Menu
GenOvis is the name of the Canadian genetic improvement program for sheep.
Genetic improvement allows you to permanently and cumulatively increase the production efficiency and profitability of your flock.
Top rams are worth much more than what they cost. It pays dividends to use them.
> Creating Genetic Progress
If you are a sheep breeder
> Using Genetics
If you are a commercial producer
The simplest way to make rapid genetic gains is to use superior rams from a reputable breeder that participates in GenOvis. After one generation, your flock will have inherited 50% of the genetics from that breeder. After two generations it will be 75% of your flock’s genetics and after three generations 87.5% of their genetics. So, using top rams for ewe replacement, with EBVs or indexes to prove their worth, has a huge impact on the future of your flock. You will move even faster if, from time to time, you buy some replacement ewes in addition to what you produce yourself.
When you buy terminal or maternal rams, you should always ensure that in addition to being physically sound, they have sufficiently high EPDs or selection indexes. The reason for using EPDs and indexes is that a ram’s physical appearance, or its raw performance for any trait, are not the best predictors of the genetics it can transmit to its progeny. Raw performance is influenced by environmental factors such as age at recording, feed, weather and management practices.
Consequently, a ram-lamb with a good weaning weight of its own, for example, may not produce progeny with superior weights as his own weight could have been influenced by being the oldest in the group, raised as a single with plentiful milk and having benefitted from exceptional management. For this reason, it is best to use EPDs or Index Values that adjust for these other non-genetic factors as well as the performance of all relatives to produce the best estimate of the ram’s genetic merit.
Ensure you use rams with superior EPDs for maternal traits to produce replacement ewes. Maternal traits like number of lambs born and total weight weaned are key to a profitable breeding flock.
For example, the 73rd ram in the list of proven elite Rideau Arcott rams on genovis.ca has an EPD of 2.08 kg for total weight of lambs weaned at first lambing and 2.54 kg for total weight of lambs weaned in subsequent lambings. If we average this to 2.45 kg over 5 lambings we get an expected economic gain of about $2,911, in comparison to a ram with an EPD of 0, if the ram is used over 2 years to produce 30 daughters per year, of which half are kept for ewe replacement.
If a top maternal ram is used to produce hybrid females (ex. Dorset by Romanov ewes), this value can increase considerably (up to 20 times) since over its entire career such a ram could produce up to 600 hybrid daughters rather than the total of 30 replacement daughters assumed above. These elite rams are indeed worth the investment!
Target terminal sires with good growth EPDs or indexes to produce market lambs. A ram which increases growth rate in its progeny by 2 kg is worth $4,008 more than an average ram, assuming it is mated to 50 ewes per year over 5 years.
If you are a sheep breeder
Being a breeder might be fun but it is not free. First, since you are typically working within breed, you hyou can’t take advantage of crossbreeding, which can have benefits as high of 30% of total productivity. Second, you need to uniquely identify animals across generations (e.g. registration) and you must collect performance records and obtain genetic evaluations from these records, so that your selection is effective. The costs of these activities, and the additional time investment, have to be recouped from the sale of breeding stock from your herd. Most successful sheep breeders are passionate about their breed, and this is the driving force behind their work.
You should choose a breed which you like, which has the attributes you are looking for, and for which there is a good commercial market, assuming you plan to sell breeding animals. You should also ensure you have good access to top animals from that breed. In Canada, breeds are generally classified as terminal, maternal, and prolific. There can be other specialized breeds (e.g. Merino for fibre production).
Each breeder can select the traits he wishes to improve in the flock. However, there are some general guidelines based on the breed of sheep.
The most effective selection tools for all traits are EPDs (expected progeny differences) produced by the GenOvis program. An animal’s performance reflects both its genetics and the effect of the environment. Only the genetic part is inherited by the animal’s progeny. EPDs use the best available statistical methods to estimate the genetic part separate from other effects, and therefore can fairly compare the genetic merit of different animals. EPDs also use data from relatives (sire, dam, siblings) as well as from the animal itself to increase the accuracy of the estimation. An animal’s physical appearance, or its raw performance for any trait, is nowhere as good a predictor as an EPD of what it can transmit to its progeny.
