Ovarian Responses in Relation to Endocrine Status Following PMSG Stimulation in the Cow

Ovarian features contributing to the variability of PMSG-induced ovulation rate in sheep

“…This has previously been reported for cattle: when response to PMSG was related to the features of the surface follicular population, ovaries devoid of large follicles and rich in small ones had the highest response (Saumande et al, 1978). Administration of PMSG, together with a luteolytic agent at different days of the luteal phase, produces a higher response after Day 8 (Phillippo & Rowson, 1975;Sreenan et al, 1978) (Schams et al, 1978).…”

“…\ 8\ p=n-\ 2\ m=. \ 0mm in diameter, and (iii) Murphy et al, 1984; day of the cycle when the stimulation is performed : Phillippo & Rowson, 1975;Sreenan et al, 1978) and while the mechanisms of PMSG action have been clarified (Dott et al, 1979), our understanding of the factors responsible for the great variability in gonadotrophininduced ovulation rate is still very limited. In cattle, this variability was linked to the number of follicles in the growth phase (Monniaux et al, 1983 (Bindon et al, 1986).…”

CONCENTRATIONS OF LUTEINIZING HORMONE, OESTRADIOL-17β AND PROGESTERONE IN THE PLASMA OF HEIFERS TREATED TO INDUCE SUPEROVULATION

“…Such a relationship has previously been demonstrated on day 10 or later (Lamond & Gaddy, 1972;Lemon & Saumande, 1972;Hallford, 1975;Sreenan, Beehan & Gosling, 1978), but other authors have been unable to show any such connection (Rajamahendran, Laguë & Baker, 1976;Schams, Menzer, Schallenberger, Hoffmann, Hahn & Hahn, 1978). However, despite the high value of the correlation coefficient this relationship cannot be used to predict the number of corpora lutea with precision from the level of progesterone (see Fig.…”

Embryo Transfer in Cattle

“…Probably the most comprehensive work in this area was that reported by Sreenan et al (1978); they compared the three synchronizing agents, PGF 2a , Norgestamet implants and intravaginal sponge pessaries (impregnated with progesterone or FGA) as the means of controlling oestrus in donors that received a dose of PMSG 2 days prior to withdrawal of progestagen or administration of PGF 2a . Although the average ovulation and fertilization rates were similar, regardless of synchronizing treatment employed, the oestrous response was higher and the ovulatory response less variable with the PMSG-PG regimen than with the progestagen treatments.…”