Strategies to increase reproductive efficiency of the ewe are crucial to the future profitability of sheep farming. Tools such as genetic selection and nutritional flushing for increasing ovulation rate are increasingly being used to improve lambing rates and, thereby, reproductive efficiency. Further, some farming systems include the breeding of ewes in their first year so that they lamb at one year of age. In order to successfully breed these ewes, they must attain puberty in their first breeding season of life. Hence, age at onset of puberty is a key event contributing to lifetime reproductive efficiency.
To study the effect of attaining puberty in the first year of life on future reproductive performance in ewes, records were collected from 2091 animals born over 5 years. In the first breeding season of life, receptivity to the ram was monitored to determine whether ewe lambs attained puberty or not. At 2, 3 and 4 years of age ewes were mated and the following traits were measured: ovulation rate (OR), number of fetuses present at scanning (NLS), number of lambs born (NLB) and live weight. Attainment of puberty in the first year of life increased NLB at 2 years of age, largely due to an increase in OR. Ewes that attained puberty in their first year were more likely to become pregnant at 2 years of age and produced more multiple births and fewer singletons. These differences were not maintained at 3 and 4 years of age. These results demonstrate that attaining puberty in the first year of life improves reproductive performance as a 2 year old, increasing NLB by 20 lambs per hundred ewes and reducing the incidence of non-pregnant ewes. This has implications for improving the efficiency of sheep production.