This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by CARRICK, M. J. Articles by SHELTON, J. N. Search for Related Content PubMed PubMed Citation Articles by CARRICK, M. J. Articles by SHELTON, J. N.

THE SYNCHRONIZATION OF OESTRUS IN CATTLE WITH PROGESTAGEN-IMPREGNATED INTRAVAGINAL SPONGES

Summary.: Two experiments were conducted to determine the efficacy for synchronization of oestrus and ovulation in cattle of 17-acetoxy-9-fluoro-11β-hydroxyprogesterone (`Cronolone') administered by daily intramuscular injections or by intravaginal sponge.

In Experiment 1, cylindrical sponges were retained in 69·4% of heifers, while in Experiment 2 `bunched' sponges were retained in 82·8% of cows.

Daily intramuscular injection of 2 mg, or insertion of intravaginal sponges containing 100 mg, blocked oestrus and ovulation in the majority of animals. Within 5 days of termination of treatment in Experiment 1 oestrus occurred in 65·0% of heifers after intramuscular treatment and 55·6% after intravaginal treatment, while 53·5% of cows in Experiment 2 were oestrous within 7 days of sponge withdrawal. Synchronization of oestrus appeared more precise after intravaginal than intramuscular treatment in Experiment 1, but this was not significant. Of the oestrous animals, 95% of heifers (Experiment 1) compared with 56·5% of cows (Experiment 2) were oestrous 1 to 2 days after termination of intravaginal treatment.

In Experiment 1, heifers were inseminated late in oestrus, resulting in a pregnancy rate 8 weeks after insemination of 53·8% of oestrous heifers following intramuscular treatment and 30·0% following intravaginal treatment (difference not significant).

In Experiment 2, cows were inseminated 24, 36, 48, 60, 72 or 84 hr after withdrawal of sponges regardless of the occurrence of oestrus. Twelve to 15 weeks after insemination the pregnancy rate was 23·0% for oestrous cows and 18·6% for non-oestrous cows (difference not significant). There was a significant (P<0·05) quadratic effect of time of insemination with the highest pregnancy rate in cows inseminated 48 and 60 hr after withdrawal of sponges (30·6 and 29·2%).

Insemination of cows 24 hr before observation of oestrus resulted in a pregnancy rate equal to that obtained from inseminations 0 to 12 hr after observation of oestrus. This is suggestive of early ovulation relative to time of oestrus or an abnormal pattern of sperm transport.

Whilst `Cronolone' impregnated sponges are quite effective in suppression of oestrus and ovulation, the occurrence of oestrus and the fertility to insemination after treatment are unsatisfactory and not superior to those reported after intramuscular injection or feeding of progestagens.