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The use of progesterone administered intravaginally and pregnant mare serum gonadotrophin given by injection in controlled breeding programs in beef and dairy cattle
Author(s) -
MUNRO R. K.,
MOORE N. W.
Publication year - 1985
Publication title -
australian veterinary journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.382
H-Index - 59
eISSN - 1751-0813
pISSN - 0005-0423
DOI - 10.1111/j.1751-0813.1985.tb07319.x
Subject(s) - intravaginal administration , zoology , beef cattle , dairy cattle , medicine , obstetrics , biology , gynecology , physiology , andrology , vagina , surgery
SUMMARY Five experiments involving 1,244 cows and heifers were carried out to investigate the factors which might influence the calving performance to fixed‐time artificial insemination following intravaginal administration of progesterone (PRID) and intramuscular injection of pregnant mare serum gonadotrophin (PMSG). Factors examined were duration of PRID treatment, time of treatment after calving, time and dose PMSG and lactational status. Experiments 1, 2 and 3 were carried out on milked Friesian cows, experiment 4 on Friesian heifers and experiment 5 on suckled and dry Herefords. All cows were inseminated once with frozen/thawed semen 54 to 58 h or 46 to 50 h after completion of PRID treatment. Overall there was a progressive increase in calving rates with an increase in the duration of treatment from 12 to 14 to 16 days but there was little or no effect of time after calving (4 v 7 weeks) at which treatment was commenced. The poorer calving performance of cows treated for 12 to 14 days was associated with relatively high peripheral levels of plasma progesterone at the time of the PRID removal, suggesting the presence at the end of treatment of residual secretory luteal tissue. There was an effect on calving performance of PMSG given at the time of PRID removal but its effect varied according to the duration of PRID treatment. After 12 days treatments (experiments 1 and 5) PMSG had little effect, whereas after 14 days treatments, 0, 500 and 750 IU PMSG gave calving rates of 2770, 40% and 46% in experiment 2 and 5%, 24% and 38% in experiment 5. In cows treated for 16 days 0, 500 and 750 IU PMSG gave calving rates of 40%, 31% and 17% in experiment 2 and 24%, 35% and 27% in experiment 5. Experiment 3 showed an effect of time of PMSG injection. Cows were treated with PRIDS for 14 or 16 days and 22% and 39% calved following the injection of 500 IU PMSG at the time of, or 24 h before PRID removal. In experiment 5, 17% and 96%, respectively, of suckled and dry Herefords showed ovarian activity at the start of treatment, but ovarian status had no effect upon calving performance. However in Friesians lactational status appeared to have a major effect. In experiment 4, 75% of Friesian heifers treated with PRIDS for 14 days and given 500 IU PMSG calved whereas calving rates of milked Friesians (experiments 1, 2 and 3) rarely exceeded 40% but were not significantly different from the calving rates of untreated cows (experiment 3). The results of the experiments described in this paper indicate the treatment most likely to be successful in widespread use would be a 14 day PRID insertion with PMSG (500 IU for heifers and 750 IU for cows) injected 24 h before PRID removal.