This is the time of year when nearly everything I do is focused on the coming breeding season. In the process of setting up our breeding groups, I try to select rams and ram lambs who will not let me down, who will go into their breeding groups focused on the ewes before them. The month before breeding is all about getting ready: getting the rams into coats that fit well; getting them up to a good weight, so that when they stop eating to chase ewes, they don’t drop from starvation; and making sure they aren’t in need of any other attention from me before we begin. I need to make sure I carefully match each ewe to the right ram and that we have enough different rams working in each breed to produce small starter flocks that aren’t too closely related. There is a lot that goes into a successful breeding season, and it begins long before the rams get into their groups with the ewes.
In the past we fertility-tested each boy slated for a breeding group a week or two before turning them out among the ewes. It was a relatively expensive process, and each of our rams always tested “highly fertile.” After a few years of shelling out a couple of hundred dollars for testing and then getting the same results year after year, I decided to take our chances without testing. (Although there are other ways of getting better-than-average odds of success, I’ve never felt the need to go there.)
Common knowledge among shepherds — based on scientific research — is that scrotal circumference is directly linked to fertility in male sheep. The bottom line is that the bigger his boy parts, the more sperm a ram will produce — and the more sperm, the more likely he will settle his ewes (the shepherding term for getting them pregnant). I’ve heard about the link between scrotal size and fertility for many years, but I’ve never actually measured any of our rams. Usually I’d just take a good look at each of my guys from the back. After looking at hundreds of rams, I felt pretty confident that I knew what a fertile ram looked like.
However, we had many ewes who failed to breed or deliver lambs during the past production year due to the parasite issue that we eventually brought under control. One bad year is workable, but if we have another year like this last one, the financial hit could cripple us. It’s important that a large majority of our ewes breed this fall and deliver healthy lambs next spring. Besides that, some of our best genetics are in this past spring’s lambs, specifically in the Romneys, and I would like to use one of those boys in a breeding group. But only if he can get the job done. In addition, our yearling ram Prague has been returned to us because he did not breed many ewes last fall at his new home. I really want to know whether he is fertile, but I don’t want to risk a number of open ewes if he is not. I’ve considered a breeding soundness exam (fertility testing) for him, but don’t want to waste the money if there are other ways to tell whether he will or will not work.
For a while, I’ve been thinking about using scrotal circumference to figure out what’s what among my ram flock. I’ve heard from other shepherds that the threshold for fertility sits around 10.5″ for lambs. That is, if his scrotal circumference measures at least 10.5″, he will likely do the job. If he measures smaller, it isn’t worth the risk. (If you are interested in the whole table of values, I found it online.) I had help for various farm tasks this past Saturday, so I added scrotal measuring to the list. We had a new helper named Nate, a sweet guy about thirteen years old, who couldn’t wait to help with the sheep. As we walked towards the ram group, I told Nate and Seth that our goal was to catch specific rams and surround their “boy bits” with a piece of twine, then convert the resulting length of twine into number of inches by holding it against a tape measure. The look that flashed on Nate’s face was priceless, but like a true professional, his look disappeared almost as soon as I saw it. Nate then got to work holding rams, unfazed by what lay ahead!
The first ram we caught was Quest, the ram lamb I really want to use in one of my larger Romney groups. He has a lovely combination of traits that are unequaled in our flock, and he is quite large for his age. Nate held him in place as I measured; Quest wasn’t quite sure what it was all about and was very happy to be released. According to the online table, an 8- to 14-month-old ram lamb must measure 30-36 mm (or 11.75″ to 14.25″) to be considered “satisfactory” for breeding. At five months of age, Quest measured 12.5″ — well into the middle of that range. Since Romneys are so notoriously slow to mature, I’m feeling much more confident about our chances of success with Quest.
After that, we turned our sights on Prague. It turned out that Quest’s measurement was about equal to the lowest measurement required of a “satisfactory” adult ram (over 14 months), so with Quest standing next to Prague, I simply did a visual comparison. I hadn’t really looked at Prague’s scrotum since he returned to us last month, but when I compared him first to Quest and then to the other adult rams in our flock, I had the answer I needed. Prague is very likely of low fertility; his scrotal circumference is no larger — and likely a bit smaller — than Quest, who is a full year younger! Because of this, Prague will be sent to auction in the coming weeks, and I will send his previous owner another of our Romeldale rams or ram lambs next spring, per our agreement.
The rest of the adult rams ranged from the very top of the satisfactory grouping into the exceptional category — pretty much as I would have expected. Now that I’ve identified my possible breeders for this year, it’s time to finish putting together my breeding groups on paper. After all, our breeding season begins in about four weeks; there is no time to lose!