Ewe udder health and its effects on lamb production

The aim of this project was to develop an udder scoring system associated with udder health, lamb survival and lamb growth rates and can accurately be used by farmers.

To do this, the following was investigated:

  • recognise and describe the range of udder and teat defects found in commercially-farmed ewes
  • factors associated with clinical and subclinical mastitis in ewes
  • the impact of udder and teat defects and udder health on lamb survival and pre-weaning live weight gain.


Lambing percentages in New Zealand have increased over the past twenty years, putting increased emphasis on ewe udder health to enhance lamb survival and maximise pre-weaning growth rates.

Many farmers indicate that they examine the udders of their ewes and make culling decisions based on this. However, there is sparse information available, and therefore guidance, on what farmers should be examining and the impacts of various udder characteristics on lamb performance.

Without this knowledge, farmers may fail to cull ewes who will not rear lambs successfully or whose lambs will display poor growth rates. Conversely, they may incorrectly cull ‘sound’ ewes.

Key programme results

Udder scores can be used to determine culling decisions or identify ewes whose lambs had greater odds of failure to survive weaning.

Udder palpation, udder symmetry and clinical mastitis scores during lactation were associated with lamb growth rates.

Benefit to farmers

This project provided information and resources to more accurately assess ewe udder health and make sound culling decisions.

Lambs that are born to ewes with udder defects will have a reduced chance of survival and the lambs that do survive grow an average of 25g less per day than lambs whose dams had normal udders so for long term productivity, understanding udder defects is hugely important.


Six presentations

  • Six to farmer and industry audiences.

Popular press articles

Scientific publications

Timeline and investment

This was a four-year project. B+LNZ investment was $345,000 over the duration of the project.


This work was led by Massey University and funded by B+LNZ, Massey University, the C. Alma Baker Trust and Lincoln University.

Lead Scientist: Anne Riddler.
B+LNZ point of contact: Suzanne Keeling.