In the GenOvis program, EPDs are calculated for many traits, including age at first lambing, lambing interval, number lambs born, lamb survival, lamb birth weight, lamb weight at 50 days, weight gain from 50 to 100 days, total weight weaned per lambing, fat depth and loin depth. Some of these EPDs are separated into the genetic component expressed by a lamb, and the genetic component corresponding to the dam’s maternal ability.
EPDs make it possible to rank animals in terms of their value as parents. If you compare two sires to each other, for example, the difference in their EPDs for a trait corresponds to the expected difference in the performance of the progeny for that trait if all other things were equal, i.e. if these progeny were born to similar dams, raised in the same environment and treated the same.
Learn more on EPDs:
It is not easy for a breeder to balance selection across all traits, especially since the more traits are selected, the less progress can be expected for each. Selection indexes combine EPDs into a single number and have many advantages. They account for the relative economic value of each trait and for how the traits are transmitted and related to each other. There are 3 main selection indexes in GenOvis, one for terminal breeds, one for prolific breeds and one for maternal breeds. In addition, for those breeders who collect ultrasound records (back fat and loin depth) to improve carcass quality, there is a different version of the three indexes which include those two traits.
Select first on selection indexes to pick your overall top ranking replacements and then look at individual trait EPDs if you wish to refine your choices.
EPDs are expressed in trait units (for example number of lambs weaned, kg of gain, mm of fat depth) and have an average value of zero for all animals across all breeds in the program. This can make their interpretation a bit challenging, but there is a simple way to find how an animal ranks in its breed: the percentile ranking. These are shown along each EPD and selection index. They show what percentage of the breed an animal ranks in.
For example, an animal with a percentile ranking of 85 for the maternal index ranks in the top 15% of its breed for that index, while an animal with a percentile ranking of 25 ranks in the bottom 25% of its breed. Using the percentile rankings associated with the selection index you wish to use is a simple and effective way to select animals in your flock or to purchase them in other flocks.
GenOvis publishes Top ram lists that you can use when sourcing quality breeding stock.
Several things have to happen before EPDs and selection indexes can be calculated for animals in your flock:
There are two key actions you can do to maximize genetic progress in your flock:
The first action is described in the next section. Ensure the animals selected are physically sound. The second action requires replacing rams quickly, because if you make genetic progress, the younger animals will generally be better than the older ones.
A commercial producer may use a ram for as long as 5 years, for economic reasons. However, if you are a breeder, you should try to move faster than this, and use mostly younger rams. Once used in your flock, these rams can then be sold to commercial producers, who can use them for a longer period of time.
Use each ram on a limited number of females, such as 15 to 25, to increase the number of rams used each generation. This will decrease the risks associated with inbreeding and with the relatively low accuracy of EPDs and selection indexes for unproven rams (some rams may end up being better than predicted and some worse, but on average you will make the expected progress).
You do not want to be in a situation where you put the entire future of your flock into the expected performance of one ram only. The selection of females has less impact on future progress of the flock, but as a breeder your ewe replacement rate should not be much lower than 20%.
Annual yearly membership per flock (no additional fee per head). Assistance is provided to new enrolees so they can enter their data and receive EPDs.
Enrolment form
CEPOQ: 1-418-856-1200, extension 221
Each animal must be uniquely identified in order to be evaluated in GenOvis. If animals in your herd are purebred (from registered parents) the simplest way to do this is to register male and female breeding animals in your flock. This is particularly important if you plan to sell breeding stock. Lambs that are not kept as sires or dams still need a unique identifier, as per the instructions provided in GenOvis.
If you are a commercial producer who maintains a selection herd for internal purposes, you could use other forms of unique identification acceptable in GenOvis without registering your breeding animals, but this will limit your options, as you would need to register multiple generations if you ever decide to have a registered flock in future.
