干旱区生态环境知识资源中心

Inducing multiple births is one of the approaches to realize the target of 2 lamb/ewe/2 year (Lindsay. 1991). Twinning per cent in Bharat Merino, a synthetic dual-purpose sheep, is low (Annual report Central Sheep and Wool Research lnstitute 2002-03). The feasibility of increasing prolificacy as a mean to augment reproductive efficiency in an otherwise monotocous breed has to be weighed on the basis of overall ewe productivity for growth and reproduction are functionally antagonistic traits.

Progestagens either alone or with gonadotropin at the end of progestagen pretreatment have been used to induce fertile estrus in anestrus ewes for reducing lambing interval (Knights et al., 2001). Naqvi et al. (1998) synchronized estrus by progesterone priming and induced superovulation with eCG and FSH in Bharat Merino sheep at semi-arid region. As the reproductive performance of Bharat Merino is distinctly influenced by agro-climate (Singh et al., 1999), it is useful to generate information on synchronizatin response of Bharat Merino ewes at temperate region. Hence, an attempt was made on a small group of postpartum. Bharat Merino ewes to induce and synchronize estrus, to induce multiple births and to study the impact of increasing litter size on ewe productivity on the basis of live weight produced at 90 days.