Influence of dose, repeated treatment and batch of hormone on ovarian response in heifers treated with PMSG

Abstract

Summary. The

Embryo Transfer in Cattle

“…PMSG and PGF 2a after 48 h); they showed that most heifers responded satisfactorily to the repeat treatments and that even at the tenth application the response was comparable to that recorded after the second treatment. The Cambridge results were more encouraging than those reported by French workers around this time (Saumande and Chupin, 1977; who applied PMSG/PG treatments at 7-9 week intervals on several occasions; the results of Christie et al (1979) were in agreement, however, with several reports showing that ovarian response after a second PMSG treatment could be comparable to that after the first Newcomb eta/., 1979;Newcomb, 1980). In considering the potential of repeat superovulation treatments, the assumption is that non-surgical procedures will be employed in recovering embryos; even so, there are those employing surgical techniques who report acceptable superovulatory responses after four successive treatments (Marshall and Struthers, 1978).…”

“…The most thorough and encouraging evidence came in the report of Christie et al (1979) who took a small group of 14 heifers (mixed breeds) and subjected them repeatedly and at intervals of 6 weeks to a standard superovulation treatment (2000 i.u. PMSG and PGF 2a after 48 h); they showed that most heifers responded satisfactorily to the repeat treatments and that even at the tenth application the response was comparable to that recorded after the second treatment.…”

“…The PMSG molecule certainly possesses both FSH-and LH-like properties and it was this that led some to suggest that the ratio of these components may differ among the batches of the preparation available to laboratories and thereby influence ovarian response (Lamond, 1970). When batches of PMSG were analysed for their FSH and LH activity by several investigators, no significant difference in the FSG/LH ratio was evident (Stewart et a/., 1976;Schams eta/., 1978); controlled comparisons of batches used in superovulation studies also failed to reveal evidence of any real difference in the ovarian response of cattle Beehan and Sreenan, 1977;Newcomb et al, 1979).…”

Physical-chemical and biological characterization of different preparations of equine chorionic gonadotropin

“…In a study of heifers superovulated with 1,000 IU of three different batches of commercial eCG, Newcomb et al [27] were unable to identify differences in the ovulation rate between batches. However, one of the batches possessed, on average, 16.7% (maximum 41%) lower total gonadotrophic potency.…”

Ovarian Response, Serum Progesterone, Estrone and Estradiol-17β Levels in Heifers Treated with Low Doses of PMSG and hCG

“…(PG)-treated (4), superovulation I (6) and II (7). The first superovulation group (S-I) was induced by 1000 IU of PMSG 0 to 24 hours (h) after injection of 18mg of PG on days 10 to 14 of the cycle, and followed by 1000 to 1500 IU of hCG at the onset of estrus (day 0).…”