1-877-833-7110 Ext. 314, lauralee.mills@clrc.ca
1-877-833-7110 Ext. 306, melanie.overduin@clrc.ca
GenOvis can help with sheep registration. You can designate the animals you want to register and information will be sent to CLRC, which provides the registration service on behalf of breed associations, so you only need to enter the information once.
To receive EPDs and selection indexes, you must record and send performance data into GenOvis for each animal to be evaluated, such as breed, animal ID, sire ID, dam ID, date of birth, and at a minimum the 50 day weight of your lambs. It is highly recommended to record a post-weaning weight as well. As much as possible, you should test all lambs produced in your flock. For ewes you must indicate the dates of lambing, and the numbers of lambs born and weaned for each lambing. This can be done directly into GenOvis. New breeders will receive assistance for entering any new data, and any older data they have collected so far.
An alternative to entering data directly into GenOvis is to use a flock management software that connects with Genovis and enter the data there instead.
To make better genetic progress for economically important traits, the main emphasis of your selection should be on the GenOvis selection indexes, and their associated percentile rankings, since they tell you how an animal ranks in the breed.
Eliminate male lambs that have obvious defects (physical soundness), paying special attention to mouth defects and feet and legs.
Select the top 10% to 15% of all remaining male lambs in your herd based on their percentile rankings for either the terminal or the maternal selection index, depending on the breed you are working with. You can refine this selection using EPDs, if desired.
Learn more on selection indexes
Keep among the selected lambs those with the most desirable conformation and breeding ability (without scrotum issues) and which are as little related to each other as possible, until you reach the number of rams required for replacement in your flock.
Unless you plan to be involved in the show ring, you should give first priority to production or reproduction traits, and that is why selection on conformation should be done after selection on indexes. If there is a weakness in your flock for a specific conformation trait, you can put more emphasis on that trait in this last step.
Selection process – an example
200 ewes with 1.1 lambings per year and 1.6 lambs weaned per ewe per year.
Test 160 male lambs per year on GenOvis every year.
Retain 10 to 13% based on selection index and any EPDs of special interest, i.e. 16 to 21 lambs. Among these, keep 11 to 15 young rams with the best conformation and breeding ability that are related as little to each other as possible.
Each ram can then be mated to produce 15 to 20 lambings, then sold to a commercial herd. The above is an excellent way to make rapid genetic progress, but if you are starting as a breeder you might begin with a less demanding approach such as using rams for 2-3 years with more lambings per ram, instead of just using younger rams. The selection method should remain the same, with the primary focus on the selection index to inform your decisions.
You can also purchase superior rams from reputable breeders. Put emphasis on each ram’s selection index and associated percentile ranking (maternal or paternal depending on the breed) and physical conformation, just as you would do when selecting rams for your own flock. You might also enquire about genomic markers for Scrapie or for other genes. If you are enrolled in GenOvis, you will soon be able to check the impact of your purchase decisions on your breeding goals based on the results for the progeny, and how these purchased rams compare to your own.
The process is the same as for males, but there is less room for selection pressure than there is for males, due tot he need to maintain an appropriate flock size. First eliminate females with obvious defects. Then if your ewe replacement rate is 20%, select the top 50% of remaining female lambs on selection index and EPDs. Among these keep about 60% with the best conformation. If 80% of these young females are fertile, you will end up with the number of females required for ewe replacement.
As an example, for a flock of 200 ewes with 160 female lambs produced per year, you should retain 80 based on selection index, then 48 after selection on conformation of which about 40 are fertile. These 40 will be what you need for ewe replacement (200*20%=40).
If you have a maternal breed but mate some of your ewes to terminal sires to produce market lambs, for example 50% to 60% of them, there will be little room for selecting females on index or EPDs. Then you will need to select replacement females primarily based on their conformation and fertility. In such case, you should reserve ewes with the best maternal selection index for purebred matings in order to produce replacement ewe lambs.
