Aging sheep

Like every other living creature, sheep age, and I’m often asked how old sheep can get. Although this seems like a simple question, like many seemingly simple things, it isn’t. When I got our first sheep, I asked the Iowa Extension Sheep Specialist how long sheep can live. He answered, “Eight years.” I commented that it was surprising, since even dogs live longer than that. His response, “Yes, but we don’t eat dogs!” No matter how hard I pushed at the time for a died-of-old-age time frame, there was no information to be had. The answer remained eight years.

Now, seventeen years later, I can much better answer that question — although my current response would have been less than satisfactory to my then-uninformed self. Old age generally comes earlier for a ram than a ewe. Ewes are generally considered “old” when they reach about eight years of age, and five or six is pretty old for a ram. I cannot say exactly why this difference exists (but suspect it has to do with both size and head-butting), but I’ve seen it here as well as on other farms. By the time a ram gets to be about five or six years old, the years he has left are very limited. If you want any more lambs from that guy, you should breed him quickly or he might be gone.

Grace is our oldest Romney, and both her fleece and her weight reflect that fact.

There are usually signs that a sheep has hit old age. Like graying hair in human beings, the first signs in sheep tend to occur in the wool: the structure of the wool tends to lose definition, colored sheep will likely gray out, staples can get a “frowsy” look (due to cross-fibering between the individual staples), and luster is often reduced. The crimp that was once very obvious becomes lost in the frowsy look of the fleece when you part it. Instead of the former crimpy staples, they look kind of mushy and much of the original structure seems to have gone. In our ewes, we usually see this beginning around the 7th or 8th year, and in our rams, somewhat sooner.

Next we will notice that the aging sheep begin to have trouble maintaining their weight under our normal conditions. This is not usually a matter of teeth but is more likely related to something in their metabolism or their place in the flock hierarchy — or something I haven’t yet figured out. I’ve found no reason why this happens at this age, but it does. And at that point, I need to make a decision: is this sheep so vital to our breeding lines that I should bring them back up to condition for their remaining year or years, or is it time to move them out?

If I still need them for some particular genetics, feeding them separately from a bucket with high nutrient content often brings their weight back up. Sometimes that’s enough and they can then hold their own weight until they eventually die of old age, usually a short time later — maybe a few years, at best. Others will need help annually to regain the weight that they lost during breeding (rams) or gestation/lactation (ewes). The question is ultimately an individual’s value to the flock compared with the extra labor and expense of this feeding. Keeping a young ewe from our lambs will be more productive over a longer period and will free up both money and time that I can then reinvest into the flock as a whole. Yet an older ewe is likely still in the flock because of the genetics she offers. It becomes a matter of balancing my responsibility to the sheep and my responsibility to the flock as a whole — and this decision is never easy.

So I still haven’t answered the question about how old sheep get. The true answer is that it depends. Rams usually begin to “fall apart” at about six to eight years of age and often die within a couple of years after that. Ewes can last longer if well cared for. If I can get them through the weight slump that can occur around age eight, they often bounce back and continue to be productive flock members until they die of old age — at any point between about ten and fifteen years of age. There are reports of sheep who live longer than this (up to about twenty-three), but they are few and far between. I did find an age converter online that was fun to play with. According to their computations, the following equation converts a sheep’s age to an equivalent human age, if the sheep is at least one year old: [sheep’s age x 4] + 14 = equivalent human age. Otherwise, if you are math averse, you can click the link and keep plugging in different ages!

 

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