‘Single step’ sheep trait analysis promises more accurate selection

Sheep Central May 29, 2017

SHEEP producer selection for important wool, carcase and meat quality traits will be more accurate and quicker with the move to ‘single step’ analysis of genomic and breeding values by Sheep Genetics.

Sheep Genetics is Australia’s national breeding evaluation service for sheep breeders and buyers and has now moved to full ‘single step’ analysis of traits to help further accelerate genetic gains in the industry.

The move is the result of long-term collaboration between Sheep Genetics, the Animal Genetics and Breeding Unit (AGBU), the Cooperative Research Centre for Sheep Industry Innovation (Sheep CRC), Australian Wool Innovation (AWI), and the hundreds of ram breeders who have contributed performance and DNA data. Sheep Genetics is managed by Meat & Livestock Australia.

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Until 2016, all genomic information was incorporated into Australian Sheep Breeding Values using a “blending” approach, which combined pedigree-based estimated breeding values with genomic breeding values from separate analyses to create a blended ASBV.

In May 2016, Sheep Genetics moved to the ‘single step’ approach to calculate ASBVs for carcase traits, and two new indices were introduced with a focus on improvement of eating quality and lean meat yield for terminal sire breeders.

Since then, researchers have been working on the implementation of ‘single step’ for the main analyses in the terminal, maternal and Merino runs, resulting in the transition now to using the ‘single step’ approach over all main analyses, as well as the worm egg count analysis for all three breed groups and visual trait analyses for Merinos.

MLA said the move to ‘single step’ analysis will mean:

Australian Sheep Breeding Values will be more accurate, as they now include all information from genomic testing.

Breeders can select young rams and ewes for traits such as lean meat yield, eating quality and others not recorded till later in life, with more confidence they’re sourcing animals with the best genes for their production system.

Together, these provide scope for faster genetic progress in all traits contributing to value chain and industry profitability, MLA said.

MLA’s program manager – Genetics, Hamish Chandler, said the move to ‘single step’ across all main analyses means information from all available sources was now being used simultaneously to calculate breeding values for individual animals.

“There are many benefits of moving to a full Single Step analysis.

“For example, genomics now contributes to breeding values for a wider range of traits and the genetic correlations between all relevant traits are now considered,” Mr Chandler said.

Mr Chandler said sheep producers would notice changes to the ASBVs of animals in LAMBPLAN and MERINOSELECT databases, the genetics evaluation services for the prime lamb industry and wool industry respectively.

“The changes are due to a number of factors, including the influence of genomic information from a larger number of animals and traits.”

Producers and stud breeders will benefit

Director of AGBU, Dr Robert Banks, said producers and stud breeders would all benefit from the changes.

“Producers will still be buying rams using LAMBPLAN or MERINOSELECT to select animals with the best index for the production system they’re working in, but Single Step analysis delivers increased accuracy of assessing the value of animals’ genes by using genomic information to all the different traits they can select for,” Dr Banks said.

“It connects sheep genetics data collected by the ram breeders with data that producers are increasingly getting from processors about lean meat yield, as well as detailed data on lean meat yield, eating quality and other traits from the Industry Resource Flock.

“For stud breeders, it opens up the possibility of testing at weaning to enable them to make more informed, accurate selections on young rams earlier than they have been able to in the past.”

Program Leader of the Sheep CRC’s Genetics program, Professor Julius van der Werf, said the move to Single Step analysis was world-leading in its innovation and ability to boost genetic gains in Australia.

“This is a crucial step in modern genetic evaluation, where an animal’s performance data is combined not only with performance of relatives through pedigree, but also with information from other animals that have a comparable genetic makeup at the DNA level. In other words, we combine pedigree information with genomic information to predict breeding value,” Professor van der Werf said.

“We know that genomic prediction can be a powerful way to increase the accuracy of an ASBV, especially for traits that are not normally measured on-farm.

“The method will account better for the fact that some genotyped animals have more relatives that are also genotyped than others, making their genomic prediction more reliable.”

Reproduction analysis will remain unchanged at this stage due to the limited records available. However, there is ongoing work to develop genomically enhanced Research Breeding Values (RBVs) for reproduction traits later this year.


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  1. Colin Earl, May 29, 2017

    Genomically-enhanced breeding values for reproduction from a system which can’t identify a gene which increases conception by 60 percent? We live in hope.

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