If you are a commercial producer
The more traits one selects for, the slower one can progress for each. This is why many sheep breeds are now specialized. Some breeds, called terminal or paternal breeds, have been selected primarily for growth rate and carcass quality (e.g. Suffolk, Hampshire, Ile de France, Canadian Arcott, Charollais). Some other breeds, called prolific, have been selected for high litter sizes (e.g. Romanov, Rideau Arcott). And yet other breeds have been selected for ewe productivity and maternal ability, and to some lesser extent for growth and carcass quality (e.g. Dorset, Polypay, North Country Cheviot). There are many other breeds of sheep in Canada besides the ones cited above, in fact more than 40.
Hybrid vigour is found in all species: crossbred animals are usually more vigorous and resistant than the average of their purebred parents. The more different the parent breeds, the stronger the effect. Hybrid vigour improves fertility, prolificacy (number born), lamb survival and lamb growth. For an F1 ewe (from the crossing of two breeds) crossed with a ram of a third breed, hybrid vigour increases the weight of lambs weaned per ewe per year by almost 35% compared to the average of the parents, which is considerable in terms of the profitability of the flock (L.D. Young and R.L. Hruska, 1989).
However, the result depends on the breeds used in the cross. The productivity of F1 females is greatly influenced by the complementarity between breeds. A common cross to produce F1 females is Dorset sires on Romanov ewes. If we cross a paternal breed with a maternal breed, the resulting F1 ewes will not be as productive as a cross between a maternal and a prolific breed.
Furthermore, hybrid vigor is not retained from generation to generation. If you cross an F1 ewe with a ram of one of the breeds in the cross (backcross), the descendants will have only half the hybrid vigour of their mother. If an F1 ewe is crossed with an F1 male of the same type, the offspring will also present only half the hybrid vigour on average.
If one uses many breeds for crossbreeding, and the female lambs from these crosses are used for ewe replacement, only a small fraction of the total hybrid vigor will be expressed. Furthermore, the offspring of these “home-made blends” will vary greatly from one animal to the other, which will complicate herd management and will reduce the homogeneity of marketed lambs. There are therefore constraints in the use of hybrid vigor, and these are quite important in the case of sheep.
There are several possible breeding systems for sheep production, which vary in how they use hybrid vigour and breed complementarity.
Advantages and drawbacks of the systems:
Key conclusion: no one system will fit every producer.
You must choose a system of using genetics (pure breed or crossbreeding) and keep it long enough to see results and make necessary adjustments. There is no magic formula. Some systems work well for some producers, but not for others. The system must match the objectives, level of management and degree of organization of your business.
Before making a decision:
Rams have a huge impact on the future of your flock. Use a reputable breeder as a supplier of good rams over time and after one generation, your flock will have inherited 50% of the genetics from that supplier. After two generations it will be 75% and after three generations 87.5%. Given the economic impact that top rams can have compared to average or lower quality rams, as shown in the previous section “why use superior genetics”, using top rams is worth the investment, even if they might cost you a bit more at first.
The easiest way to go is to purchase rams from breeders that have the information to prove that they are indeed good rams. In practice this means rams that have EPDs and selection indexes from the GenOvis program. Why? Because these are calculated by a third, neutral party, and because EPDs and selection indexes are the most effective way to assess the genetic value of a ram and rank it among other rams in the breed. An animal’s physical appearance, or its raw performance for any trait, is nowhere as good a predictor of what it can transmit to its progeny as an EPD.
Information on EPDs, selection indexes and the percentile rankings associated with them can be found here.
It might seem like the cheapest solution at first, but it may not be. The rams you produce must fit within the production system you have chosen. They should be of the breed you will use to produce market lambs or of the breed you will use to produce replacement females. This means you have to identify all the animals of that breed in your flock uniquely, collect data for all the traits you want to select for, and enrol in GenOvis in order to receive EPDs and selection indexes. Without this, your selection will not be very effective, and it will cost you more in the longer term than if you purchased top rams from a reputable breeder.
