Administration of pregnant mare serum gonadotropin to Japanese quail (Coturnix coturnix japonica):: dose response over seven days and comparison of delivery by daily injection or osmotic pump

AIMS: This study is part of a research programme that aims to develop a method of hormone treatment to stimulate breeding in female birds. The aims of this study were to compare dose rates and two different delivery methods, daily injection or osmotic pump, for hormone treatment of Japanese quail (Coturnix coturnix japonica) with pregnant mare serum gonadotropin (PMSG). METHODS: PMSG (0, 5, 10, 20, 40 and 80 IU PMSG/day) was administered to 6-week-old Japanese quail housed under short-day, cool-temperature conditions (8L:16D at 7-10degreesC) by daily injections or osmotic pump for 7 days. Three additional groups were untreated: one group was dissected at Day 0, and two groups were maintained under either short-day, cool-temperature or long-day, warm-temperature (16L:8D, 20degreesC) conditions for 7 days. Cloacal diameter was measured daily, and ovarian and oviductal mass and plasma oestradiol concentrations measured at the end of the treatment period. RESULTS: PMSG treatment stimulated ovarian and oviductal growth. After 7 days of treatment with 10-20 IU PMSG, ovarian and oviductal mass were similar to those in birds moved from short to long days. Females treated with the highest doses of PMSG (40 or 80 IU) had significantly larger cloacal diameters and ovarian and oviductal mass than other treated birds or birds maintained under long-day, warm-temperature conditions. Daily injections and osmotic pumps were equally effective methods of delivery. However, there was considerable variation in response to PMSG among individual birds and this was particularly obvious at the higher doses (20-80 IU PMSG). There were no differences in plasma oestradiol concentrations between groups treated using daily injections or osmotic pumps. CONCLUSIONS: A dose of 10 IU PMSG/day was chosen for use in future experiments with Japanese quail, for the first 7 days of treatment. The delivery method of choice for future studies will depend on the practical considerations of the research in question.