Across-flock analysis: Comparison of sheep across different flocks.

AGBU: Animal Genetics and Breeding Unit. AGBU run the Sheep Genetics analysis and routine evaluations and are responsible for the research and development of the Sheep Genetics evaluations.

Age stage: Age stages refer to when a trait is recorded and reported. Most ASBVs are reported with an age stage at the beginning that refers to the age that trait is targeting (see table below).

Age name 


(Upper case) 

Average age of the management group* 

Age range





40-149 days 

Post weaning 


150-299 days 



300-449 days 



450-659 days 



660 days or older 


AI: Artificial insemination.

ASBV: Australian Sheep Breeding Values (ASBVs) are the best prediction of an animal’s merit for a particular trait. They are an indication of how an animal’s progeny will perform and are comparable across flocks.

BLUP: Best linear unbiased prediction. The statistical method used to estimate breeding values such as ASBVs.

Breed code: A two digit code, generally a number but can be letters that identifies the breed of sheep. See PDF list of codes in the related information to the right.

Breeder: A person who participates in the Sheep Genetics genetic evaluation. In relation to data being submitted to Sheep Genetics, a ‘breeder’ is the person, organisation or business that is the registered owner of the data.

Breeding objective: Describes future production goals. When identifying a breeding objective consider current flocks’ performance, target market, profit drivers and the environment. 

C site: 45mm from the centre of the spine at the 12th/13th rib, where eye muscle and fat depth is measured by an accredited muscle and fat ultra-sound scanner.

Cross-breed analysis: Comparison of sheep across different breeds within a breed group. For example, multiple breeds are analysed in the Terminal and Maternal LAMBPLAN analyses.

Dam: A female sheep with progeny.

Data manager: A person, organisation or business who provides a service required by a breeder to prepare and submit the breeder’s data. See the Service providers page for a list of data managers.

Environment: All non-genetic influences that affect a sheep’s performance.

ET: Embryo transfer.

Eye muscle depth (EMD): The depth of eye muscle (Longissimus dorsi) measured at the C site.

Ewe: A female sheep.

Fat depth (FAT): The depth of subcutaneous fat measured at the C site.

FBV: Flock Breeding Value. The genetic performance (breeding value) reported by Sheep Genetics that describes the performance of a sheep trait within a flock. FBVs are not comparable between flocks.

Genetic advisor: A person, organisation or business who provides a service required by a breeder to advise on genetic aspects of a breeding program. See the Service providers page for a list of genetic advisors.

Genetic correlation: The genetic relationships that exist between traits. It describes the general direction a trait moves in when another trait is increased or decreased.

Genetic linkage: When two or more flocks share common genes.

Genetic parameters: The heritabilities, genetic and phenotypic correlations, variance and adjustment factors used in the Sheep Genetics analysis.

Generation interval: The time interval between generations, defined as the average age of parents when their progeny are born.

Genotype: A combination of the genes of a sheep.

Management group: A management group is used to group sheep accurately for the Sheep Genetics analysis. Sheep run under the same conditions up to a given measurement can be included in the same management group.

 Heritability: The average proportion of the differences between sheep (after adjusting for known non-genetic influences) that can be passed on to their progeny.

ID: Sheep identification system 16-digit identification number.

MateSel: Computer software used to optimise genetic gain and inbreeding. MateSel is available to Sheep Genetics members after a training session.

Merino Superior Sires (MSS): Publications and activities from Australian Merino Sire Evaluation Association (AMSEA).

OVIS: The name of the best linear unbiased prediction (BLUP) software used to calculate ASBVs.

Phenotype: The actual performance for a trait measured or scored for a sheep.

Progeny test: A comparison between the progeny of a group of sires that were mated to randomly selected females. Pregnant females and progeny for all sire groups are run under identical conditions for the test.

Ram (or male progeny): An entire male.

Scored traits: Those characteristics of a sheep that are evaluated subjectively – by hand and/or eye – relative to a set of standards. For more information on scored traits, please refer to the Visual Scores Guide.

Selection: The choice of sheep to be used as parents.

Selection accuracy: The correlation between true breeding value and estimated breeding value.

Selection criteria: The traits used to evaluate sheep for a particular breeding objective.

Selection differential: The difference between the average phenotypic or genetic merit of the selected parents and the average merit of the group from which they came.

Selection index: Indexes take a range of important production traits and combine them into one number. They are a useful way to rank animals quickly and easily.

Selection response: The effect of selection on the merit of progeny, measured as a deviation of the merit expected if parents had been chosen at random, rather than by selection on a trait or combination of traits.

Sire: An entire male sheep that has progeny.

Tier: A section of the ewes within a flock group that has been selected for mating and is considered to be of a different genetic standard compared to other sections of the flock group.

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