2017 By the Numbers

I’m finally getting around to totaling up my 2017 lamb crop numbers. Partly because I’m about to order vaccine for the 2018 crop already, and I need to know what to buy! Here’s how the season turned out, and what changes I’ll make this year to continue to try to knock out sources of loss.

 

• 63 ewes lambed
• Tagged 121 lambs born live, which renders a 192% lambing rate of ewes that lambed
• There were 2 full-term stillborns and 1 perished fetus observed
• 13 singles, 39 sets of twins, 11 sets of triplets

There were 96 exposed ewes here , so clearly quite a few that didn’t breed or lost pregnancies. 33 of those were ewelambs, and I don’t manage them specially, so am ok with few of them having lambs (only four of them did).

There were four mature ewes that didn’t lamb. One didn’t lamb last  year either, so she was butchered in the summer. The other was a 3-y.o. purchased ewe that hadn’t been bred as a yearling or 2-y.o. and was very fat. Over-fat ewes can be known to have trouble with conception. She was a very friendly ewe, so I sold her to a pet home.

The remaining two open ewes confused me, they were 2-year-olds, and they blood tested positive for pregnancy in late spring. I suspect they were bred late and pregnant, but then lost their fetuses. Last winter was an extremely stressful season with all the rain, cold and mud. Plus we had a livestock guardian pup who was prone to chasing. I also don’t think my hay was as nutritious as I would have liked, so some of the ewes were in lean condition heading into lambing. Given all those factors, I decided to give those two ewes a pass and give them one more year.

If I exclude the ewelambs, there were 63 mature ewes here, which had 117 live lambs between them, rendering a 186% lambing rate. I can do better here, but I’m still concentrating more on growth and milk genetics, so I  still have more singlers here than I’d like in the long run.

And now, the deaths! I’m definitely getting into the league where losses are higher because I can give less individual attention, and I’m ranging the sheep out into bigger areas where they are more vulnerable to things like predation and accidental death. Here I’m counting pre-birth deaths, just because I want to assess root causes of my biggest loss points. So, out of 124 conceptions, I  lost 22 lambs, or 18%.

Categorizing the cause of death is sometimes hard. When I necropsy, often the problem isn’t clear. I force myself to choose a best-guess answer, just so that I can categorize them. I frequently deduce clostridium when there is no other obvious cause, just because it’s a disease that usually has no outward symptoms. They say, the main “symptom” is dead lambs! Sometimes I can tell by the condition of the intestines and kindeys, other times, not. There were a few found-dead lambs in the pasture that were too autolyzed to necropsy. But given their position, dropped-dead in the middle of wide-open grassy spaces, I still suspect clostridium. It’s a drop-dead kind of disease. Where other diseases come on more slowly, and the lambs will tend to hole-up at the edge of the field, behind water tanks, or anywhere where they can find shelter and privacy. Clostrium lambs usually have full stomachs and intestines, because they were eating right up until the day they died. Lambs that die from her causes may be empty in the top half, meaning, they’d stopped eating a day or two before as they started to feel poorly.

Given all that guesswork, here is my best crack at my main causes of loss. Clostridium is my #1 issue, with some combination of internal infection/pneumonia/acidosis coming in 2nd place. That second category is especially fuzzy, but I  think pneumonia is playing a center role. So, here I am with two diseases for which I vaccinate, still giving me trouble.

The good news is, I think I can knock these out by changing my vaccination schedule. What I had been doing was giving the ewes a CDT and pneumonia booster in the last 3 weeks of pregnancy. This is when they are starting to produce colostrum stores. So, in theory, they should be experiencing an immune response to the vaccine and also adding it to the “library” of maternal immunity in their milk. Maternal immunity should last for 30-60 days, at which time, I’d vaccinate the lambs, and booster them again at 90 days. We know maternal immunity is imperfect, and we see it here, most of those lambs died in that window when their maternal immunity should have been protecting them.

The other thing I had tried this year was adding an oral innoculation to be given at birth, which protected for some strains of clostridium. I don’t think this helped me, either. The tricky thing about giving any innoculation early in life is, it can actually reduce maternal immunity affects. So this is why most folks wait until 60 days to do their first vaccine.

