The aim of this study was to determine whether the presence and number of male and female twins affected the future milk yields of female ewes in adulthood. The study was based on 10,049 milk production records from 12 dairy sheep farms in Spain. Total milk yield (TMY) was categorized as either Low or High, and daily milk yield (DMY) was categorized as either Low/1, Intermediate-low/2, Intermediate-high/3, or High/4. Twins were categorized as follows: (1) ewes born without a twin (0 T), (2) ewes born with at least one female twin (at least 1FT: 1 and 2 sisters), (3) at least one male twin (at least 1MT: 1 and 2 brothers), or (4) with one male and one female twin (1MT+1FT: one brother and sister). Correspondence analyses indicated that ewes in the 0 T group were associated with low TMY and DMY, and twin births (at least 1MT and 1FT groups) were associated with 2-4TMY levels, and 3-4DMY levels. Mixed-effect-model indicated that ewes in the at least 1MT group had a positive effect on TMY (P< 0.05) and DMY (P < 0.01), than did ewes in the 0 T group. In summary, litter size and litter sex ratio in intrauterine life had a positive effect on milk production in ewes in adulthood. This effect is positively evidenced in ewes born with at least one-male-twins. This information might be useful in identifying ways to improve the economic-productive efficiency of sheep dairy systems. • Relationship between the presence and number of male and female twins • during foetal life affect the productive performance of adult dairy ewes. • Dairy lamb from male-twins’ parturition has positive effect on milk production • during adulthood compared with dairy ewes from singleton parturition. • The results can contribute to the development of management strategies and facilitate decision-making for increasing the efficiency of dairy sheep production systems.
Contreras-Solís et al. (Sun,) studied this question.