Oestrus synchronization in dairy heifers using a progesterone releasing intravaginal device

This paper describes a pilot trial carried out, to investigate the use of progesterone releasing intravaginal device(PRID) in controlled breeding in heifers under South African conditions. PRID's containing progesterone and oestradiol benzoate were employed for oestrus synchronization and reproductive management in ten 18-month-old, well-managed, heifers in a commercial Transvaal highveld dairy herd. PRID's were inserted into the vagina of each animal and removed after 12 days. Oestrus observation was done continuously and on the first observed oestrus the heifers were artificially inseminated once. Oestrus detection continued normally for returns to oestrus. Pregnancy was confirmed by rectal palpation eight weeks after breeding if no return to oestrus had occurred. The incidence of clinical oestrus within 3 days after removal of the PRID's (defined as the oestrus response) was 90%. The conception or pregnancy rate following the first artificial insemination was 77.8%.