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Angus Cattle Structural Assessment Program

Structural problems in cattle have a substantial effect on both the reproductive and growth performance of a beef herd. It is widely recognized that structural problems in sires have detrimental effects on conception rates, calving patterns and thus profitability. Similarly, females with inadequate structural characteristics are more prone to weaning lighter calves or conceiving later in the breeding season than their more functional counterparts. These structural problems are filtered through the supply chain resulting in reduced income for the producer, feedlot and thus reducing the overall productivity of the Australian Beef Industry.

The current trend for improving consistency and quality of product has shifted producers’ focus towards selecting seedstock on carcass and growth genetic traits (EBVs). Whilst, this selection has been, and will continue to be pivotal in developing the Australian beef industry, we must not forget the fundamentals of livestock breeding.

The Beef Class Structural Assessment System was designed by the MLA, the BIA and several breed societies to address structural problems in the beef industry. Detailed analysis of three thousand animals in genetically linked herds indicated that structural characteristics such as leg and foot structure were moderately to highly heritable. BEEFXCEL now services many seedstock operations in their selection and grading of stock using the Beef Class Structural Assessment System.

Te Mania Angus is continually expanding their structural assessment program in order to optimise soundness and performance in their stock. The program involves an independent assessor from BEEFXCEL analysing the structural composition of the herd on an individual basis. The program used at Te Mania Angus comprises of:

  • An annual assessment of all sale bulls;
  • An annual assessment of all breeding females and donor cows
  • All animals deemed inadequate are culled.

Structural Scores

The Beef Class Structural Assessment System (1-9 scoring system for feet and leg structure)

  • A score of 5 is ideal;
  • A score of 4 or 6 shows slight variation from ideal, but this includes most sound animals.
  • An animal scoring 4 or 6 would be acceptable in any breeding program;
  • A score of 3 or 7 shows greater variation but would be acceptable in most commercial programs. However, seedstock producers should be vigilant and understand that this score indicates greater variation from ideal;
  • A score of 2 or 8 are low scoring animals and should be looked at cautiously and inspected very closely before purchasing;
  • A score of 1 or 9 should not be catalogued and are considered immediate culls.

– Jim Green, BEEFXCEL  Ph 0402 003 137

Angus Trial Structural EBVs – Dec. 2009

The BeefClass Structural data was re-analysed following submission of further records scored by accredited assessors. At present, there are five traits analysed for over 9000 animals which were scored before they were 750 days of age. The number of traits analysed is likely to be expanded early in 2010 as further research is conducted on the structural scores available.

The five traits analysed (and the flags associated with the EBV) are:
FA: Front Feet Angle (ST indicates steep angle, SH indicates shallow angle)
FC: Front Feet Claw Set (OD indicates open divergent claws, SC indicates scissor claws)
RA: Rear Feet Angle (ST indicates steep angle, SH indicates shallow angle)
RH: Rear Leg Hind View (BL indicates bow legged, CH indicates cow hocked)
RS: Rear Leg Side View (SR indicates straight rear legs, SI indicates sickle hocked)

More positive EBVs indicate a higher genetic potential for the desirable form of the structural trait compared to the average for the analysis.

The EBV flags only appear against animals that have more extreme, negative breeding values. The flags indicate the type of undesirable structural variation the animal tends to have. For example, a bull with a flag of ‘ST’ next to its FA EBV may produce about 35% or more progeny with steep feet angle; while a bull with a flag of ‘SH’ may produce 35% or more progeny with shallow feet angle. Therefore, using EBVs and flags in combination will assist breeders in making the right decision to improve the structural soundness of their herd.

Sires with at least 40% accuracy for a Structural EBV are reported.