Retaining twin lambs born to hoggets as replacements?

This is a five-year project to study the lifetime ewe efficiency.

This project has two aims:

1) To demonstrate that both single and twin ewe lambs born to ewe hoggets can be bred as ewe lambs and their lifetime performance is not compromised. 
2) To determine if ewe lambs grown to heavy pre-mating weights achieve a heavier mature weight and any effect on ewe efficiency are discovered. 


Mating ewe lambs is now an accepted practice for over 30% of farmers. Several flocks are achieving 120% of lambs, meaning there are growing proportions of twin-lambs being produced by hoggets. Most farmers do not retain the ewe offspring from these hoggets as they are born later and are smaller than lambs from mixed-age ewes.

While not retaining these ewe offspring leads to a production efficiency gain over the ewe’s lifetime, it does not enable any genetic gain by using a younger ewe flock to be realised.

There is some evidence to suggest that while twin-ewes from hoggets are born smaller, they produce the same weight of lamb weaned as heavier ewes born to mixed-age dams. If this is correct, there is a potential efficiency gain by producing more weight of lamb weaned per unit of maternal weight per lifetime. The lifetime effects of mating the twin-ewe progeny of ewe hoggets at 8-9 months of age remain unknown.

Due to the availability of alternative forages such as red clover, chicory and plantain, some farmers can achieve ewe lamb mating weights in excess of 50kg. Farmer experience suggest these animals may grow to excessive mature weight which reduces their lifetime profitability due to increased feed consumption. If this is correct, there may be an optimal pre-mating growth strategy for ewe lambs that will reduce the negative impact of excessively heavy mature ewes while still achieving high hogget breeding performance.

Benefit for farmers

If farmers can confidently retain ewe offspring of hoggets, they may achieve greater efficiency (more kg of lamb weaned per kg of ewe live weight) and they have the potential to capture additional genetic gain generated by using a younger ewe flock.

This research will also assist farmers in understanding the consequences of excessive ewe lamb growth on lifetime efficiency.

Timeline and investment

This is a five-year project to study the lifetime ewe efficiency and is due for completion in February 2023. B+LNZ investment is $415,000 for the duration of the study.


This project is led by Massey University and co-funded by B+LNZ and Massey University.

Lead Scientist: Hugh Blair (Massey University).
B+LNZ point of contact: Suzanne Keeling.