Shearing and cold weather

I got a question via email the other day from a younger shepherd who has purchased some of our breeding stock in the past year. I could tell when I delivered the sheep that he is dedicated to his flock, so I wasn’t surprised at his question — he is obviously dedicated to caring for his sheep. He asked:

Hey, I have a question about after shearing: are you ever afraid of the ewes getting cold? You saw my barn — it is open to the south; will they get too chilly? As for nutrition, they will be getting some of the best alfalfa I have ever seen, as well as some grain. I’m just worried about them getting chilled and catching pneumonia.

This seems like a valid concern, but some facts about sheep digestion and metabolism influence the answer. Sheep do not digest the way our bodies do. They have a rumen — essentially a huge fermentation vat — that contains millions of microorganisms (such as bacteria and protozoa) that break down the fibrous food (grasses, forbes and hay). When these microorganisms do their job, they give off lots of gas, resulting in the continual belching that is so common among sheep. In addition, the fermentation process produces heat. This is one reason why sheep don’t like to eat when it is very hot out — they don’t want the additional heat of digestion! The colder the temperatures, the more the sheep need to eat for two important reasons: they need the extra caloric intake to offset the calories used to keep warm, and the additional fermentation from the extra feed will produce more heat to keep them warm. We always feed more hay in the days immediately following shearing, especially since it is usually below freezing at the end of January in Iowa. Extra hay never hurts a sheep, but lack of it can, so we err on the side of caution.

Keep in mind that for the entire year, our sheep have been growing their fleeces, sometimes as much as nine inches per year. All of that insulation keeps them toasty warm, even in cold Iowa winters. In fact, they’re sometimes too warm! Years ago, when we didn’t shear before lambing, we used to have ewes deliver their lambs in snowbanks during a blizzard. The ewes couldn’t feel the cold, but their wet lambs froze. When we remove their wool during shearing, their metabolism must adjust to their new reality. Within a matter of days, a white-fleeced ewe’s pink skin — so evident immediately following shearing — becomes coated with a short layer of white wool, thick enough that you can separate it with your fingertips! From what I have read and observed, it takes them about four or five days to make the transition to a faster/warmer metabolism — and it is during this time that we provide extra hay. We always provide extra when it is really cold, but after shearing, we put out even more.

Keep in mind that although grains like corn can help with added energy (they are carbs — low in protein but high in energy), they don’t produce heat like hay does. For this reason, we don’t increase grain rations in the days following shearing, but we do increase hay by about 20-25% — or more if it is very cold.

Our ewes stayed in the barn post-shearing in 2016. The shared body heat of the flock kept temperatures comfortable.

We’ve occasionally sheared when the high was sub-zero on shearing day and for several days after. If it is extremely cold (in the single digits or below), we give the sheep access to the inside of the barn and hang a few heat lamps for those who are having the hardest time with the change — usually the very old or the very young. If the differential between the ambient temp and their ability to warm up is too great, they can experience “wool slip,” where the remaining wool drops from the follicles due to the stress of their situation. This has to do with low blood glucose levels, the production of cortisol, and how wool is produced — but in the end, one can end up with a bald sheep, at least temporarily, and that isn’t a good thing in winter!

The fear of pneumonia is an understandable one, since what we call “summer pneumonia” can appear when the sheep are exposed to temperature differentials of 30 degrees or more in a  24-hour period — but as the name suggests, it usually happens in summer. I think it tends to have more to do with humidity (which is high during Iowa summers), and I’ve never had a pneumonia case following our January shearing, which falls during a low-humidity season.

We have sheared in late January for many years, now, and to avoid problems, we do the following:

  • Coat all sheep immediately following shearing.
  • If it is below 20 degrees, keep the sheep in a single group with access to a barn. Have at least a few heat lamps on for the first couple of days. Keep in mind that crowding them a bit adds body heat to any space, even outdoors.
  • Feed additional hay — more than they can eat for the first five days or so.
  • Keep a close eye on the flock and identify any individuals who are struggling with the shift in metabolism.

We usually shear about two or three weeks before the first lambs arrive (mid-February), which means we shear at the end of January when Iowa temperatures can be wicked. With a little advance planning, however, our flock is no worse off because of the weather. In fact, many of our older girls will actually “volunteer” for shearing — standing at the gate to the shearing floor. They are bulky and hot, and they can’t wait to shed their heavy coats and walk away at least twenty pounds lighter! As a matter of fact, they often gambol as they leave the floor, happy to display their newfound joy and acting like a young lamb!

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