Shepherd to Shepherd: Producer Forum Blog #3

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For our third producer forum we asked our four shepherds, all enrolled in NSIP, how they select their breeding rams and how they make breeding decisions on their farms. Their answers, shared below, reflect the differences among the farms in environment, markets, individual flock goals and management styles. As a reminder, our producer forum includes: Michelle Canfield (Canfield Farms, Western Washington), Lynn Fahrmeier (Fahrmeier Katahdins, Western Missouri), Roxanne Newton (Hound River Farm, South Georgia), and Etienne and Isabel Richards (Gibraltar Farm, Central NY)

  1. What traits do you look for when selecting a breeding ram?

Canfield: I always seek a ram that’s above my median scores for all traits I’m working on (WWT, PWWT, NLB, NLW, MWWT, FECs, and Index). I try to avoid rams that are over 0.6 for BWT, as for me, that’s about the threshold where I start to see dystocia in my ewe lambs when they deliver from these sires. Ideally, a purchased ram should score in the top 1/3 of my ewe flock for all traits, so that he’s helping to move my averages up in retained ewe lambs. Sometimes I have to compromise on one trait, and that’s ok. I’ll just try to pair him wisely with ewes that are stronger there, and use a different ram with ewes that are weaker on that trait.

 Because I buy from fellow breeders I trust, I really don’t pay any attention to appearance or ask to see photos. I trust that they wouldn’t send me something truly wonky-looking, or in poor health. In general, I’m not picky about the finer details of conformation, as long as they are generally sound and in good condition. Now that we have genomics, I will favor rams that have had DNA submitted to NSIP.

 I prefer to buy rams from grass-fed systems that have somewhat “austere” husbandry practices, as I want to make sure he comes from an environment that tests hardiness. A farm where the sheep are coddled and fed maximally may mean that he or his progeny would not thrive in my “range-ey” environment.

Visually, I want a healthy-looking ram with good feet and legs, a mouth where his teeth meet the pad properly. His Body Condition Score should be more than a 3 but less than a 4. Fat rams don’t work on hot days. In my operation, I would prefer a shorter ram with a large heart girth. Testicles should be even in size and the larger the better because that is a great sign of early maturity. The measured genetic traits that I am focusing on are mainly maternal. GEBV for Number of Lambs Weaned (NLW) would ideally be larger than the GEBV for Number of Lambs Born (NLB). Maternal Weaning Weight (MWWT) and Weaning Weight (WWT) should be above average, but I am not trying to maximize those two traits. I think focusing on Fecal Egg Count GEBVs is important but not at the risk of losing maternal traits. Scrotal Circumference, and Eye Muscle Depth GEBVs are available; I want an animal that is better than average in those traits as well. It would be nice if more producers took the time to measure Fecal Egg Counts, Scrotal Circumference and Eye Muscle Depth. I have done them all and I know it takes time and I have not been able to measure those traits the last couple of years. Thanks to those breeders that do measure those traits.

When purchasing a breeding ram, we start early by contacting breeders who have similar selection criteria. Parasite resistance is a very important component of our breeding program so we look for NSIP enrolled rams that have two or more fecal egg counts collected and also have FEC GEBVs in the top 10-20% for the breed. Parasite resistance is a survival trait in our area of South Georgia. At the end of the day, you can’t sell a dead lamb, no matter how good his other traits are.

Along with parasite resistance, we prefer sires with above average growth and maternal traits. It’s really hard to find that combination in one animal. Since we use multiple sires, we often can find rams that excel in one or two of those traits and also meet our minimum threshold for the other traits of interest. We are careful to pair those rams with ewes whose GEBVs complement the ram’s best traits and/or strengthen their weaker traits. We try not to maximize birthweight or postweaning weight EBVs because we don’t want sheep that have too much frame, have difficulty maintaining condition or that increase the risk of lambing difficulties due to heavy birth weights.

Over the last several years we have learned to really appreciate the easy-care traits of Katahdins. It seems that when growth, milk or prolificacy is maximized, trouble is imminent. A ram with balanced GEBVs that breeds true, is structurally sound, sheds well and has a good temperament is what we’re looking for.

We look for functional conformation and large, muscular hind legs, as well as low enough relatedness to a sufficient number of our ewes to allow us to use the ram for multiple years. We want GEBVs at or above the 80th percentile for our ewe flock for PWWT, MWWT and WFEC. We use a percentile ranking based on the ewes that lambed the current year as our goal is to produce ewe lambs that will improve our ewe flock. We are willing to compromise on one of the GEBVs if needed, but it still needs to be above the 50th percentile of our ewe flock.

When selecting ram lambs from our own flock, we use the criteria above as well as the following: above average measured loin eye depth (adjusted to a constant age) as compared to the other ram lambs; above average measured scrotal circumference (adjusted to a constant age) as compared to the other ram lambs; above average weight gain from actual weaning at 100-120 days (not 60-day WWT) to five months old when we market the finished meat lambs. We look for ram lambs that did not require deworming during the growing out period (we deworm lambs with high fecal egg counts in the two samples we take; those not gaining weight as well as the other lambs between weighing periods; and those with high FAMACHA score). We grow out over 60 ram lambs to five months old each year that are sold as finished lambs, so we have a nice large contemporary group to compare our breeding ram lambs to. We prefer ram lambs whose dams have lambed at least three times and consistently weaned above average litter weights at actual weaning. If we have promising candidates out of younger ewes, the dams must have had weaning litter weights above 75% for their age group.

2)  What steps do you take and what criteria do you use to decide breeding pairs?

