Tracking the traits

01-10-2009 | Mark Young

Most farms have plans for things like fertiliser application, mating and finances. Some are formal, some not so formal. It is probably a fair assumption that many farms have less formal plans for sheep genetics.

By putting pen to paper, not only can a plan be defined for what traits need improving but performance can be tracked year to year. A genetic plan helps formalise ram buying decisions. In later years you can review these decisions with reference to the changes in performance you have seen.

Ram buying has by far the biggest impact on genetic gain of any decision made for a commercial flock. Without a plan your genetic improvement programme can be like a rudderless boat with no sense of direction.

Animal breeding is a "long game". While some traits can respond to selection relatively quickly, others take several years to "build up" before you see significant changes - for example, lambing percentage.

The first step of the genetic plan is to characterise the type of sheep production system you have - do you breed your own replacements? Or do you buy these in and all lambs produced are sold for meat production? Or do you specialise in wool production? These are termed "dual-purpose, terminal sire and wool systems". SIL has ways of combining genetic information for different traits in each system.

You might have a mixture of more than one system e.g. older ewes go to a terminal sire ram, while replacements come from younger ewes mated to dual-purpose rams. You also need to consider what traits are important to your system. For example, you may want to send lambs straight to the works at weaning, lamb hoggets, and build up facial eczema tolerance.

The second step is to record key traits at current performance levels and decide on what performance goals you have for the future. You need to know what market you are aiming for in the medium to long-term. Since breeding takes time, you may have to do a bit of "crystal ball-gazing" to gauge where markets may be heading. For example, will wool prices increase relative to lamb or will heavier lamb carcases be what the market requires in 10 years?

The third step is critical. By comparing current performance with what you want in the future, you can determine which traits need to be changed.

You may wish some traits to remain at the same level and increase or decrease others. It will also help target which traits will be the primary focus when you buy rams. By writing this down it is easier to define the focus of your genetic plan and monitor progress over time.

While environment and management play a big part in what performance you get, genetics is an important contributor. Without good genetics it is harder to achieve high performance.

Having identified the traits you want to change (and those you want to remain the same or "hold"), the fourth step is to find a ram breeding flock that is measuring these traits and is improving those you want to change as part of its own genetic programme. This will mean you can achieve greater genetic change over time, for the traits you want to change, as they move forward. Breeders can display genetic trends for their flock(s) to give you an idea of the genetic gains they are making in traits of interest to you.

If a trait is important to you, and a flock has no genetic information for that trait, you are taking a chance. For example, if you are in a facial eczema (FE) susceptible area there is limited value in buying rams with exceptional growth rates if you cannot reliably rate the rams for FE-tolerance genetics.

SIL can estimate genetic merit in rams for many traits - providing the flock is recording that particular trait. Within each of the production system types - dual purpose, terminal sire and wool - SIL groups traits of a similar nature together. For dual-purpose sheep these are growth, carcase merit, lamb survival, wool, reproduction and health traits such as parasite resistance or resilience and dag score. For terminal sire sheep these groups are lamb growth, carcase merit, lamb survival and health traits. For wool sheep the groups are similar to those for dual purpose but greater emphasis is put on wool.

Finally, the fifth step. With your ram breeding flock chosen, you or the flock owner can look for individual rams that meet your objectives. Some rams may be less suitable due to genetic merit being too high for some traits and not high enough for others. It can be important to get the "balance" of traits right in a ram to address the breeding goal of your genetic plan.

It goes without saying that the rams chosen should be reproductively sound. A ram may have the best genetics the world can offer, but if he cannot pass these on to his offspring, his genes are worthless.

In summary, a good genetic plan involves the following steps:

• Characterise your production system

• Record your current performance and decide on your performance goals

• Determine your breeding goals by comparing performance with your goals to find which traits you want to change and which you want to "hold"

• Select a ram breeding flock with the genetics that allow you to address your breeding goals

• Select a group of rams that will move your flock genetics in the desired direction.

SIL is part of Meat & Wool New Zealand. For more information on using SIL information to buy rams, visit the SIL website (www.sil.co.nz) or call 0800-silhelp (0800-745-435).

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