Essentially, you will have to become a breeder as well as a commercial producer, and you should refer to the “breeder” section on this site to find out what this entails. Some commercial flocks do maintain breeding herds to supply their male and female replacements, but usually these are large flocks and they did not begin this way. Most often, these flocks are run by successful breeders that also have their own commercial flock. Even they occasionally purchase top rams outside of their flocks, to bring in new genetic lines.
In conclusion, if you want an effective way to improve your flock genetically, purchasing top rams with good EPDs and selection indexes is by far the easiest approach.
Producing your own rams from your herd
If you decide to produce your own rams, use the approach described here in the breeder section.
As discussed earlier, this approach requires enrolling in GenOvis to be effective.
To produce market lambs: look for high rank for the terminal index (GAIN or CARC)
To produce replacement females, choose rams that rank high in their breed for the maternal higher prolificacy index (MAT-HP). If your flock already has high prolificacy, use the maternal index (MAT), which will put more weight on the other maternal traits. If you still need to improve prolificacy, use the maternal higher prolificacy index (MAT-HP).
Ensure that the percentile ranking for the index is high enough, preferably above 70. You can also fine-tune your selection by purchasing rams that have good EPDs for the traits you wish to emphasize among those rams that rank high for the selection index.
Other criteria such as physical soundness and breeding ability are important. Presumably, if you purchase a ram from a reputable breeder, the ram will already have been screened by the breeder for both of these. Finally, if purchasing rams to produce replacement females, choose rams with different pedigrees over time to prevent increases in inbreeding in your flock.
Unless they use hybrid (F1) females from another source, many commercial producers produce most of their own female replacements. If you are in that situation and are not enrolled on GenOvis, you will not have solid information to select the best females from your flock. As a result, your flock will incur a “genetic lag” compared to the flock supplying you with maternal rams, because your ewes will be daughters of rams born 2-3 years away on average. If you wish to fill this gap, you can buy replacement ewes at regular intervals. However, as a rule, the gap is not too large and will remain the same over time, so female purchases will have less effect on the genetic progress of your flock than the purchase of top rams. If you are enrolled in GenOvis, you will have solid data on which to select the best females for replacement. In this case, the recommended approach is the same as for a breeder who selects females and is described in “selection of females” in the breeder section.
If you purchase top males from a reputable breeder, with selection indexes and EPDs to prove it, you can make very significant genetic progress without having to invest the time and expense required for running a full genetic improvement program, which would entail registration, data collection and genetic evaluation. After one generation, your flock will have inherited 50% of the genetics from that supplier. After two generations it will be 75% and after three generations 87.5%. So using top rams for ewe replacement is the simplest way to make progress.
However, many commercial producers are enrolled in GenOvis. There are good reasons for this. First, being enrolled in GenOvis will help you with the selection of female replacements, as indicated earlier. But more than anything, it will provide useful, factual information for decision making for both flock management and genetic improvement. You will have up to date information on the production of your flock, how it changes over time, and how it compares to other flocks in your province, this for all the traits you are interested in. You will be able to find out how the progeny of the rams you purchased are performing, helping you to decide where to source your genetics. Examples of the GenOvis reports that are available for these purposes can be found here.
Flock Management Software
An alternative to entering data directly into GenOvis is to use a flock management software that connects with GenOvis and enter the data there instead. A list of flock management software programs can be found here. However, currently, only some sheep flock management software programs connect with GenOvis. They are :
The advantage of using flock management software is that it will provide you with a lot of information that will assist you in managing your flock, in addition to what you will have with GenOvis. Some of these programs also use methods to speed up data entry, such as e-readers to scan electronic tags and electronic scales. Once the data is entered into these programs, it can be sent to CLRC for registration or GenOvis for genetic evaluations. The cost of these management programs can be found on their respective Web Sites.
Working together to enhance genetic progress in the livestock industry.
© 2026 Genetic Services Network - All Rights Reserved