Effects of progesterone and Pregnant Mare Serum (PMS) adminsitration in the anoestrous ewe.  I. Oestrus, ovarian changes, and gonadotrophic potency of the pituitary gland

Raeside, J. I.; Lamond,

doi:10.1071/ar9560591

Cited by 9 publications

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“…Treatment with progesterone did not induce oestrous activity during the non-breeding season. This is in agreement with observations by Raeside & Lamond (1956), Gordon (1958) and McDonald (1961) who have shown that gonadotrophin as well as progesterone is necessary to induce ovulation with oestrous in anoestrous ewes. Wishart (1966), Cumming & McDonald (1967), Moore & Hoist (1967), and Robinson & Smith (1967) have reported that the onset of the breeding season was advanced by treatment with a single course of progesterone during late anoestrus.…”

Section: Seasonal Variation In Oestrous Behavioursupporting

confidence: 94%

Effect of Oestrogen on Oestrous Behaviour and Its Variation With Season in the Ewe

Fletcher¹,

Lindsay²

1971

Journal of Endocrinology

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The effects of dose of oestrogen and season on the expression of oestrous behaviour was studied in 60 spayed and 16 intact ewes.In progesterone-primed spayed ewes the incidence and duration of oestrous behaviour increased and the interval between injection of oestrogen, and onset of oestrous behaviour decreased as the dose of oestrogen was increased. The linear regression of duration of oestrus on log dose of injected oestrogen provided the most precise measure of the effect of changing dose level of oestrogen on oestrous behaviour.The sensitivity of spayed ewes to constant levels of oestrogen increased to a maximum near the middle of the breeding season and then declined to a minimum during the non-breeding season. In progesterone-synchronized intact ewes the interval between the end of progesterone treatment and onset of oestrus was at a minimum, and duration of oestrus at a maximum, near the middle of the breeding season. By bioassay it was estimated that endogenous oestrogen production was greater near the middle ofthe breeding season than at either the beginning or end.It is concluded that seasonal variation in the expression of oestrous behaviour in intact ewes is controlled by changes in both the production of endogenous oestrogen and the sensitivity of ewes to it.

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Section: Seasonal Variation In Oestrous Behavioursupporting

confidence: 94%

Effect of Oestrogen on Oestrous Behaviour and Its Variation With Season in the Ewe

Fletcher¹,

Lindsay²

1971

Journal of Endocrinology

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“…The ovulations induced by injections of progesterone and PMS appeared to be normal and were associated with a weight increase of the uterus which assumes cyclic activity at an induced oestrus (Robinson, 1950;Raeside & Lamond, 1956). Also, ovulation was associated with an apparent release of gonadotrophin from the pituitary gland.…”

Section: Discussionmentioning

confidence: 94%

“…The weight of the uterus in control ewes was significantly lower than in ewes injected with progesterone and PMS, or of those subjected to the short-day treatment. This weight increase in the treated groups was presumably in response to the attainment of cyclic activity shown to occur in the uterus when ovulation is induced (Robinson, 1950;Raeside & Lamond, 1956).…”

Section: The Weight Of the Ovaries And Uterusmentioning

confidence: 92%

“…Their results confirm much earlier work that ovulation normally follows the injection of PMS (with or without progesterone pre-treatment) though oestrus may not accompany the ovulation (Cole & Miller, 1933;Gordon, 1958; and many others). However, Raeside & Lamond (1956) were unable to identify the factors involved in the failure of oestrus which they observed.…”

Section: Introductionmentioning

confidence: 96%

“…Although non-lactating animals conceive at normal rates when oestrus is induced, conception rates have been low in ewes lactating strongly when treated (Gordon, 1958;Allen, 1959). Raeside & Lamond (1956) attempted to assess the normality of induced ovulations. Their results confirm much earlier work that ovulation normally follows the injection of PMS (with or without progesterone pre-treatment) though oestrus may not accompany the ovulation (Cole & Miller, 1933;Gordon, 1958; and many others).…”

Section: Introductionmentioning

confidence: 99%

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The Induction of Breeding Activity in Lactating Ewes During Anoestrus

