a varying degree. This helps them cool out faster after long rides. Understandably, if you take away an animal’s natural winter coat, you’re obligated to replace it. Hence the blanket.
Some horses, due to genetics, simply don’t grow as thick a winter coat as others. For example, some Thoroughbreds and Arabians have pretty wimpy winter coats as compared to, say, a Shetland pony.
Such breeds, if living in places with harsh winters, may need extra help to keep them warm. Additionally, older horses and those with metabolic diseases or other health issues may need help staying warm in the winter regardless of their own coat length and should be blanketed.
OK, so what about cattle? No one drives past a herd of a hundred and sees each steer with his own jacket. Personally, I’ve never seen coats on adult cattle but they do exist, mostly for use in keeping show animals clean.
Dairy calves, however, are another manner. These calves are typically born inside and are removed from their mothers very early. These calves are susceptible to cold stress, which can occur in calves under three weeks of age in temperatures below 50 degrees F, especially if the calf is already sickly. For these reasons, calf jackets are a common management practice in some dairies.
Protocols vary, but a general recommendation is to utilize calf jackets during the first three weeks of life when the ground is frozen.
Goats & Sheep
Adult sheep and goats tend to follow the same guidelines as cattle. With the exception of very old or sickly livestock animals, they don’t need winter coats.
There are two exceptions for sheep. Some hobby farmers will put coats on sheep to help keep the fleece clean prior to shearing. Likewise, if cold weather occurs after shearing, these sheep may need a blanket. Lambs and kids, if born in winter, do benefit from a snug blanket to prevent cold stress just like dairy calves do.
Plus what’s cuter than a lamb in a jaunty jacket?