SRS® Sheep

No mulesing

No mulesing

Mulesing is the surgical removal of breech skin folds in sheep. It is done to prevent fly strike associated with urine wetting of the skin of sheep that have wrinkly skins.

Merino sheep bred on SRS® selection principles have the great advantage of not having to be mulesed. The sheep are plain bodied and totally free of any skin wrinkling. When the sheep's skin is like this, it remains dry at all times. Urine is not trapped in the breech region and rain droplets are not trapped along the sheep’s back. Consequently, the weeping dermatites that produce conditions such as 'urine scald' and fleece rot (from prolonged rain) do not occur, and the sheep are not predisposed to blowfly strike of any kind. Mulesing is not required and neither is insecticidal treatment.

Please click here for our latest newsletter which details the non-mulesing status of our 36 SRS® Merino and Poll Merino studs.

Image 1. Merino ewes and lambs at Keri Keri Merino Stud, an SRS® flock. Mulesing was discontinued in 2002. The sheep are plain bodied and naturally resistant to fly strike. (see www.kerimerino.com.au).

The possibility of being able to breed plain-bodied Merino sheep that are naturally resistant to breech strike and therefore do not need to be mulesed, arose from the field investigations by Australian scientists, Drs. H.R. Seddon and H.B. Belschner, in the early 1930s. Unmulesed Merino ewes were graded as having plain breeches (A class), wrinkly breeches (B class), and very wrinkly breeches (C class). The incidence of breech strike in each class of sheep is shown below.

Table 1. Incidence of breech strike in plain-breeched (A class), wrinkly (B class) and very wrinkly breeched (C class) sheep over four consecutive seasons.

Belschner and Seddon’s plain-breeched (A class) Merino ewes were much less susceptible to breech strike than wrinkly breeched Merinos.

In SRS® Merino flocks, the sheep are again much plainer breeched than the plain-breeched (‘A class’) sheep studied by Belschner and Seddon. Our sheep do not need to be mulesed because the animals are rarely fly struck.

Image 2. This 15 month old Merino ram is the plain bodied type that can breed sheep that are naturally plain-bodied and do not need to be mulesed. The ram, pictured here in 4 months wool, weighs 115 kilograms and produced a high fleece weight of 17.1 micron wool.

Merino studs implementing SRS® breeding principles have stopped mulesing, some as long as four years ago. These rambreeders can produce large numbers of Merino rams which can be used to change the sheep in many Merino flocks rapidly to a much plainer breeched sheep that do not require mulesing.

Also, in SRS® flocks, large numbers of Merino rams and ewes are now being bred that do not grow wool in the breech region.

Image 3. This young Keri Keri Merino ram is unmulesed and free of wool on the breech, scrotum and around the pizzle (see www.kerimerino.com.au).

Breeding Merino sheep with breech regions naturally free of wool is an additional way of permanently protecting sheep from breech strike. These sheep may not require crutching (crutching is the shearing of wool from the breech region. It is usually done once a year in Merino flocks).

Comfortable in its environment

Comfortable in its environment

Where possible, the sheep are selected for the capacity to thrive and reproduce under conditions of low feed availability in both hot and cold environments as well as thrive in high summer rainfall environments. It is like a ‘safety net’, a way of ensuring that the animal is bred to be always comfortable in its environment, even when the natural conditions are challenging.

Image 4. Keri Keri, an SRS® Merino stud: in severe drought in 2003 (top left), low feed conditions in 2004 as drought persists (top right); 8 months old mixed sex lambs thriving in 2004 drought (bottom left); and a short while later, 13 month old ewes thriving in 2004 drought (bottom centre); fleece of a 13 month old Merino ram (unshorn) in 2004 after having being joined at 6 months of age. Summer temperatures reach 50 degrees Centigrade. The adult ewes produce about 9 kilograms of 21 micron wool per year (see www.kerimerino.com.au).

Such efficient metabolic capacity is necessary for the sheep to deliver three income streams:

• to produce high fleece weights of fine diameter wool in a sheep that is rain proof

• to produce lambs of high carcase weight and high red meat yield

• to wean 120% or more lambs with minimal sheep losses

The approach we use is to select for big framed and plain-bodied sheep with a ‘triple wedge’ shape (long neck, angular shoulders, long loin and wide hindquarters). Supplementary feeding is avoided as is housing of rams.

Often in rambreeding flocks, ewes which routinely rear multiple lambs and milk from four (rather than two) teats are used as the preferred dams.

Image 5. Four teated ewes in this Merino flock wean about 120% of lambs, or about 10% more lambs than the two teated ewes. The lambs from four teated ewes are also about 10% heavier.

Lambs with long and fine outer coats are also preferentially kept for breeding. The long and fine outer coat of the lamb protects it from harsh weather. It is also an early indicator of sheep with high levels of fibre density and fibre length and capable of producing high fleece weights of fine diameter wool.

