Efficacy of two types of vaginal sponges to control onset of oestrus, time of preovulatory LH peak and kidding rate in goats inseminated with variable numbers of spermatozoa

摘要

In small ruminants, progestagen-impregnated vaginal devices (sponges) are useful tools to manage reproduction irrespective of season and to the application of timed artificial insemination (AI). A novel progestagen releasing vaginal-controlled release device (Chronogest CR), loaded with less (20 mg) cronolone using proprietary procedures, was developed and its efficacy (synchronising ability, fertility and prolificacy following sponge removal) evaluated versus the existing Chronogest sponge containing 45 mg of cronolone in goats. Females (n = 199) were maintained in field conditions and inseminated with graded amounts of spermatozoa at two stages of the year (breeding and non-breeding seasons). The use of the new Chronogest CR sponge was associated with an earlier initiation of the LH surge (28.7 h versus 30.8 h following sponge removal, P < 0.01). A similar degree of synchronisation of the LH surge was obtained with both types of sponges. In both treatment groups, a longer time interval between sponge removal and the LH surge was noted in females with high milk production. Fertility and prolificacy were high and unaffected by the type of sponge used or the amount of spermatozoa inseminated. It is concluded that the new Chronogest CR sponge allows a reduction of the progestagen load from 45 to 20 mg without detrimental effects on synchronisation, fertility and prolificacy.