The Selection of Replacement Ewes, and the use of records and visual appraisial to help in that selection
by A. Richard Cobb, Extension Sheep Specialist, University of Illinois
This was originally written in 1994 and updated in 2004
One of the main reasons for the long term success or failure of a flock is the selection of replacement ewes to be added to the breeding unit of that flock. Whether purchased or raised, replacements need to compliment or advance the genetics already working within the flock. While it is true that ram selection can have the greatest short term impact on a flock, the selection of replacement females of sound structure and genetics will help to ensure the continuance of a high quality, problem-free breeding unit.
To make intelligent replacement additions to a flock that will benefit that flock a shepherd must have an idea what it is he or she wants to produce. Every producer should have an end product in mind. This end product can change in the future, many do, but -without a goal there is no basis to select replacements on. For best results, shepherds should consider as many factors as possible before deciding what type of sheep and program they wish to establish. One of the great things about sheep is that there are enough breeds that every producer can find the one to satisfy their wishes and to fit their particular set of circumstances. In fact, each breed offers multiple types and kinds within it already selected for different end products and so the genetics are available to be tapped and used.
Lets look at four different producers; a commercial producer wanting to produce a maximum number of lambs to sell on the market; A producer raising purebred sheep so that his children can benefit from the experiences he had doing the same thing; The owner of a nationally competitive purebred flock of Hampshires; and a lady producing fleeces for sale to spinners. We would expect that the animals they select will be as different as night and day. Actually, by using good selection practices, they can each satisfy their needs and find replacements that will fill those needs and still give them long lived productive ewes.
A SHORT PENCIL IS BETTER THAN A LONG MEMORY
The first step in selecting replacements and in maintaining a quality flock is YOU, the shepherd or producer. You have to make a commitment to determining what kind of a flock you want to have as well as what you want to produce. Then, you must make a commitment to learn as much as possible about the production of sheep so that your goals can be reached.
The next step in selecting good replacement animals from your flock is RECORDS. Without records, we have only visual appraisal and our memory to assist us. Records are a personal thing. By that I mean each producer can record as much or as little as they wish about their sheep. The key to records, and really the only reason to keep them, is to use them to help you to make decisions. Record what is important to you or what you will use. A lambing or barn record is a place to begin.
Here at school we record the following:
1. Date of birth
2. Sex of lamb born
3. Identity of lamb
4. Type of birth
5. Sire and Dam
6. Birth Time
7. Birth Comment
8. 30. 60. 90. 120 day weights
10. Scrapie Identification Number
By recording the above information, we feel we have a good idea what is happening with our sheep. The information is recorded on a hand written barn sheet as it is collected and then transferred to computer for storage. We can call up the complete lambing information on each of our ewes. This allows us to know when a ewe was born, how many times she has lambed, how many lambs she has produced and raised to weaning and what they weighed at different times. By using the records we can compare each ewe in the flock to her contemporaries, or ewes born at the same time (not necessarily just the same year, but rather fall born to fall born and spring born to spring born) and see how she ranks compared to them. We try not to keep ewe lamb replacements from ewes that are near the bottom of these rankings. Without records we would have no idea how a certain ewe ranked.
Some very good computer programs are available but are not necessary for successful record keeping. A simple notebook or a collection of your barn sheets will also work. Individual ewe performance records are also available for producers to use.
Because we have records we have something to help base our selections on besides just looking at the sheep. Visual appraisal is extremely important but mainly from an evaluation of structural soundness standpoint. It is true that in certain types of production the appearance of the sheep is much more important than in others. However, looks should not be the only means of selection just as records should not be. Rather a combination of the two will always work best in the long run.
You may not think all the information we keep is necessary. That’s fine, if it isn’t important to you then don’t keep it. Actually some of what we record it isn’t important to most people. I mean who cares what time a ewe lambs? We started collecting this information 20 years ago when we were trying to influence the time of lambing by the time of feeding. We found that we could influence it some, but not much. We have continued to record to collect the time of lambings. Perhaps we should check now to see if families or ewes sired by one ram tend to lamb in a certain time frame.
Lets look at the reasons we record the other information we do.
Date of Birth – Some people feel that fall born or at least ewe lambs born in early part of each lambing season are produced by better ewes, in terms of reproductive capability, than other ewes in the flock. This allows us to ID those ewe lambs.
Sex of lamb born – This speaks for itself.
Identity of lamb – In order to keep records, we have to identify each animal. This can be done by tags, ear notches, tattoos. With the Individual Animal Identification Program on the horizon, electronic IDs will become part of this as well.
Type of Birth – Lets us know which lambs were born as twins and triplets when we make our selections. I wonder with the recent thinking that up to 40% of fertilized eggs may abort in the first month of pregnancy, what determines when is a twin is a twin?
Sire and Dam – Necessary to maintain in a purebred flock or if we want to identify how families or lambs sired by one ram or out of one family of ewes do in comparison to the rest of the lambs.
Birth Comment -For us is an estimate of the difficulty a ewe had giving birth. OK means everything went well, no problems. BP means the lamb was born backwards and that it was pulled, HP means it was a difficult birth, a hard pull. This is important, as our experience shows that ewes that have difficulty in the birthing of one lamb tend to repeat this practice and so we tend not to keep daughters of hard lambing ewes. We have difficulty remembering if a ewe had problems lambing if we didn’t write it down. because five months after the fact when we are making our final selections, we just wouldn’t remember.
Taking 30, 60, 90 and 120 day weights - Record keep is time consuming and costs money as we are paying students to help us and there are other things they could be doing. We do it because we feel that 30 day weights are the most accurate measure of a ewe’s milking ability and we also give Bo-Se shots and vaccinate for overeating at that time and repeat the shots and vaccinations at 60 days so we are handling the lambs anyway. We could do away with either the 90 or 120 day weights and be alright but I like to look at the weights and our customers like to see the added in-formation and so we continue.
