RELEVANT TERMS

• AMFU, CAFU, NHFU, and DDFU - untested for the genetic disorders but believed to be free.
• AMF, CAF, NHF, and DDF - tested for genetic disorders and are free.
• AM% - the _% probability that the animal is an AM carrier.
• NH% - the _% probability that the animal is a NH carrier.
• CA% - the _% probability that the animal is a CA carrier.
• DD% - the _% probability that the animal is a DD carrier.
• Calving ease direct (CEM or CEdir) and Calving ease Daughters (CED or CEDtrs) - genetic estimate of ease of dam or daughter as 2yo heifers to calve without assistance
• Birth weight (Bwt) - Estimates of the genetic differences between animals in calf birth weight.
• 200 day weight - Estimates of the genetic differences between animals in liveweight at 200 days of age.
• 400 day weight - Estimates of the genetic differences between animals in liveweight at 400 days of age.
• 600 day weight - Estimates of the genetic differences between animals in liveweight at 600 days of age.
• Mature weight (Mwt) - Estimates of the genetic differences between animals in cow weight at 5 years of age.
• Milk - Estimates of the genetic differences between animals in milk production, expressed as variation in 200-day weight of daughter's calves.
• Scrotal size (SS) - Estimates of the genetic differences between animals in scrotal circumference at 400 days of age.
• Days to calving (DOC) - Estimates of the genetic differences in female fertility, expressed as the number of days from the start of the joining period until subsequent calving.
• Carcase weight(Cwt) - Estimates of the genetic differences between animals in carcase weight, adjusted to 650 days of age.

AUSTRALIAN ANGUS SELECTION INDEXES

There are four standard selection indexes calculated for Australian Angus animals. These are:

• Angus Breeding Index (ABI)
• Domestic Index (DOM)
• Heavy Grain Index (GRN)
• Heavy Grass Index (GRS)

The Angus Breeding Index - is a general purpose selection index that is suitable for use in the majority of commercial beef operations, whereas the Domestic, Heavy Grain and Heavy Grass selection indexes are specific to beef operations targeting a defined production system and market endpoint.

Angus Breeding Index - estimates the genetic differences between animals in net profitability per cow joined in a typical commercial self replacing herd using Angus bulls. This selection index is not specific to a particular production system or market end-point, but identifies animals that will improve overall profitability in the majority of commercial grass and grain finishing beef production systems. This selection index is particularly suited to commercial producers who sell progeny into different markets, or to seedstock producers supplying bulls to commercial clients who produce for a range of different production systems and market end points.

Domestic Index - estimates the genetic differences between animals in net profitability per cow joined in a commercial self replacing herd targeting the domestic supermarket trade. Steers are assumed to be finished using either grass, grass supplemented by grain or grain (eg. 50 – 70 days) with steers slaughtered at 490 kg live weight (270 kg carcase weight with 12 mm P8 fat depth) at 16 months of age. Daughters are retained for breeding and therefore maternal traits are of importance. Emphasis has been placed on eating quality and tenderness to favour animals that are suited to MSA requirements.

Heavy Grain Index - estimates the genetic differences between animals in net profitability per cow joined in a commercial self replacing herd targeting pasture grown steers with a 200 day feedlot finishing period for the grain fed high quality, highly marbled markets. Steers are assumed to be slaughtered at 760 kg live weight (420 kg carcase weight with 30 mm P8 fat depth) at 24 months of age. Daughters are retained for breeding and therefore maternal traits are of importance. There is a significant premium for steers that exhibit superior marbling.

Heavy Grass Index - estimates the genetic differences between animals in net profitability per cow joined in a commercial self replacing herd targeting pasture finished steers. Steers are assumed to be slaughtered at 620 kg live weight (340 kg carcase weight with 12 mm P8 fat depth) at 22 months of age. Daughters are retained for breeding and therefore maternal traits are of importance. Emphasis has been placed on eating quality and tenderness to favour animals that are suited to MSA requirements.

Accuracy (Acc) - Provides an indication of the reliability of an EBV. As more performance information becomes available on an animal (or its progeny, or relatives) then the accuracy of its EBVs for particular traits will increase.

