You will hear the story of a sheep development project that we believe is unique in North America. If there is any person or group that is doing similar work with composite sheep, we would be delighted to hear from them.
SIREMAX™ was conceived by a group of sheep producers at the Iowa Sheep Symposium in November 1992. Soon after, we were advised by geneticists that it would take at least ten years of data analysis and selection before we could make any claims for a new composite sheep. We sold our first ram offering in the summer of 2003. We currently have yearling rams and 2007 ram lambs available.
SIREMAX has only one goal: To produce composite terminal sires that are competitive with established terminal sire breeds, and whose selection is based on objective performance recording and BLUP (Best Linear Unbiased Prediction) based analysis.
SIREMAX is not yet a breed. For now, SIREMAX is just the production environment, including the database, in which these sheep are made. It is the selection of breeding groups in the fall, and data recording at lambing time. It is lamb weighing at weaning and at scanning. It is the recording of back fat and rib eye data, and it is the use of BLUP technology to analyze these data to rank all lambs in order of estimated breeding value.
SIREMAX isn't just the 300 ewes that lambed this spring. It is the nearly 4000 (after 11/07) database records that have accumulated over the last 14 years; every record representing a sheep that has been through the system, adding to the accuracy of the selection process.
SIREMAX sheep have become much bigger, leaner, and more muscular than the original base flock. There is still obvious variation, but variation is important in a closed flock. To minimize inbreeding, we keep the genetic pot stirred with hand picked breeding groups, and exchange top stud sires between Siremax flocks.
Some seedstock producers scan a few of their lambs, some only the stud rams they use. Every sheep offered for sale, be it ram lamb, yearling ram, or older ram, will have an Expected Progeny Difference (EPD) for 'market' weight, fat depth and eye muscle depth. So has every ewe in the flock. No sheep is a SIREMAX™ sheep unless it has a current retrievable record in the SIREMAX™ and Lambplan databases.
If you find this intriguing, read on.
Siremax sheep are composites. That means that they are crossbred sheep which have been bred back on themselves to 'consolidate' the cross. There are numerous examples of composite breeds: Polypay, Columbia, Montadale etc. Each of them has genes from contributing breeds, added to a recipe to meet a need.
In 1993, we bought 130 Columbia ewes from 5 different flocks in North Dakota. These were bred to eight 1/2 or 3/4 Texel rams, which also came from 5 different flocks. In 1994 and 1995, we went outside the flock for an additional 8 Texel crossbred rams, and also used top ranked ram lambs produced within the flock.
After using the 16 Texel crossbred rams, we ran out of unrelated sheep, and we needed a new resource that would improve our flock performance. So we bought 5 rams from the terminal sire composite flock at the USDA Meat Animal Research Center (MARC) in Clay Center, Nebraska. The MARC composite flock included the only available sheep with Expected Progeny Differences (EPDs) for growth, and was originally created in 1980 by mating Columbia rams to Hampshire-Suffolk crossbred ewes.
In 2001, a Canadian Arcott ram lamb with impressive numbers was imported to add some outside genes and to see if he would benefit the Siremax flock performance. His first lambs were scanned in October 2003. The Canadian Arcott is also a composite, primarily Suffolk and Ile de France. For the next few years we expect to work on expansion of ewe numbers, and rapidly raising the flock average performance.
There are a number of terminal sire breeds in North America that include many very impressive sheep. Typically, however, little is known about these sheep beyond individual performance. Most commercial producers do not ask for records. If there are any, they are limited to post-weaning rate of gain, and nothing is known about a ram's genetic make-up and his ability to pass his performance onto his progeny. More importantly, a high rate of gain does not guarantee a good carcass. There are aspects of fast-gaining lambs that the lamb industry likes, but uniform, lean, muscular carcasses of a required weight are more important than gain alone. Are there Suffolk and Hampshire rams that deliver these traits? Of course, there are many, but there is no concerted effort that we know of to find out where they are, and to use them.
Siremax founders chose the Columbia as the base breed for its size, carcass leanness, and hardiness. For three years we only used Texel crossbred rams and their top progeny for muscle and lean growth. Then, over four years, we used the MARC composite rams. The last of the original Columbia ewes lambed in 1997.
Each year, the production cycle begins in early November, we choose our breeding groups using the year's flock performance analysis from Lambplan in Australia (see below). EPDs for all sheep that have left the flock continue to be updated by the current performance of related ewes and lambs.
EPDs are combined to provide a single index that allows ranking from top to bottom. We use the indexes to select replacement ewe lambs, to identify cull ewes, and to select ram lambs and older rams for breeding and for sale. Using our knowledge of sheep pedigrees, ewes and ewe lambs are allocated to about 12 breeding groups, each with an unrelated top index-ranked ram. These breeding groups become the beginning point for the year's data input.