Comment – In this column we record any comment that can help us to remember the lamb. Such comments as, Raised on 88-49, Broken leg, Ewe crazy etc. We also record the following in this column although you may find it easier to have separate columns for:
Date of removal from flock – This lets us know at a glance when the animal left the flock. This information is extremely important with the new Scrapie regulations
Reason for flock removal – This goes right along with the previous category. It is good to know at a glance why an animal left the flock. Was it culled, and if so why? Was it sold to another breeder? Was it sold as a young lamb? This information can be extremely helpful from a flock health standpoint. For instance, if a number of ewes are leaving the flock because they developed mastitis, then you as a producer need to do something about your weaning process. For protection of your flock under the new Scrapie regulations, record when every animal leaves your flock and why. Be sure to record who you sold the animal to.
Scrapie Identification Number – When this paper was originally written, Scrapie identification numbers did not have to exist for each animal. In 2004 when the paper is being updated, Scrapie Identification numbers are absolutely necessary for any animal that leaves your farm, regardless of the age it leaves. Record the Scrapie number given each animal weather you are on the Scrapie Eradication or Scrapie Certification program. In addition, Record who bought the animal from you or how it was disposed of. This may be extremely important to you someday.
The above records have aided us in our effort to select for minimum care ewes that will lamb by themselves and raise a fast growing lamb with no help. We wean our lambs at 60 days and turn the ewes to grass and expect them to maintain themselves. We need these type females because our program is based on producing lambs for our own meat lab and we produce 50 lambs or so for them each semester for a total of 110 lambs a year. Because we need variation in carcasses for teaching reasons we use different breeds of rams on our base ewe flock, which is predominantly Dorset, to produce different sizes and types of lambs. In the spring of 93 we exposed our ewes to three rams, all at the same time. One was a Suffolk, one a Callipyge Dorset and the third a Romanov/Dorset crossbred. As expected, they sired lambs with great differences, just what we wanted -for the meat lab!
We selected replacements from the fall crop using the following criteria that we got from looking at the ewes and referring to our records.
1. Any ewe that is severely structurally incorrect or has exhibited a rectal or vaginal prolapse was not retained. The structural incorrectness decision was made by visual appraisal. If a ewe lamb prolapsed, and two did, we removed the rectal prolapse to salvage her, and then recorded it column that calls for comments. We always refer to the comments column be-fore making final selections. Our experience is if you don’t write it down, you will-forget and a ewe with a prolapse removed by a rubber band looks just like a normal ewe. She will not mention to you that she has a problem, even if you ask, and chances are she will have problems keeping her insides where they belong.
2. We do not keep daughters of ewes that exhibit large pendulous udders have large balloon teats or poor teat placement. All are all inherited traits and contribute to problems for the shepherd and raising any lambs these ewes produce. We record in the comment column if a ewe shows any of the above traits.
3. Ewe lambs have to be conceived within 35 days of their mother’s exposure to a ram. We record when we first turned the rams with the ewes and we also record when we turned ewes with rams at a later time. In other words, all of our ewes were not exposed at the same time and so it is penalizing a ewe that weaned a lamb in spring 1993 and then was exposed in May if we went only by the first exposure date (April). By selecting ewe lambs conceived within the first 35 days or two heat cycles we have helped to eliminate the lambs of slow breeding ewes being added to the breeding flock.
4. We select ewe lambs that weighed more than 90 pounds at 120 days. Remember these are Dorsets, and 90 pounds at 120 days is a decent weight. Our range was from 73 to 115. If a ewe was close to 90 pounds we looked if it was a twin or single and the performance of it’s mother. If you think 90 pounds isn’t real heavy at 120 days then weigh your own and see how many you get over that. Don’t weigh just the good ones, weigh them all. We are different from most flock as our weights are only adjusted for days of age. We try to weigh all lambs within a week of their birthdays and then figure ADG on the lambs and convert it backwards or forward to the month weight we are taking. We weigh each lamb each month, but we do not adjust weights for age of day or type of rearing.
5. The time that a lamb was born has absolutely no bearing on whether it is retained or not.
The above has been an example, using our flock, of collecting records and applying them to help us to select replacement females for our flack to meet the unique set of circumstances that our flock exists under, and to meet the goals of our program. I’m not saying it is right but it is the way we do it using what information we have made available.
Buying replacement ewes from another flock.
1. A sheep is only good as the program it comes from and the program is only as good as the shepherd behind it. If you don’t trust the shepherd, then don’t buy replacements from the program.
2 The selection of show sheep based only on visual appraisal can be great for the short term goal of showing the animal. If a buyer wants to include the animal in the breeding lock then they should talk to the seller about the ewe and her family. Some people will even tell you the truth. If you make selections only on visual appearance your goal should be short term.
3. If you can locate a flock that produces the type of replacement female that benefits your flock, establish a relationship with the flock and purchase a given number of ewes each year.
4. Health concerns should be utmost in your mind when purchasing replacement females. Buying Foot Rot can quickly destroy the fun of raising sheep. Ideally, visit any flock you buy replacements from and check for foot rot. If visiting is impossible, talk with the shepherd and ask if they have foot rot. Even if the answer is no, inspect each animal for the problem and quarantine each new arrival for at least 30 days. This may sound harsh to you, but it will pay off in the long run.
The selection of replacement ewes is really up to the shepherd. To establish a flock that will continue to exist over the years a producer must have an over all goal and select ewes that will help him or her reach that goal.
Records are necessary for intelligent flock selections. As a producer, record what ever you feel is important and then use those records to help in the selection process.