Choosing the right age to breed maiden ewes
Determining the optimum age for first breeding maiden ewes isn't always straightforward - there will be gains in some areas and losses in others. For example, delaying maiden ewe breeding for 12 months will result in higher wool production from the ewe, but this needs to be carefully weighed-up against the potential for fewer lambs over the ewe's productive life cycle.
Conception rates and body weight of ewes
Maiden ewes need to attain a minimum body weight of about 33-35kg to reach sexual maturity, and generally at this weight have a conception rate of about 80%. Heavier ewes should do even better. A slight difference in weight, just by a few kilograms, reduces the conception rate by as much as 40%. If a ewe is lighter than 28kg they will not conceive, so ewe lambs born late in the lambing period may have difficulty reaching the required breeding weight in the following year.
In a well-managed breeding program, the average ewe is joined 5 times, first at about 1.5 years and last at 5.5 years, and can be expected to rear an average of 3.5 lambs over that time.
Delaying the first joining will not increase the productive breeding life of the ewe. It will, however, reduce the number of joinings possible during this period to 4, and reduce the total average number of lambs per ewe to 3. This means that about 50 fewer lambs will be produced per 100 ewes in their productive life span.
However, the benefits of delaying maiden ewe joining include:
- improved wool production
- increased growth rate
- higher final saleable value for their meat.
Wool production and lambing
Ewes that do not have a lamb will produce a heavier, higher quality fleece. Lambing places additional demands on the ewe and wool production is generally less.
The effects on wool production will be similar for ewes that lose their lamb after birth. However, ewes that conceive, but do not carry their lambs to term, will lose little in wool production.
Ewe mothering ability
Although mothering ability is heritable, it's something that is largely learnt through experience. Ewes on their first lamb, regardless of age, are generally poorer mothers, and a significant proportion of lamb losses that occur after birth can usually be attributed to this.