Canfield: When I plan breeding pairs, I use a big spreadsheet with ewes on the rows, and columns for the rams. I start by putting an “X” in any cell of a combo that can’t go together, e.g., inbred pairs. Then I filter by source ewe family and try to spread the rams out evenly over related ewes, to maintain diversity. Where possible, I try to pick a ram that will improve upon a ewe’s biggest weaknesses. I don’t stress too much about the details of exact “pedigree GEBVs” of the potential lambs out of each pairing. I’m mostly shooting for moving averages of the mob, not for achieving a particular standout individual. Plus, I find that Murphy’s Law always prevails: if you were hoping to get a ram lamb out of a certain pairing, the ewe will surely have triplet ewe lambs, and vice versa!

It takes quite a few iterations through the spreadsheet before I have “load balanced” sets for each ram. I may give mature rams a larger set than ram lambs. Though I find seven-month-old Katahdin ram lambs to handily be able to breed two dozen or more ewes in one cycle.

I try to rank ewes and rams based on several of the traits above as well as the US Hair Maternal Index. I generally try to breed the ram ranked the highest in a particular trait to a group of ewes that also rank high in that trait. For example, if I know a ram with a very high NLW GEBV needs to breed 20 ewes, I will mate him to my top 10 ewes for NLW. I will repeat this process for each ram based on his best trait. I will then start assigning the remaining ewes to each ram to avoid high inbreeding or to balance out a weak area that a ewe has. 

Once rams are selected, we determine relatedness for each potential pairing, trying to keep the inbreeding co-efficient at or below 5%. This is a very important step when using homegrown rams. We’ve been consistent with our breeding criteria over the last 10-15 years and have made progress for every trait of interest. We follow the genetic trends for our flock provided by NSIP and when progress slows for a particular trait, we can then put more emphasis on that trait when selecting our next sires. This year we purchased a ram with a high PEMD GEBV, a trait we have not selected for previously, so it’ll be fun to see how that works out.

Richards: First we decide on the constraints for the year: the maximum inbreeding we will tolerate for the year (typically we try to stay below 3%); and the maximum and minimum number of ewes we can assign to specific rams. We limit new rams to 25 ewes so we can test their offspring before committing to a larger proportion of our ewes. We allow a maximum of 25 ewes to a ram lamb and 50 to an adult ram as we only breed for 20 days with our preferred pairings and then put in a cleanup ram for 14 days.

Next, we set our breeding goals: the minimum PWWT and MWWT and maximum WFEC we prefer. We also try to maximize PWWT and MWWT and minimize WFEC, all three at the same time in a balanced way

We then run a software program to create breeding pairings based on the ewes and rams we have available, the constraints provided and the breeding goals. We then compare the percentiles of the breeding pairings created with that of the previous year. We adjust the emphasis on PWWT, MWWT and WFEC in order to improve on the 75th percentile of our previous years’ breeding pairings for all three EBVs. This allows us to get as many pairings as possible that match our breeding goals, with the best possible combination of PWWT, MWWT and WFEC that allows us to advance in all three traits. We also make manual adjustments to accommodate knowledge that we have that are not taken into account by the software. It sounds complicated but it is not.

3)  Are your criteria consistent from year to year, or do they change?  How so?

Canfield: My method is the same every year, though eventually I may start “capping” how much I let MWWT and NLW increase. I think my environment can only support so much before this may start introducing problems due to limited inputs on grass. For now, I’m still trying to increase on all metrics.

My criteria have changed over time. Post Weaning Weight (PWWT) used to be very important when I was selling to a company that sold lamb to restaurants and at farmer markets in Kansas City. When that program stopped and I started selling to the ethnic market, I became very concerned about the maintenance cost on my ewes. I want smaller more compact, easy fleshing, early maturing ewes in my flock now. So, selecting for tall, long legged, late maturing, and fast-growing lambs would be counterproductive in my context because the ewes would be much larger and more expensive to maintain. I have found that the cost of keeping a light lamb on the farm for 10 extra days is next to nothing compared to the cost of an extra 500 pounds of feed needed to maintain a ewe that weighs an extra 50 pounds for 365 days. While NLW is important in any production system, it becomes even more important when selling into the ethnic light lamb market. Shepherds that have ewes that raise and sell twins and triplets into that market are very successful.

Newton: Our selection criteria have been fairly consistent over the last ten years. Early on, we were trying to find our market for both meat lambs and breeding stock. Now that we are committed to a set of flock goals and have the tools to implement them, we just try to make steady progress. Each year there may be minor tweaks for some traits, but we’re more interested in the big picture: What do we want our flock to look like going forward and how do we get there? GEBVs are an important tool that makes selection decisions more accurate and less time consuming. We have learned that if you trust the data, you will increase the overall productivity of your flock. We are now participating in the new GEMs project that ideally will allow us to select sheep that are more resilient to our challenging environment by identifying animals that maintain body condition, are more resistant to parasites, and have less lambing and udder problems. Anytime we’re able to reduce labor and costs, it’s a good thing.

Richards: We learned about the pitfalls of corrective breeding at an early stage of our journey as shepherds. Using a ram that excels in one trait (for example WFEC) but is not at least average in the other traits that you select for will produce daughters that might have better parasite resistance but their PWWT and MWWT are lower than your current ewes so you end up not keeping them and not making any progress at all. Since that point we avoided the use of rams that will take us backwards in any trait of importance, that is why the ram must be at least at the 50th percentile of the ewe flock for PWWT, MWWT and WFEC.

For the last few years, the traits we focus on (PWWT, MWWT and WFEC) have stayed the same, it is just the emphasis that has changed. The emphasis has to change because we want to make progress in all three at the same time but progress does not always happen at the same rate.

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