The shepherd always tries to persuade the sheep that their interests and his own are the same.
Gestation in sheep, the time between conception and the birth of lambs, can be from 142 to 152 days, with the average coming in at 147, or roughly five months. Farmers who want to control when lambs will be born, keep the ram away from the ewes until about five months before they want lambs. There may be a lag-time of a few days, since the ram may not successfully breed ewes starting from the first day they are together. Ewes come into heat about every seventeen days, and that schedule can be strongly influenced by the presence, scent, and romantic entreaties of the ram, so most ewes will be receptive to the his efforts pretty quickly. However, their best efforts do not always pay off immediately, and it may take a few heats for a ewe to be successfully bred. Younger ewes may not respond as positively to the ram as older more experienced ewes, and ewes in poor condition may be cycling irregularly, or not at all. We anticipate breeding season to last about a month, which corresponds to about a month of lambing season the following spring.
The braver the farmer, the earlier in the spring (or even into late winter) they are willing to deal with newborn lambs, and a farmer who wants good sized lambs by Easter plans on them arriving some time in January. Cold weather lambing can demand significantly more attention from the farmer who has to ensure that newborn lambs, wet, weak and hungry, get dried off and fed before they freeze. (On February 6th we had a high temperature of 18 degrees, and a low of -15. A lamb born in January would still weigh somewhere in the low teens, or maybe single digits by then.)The counter approach is to plan for lambing on pasture, once the sheep are out in the fields eating grass. The danger of killing cold has passed, but parasite, insect and predator pressure are much higher, and the the growing season has been shortened for the farmer who is looking to produce a good sized lamb for late fall processing. Between these two polls is the middle ground of spring lambing in winter quarters.
Here at The Farm School, we put our two rams in with the ewes as close as we cab to November 1st, and we start looking for lambs the first week of April. The sheep are still in their winter pen, and expect to be out on pasture grazing full time by the first week of May. Our rams went in with the ewes on Halloween this year, and we thought that we’d be right on schedule, but our first lamb was born on March 7th, more than three weeks early. Our adult students in the Learn to Farm Program manage lambing, taking turns checking on the expectant ewes every two hours, day and night. Their call, letting me know that there seemed to be a lamb out there with the ewes, was a shock. After going back to the calendar, counting days to double check dates to make sure we weren’t crazy, we started exploring what could have gone wrong. Quickly we determined that one of our ram lambs must have been breeding ewes before leaving the farm.
We maintain a sheep record book to document ewe health and lambing history, as well as ear-tag numbers for all of our animals. Under lamb #92 was a note that it looked like one of his testicles had been missed during castration. This remaining testicle, getting the hormones, blood and support meant for two, had grown to full size very quickly, and had enabled little #92 to start breeding ewes at a young age. Typical ram lambs can reach sexual maturity as early as four months old, still at only half their full size and weight, and start breeding ewes as soon as they can achieve the required physical altitude needed to get the work completed. It seemed that our rough ram-lamb fit that bill.
One of the most interesting aspects of livestock farming is the effort to improve the genetics of your animals through selective breeding. By eliminating under performing animals and keeping those that thrive, by buying in premium bulls, rams, or semen, and by keeping only those offspring that meet a high standard, a farmer can, over time, move a livestock group toward greater vigor and economy. We have been moving our sheep herd away from the Border Leicester breed, known for good wool production, toward the Dorset breed, known more for meat production. We purchased two beautiful Dorset rams last year, and we have been using them to breed our ewes, while keeping their ewe lambs and retiring older Border Leicester ewes. However, #92, a cross-bred ram lamb, selected by nothing other than a missed castration, has introduced himself into our careful genetic work, jumbling up our breeding program.