04/S02 Mating Ewe Lambs

Summary

There were many interesting results to come out of the Mating Ewe Lamb project as the individual lambs were followed through joining as ewe lambs and again as 1.5 year olds. The results from joining as ewe lambs highlighted that conception rates may not be solely attributed to the ewe live weight at joining. Much of the literature recommends that in order to achieve higher conception rates in ewe lambs they need to be between 45-55 kg live weight and condition score 3.
There was also a trend between condition score and conception rate and when investigated further a correlation between body weight and condition score was shown at joining. As a result the two effects can not be separated, so it can not be concluded if it was a body weight or condition score effect or a combination of both. The trial showed that while body weight and/or condition score was important, it also indicated that age was also very important. In this trial conception rates over 60% were achieved when animals were over 8 months of age. In addition there was a correlation seen between condition score and body weight, so naturally there was a trend between conception rate and condition score. It is also important to not exclude the possibility of a breed/maturity effect influencing the results.
The results from the subsequent joining as 1.5 year olds showed that conceiving, singles or multiples as a ewe lamb did not affect the mature weight (taken as 1.5 year olds), as compared to those ewes who failed to conceive as ewe lambs. The results also indicated that there was a benefit in early weaning that was used in the best practice group, where the best practice group ewes were more likely to conceive as 1.5 year olds if they had conceived as ewe lambs. This is in comparison to the ewes in the current practice group who were less likely to conceive if they had conceived as ewe lambs. The early weaning did not appear to affect the performance of the lambs that were weaned at 12 weeks; whilst only one set of data was available the early weaned lambs were actually almost 2kg heavier, than those weaned later.
Overall it appears as long as ewe lambs are managed well and kept in at least a condition score 3 and growing; there is no negative effect of joining ewe lambs.