RECESSIVE GENETIC CONDITION

INFORMATION FOR BULL BUYERS

This is information for bull buyers about the undesirable genetic conditions, Arthrogryposis Multiplex (AM), Neuropathic Hydrocephalus (NH), Contractural Arachnodactyly (CA) and Developmental Duplications (DD).

Putting Undesirable Genetic Recessive Conditions in Perspective

All breeds of cattle, in fact all mammals including humans, have undesirable genetic conditions. Fortunately, advances in molecular genetics have facilitated the development of DNA tests for their management. Angus Australia is at the forefront of development of strategies to manage undesirable genetic conditions and Angus members are leading the industry with their uptake of this technology.

What are AM, NH CA and DD?

Arthrogryposis means 'curved or hooked joints'. Multiplex indicates there are multiple abnormalities associated with the condition. Animals with the NH condition have a large head. Both AM and NH affected calves are not born alive. Whilst; calves affected by CA are born alive and can reproduce, muscle contractures restrict the movement of joints, particularly in the hind legs. Abnormal muscle contracture decreases dramatically as a calf ages, while muscle development always remains poor. DD causes duplication of limbs, etc.

How are the conditions inherited?

Research in the U.S. and Australia indicates that AM, NH CA and DD are simply inherited recessive conditions. This means that a single pair of genes controls the condition. For this mode of inheritance two copies of the undesirable gene need to be present before the condition is seen; in which case you may get an abnormal calf. A more common example of a trait with a simple recessive pattern of inheritance is black and red coat colour. Animals with only one copy of the undesirable gene (and one copy of the normal form of the gene) appear normal and are known as “carriers”.

What happens when carriers are mated to other animals?

Carriers, will on average, pass the undesirable gene form to a random half (50 %) of their progeny. When a carrier bull and carrier cow is mated, there should be a 25% chance that the progeny produced will have two normal genes. There should be a 50% chance that the mating will produce a carrier. However, there could be a 25% chance that the progeny have two copies of the undesirable gene.

Key point: The number of reported observations of AM, NH CA and DD calves is very low and there is certainly no need for panic.

Key point: With today's DNA tools undesirable genetic conditions can be managed!

If animals tested free of the undesirable gene are mated to carrier animals the condition will not be expressed at all. All calves will appear normal, but approximately half (50%) could be expected to be carriers.

How is the AM NH CA and DD status of animals reported?

A DNA-based test has been developed that can be used to determine whether an animal is a carrier or free of the AM, NH CA or DD gene. Angus Australia uses sophisticated software to calculate the probability of (all untested) animals to be a carrier. The software uses the test results of any relatives in the calculations and the probabilities may change as new results for additional animals become available. The genetic status of animals is being reported using five categories:

• AMF Tested AM free
• AMFU Based on pedigree AM free – Animal has not been tested
• AM__% _% probability the animal is an AM carrier
• AMC Tested AM-Carrier
• AMA AM-Affected

For NH CA or DD, simply replace AM in the above table with NH CA or DD. Registration certificates and the Angus Australia (AA) web-database display these codes. This information is displayed on the animal details page and can be accessed by conducting an “Animal Search” from the Angus website or looking up individual animals listed for sale in a sale catalogue.

Implications for Commercial Producers

Your decision on what genetic condition statuses are acceptable will depend on the genetics of your cow herd (which bulls you previously used), whether you have a straightbreeding or crossbreeding enterprise and whether some female progeny will be retained as breeders. Angus Australia seedstock breeders are being proactive and transparent in managing these genetic conditions, endeavouring to provide the best information available. The greatest risk to the commercial sector from undesirable genetic recessive conditions comes from unregistered bulls with unknown genetic background. The DNA testing that Angus Australia seedstock producers are investing in provides buyers of registered Angus bulls with unmatched quality assurance.

For further information contact Angus Australia's Breed Development and Innovation Manager at (02) 6773 4602.

Key point: For the condition to be expressed the undesirable gene needs to be present on both sides of the pedigree and both the sire and dam need to be a carrier.

Key point: The genetic status of an animal is subject to change and will be reanalysed And adjusted each week as DNA test results of relatives are received.

• 2012 Catalogue
  
  
• 2013 Catalogue
  
  
• 2014 Catalogue