By Jim Morgan, PhD
Many flocks use marking harnesses on their breeding rams to help manage their lambing ewes. They are not 100% in catching all matings but, in our flock about 90% of the time, the marks do identify the mating that leads to the ewe becoming pregnant. Typically, a shepherd will use a light colour for the first cycle and then near the start of the second cycle change to a different colour. In our flock, the colour of the crayon is changed on day 14 or 15.
Prior to the start of lambing, based on the markings, it is possible to make a chart of the predicted order in which the ewes will lamb. In our system, the vast majority of ewes lamb at 145-149 days. When walking through the flock, it saves time to only have to closely look at the ewes that are predicted to be near lambing. We find it useful.
But what else can a marking harness tell you?
One year, every ewe in one breeding group marked in the first 15 days. Then at day ten in the second cycle, after we changed the colour of the marking crayon, every ewe was marked again. It told us that the ram wasn’t very fertile. If only one or two ewes had been marked with a different colour, we would have blamed those ewes. A marking harness can alert you to an infertile or sub-fertile ram when there is still time to do something about it, which is much better than finding out months later when ewes fail to lamb.
Managing a prolapsing ewe
About one out of 80 lambing ewes will prolapse in our system. Knowing when the ewe is predicted to lamb helps us decide how to manage that prolapsing ewe. If there is only a week left before the expected lambing date, we would use a harness. If she still has three or four weeks to go, we would probably resort to suturing.
Late gestation nutrition
Early in our shepherding careers, we noticed that the average gestation length in our flock increased from 147 to 150 days and our lambs were born about 1.5 lb. lighter on average (several 6.5 to 7.5 lb. lambs). Both of these were quantifiable. It seemed that it took two days after birth before any of the lambs were hopping around. The vast majority of the lambs were pretty lethargic. But the behavioural observation fit with the other data and we concluded that our flock had had some adverse nutritional event during late gestation.
Ewes switching breeding groups
One year we were using a green crayon for a ram in one breeding group and a yellow crayon for another ram in a different breeding group. After the third cycle, I noticed a yellow marked ewe in the green group. After checking eartags, we realized we had a ewe that went over or through two 32” electrified cross-fences and around some electric netting. Never would I have considered that a ewe would do that, since we rarely have ewes that get out. I now use different coloured crayons for every ram in their separate breeding pastures. This is important for maintaining accurate sire records.
Changing rams in a breeding group
When registering lambs, it is important to know which ram sired your lambs. A safe waiting period between two rams is ten days or maybe even two weeks. When using harnesses, you can shorten the period between taking one ram out and putting another one in to four days. Rarely have I seen a ewe that will breed for longer than 36 hours. You can be certain that a ewe that didn’t get marked by the first ram and then did get marked four days later by a new ram was bred by the second ram. But this only works if the shepherd goes out every day and looks for newly marked ewes.
It is important to watch lambing dates. If the gestation length for a ewe doesn’t make sense in terms of who you think the sire is, then it is best to either blood test the lambs or not register them.
In our system, about one out of 20 or 30 ewes doesn’t get marked, but most of them usually go ahead and lamb.
More rarely, we have ewes that don’t lamb. Most of these ewes are good candidates for culling, but marking records can tell us whether the ewe did not cycle at all (no marks), or cycled repeatedly but did not conceive (marked every cycle) or conceived in the first cycle and then lost the pregnancy later in the year (marked in the first cycle only).
Making culling decisions
Occasionally, a flock will run short on winter feed. In the midst of winter, trying to decide which ewes to cull can be difficult. Marking harness records could tell you which ewes did not get marked, or which ewes got marked several times. These ewes have a lower probability of lambing and may be better candidates to cull. A ewe that always takes three cycles to become pregnant makes management more difficult.
Selecting ewes for out-of-season lambing
This task is always difficult, as there are more variables, including ewes that cycle and get bred but do not conceive. But that being said, marking records provide the shepherd with more information about his or her ewes and their ability to cycle in the spring.
If some ewes are marked, then you know the ram is detecting estrous and you know how many ewes are cycling out of season. If a ram marked most of the ewes but none of them lambed, it indicates that many of the ewes were cycling but the ram probably has sub-par fertility at this time of the year.
Catching the ram
We often remove rams from the breeding pen without taking all the ewes back to the sorting pens. The sheep could be in a distant part of the rotation or across the highway from the sorting pens. By dropping a little grain or alfalfa hay on the ground, the harness straps make it handy for us to catch and control the ram as we get him out of the pen or into a cage on the trailer or back of the truck.
Problems with harnesses
Harnesses do not work for everyone. If the pastures or pens have brush or junk that can catch a harness, a ram could get caught or become entangled, and maybe even be severely injured.
Crayons can be purchased for three sets of temperatures (hot, warm, cold). The wax of the crayon needs to melt in order to mark the ewe. A hot crayon will not melt if the temperature is 300F. A cold crayon will melt all over the ram if the ambient temperatures are in the 70’s or 80s, thus requiring replacement. If temperatures change dramatically, the shepherd needs to catch the ram immediately and change the crayon to keep the harness working.
Harnesses can also rub the ram raw, if not adjusted correctly. They can even cause bleeding. Some folks say the harnesses are only 25-50% successful in helping to identify when ewes are bred and when they will lamb.
Harnesses are less useful for those with off-farm jobs that do not allow them to see the ewes in the daylight every day to check for marks. Some rams have a light touch or maybe a cooler chest and are less likely to leave marks.
In summary, marking harnesses are a useful management tool. They provide much more information for managing your flock than just telling you when a ewe is likely to lamb.
Editor’s Note: Many producers prefer applying a mixture of paint and vegetable oil directly to the chest of the ram to using a marking harness, but it can be very time-consuming for producers with several rams, as the paint has to be reapplied daily.
Jim Morgan raises Katahdins in Arkansas and is Operations Manager for Katahdin Hair Sheep International.