The Selection of Replacement Females: The Key to a Successful Long-Term Sheep Program.
by Richard Cobb
The most important ingredient in selecting replacements and maintaining a quality flock is YOU, the shepherd or producer. In Illinois, sheep flocks come in all sizes and shapes, from commercial flocks producing large framed slaughter lambs or small framed “Ethnic” lambs to purebred or club lamb flocks producing lambs that are necessary to compete in that arena. We even have producers whose main interest is producing fleeces of various colors and fineness. Each of these situations require different types of females to allow the flock to prosper.
To make intelligent selections or additions to a flock a shepherd must have an idea what it is he or she wants to produce. This end product will often change in the future, but without a desired end product in mind at the time of selection, producers will find it very difficult to select replacements that will benefit them in the future. 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.
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 available for use that every producer can find the one to satisfy their wishes and to fit their particular set of circumstances. In fact, most breeds offer multiple types and kinds already selected for different end products and so those genetics are available to be identified and used.
A SHORT PENCIL IS BETTER THAN A LONG MEMORY
Once a desired type of ewe has been identified, 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.
To me, records are a personal thing. They are for the use of the producer first and not for the merchandising of your animals. By that I mean each producer can record as much or as little as they wish. The key to records, and really the only reason to keep them, is to use them to help you to make intelligent decisions for the future of your flock. Record what is important to you or what information you will actually use. Also, be sure to record the information accurately and to record the information on all your sheep. This is necessary to make unbiased decisions.
A good place to start keeping records is on a handwritten barn sheet or a notebook that you carry with you when working with the flock. I always used a clipboard to hold the papers. It is important to transfer the information to a second location asap after collection. This will assure that valuable information will not be lost if your barn sheet or notebook is lost or “eatern” by the sheep. The second location can be another notebook or a computer program. A number of sheep information programs are available. At the University of Illinois we recorded the following information:
1. Date of birth 6. Birth time
2. Sex of lamb born 7. Birth comment
3. Identity of lamb 8. 30, 60, 90, 120 day weights
4. Type of birth 9. Date of removal from flock
5. Sire and Dam 10. Reason for flock removal
After recording the above information we felt we had a good idea what was happening with our sheep. The information was recorded on a hand written barn sheet as it was collected and then transferred to a computer in the office for storage. Computer programs are readily available but are not necessary for successful record keeping. A simple notebook or a collection of your barn sheets will work just as well. Individual ewe performance records are also available for producers to use.
We could call up the complete lambing information on each of our ewes. This allowed 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 could compare each ewe in the flock to her contemporaries, or ewes born at the same time, and see how she ranks compared to them. We tried 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.
Because we kept records we had something to help base our selections on besides just looking at the sheep. Visual appraisal is extremely important but mainly only from an evaluation of structural soundness standpoint. It is true that in certain types of production systems 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.
You may not think all the information we kept is necessary. That's fine, if it isn't important to you then don't keep it. Actually, some of what we recorded wasn't important to most people. I mean who cares what time of day a ewe lambs? We started collecting this information 25 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, and we just continued to record time of lambing. Perhaps we should check now to see if families of ewes sired by one sire tend to lamb in a certain time frame.
Birth comment for us was an estimate of the difficulty a ewe had giving birth. OK means everything was fine, 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 showed that ewes having difficulty in the birthing of one lamb tend to repeat this practice. In addition, a recent beef study shows that calves that had problems being born were much more apt to die at an early age than calves that did not experience problems. Could the same apply to lambs? We tried not to keep daughters of hard lambing ewes, and we eliminated those ewes as well. We of course would not have known if a ewe had problems lambing if we didn't write it down because five months after the fact we are making our final selections, we could not remember.
Taking 30, 60, 90, and 120-day weights is time consuming and costs money as we were paying students to help us and there were other things they could be doing. We did it because we felt 30 day weights are the most accurate measure of a ewe's milking ability and we also gave Bo-Se shots and vaccinated for overeating at that time and repeated the shots and vaccinations at 60 days as we were handling the lambs anyway. We could have done away with either the 90 or 120-day weights and be ok but I liked to look at the weights to use in selection.
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 weaned our lambs at 60 days and turn the ewes to grass and expect them to maintain their body condition score by themselves.
We selected replacements using the following criteria that we got from looking at the ewes and referring to out records.
1. Any ewe lamb that was severely structurally incorrect or had exhibited a rectal prolapse was not retained. The structurally incorrectness decision was made by visual appraisal. If a ewe lamb prolapsed, we removed the prolapse to salvage her and then recorded it under the column that calls for comments. We always referred to the comments column before making final selections. Our experience is that if you don't write it down you will forget and a ewe that had a prolapse removed by a rubber band looks just like a normal ewe lamb. She will not mention she had a problem even if you ask, and chances are high she will have problems keeping her insides where they belong if she is retained for breeding.
2. We did not keep daughters of ewes that exhibited large pendulous udders or have large balloon teats or ewes that exhibit poor teat placement. The reason for that was that ewes with those problems increased our workload, often making it necessary to milk the ewe to reduce teat size. These are inherited traits and counter to flock and shepherd well being. We record in the comment column if a ewe shows any of the above traits.
3. We did not keep daughters of ewes that were nervous, crazy , stupid or difficult to work with.
4. Ewe lambs replacements had to be conceived within 35 days of their mother's exposure to a ram. This does not mean the first 35 days of the lambing season, but rather the first 35 days that the mother was exposed. (she may have been exposed at a different time than other ewes) By selecting ewe lambs conceived within the first 35 days or two heat cycles we helped to eliminate the daughters of slow breeding ewes being added to the breeding flock.
5. We selected ewe lambs that weighed with the heaviest in the weaned group. We did consider if ewe lambs were twins or triplets and took that into consideration.
6. 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 select replacement females for our flock to meet the unique set of circumstances that our flock needed to meet the goals of our program. I'm not saying it is right or wrong, but it was the way we did it using the information we had available.
Each of you has a flock with unique circumstances and different goals and you need to use records as well as visual appraisal to help you select replacements to meet those goals.
Buying replacements from someone else.
1. The role of health of a replacement ewe or stud ram purchase and the flock they come from should be the number one concern when buying. Do not buy Foot Rot!, Also, isolate all newcomers to your flock for at least a month to observe for problems.
2. A sheep is only as good as the program it comes from, and the program only as good as the shepherd behind it. If you don't trust the shepherd then don't buy replacements from the program.
3. 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 flock then they should talk to the seller about the ewe and her family. Some people will even tell you the truth. If you buy on visual appearance only, your goal should be short term.
4. If you locate a healthy flock that can produce the type of replacement females that benefits your flock then establish a relationship with the flock and purchase a given number of ewes each year.
The selection of replacement ewes is really up to the shepherd. To establish a flock that will continue to prosper over the years a producer must have an over all goal as to the type of lamb produced and select ewes that will help him or her reach that goal.
Records are necessary for intelligent within flock selection. The producer should record whatever they think is important and then use those records as well as visual appraisal to help in the selection process.