STRUCTURAL soundness, a term commonly used to describe the conformation of an animal (e.g. feet, legs, udders), is an important trait in beef herds, with animals needing to conform to certain structural requirements to ensure high levels of mobility, production and adaptability to the environment.
Structural soundness can have a considerable impact on the profitability of a beef enterprise, with poor structural soundness resulting in:
Importantly, structural soundness is heritable and can be improved in both the short and long term by selection. There are also no known antagonistic genetic relationships between structural soundness and other traits of importance, enabling structural soundness to be improved genetically without impacting negatively on other traits.
While it is common practice to informally observe animals and assess their structural soundness, animals can be more formally assessed using the Beef Class Structural Assessment System.
The Beef Class Structural Assessment System uses a standardised scoring system for traits such as feet and leg structure, udder evenness and attachment, teat size and shape, capacity, sheath and naval attachment, and muscle score.
For feet and leg structure, udder evenness, teat size and shape, a 1 – 9 scoring system is used whereby:
For capacity, sheath and udder attachment, a 1-5 scoring system is used, with a score of 5 being considered ideal.
In December, five new EBVs were included in Angus BreedPlan for structural soundness traits, with EBVs now being routinely published in each fortnightly Angus BreedPlan analysis for:
The five Structural Soundness EBVs are expressed as differences in the percentage of progeny that will have desirable structure for each respective trait, with higher EBVs indicating a greater number of progeny with desirable structure.
For example, a bull with a Front Feet Angle EBV of +20 would be expected to, on average, produce 15pc more progeny with desirable front feet angle than a bull with a Front Feet Angle EBV of -10, all other things being equal.
The availability of EBVs for structural soundness has several major advantages over traditional approaches that have relied on trying to identify animals with superior structural soundness genetics by assessment of their own structure alone:
With tools such as the Beef Class Structural Assessment System and Angus BreedPlan Structural Soundness EBVs available, beef producers have the ability to select for improve structural soundness in their beef herd by utilising a range of different selection strategies.
Culling animals with unacceptable structural soundness
All animals in a beef breeding program should be assessed for structural soundness, using either the Beef Class Structural Assessment System or a less formal method, and any animals with unacceptable structure culled from the breeding herd.
Culling animals with unacceptable structural soundness predominantly serves to improve the structural soundness of the “current” breeding herd:
Culling animals with unacceptable structural soundness does also ensure that the genetics of any animals with unacceptable structure won’t be passed into the next generation, albeit with the knowledge that Structural Soundness EBVs provide a better indication of an animal’s breeding value than the animal’s own structural soundness.
Consider structural soundness EBVs when selecting animals
Structural Soundness EBVs should be utilised when selecting animals by way of improving the structural soundness of the “future” breeding herd (i.e. the next generation).
Selecting animals that have superior Structural Soundness EBVs (or avoiding animals with inferior Structural Soundness EBVs) is paramount to genetically improving structural traits in a beef breeding enterprise.
As with selection for any trait, genetic improvement for structural soundness will be achieved if the animals selected for breeding this year are genetically superior to those used in previous years. This is particularly important when selecting sires due to the overall influence of their genetics in a herd both in the short term and long term.
Balance selection for structural soundness with other traits of economic importance
While structural soundness is important in a beef enterprise, similarly to selection for other traits, selection for improved structural soundness should be balanced with selection for other economically important traits.
When making selection decisions, appropriate emphasis should be given to each trait based on the relative economic importance of the trait to the individual beef enterprise. The overall objective of any selection program should be to maximise enterprise profitability, rather than focussing on improvement of an individual trait of interest.
In December, five new Structural Soundness EBVs were included in the routine Angus BreedPlan genetic evaluation.
The Structural Soundness EBVs published within Angus BreedPlan are calculated from subjective structural soundness scores that have been collected by an accredited scorer when animals are younger than 750 days.
Structural soundness scores for Angus BreedPlan are collected using the Beef Class Structural Assessment System.
Scores are collected for 5 traits related to feet and leg structure using a 1 – 9 scoring system, where:
Use of accredited technicians
Structural soundness scores for Angus BreedPlan must be collected by an accredited technician. A list of accredited technicians can be accessed from the BreedPlan area of the Angus Australia website, or by contacting staff at Angus Australia.
Structural soundness scores not collected by an accredited technician will not be included in Angus BreedPlan.
When should animals be scored?
Angus BreedPlan can analyse structural soundness scores from animals that are less than 750 days of age at scoring (i.e. 25 months). The majority of animals are scored as either yearlings or rising 2 year olds.
Structural soundness scores can be collected on mature cows but are not currently utilised in the calculation of Structural Soundness EBVs.
While more than one set of structural score information can be recorded for an individual animal, Angus BreedPlan is only analysing the first set of structural score information for each animal at this stage.
While bulls are most commonly scored, structural soundness scores can be collected on both heifers and bulls.
It is important to try and score as many animals within each contemporary group as possible. Collection of structural soundness scores for only a selection of animals (e.g. only collecting scores for sale bulls rather than the entire bull drop) may result in data biases and the subsequent calculation of Structural Soundness EBVs that do not reflect the true genetic merit of animals.
There needs to be some variation in scores for them to be used in the Angus BreedPlan analysis. Scoring all animals in a group with a structural soundness score of  does not identify any differences in structure between animals, and consequently does not provide any useful information for the calculation of Structural Soundness EBVs.
A management group should be recorded for any animals or group of animals that have been treated differently or exposed to significant non-genetic influences prior to measurement that may affect their structural soundness scores. For example, differences in feed, or animals being run on different types of country (i.e. soft, rocky).
Structural soundness scores should be recorded for all animals in a contemporary group on the same day. Angus BreedPlan will not directly compare scores collected on different days. Likewise, the same accredited technician should be used to score all animals in a contemporary group.
If foot trimming is practiced, structural soundness scores should be collected prior to trimming so that differences between animals are accurately described.
If there is variation from foot to foot, the score that is collected should reflect the worst foot.
Structural score information can also be collected for a range of other traits such as sheath and navel scores, udder evenness and attachment, teat size and shape and capacity. These scores are not currently included in the Angus BreedPlan analysis however they may be used to develop Structural Soundness EBVs for these traits in the future.
Structural soundness scores can be submitted using either:
Source: Angus Australia