Skip to main content

Your internet browser is out of date and not supported by this website. For the best viewing experience on wool.com, please update your browser to one of the options below.

AWEX EMI 1199 -5
Micron 17 1658 -7
Micron 18 1592 -13
Micron 19 1529 -12
Micron 20 1457 -11
Micron 21 1428n -
Micron 26 624n +9
Micron 28 443n -
Micron 30 382n +9
Micron 32 335 +5
Micron 16.5 1692 -2
MCar 645 -3

Udder assessments help identify your passengers

An udder assessment of your breeding ewes at lamb marking helps you to identify which ewes to keep and which should be removed, improving your flock’s reproductive performance, writes Amy Lockwood of AWI Extension WA.

Lifetime reproductive performance is a key driver of the profitability of Merino enterprises. Reproductive efficiency, selection pressure and consistency of production within a flock can be increased by identifying breeding ewes with poor performance to remove from the replacement breeding flock, i.e. the ‘passengers’ or bottom 25% of ewes. It’s also important to identify those with superior performance to retain in the breeding flock, i.e. the ‘performers’ or top 25% of ewes. 

Assessing udders as ‘wet’ or ‘dry’ at lamb marking is one of several tools used to identify passengers and performers. A ‘wet’ udder assessment means that the ewe has reared at least one lamb. ‘Dry’ ewes are those that have lambed and failed to rear a lamb, also known as ‘lambed and lost’. If you don’t pregnancy scan, dry ewes could also be ewes that failed to conceive. 

Ewes are considered performers if they are assessed as ‘wet’ each year, successfully rearing a lamb at their first two lambing opportunities. In contrast, passengers fail to rear a lamb at their first two lambing opportunities. Research has shown that culling passenger ewes that have consecutively failed to rear a lamb (twice lambed and lost) has a similar impact on lifting the reproductive performance of the flock as culling ewes that consecutively fail to conceive (i.e. ‘twice-dry’ ewes). The main benefit of culling these ewes is a decrease in the number of dry ewes in the flock, leading to increased reproductive rates. 

Udder assessment is best done at lamb marking and is recommended for both flocks that do and do not pregnancy scan. Udders can be assessed at weaning but you may incorrectly assess ewes as ‘dry’ if they have naturally weaned their lambs before you conduct weaning (for example, ewes that conceived early in the joining period and have 14-week-old lambs at foot). Assessing udders at lamb marking is the most reliable way of identifying ewes that have conceived and reared lambs if you do not pregnancy scan your ewes. 

What to look for 

Wet

Dry

Full, warm udder (N.B. some ewes may only be lactating on one side of the udder) 

White, opaque milk stripped from teat 

Clean teat/s 

Birth stain on breech 

Small, floppy/soft, cool udder with some development 

Fluid may be difficult to strip from the teats. The fluid is different to milk and may range from watery to thick, be clear or various colours different to the colour of milk, and may have white flecks. 

Dirty/greasy teats 

Birth stain on breech 

 

Dry ewes that were not pregnant or have failed to lamb will have the smallest udders, no stain on the breech, and they are often fatter. Maiden ewes that are dry will have no udder development, whereas older ewes that have previously lambed will have some udder development. 

Keep an eye out for udder abnormalities 

Damaged or abnormal udders reduce milk supply to the lamb/s, significantly compromising lamb performance and survival. Identify any udder abnormalities when assessing ewes as wet or dry. Ewes with mastitis or unsound udders should be culled. 

Udder abnormalities include: 

  • Mastitis
    • One or both sides of the udder are hard and often lumpy
    • Milk stripped from the teat may be watery and have clots, blood or pus
    • If the ewe has ‘black mastitis’, the udder will look black/purple and feel colder than normal due to the death of the tissue. These ewes will require treatment with antibiotics.
  • Missing teats
  • Teats damaged from shearing cuts
  • ‘Blown’ or ‘bottle’ teats that are much too large and prevent the lamb from drinking
  • Blind teats
  • Abnormal udder development
  • Cheesy gland.

More information: 

This article appeared in the Winter 2025 edition of AWI’s Beyond the Bale magazine that was published in June 2025. Reproduction of the article is encouraged. 

Articles That Might Interest You

Feedbase Options
Choosing the right pasture mix for the enterprise and location is essential, particularly in a more variable climate. Read more
Joining
Rams are high performance animals that work very hard over the joining period. They contribute half of the genetics of their progeny and are the primary drivers of genetic improvement in a flock, so need to be given every opportunity to pass on their genes. Read more
Lambing
AWI provides woolgrowers with new tools, information and skills to increase the number of lambs weaned across wool-growing flocks. Read more