While many farmers check their ewes’ udders at weaning, research led by Massey University’s Anne Ridler, found many ewes with apparently normal udders at weaning, had udder defects four to six weeks later.
This is possibly due to post-weaning mastitis and because it is easier to feel defects once the ewe has dried off.
Studies on lower North Island farms have shown that between 2 and 7 per cent of mixed-age ewes have udder defects. Lambs born to these ewes are three to four times more likely to die than those born to ewes with healthy udders. Lambs that do survive grown an average 25g less per day so their weaning weight is, on average, 2kg lighter than lambs from ewes with normal udders. Ewes with udder defects will wean 11 less kilograms of lamb than their healthy flock-mates.
To effectively check udders, it is important to palpate the udder while the ewe is standing in a race, gently squeezing both halves of the udder. It should also be possible to roll the teats between the fingers.
Generalised hardness of the udder would often be called mastitis. If the infection is recent, the udder will be hot and swollen, but more commonly, the udder half or halves will feel hard all over. If the affected udder half is milked, the secretion may be watery, bloody or clotted (in the case of recent infections) or very thick and discoloured (long-term infections). In some instances, there is no discharge at all. Ewes with generalised hardness in one or both udder halves should be culled.
As a general rule, ewes with lumps within their udder tissue should be culled as their lambs will be less likely to survive or have slower growth rates. Lumps can be small or large and are usually only found in one half of the udder, but can be in both.
It is normal for ewes to have lumps just in front of, or just behind the udder but not in the udder tissue. At weaning, about 3 per cent of ewes will have these lumps and at four to six weeks after weaning, around 1.5 per cent of ewes will have them. Ewes with these lumps do not need to be culled.
These can be seen or felt on the outside of the udder and are usually a result of infections within the udder tissue. There is usually generalised hardness/mastitis or lumps in the affected udder half, but not always. There is insufficient data on the effects of a small burst abscess with no other obvious udder defects, but the safest option is to cull.
While abrasions and scarring on teats is normal due to damage from lambs, ewes with missing or very damaged tests should be culled. Ewes that have a thickened core down the centre of one or both teats at four to six weeks after weaning should be culled. This thickened core is not important at weaning and is only a problem if it is still there at four to six weeks after weaning.