The plain bodies and no skin wrinkle in SRS® Merino sheep means that the animals are more easily shorn; reducing the suffering to the animal and the person shearing the sheep. The shorn wool is also more uniform and can be classed into fewer and larger wool lines.
SRS® Merino breeders, John and Wendy Gill, ‘Booyamurra’, Coolah, New South Wales, Australia, state:

“We started on a SRS® Merino breeding program 10 years ago using Wallaloo Park rams exclusively. We are delighted with the results for the following reasons:

• increased the wool cut by 2 kgs to 8 kgs per ewe and reduced the fibre diameter by 2 microns to 19.5 microns.

• narrowed the micron range of the wool clip lines from 4 micron to 2 microns.

• far less skin pieces and shearers say they are heaps better to shear.

• reduced body strike to nearly zero and now rarely jet any sheep.”

High meat value

First-cross ewes such as the Merino x Border Leicester cross are mainly used as prime lamb dams in Australia. The Merino ewe, despite its more valuable fleece, is considered less capable of producing a lamb of sufficient meat quantity and quality to meet market requirements.

However, a recent study has shown that prime lambs bred from Merino ewes sourced from an SRS® flock had an average dressed weight that was 20% higher than lambs from first-cross ewes.

Table 2. Merino ewes can be excellent prime lamb dams.

Knowing this, our aim now is to breed prime lambs from Merino x Merino joinings.

High wool value

High wool value

SRS® Merino sheep have been bred for high levels of fibre density and length. With many wool fibres and long wool fibres on its body, the sheep are able to produce high fleece weights. The high density is also associated with the fleeces being fine in fibre diameter. Examples for individual of SRS® Merino ewes in a fine wool flock are shown in the Table below.

Table 3. Fleece and fibre characteristics of individual SRS® Merino ewes from a fine wool flock.

Image 6. The fleeces of SRS® sheep consist of long fibre bundles, each about the thickness of a matchstick.

The fibre bundles are a mirror image of the number of fibres growing from follicle groups in the sheep’s skin. Sheep with SRS® fibre bundles have measurably higher densities than thick stapled sheep.

Table 4. Follicle densities (left) and number of follicles per group (right) of Merino rams with fleeces consisting of long fibre bundles or thick staples (531 rams from 52 flocks were sampled).

SRS® sheep have the capacity to produce wool at least as long as 200 millimetres per year under paddock conditions.

Image 7. Twelve month old SRS® Merino ewe hoggets growing more than 200mm of 17.5 micron wool in a drought year when only 100mm rain fell.

Worsted processing trials conducted from 1997-2002, by Itochu Wool Limited, the largest buyer of Australian wool, show that SRS® wool processes exceptionally well during topmaking, spinning and weaving. In all, 16 trials were carried out in Italy, Japan, Thailand, India and Australia, covering Merino wools ranging from 17.3 to 20.7 microns.

In each trial, SRS® wool was compared with traditionally bred wool of high quality. The raw wools were matched carefully for fibre diameter, wool length, staple strength, position of break and vegetable matter content. Because SRS® wools are naturally longer, a considerable proportion of the SRS® wool was bought as ‘prem’ wool (less than 12 months growth). The topmaking advantages of SRS® wool in these trials is summarised in the Table below.

Table 4. Topmaking advantages of SRS® wool versus traditionally bred wools of high quality.

SRS® wools produced consistently longer Hauteur, less short fibre and less noil.
Itochu Wool Ltd reported that yarns made from SRS® wool were soft and silky and similar in texture to cashmere. The yarns were exceptionally strong with very good natural stretch and elasticity. Yarn breakages during spinning were reduced by 20% to 30%. The fabrics had excellent drape, a natural ability to stretch, less creasing and a deep rich appearance after dyeing, particularly with pastel colours.

New genetic types

New genetic types

Using the breeding technology Dr. Watts has developed, he has been able to develop new genetic types of sheep, capable of combining high wool quantity and quality with high meat and milk production (see www.australianmeatmerino.com). This has allowed the exceptional meat attributes (see below) of non-fleece producing breeds to be infused into the Merino.

Image 8. The meat ram (left) weighed 83 kilograms at 5 months of age and the other meat ram (right), 115 kilograms at 12 months of age.

This 12 month AMM® ewes (recently shorn) are a product of this new genetic type. The ewes can produce high lambing percentages at this young age. At seven months of age these sheep can reach live body weights of 60 kilograms and carcase weights of 26 kilograms. The ewes are producing high quality wool of about 16.5 microns fibre diameter.

Notable Sires

Notable Sires

Some of the top performing Merino and Poll Merino rams in the SRS® breeding system include:

Straban Merinos