Genetic Focus Testing: SD Across Benchmark Update (June 2026)
Genetic Focus testing
‘SD Across’ benchmark database update – No 5 (June 2026)
To assist users of ‘Genetic Focus’® testing, a benchmark database for ‘SD Across’ measurements is now being maintained by Art of Fibre. As outlined in our information sheet on the topic (available on request), this SD measurement targets the genetically influenced variation in diameter between fibres and does not include the environmentally influenced variation in diameter along fibres. It therefore provides a focus on the genetic influences on fleece quality.
The outcome of using Genetic Focus testing is to increase uniformity of fibre traits, which in turn, greatly improves processing performance of fleeces and increases the predictability of fleece traits with progeny. It is also highly correlated with fibre alignment and superior ‘character’ of fleeces. It therefore has benefits for end-use of fleeces, genetic improvement and showing/fleece competition attributes. Fibre uniformity, therefore is the key to breeding for quality fleeces.
The purpose of these updates is to place Genetic Focus test results into context by comparing the results against all other Genetic Focus testing, as well as comparisons based on age, fleece colour and species.
Eventually, individual breeders will be able to maintain their own rankings on ‘SD Across’ as they accumulate their own test results over time.
The following table shows averages for ‘SD Across’ and the ranges for high, low results for ‘SD Across’ based on age. The bottom row contains the averages for suri alpacas.
| Age group (yrs) | Avg Mean diameter (µ) | Avg SD Across (µ) | Range for lowest 10% (µ) | Range for highest 10% (µ) |
| 1 | 17.0 | 4.8 | Less than 3.7 | Higher than 6.2 |
| 2 | 18.8 | 4.9 | Less than 3.8 | Higher than 6.4 |
| 3 | 20.1 | 5.0 | Less than 4.0 | Higher than 6.5 |
| 4 | 21.1 | 5.2 | Less than 4.1 | Higher than 6.6 |
| 5 | 22.2 | 5.5 | Less than 4.3 | Higher than 7.1 |
| Suri – all ages | 22.0 | 6.4 | Less than 5.0 | Higher than 8.1 |
As an example, for a 2 year old alpaca with SD Across score of around 4.9 microns, then it would be regarded as generally average for a two year old alpaca. If it had an SD Across of less than 3.8 microns, then they would be regarded as being in the lowest 10% which indicates superior genetics. If an alpaca scored higher than 6.4 microns however, then they would be in the higher 10% for two year old alpacas. Like overall SD, the lower the SD Across score the better.
The first linear graph below shows the distribution of SD Across for all huacayas and specifically one, two, three and four year old huacayas. The second graph shows distribution of SD Across scores for all suris. The graphs can be a guide as to how your alpacas compare with all other alpacas tested.
The following table provides the averages for the SD Across results for various colours. The ‘number identified’ is the number of times that colour was attributed to a sample by the relevant breeder. Where a colour is reported less than about 100 times, then the averages should be regarded as indicative.
As was expected, the darker colours tend to have a higher variation in diameter of fibres. Interestingly, we are starting to see significant difference in fibre variability between true black and bay black fleeces. Integrity of fleece colour averages for SD Across will improve with increased volume of Genetic Focus test data.
| Colour | Number identified | Avg diameter | SD Across | Colour | Number identified | Avg diameter | SD Across |
| Appaloosa | 76 | 19.2 | 5.1 | Fawn | 76 | 20.1 | 5.0 |
| Beige | 229 | 19.3 | 5.0 | L. Fawn | 223 | 18.9 | 5.0 |
| Black | 183 | 22.1 | 5.7 | M. Fawn | 257 | 19.5 | 5.0 |
| B. Black | 29 | 19.7 | 5.2 | D. Fawn | 116 | 20.5 | 5.1 |
| T. Black | 32 | 22.1 | 5.8 | Grey | 55 | 21.4 | 5.6 |
| Brown | 51 | 20.4 | 5.1 | R. Grey | 23 | 20.6 | 5.7 |
| L. Brown | 51 | 18.7 | 4.7 | S. Grey | 36 | 21.1 | 5.6 |
| M. Brown | 141 | 20.9 | 5.3 | Multi | 26 | 20.4 | 5.7 |
| D. Brown | 90 | 20.8 | 5.4 | Roan | 27 | 19.4 | 5.1 |
| White | 789 | 19.4 | 4.8 |
Finally, it should be noted that SD Across scores tend to be higher than overall SD scores, simply because of the way they are mathematically calculated. For instance, an alpaca with overall SD of 4.0 microns could possibly have an SD Across score of 5.0. It is important to note, therefore, that Across SD results should not be compared with overall SD results.
For further information, contact Paul Vallely at info@artoffibre.com
If you would like to download the PDF copy of this paper you can find it here (SD Across Update)