Choosing a ram

Many studs offer rams for sale based on a quality grade which divides animals into categories.

The stud's classer will categorise animals based on either:

• visual assessment
• objective measurement
• combination of both.

The higher the grade of ram, the higher the price tag will be.

Objective grading

Studs that use objective measurements such as fleece weight, fibre diameter and body weight as selection tools are in a better position to correctly separate rams into performance grades.

Selection index

Use a selection index to reduce the risk of accidentally culling some of the superior animals.

Visual grading

Use visual grading to identify obvious faults. Most studs class their rams visually when they are about 6 months old to remove obvious conformation and wool faults. After the first adult shearing, an objective and visual assessment is commonly used to further class the rams to remove any culls.

Where selection is based solely on visual grading, the accuracy of the grading depends on the classers' ability, experience, personal likes and dislikes. Irrespective of how competent a classer is, there are certain economically important wool traits, such as fibre diameter, that cannot be reliably assessed visually.

Genetic gain and lag

If you have been with the same stud for some time your flock should make average genetic gains at the same rate as the stud.

However, the lower the quality of ram you purchase, the greater the 'lag' period in reaching a specified genetic level. On average, this lag is about 2 generations between stud and commercial breeders.

Purchase price

Be careful when choosing a ram, as a higher price does not always equate to better genetics and a higher progeny performance in your flock. In some cases, cheaper rams might be more suited to your breeding objective.

Many sheep farmers buy lower grade rams because they can't see the value in paying more per ram. If you purchase 20 or more rams per year, obviously this can represent a substantial cost saving. However, the effect that lower grade rams have on genetic lag should not be under-estimated as this can lead to lost income.

You will need to weigh up the initial savings against the lower performance of progeny of cheaper rams. It may still be good business to buy lower performing rams if the price difference is large; however, where rams are not classed objectively, there may be little difference in progeny performance between expensive and cheaper rams.

Genetics vs environment

A ram that has been bred and grown in a mild environment or on good quality pastures will nearly always perform better than an animal that has been reared under drier and harsher conditions.

A ram grown under easy nutritional conditions may carry the best genes for appetite. However, a ram raised under challenging conditions may have the best genotype for feed conversion efficiency.

However, this may not be a true reflection of the relative genetic merits of the different animals. Genetically, they could be very much the same as they appear, or differ greatly.

Genetic and environmental factors are measured by:

• Genotype (or genetic make-up) - fixed at the moment of conception. Once a sheep receives its genes, which are the direct link between parent and offspring, those are its genes for life. Different sets of genes are switched on and off under different environments.
• Phenotype (or physical appearance) - a combination of its genotype and the influence of the environment in which it is reared and lives.

Buying outside your environment

If you buy rams that are bred in a different environment to yours, (particularly if their original environment is less harsh), their phenotype will alter as they become acclimatised to their new home. For example, fleece and body weights may become lighter. More importantly, the ram and their progeny may bear very little resemblance to their parents. This deviation will depend on the difference between the environment in which the ram was bred and the new home environment.

When considering the purchase of southern bred rams, consider how these rams and their progeny will perform in your own environment, in terms of lambing percentages, fibre diameter, fleece weight and body weight.

Some studs offer this information to their clients by participating in bloodline comparisons and central test sire evaluations in various environments. You can also do on-property trials, or find information from other producers to check the performance of the stud in their environment.

An animal's phenotype can be very misleading so you should use objective, reliable data sources when choosing sires.

The safest option is to buy rams from as near to your farm as possible. You should also buy rams from a stud that raises rams under near-commercial conditions.