At lambing time, each lamb is tagged with a year number and sequential number, and records are compiled of lamb ID, ewe ID, sire ID, sex, birth weight, birth type, and rear type. At weaning (average age 8-10 weeks), weights are added to these records. At scanning time (average age 18 weeks) we add the post-weaning weight, and ultrasound scan measurements of fat depth and rib eye depth. These data are sent to Lambplan, and the cycle is complete.
If there is any doubt, at lambing time, about matching each lamb to its biological mother, we either have all possible lambs, dams and sires genotyped, or we do not tag the lamb.
RAM LAMBS - Our stud rams are selected from the top 5% each year. Before 2003, few rams were offered for sale outside the top 20%. This changed as a higher percentage of each lamb crop met rigorous standards of performance. Currently we market about 50% of our lambs to packers. We make every effort to use ram lambs for breeding as this accelerates genetic progress. We have suffered no decrease in fertility or lambing percentage using ram lambs.
EWE LAMBS - Ewe lamb retention varies with available resources each year, but we are striving to expand. The need to maintain genetic diversity in a closed composite population requires a minimum of 300 ewes, preferably 500. However, at least 50% of each year's ewe lambs go to market. Currently no ewe lamb is retained whose index falls below the average for that year's lamb crop.
In addition to culling on the basis of performance analysis, we also optimize physical soundness in retained breeding stock, with particular focus on mouths, feet and legs, and testicles. There is no ideal type or breed standard for Siremax sheep. We do not select breeding stock with tape measures, nor with an eye toward an ideal or uniform flock appearance. We do select by following the numbers, tempered only by a shepherd's experience of what makes a productive and manageable sheep.
On average, young ewes are genetically superior to old ewes, so we keep the flock young. 80% of the Siremax flock is 3 years old or younger. Unlike commercial flocks, in which long-lived ewes contribute to profitability, the value in the Siremax flock lies in the genetic superiority of the younger stock, so older ewes are phased out quite rapidly.
Siremax flock replacements are managed as commercial sheep. Breeding groups and gestating ewes are out in blizzards. Lambs are out on pasture in summer storms, before and after weaning. When these pastures dry up performance may decline, and occasionally we lose lambs to bloat, pneumonia, predators and broken bonds between ewes and lambs.
However, to identify genetically superior sheep, we know that we must provide sound nutrition and health care so that every Siremax lamb has an equal chance to excel in a good commercial environment.
We have mentioned Lambplan a couple of times, and we have also said that any Siremax sheep without a database record is 'just a sheep'. So what is Lambplan?
Lambplan is a division of Meat and Livestock Australia. At its heart it is a database now consisting of the records of over 1.5 million sheep. Its purpose is to use raw data, provided by producers, that objectively measure all kinds of traits of economic importance, and to convert these data into estimates of genetic value for each individual sheep. Using a statistical model named BLUP (Best Linear Unbiased Prediction) the software gathers information about the performance of an animal, and all related animals, in previous, contemporary, and subsequent generations. Over time, and with large numbers of records, it is able to reduce the effects of environment and management on performance, leaving the genetic effect as the sole influence on performance. Estimates of this genetic effect, or breeding value, are calculated for each trait. These breeding values can be combined into a single value, or index, which is used to rank animals in terms of their overall breeding value.
Siremax has provided lambing records, weaning records, and scanning records, to Lambplan for each of the last 14 years. In turn, Lambplan has provided Siremax with data for post weaning weight, fat depth and eye muscle depth, and indexes that rank every sheep that has been a contributor to the Siremax project-about 4000 sheep after scanning in 2006.
We currently have ram lambs for sale. Some of these rams have been used within the Siremax flocks and have progeny tested EPDs. Selection is still good (February 2008).
The price of each ram depends on his index. Generally, older rams have lower indexes. Rams are priced from US$350 to $650.
Siremax sells no female sheep, except for slaughter. However, we are open to expanding the number of Siremax flocks. We would be glad to discuss serious proposals with interested sheep producers.
™ All rights reserved. The owners of this website, below, assert their right to restrict the use of the trademark SIREMAX™ to sheep that have continually updated records in the SIREMAX™ database and the Lambplan database.
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Siremax™ Southwest Minnesota Flock: John and Julie Essame 6352 208th Avenue Belview MN (USA) 56214-3025 Tel: (507) 925-4415 |
Siremax™ Spruce Shadows Farm Flock Located in East Central Minnesota Cindy Wolf & Kelley O'Neill 29182 Hartwood Drive Rushford, MN (USA) 55971 Tel: (507) 864-7848 Cell: (507) 450-5453 |
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Siremax™ Dakota Flock Michael & Brandy Merwin 201 12th Street SE Hettinger, ND (USA) 58639 Tel: (701) 567-2793 |
