Exciting drop semen sires

Semen Sires

Newsletter 2003

Client Success Story

Pattianne and Tony Gay

Contributed by Pattianne Gay

Tony and I run a grazing business at “Clonalton” near Boorowa in the South West Slopes of NSW normally running around 15000 Merino sheep in a self replacing flock. Up until 5 years ago we were focused on breeding the typical medium wool sheep flock with wool produced per head averaging 5.8 kg of 20.5 micron.

We started benchmarking our business and it became quite clear that our livestock productivity figures were way off the mark and a significant weakness in an otherwise sound business.

After analysing NSW wether trail data and inspecting a number of studs we decided to change our ram source to Cressbrook. We were impressed by Cressbrook’s strong history of using objective measurement, focused breeding goals, sheep selection criteria, ram management, the visual qualities of the wool and sheep and the integrity of the Fulloons.

We have made a fairly rapid change over to the Cressbrook bloodline over the past three years including purchasing Cressbrook blood CFA ewes to hasten the bloodline change and now have 75% of the flock at least 50% Cressbrook based.
We now have three drops of sheep from the Cressbrook influence including this years lambing. Whilst it is early days in a breeding sense, the results so far have been very pleasing

  • The visual attributes of the wool in the Cressbrook cross progeny have improved significantly being softer handling and brighter with a more defined crimp.
  • The micron of these sheep has reduced by at least one micron with little difference in fleece weight, compared to similar aged sheep from previous years.
  • Our first lambing from Cressbrook cross maiden ewes this year showed a significant improvement in lambing percentages over our previous maiden ewes, We normally mark between 55 to 70% in our maiden ewes. This year we had our largest joining of maiden ewes ( a total of 2000) and they averaged 82%. Whilst this could be a freak occurrence or due to hybrid vigor, it was a bad drought year for us. By comparison our adult ewes produced the normal average of 95%.

We are looking forward to continuing our breeding program using Cressbrook rams confident that we are producing a Merino flock that will help us to increase our profitability into the future.

Staple Strength and Variation in Fibre Diameter

Dr J.Smith for Select Breeding Services

Staple strength is an increasingly important determinant of the price received for fine wool. Staple strength itself is a relatively expensive trait to measure for the purpose of estimating genetic potential, but coefficient of variation of fibre diameter (CVD) is a useful selection criterion for staple strength. The correlation between CVD and staple strength is moderate to high and negative (i.e. as CVD increases, staple strength tends to decline), and CVD is cheap to measure since it is derived from the measurement of mean fibre diameter. There are two components to fibre diameter variation: variation in diameter between fibres and variation along fibres. The measure of CVD obtained from fleece sampling for mean fibre diameter is a combination of the two. These factors in mind, CVD should be used in breeding programs primarily in the context of the economic value of improving staple strength. For any given mean fibre diameter, there may also be some benefit in terms of spinning performance from reduced CVD. However, price signals in relation to CVD are not strong at the present time.

The components of fibre diameter variation and their specific relationships with staple strength have, until recently been the subject of investigation primarily in Mediterranean environments where staple strength tends to be a regular problem. However, this subject is now being addressed within the Australian Sheep Industry CRC’s Precision Wool Project. This Project includes a preliminary survey aimed at determining the extent, particularly of along-fibre variation in diameter within- and between-flocks across several important wool growing regions in NSW.

An important tool in this work is the OFDA2000 instrument, which has the capability of measuring fibre diameter variation both along and between fibres. However, there are some wool metrology issues to be resolved in conjunction with the on-farm survey and other research that is in progress.

In general, it seems a ‘flatter’ fibre diameter profile (indicating lower along-fibre variation) is desirable for greater staple strength. This is opposed to a profile that varies widely along the length of the staple. There is little doubt that environmental conditions (including climate and nutrition) influence fibre diameter profiles. Preliminary evidence from the Precision Wool Project indicates that physiological state of animals within a flock (e.g. litter size of breeding ewes, and growing versus adult sheep) can also affect fibre diameter variation along the staple. There may also be considerable within-flock genetic variation in fibre diameter profile characteristics and that is under investigation at the CSIRO FD McMaster Laboratory, Armidale. Figure 1 demonstrates variation that can be observed within a flock of fine wool hoggets.

Given the confirmation of a sound relationship between staple strength and fibre diameter profile characteristics, the development of a useful and easily described method for measuring and reporting fibre diameter profile characteristics may have important applications both in the prediction of wool processing performance and in the enhancement of Merino genetic improvement programs.


Figure 1 Example of fibre diameter profile variation within a flock of fine wool hoggets

The profiles of the three animals shown indicate they have similar mean fibre diameter (approx. 16.5mm) but differ markedly in profile pattern and along-fibre variation in diameter.


Yass Wether Trial Results 2003

The Yass wether trail began in 2000 and comprises 7 bloodlines, each contributing 50 randomly selected wethers. The third year results shown below are adjusted for spinning fineness. It can be seen from the results that the Cressbrook team has by far the best FDCV and staple strength, and hence lower spinning fineness.

BloodlineNumber of wethersCFWFDFDCV
Cressbrook463.13 kg18.518.4%
Average of Other BL260 total3.22 kg18.820.2%
BloodlineStaple StrengthBWT3 yr Net PriceIncome Per HaProfit Per Ha
Cressbrook51N/Kt53.0 kg$13.96$437$257
Average of Other BL41N/Kt50.9 kg$11.54$361$151

Cressbrook Hoggets cut on average 4.1kg

In the 2003 hogget shearing Cressbrook hoggets cut up to 6kg and averaged 4.1 kg. Off shears the one year old rams had an average body weight of 58kg and weighed up to 75kg.

Although current market conditions favour high body weight sheep, we at Cressbrook have chosen to keep our body weight constant in our selection index. We feel that the high mutton prices being experienced currently are a result of very low supply and that it is too early to make changes in our breeding direction based on spot prices.

Points for the diary

January/February on property ram inspections welcome

Sale Date: 15th of Feb 04

Numbers: 250 Rams

Format: Inspection time: 9:00am

Stud Sires : 15 Helmsman

Single Pens : 103 Open Cry

10 Pens of Three: Open Cry
Lower Grades: 102 Helmsman