I had mentioned my troubles to Jim Morgan, director of Operations at Katahdin Hair Sheep International (KHSI, our registry). He pointed me towards Dr. Bret Taylor, a researcher at the USDA research station in Dubois, ID. Dr. Taylor had given a presentation on lamb vaccination at the 2017 ASI convention. I emailed him, and he offered some helpful advice. He was kind enough to share a pre-publication proceedings document which summarized some of their findings on lamb vaccination, which is an under-studied topic. It was useful in understanding the performance of early lamb immunity. Here was  his general advice:

1. Before lambing, provide an annual booster vaccination to the ewe of the targeted organisms. In order for the booster to be effective at raising colostrum antibodies, a primary and secondary vaccination must be given sometime earlier. Generally, primary and secondary vaccinations are provided early in life to the ewe (i.e., lamb).

2. The most opportune time to provide a primary vaccination to a lamb is beyond 3 weeks of age. Newborn lambs (less than 1 week old) have an immature immune system, and thus, cannot respond to the vaccination as needed. This is why passive transfer (antibodies in the colostrum from the ewe) is so important.

3. In order to “lock in” the vaccination response, a secondary vaccination must be given to the lambs per the manufacturer’s instructions. Generally, secondary vaccinations occur 1 to 3 months after the primary vaccination for animals with fully functional immune systems and that are healthy.

4. Due to logistics and management, some producers only have the opportunity to vaccinate lambs when they are less than 3 days of age. Although this is neither optimal nor recommended, this strategy can be effective but only if a secondary vaccination is soon to follow within the next 2 to 4 weeks.

In discussing more with Jim Morgan, I decided to map out the ages I’m seeing deaths from vaccinate-able diseases. This gives me the following plot:

The green lines are the average age where I’m giving vaccines now. The blue lines show where I think I should be giving vaccines, to try to catch this window of vulnerability. I think I’m going to target vaccinating the lambs at the individual age of 10 days, then hit them again when the average age is 50 days. Possibly a third time at 80-90 days average age.

The tricky part is vaccinating young lambs. They are easy to handle right at birth, but by a couple of days old, they’re pretty spry and hard to catch. Once there are a lot of lambs on the ground, handling the mob of sheep with dogs is hard: the lambs tend to get trampled, the ewes are panicky, and it’s very chaotic. This was part of why I preferred waiting until the lambs are 60 days old. By then, they are robust enough to handle sorting, and the ewes are less freaky and defensive.

Given that there is warning against vaccinating right at birth when the immune  system is immature, and I’m seeing most deaths between 15-90 days, I think ten days might be my sweet-spot for the first vaccination. I think I’m going to keep a management list, and try to vaccinate lambs right on their 10-day birthday, so each day, catching and vaccinating the lambs that are 10 days old, and marking them off the list, in “rolling” fashion. I think this might still be a lot of work, but there is perhaps reasonable  hope at being able to catch them at this age without needing to use the dogs. We’ll see!

One other thing that’s been on my mind is the Bo-Se injection. I had never used it, until two seasons ago, one of my dead lambs was necropsied by the WSU lab and declared to have died from Se deficiency. So my vet recommended I start using Bo-Se. I did so with trepidation, as it’s easy to kill animals with Se overdose, and the range between deficiency and excess is dangerously narrow. I used it for the first time in 2016, and had several healthy, vigorous lambs die in their first day or two of life, which is really unusual for me. I suspected it might be the Bo-Se. I had also increased the Se content in the ewes’ mineral mix, hoping to address the problem nutritionally rather than with what I consider to be a stop-gap, injecting at birth. This spring, I reduced the Bo-Se dosage to 3/4 of the recommendation, but still had some odd sudden deaths of day-old, healthy, well-fed lambs. It’s possible it’s clostridium, even that early. But I am still  suspicious of the Bo-Se. So I’m going to drop it.

As we head into 2018, I’m readying my lamb supply shopping list, and thinking ahead to the birthing season, which is now just ninety days away! So looking forward to sunnier and longer days, plus warmer temps! Happy New Year!