The TransTasman Angus Cattle Evaluation (TACE), which is conducted every two weeks, now includes the regular analyses of coat score data to produce Coat Type Research Breeding Values (RBVs).
Coat type, being the subjective assessment of an animal’s hair length, has been identified as a trait of importance in some breed programs, particularly for the adaptability of Angus genetics in hotter environments.
While further research is required to confirm the relationship between coat type and traits associated with the profitability and productivity of Angus animals in Australian production systems, anecdotally, animals with shorter, sleeker coats are commonly considered to have better heat tolerance and tick resistance. Additionally, there is also suggestions that they will have reduced dag burden in feedlot environments, particularly in the colder, wetter periods.
Understanding the Science
The research that underpins the Coat Type RBV analysis was conducted by the School of Environmental and Rural Science at the University of New England (UNE). This involved analysing and modelling the coat score data recorded on animals on Angus Australia’s database to further understand its overall genetic basis, and the genetic relationship between coat scores taken in the warming versus cooling months of the year (figure 1).
The research has shown that coat score is under genetic influence, being moderately heritable and similar to the weight traits of birth weight, 400 day weight and 600 day weight. When comparing scenarios (i.e. scoring period) the heritabilities were similar for all records, warm month and cool months.
The genetic correlation between the coat scores recorded in the warm months to cool months was high but not 1.00, meaning they should be considered different traits. For this reason, a bivariate (two trait) model was applied for the Coat Type RBV analysis. This means that all coat scores are potentially used in the analysis, but with the scores collected in the cool months being used as a correlated trait for the reported Coat Type RBV, which stems directly from the scores collected in the warm months.
Additionally, to maximise accuracy the Coat Score RBV analysis uses all available data including coat score phenotypes, pedigree and genotypes.
|Figure 1 – Heritabilities and Genetic Correlation of Coat Score Phenotypes|
|Trait||No. of records||Heritability||Genetic Correlation
|Score from Warm Months||3,044||28%
|Scores from Cool Months||3,352||32%
* Warm months included coat scores recorded from November to March and cool months from April to October
The next phase of this research will be to understand the genetic relationship between coat type and the production traits such as calving ease, growth, fertility, temperament and carcase quantity and quality. Further research is also required to better understand the relationship between coat type to heat tolerance, parasite resistance and dag burden.
Understanding the Research Breeding Values
Coat type RBVs are now published for all animals included in the Coat Type RBV analysis that have greater than 25% accuracy. At the time or writing this article there were 23,262 Angus animals meeting this criterion.
The Coat Type RBVs can be viewed, searched and downloaded from angus.tech via the Angus Australia website. A Coat Type RBV sire report is also produced every quarter and is available to download from the Research section of the Angus Australia website. A list of top 50 Angus sires with the lowest (i.e. slickest) Coat Type RBVs are available if you CLICK HERE. These sires have at least one progeny recorded for coat score and a minimum of 50% accuracy.
By definition, Coat Type RBVs provide estimates of genetic differences between animals in coat type, being the subjective assessment of an animal’s hair length, and are expressed in score units.
Lower Coat Type RBVs indicate an animal is expected to produce progeny with a shorter, slicker coat. For example, a sire with a CT RBV of -0.30 would be expected to produce progeny that have, on average, 0.25 of a score shorter, slicker hair than a sire with a CT RBV of +0.20, all other things being equal.
It is important to note that the Research Breeding Values are subject to greater potential change than EBVs routinely reported as part of the TransTasman Angus Cattle Evaluation and should be used with some caution in animal selection decisions. The Research Breeding Values may change as improvements are made to the analytical models that are used, and as additional performance information is collected.
How to be involved
Angus Australia member are encouraged to score their Angus animals for coat type and submit it for inclusion in TACE to create Coat Score RBVs.
A guide to collecting coat type scores is available from the Angus Australia website. Important points to note from this guide are:
Coat scores are collected on a 1 (short) to 7 (very hairy) scale based on the visual appearance of the animal. The full visual guide is available from the Angus Australia website.
They can be recoded on bulls, heifers and steers.
They should be recorded when animals are between 300 and 750 days of age
Half scores can be used to identify animals who exhibit a coat score which is intermediate to the scores listed.
All animals should be scored by the same scorer on the same day.
If the scorers are changed, appropriate management groups will need to be assigned to capture variation in scorers.
While scores will be effectively analysed that are recorded from all months of the year, it is still recommended to score animals during late spring to early summer when some animals have shed their winter coat, while others have not. E.g. For spring calving herds, animals would normally be scored as yearlings, often in association with their 400 day weight measurement. While for autumn calving herds, animals would normally be scored at ~18-20 months of age, often in association with their 600 day weight measurement.
To further discuss the collection of coat type scores or how to access and interpret the Coat Type RBVs please contact one of the following:
Queensland, Northern Territory, Northern Western Australia & Northern New South Wales
Phone 02 6773 4644
Mobile 0417 219 405
Victoria, South Australia and Southern Western Australia
Phone 02 6773 4625
Mobile 0401 261 217
Southern & Central New South Wales, Tasmania and New Zealand
Phone 02 6773 4626
Mobile 0433 532 453