Oestrus and ovulation responses of gilts vary with different gonadotrophin treatments

摘要

When gilt availability is limited, a common method used to stimulate the onset of puberty is the injection of gonadotrophins such as 400 IU eCG plus 200 IU hCG (PG600). However, up to 30% of treated gilts do not show an oestrus response within seven days (Kirkwood, 1999). We hypothesize that this non-oestrus response is due to the hCG component of PG600 causing some gilts to either ovulate or luteinize follicles. In either event, the production of progesterone (P4) will block behavioural oestrus. Iftrue, then injection of eCG alone (i.e. no hCG component) should result in an improved oestrus response.