Lambs born to ewes with udder defects are 3 times more likely to die. Those that survive will be about 2kg lighter at weaning on average.
Four to six weeks after weaning is the ideal time to check ewes’ udders to ensure there are no defects that could compromise lamb survival and growth rates.
Studies carried out by Massey University on North Island farms found that on average, five percent of mixed-age ewes have udder defects. Lambs born to ewes with udder defects have a death rate that is three to four times higher than lambs whose dams have normal udders.
Those that do survive, grow an average 25g/day less and their average weaning weight is 2kg lighter than their contemporaries.
When is the best time to check udders?
Research has shown that checking udders a few weeks before mating is better than examining udders at weaning. It is easier to feel some defects once the udder has dried off and many ewes with apparently normal udders at weaning are found to have udder defects four to six weeks later. This is possibly due to post-weaning mastitis.
How to check udders
To check udders effectively they must be palpated. This is best done while the ewe is standing in a race. Both halves of the udder should be gently squeezed and if possible, the teats rolled between the fingers.
What to check for
General hardness would indicate mastitis. If the infection is recent, the udder will be hot and swollen, but more commonly the infection will have been there for some time and the udder half or halves will feel hard all over.
Ewes with generalized hardness in one or both halves of their udder should be culled.
Lumps within the udder tissue can range in number and size. As a rule, ewes with lumps within the udder tissue should be culled.
If a farmer is short on ewe numbers, then retaining ewes with one or two very small lumps might be alright, provided the lumps are not near the teats.
It is normal for some ewes to have lumps just in front of, or behind, the udder. These are attached to the udder but not within the tissue. Ewes with these lumps can be retained.
Burst abscesses can be seen or felt on the outside of the udder. They are usually a result of infections within the udder tissue. There is usually generalised hardness/mastitis or lumps in the udder half (in which case the ewe should be culled), but not always. There is insufficient data on the effects of a small burst abscess with no other obvious udder defect, but culling is the safest option.
It is normal for ewes to have abrasions and scarring on their teats from lambs, however ewes with missing or very damaged teat ends should be culled.
Ewes that have a thickened core down the centre of one or both teats four to six weeks after weaning should be culled. A thickened core is not a problem if it is present at weaning.
For more information for ewe udders go to this video: Examining ewes' udders to identify possible problems.