This fact sheet was developed by students enrolled in Purdue's ANSC 442 Sheep Management course in Spring 2006, as a semester project. These fact sheets provide useful information on various topics related to sheep. View the list of fact sheets.

Ram Selection

There are many things to consider when selecting a new ram for your flock. We have listed several general factors that are important to keep in mind when selecting that replacement buck.

Testicle Size

When selecting a replacement ram you must analyze testicle size. Testicle size is directly related to fertility. Larger testicles indicate more sperm producing ability. When choosing a buck Scrotal Circumference can also be used as an analytical tool. A general rule of thumb states that any ram prospect with a Scrotal Circumference under 30 cm should not be used. In addition, a Breeding Soundness Exam (BSE) can be conducted to check for sterility in the buck so that you know the prospect is fertile before purchasing.




It may seem as though the mouth doesn't make much difference when it comes to selecting a ram for reproductive purposes, however a ram with parrot or monkey mouth can be detrimental to a flock. A normal lamb's mouth (black lamb above) will have a bottom jaw that meets with the top of the mouth. In some cases genetic defects cause the two to be off. If the lamb has an overbite it is called "parrot mouth" and if it has an under bite it is called "monkey mouth." Both defects can inhibit the animal from eating properly and in turn affect its growth. So when selecting a ram look for a mouth where the top jaw meets the bottom jaw.

Structural Correctness

Choosing a ram that is structurally sound is very important. You want to choose a ram that structurally has the ability to breed ewes on the terrain of your production facility. You also want to make sure the ram has enough structural integrity to offer longevity towards your investment in him. When looking for structural correctness keep these things in mind: the legs should be straight with good heavy stout bones. Front legs should be set under the animal and not out at sides. Pasterns should be short with toes pointing straight ahead. An animal should walk with a long, smooth stride and should track as wide or wider on the hind legs as the front legs.


The temperament of a ram may not affect his reproductive ability; however it may limit your management options. If a ram is ill-tempered he is harder to handle, move, and administer medications to (if necessary). A mild temperament ram will allow you to move the flock easier and administer medication if necessary. While the temperament is not important to the reproductive success of your ram it is important to your management system and should be kept in mind when selecting a replacement buck.

Breed characteristics

Depending on what type of operation you are running there are different ways to look at Breed characteristics. If you are running a commercial Flock then the breed characteristics aren't as important since you aren't breeding for one breed. A commercial flock is one of the easier ways of raising them because you base your selection on the growth qualities and muscling aspects more then breed type and other qualities. In a commercial breeding system you select a ram that will increase all the aspects of the terminal traits and you really don't care as much what color they are and if they match all the criteria of a certain breed.

If you want to choose a certain breed ram you should first look up all the criteria it takes for it to be considered like that breed. Suffolk for example is a larger framed terminal type sheep that is predominantly white bodied with black legs and head. They also have a roman nose which is arched. This is breed specific, every breed has different criteria and every breed has different things that make them disqualified, for example if a Dorset, which is all white, has any black spots in the wool that is a disqualification. They also may not have a black nose it must be pink.

These are just a few things for these breeds to get the complete list you should research the breed through their association.




Muscling is a major selection criterion for choosing a new ram for your flock. You should look for a ram that has adequate muscle conformation through the rear Hindquarter and down the leg. They should also have a thick wide top across the loin and back to add width and thickness overall. Their loin should be long and thick with average or better width. This is where you can give and take a little bit; you either get a longer loin that is not as wide or you can give up a little length to add width to your ewes.



You should look through and evaluate your ewes and determine what you should improve on. If your ewes are shorter bodied but really thick then I suggest that you buy a longer loin ram that isn't as thick to help add a larger frame and balance out the muscling. If they are longer ewes and need thickness then I would look for a wider thicker ram to help add thickness to balance out the body.

Growth and Development

Growth and Development is another important aspect in selecting a new ram. You don't want to select a ram that produces lambs that are slow growing and mature out at a smaller size and structure. This is important and great way to see how a ram produces would be to look at his sire and see all the lambs he has produced and how they look compared to him. Another way would be to compare the data sheets on weaning weight and birth weight as well as finishing weights if they are available. If you are selecting an older established ram to purchase then you should go to the farms when lambs are on the ground to see what type of lambs he generally produces and compare the farmers' ewes to yours to get an idea what he might do for your flock.

If looking for a buck lamb, you generally want to look at their frame size at that time a smaller framed ram will not develop as large and won't have the capacity and ability to carry a large weight which in the end could hurt your finishing weights. You should also try to see how much he weighed when he was born and compare it to when you look at him and try to figure up how much he has gained in that amount of time that helps to determine how his development through the weights are, if he is a fast growing lamb that has excelled that is a great quality.

Shawn Zolman
Kristen Culy
Sun Yan

*Pictures provided by Shawn Zolman*