Allen¹,

Ge²

1960

Reproduction

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Forty lactating ewes were used in experiments to compare reproductive phenomena when they were slaughtered : ( ) during normal anoestrus (Control), (2) after breeding activity had been induced by a series of three intra-muscular injections of 50 mg of progesterone (in oil) at 3-day intervals, followed after 48 hr by a subcutaneous injection of 750 i.u. of PMS, (3) after breeding activity had been induced, in response to the animals' endogenous endocrine secretions, by artificially manipulating the diurnal light : dark ratio.Untreated control ewes showed no evidence of recent ovulations but a degree of ovarian activity was present as measured by the number of medium-and large-sized ovarian follicles.Injections of progesterone and PMS induced ovulation in nineteen of the twenty ewes treated and oestrus accompanied ovulation in twelve ewes. However, in ewes which mated there was a complete failure of fertilization which could not be attributed to poor semen quality.Manipulation of the diurnal light : dark ratio induced ovulation in all ten treated ewes and oestrus was observed in nine ewes. Oestrus was preceded by a 'silent heat'. The response to this form of treatment was slow but uniform. Of the ova recovered 41.2 % were cleaving. A semi-quantitative estímate of the potency of total gonadotrophin in the anterior pituitary gland indicated a significantly higher level of gonadotrophin in untreated control ewes than in ewes which ovulated, suggesting that both forms of treatment induced a release of gonado¬ trophin from the anterior pituitary gland.The results are briefly discussed.

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The induction of pregnancy in the anoestrous ewe by hormonal therapy V. Progesterone-pregnant mare's serum therapy on Clun forest maiden sheep and general conclusions

Gordon

1963

J. Agric. Sci.

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In a previous paper (Gordon, 19586) results were given on the application of progesterone-p.M.s. therapy in out-of-season breeding which showed that non-lactating ewes conceived more readily than lactating animals. In the trials with ' dry' sheep the most promising results, in terms of conception percentage, were noted in maiden yearling ewes. While results given earlier in this series (Parts II and III) suggest that a solution to the problem of out-ofsoason breeding, especially in lactating ewes, may lie in the use of repeated progesterone-p.M.s. therapy, there is some doubt whether such extended therapy is justifiable in applications to yearling (maiden) animals. Obviously, if there is strong evidence that a satisfactory practical result follows standard (single course) treatment, such information would be useful to the flock-owner. Trial 1The present work was to provide further information on the response of the maiden ewe, and to establish some of the reasons why this category of animal usually shows a better conception percentage than either mature 'dry' or lactating ewes. The work was restricted to animals of the Clun Forest breed, this being an obvious choice of sheep which flock-owners would use in out-of-season breeding. MATERIAL AND METHODSSheep. Experiments were undertaken in two flocks of Clun maiden ewes, made available by two co-operating farmers in Hampshire in 1958. A total of seventy-six was involved (flock 45, forty-seven ewes; flock 46, twenty-nine ewes), the sheep being approximately 1 year old and not previously exposed to the ram. Ten Clun rams were used in the matings (five per flock).Hormones and method of administration. Progesterone was used as an oil solution, 1 ml. containing 10 mg.; the solution was given intramuscularly.A freeze-dried preparation of P.M.S. was subcutaneously injected in all treatments.Treatment and field procedure. Treatment consisted of three doses of 50 mg. progesterone administered at intervals of 3 days; 750 i.u. of P.M.S. was given 2 days after the final progesterone injection. Injections commenced 29 March in flock 45 and 3 April in flock 46. In each instance, treatment was applied simultaneously to all animals.In flock 45, the first part of the experiment consisted of observations on the incidence of spontaneous oestrus in the Clun yearling ewe during the latter part of the normal breeding season. Two rams were 'raddled' and introduced among the fortyseven ewes on 10 February. Daily inspection for matings was made for a 47-day period which ended 29 March, the time at which hormone treatment commenced.The full complement of rams joined each flock following administration of P.M.S. All rams were ' raddled' and a daily record of matings maintained for a period of 2 weeks after the end of hormone treatment. Sheep were identified by plastic eartags, and prominently marked on the fleece for easy field recognition. The sheep on each farm were kept together in the one group for the period of pregnancy. They were on grass for the period of the experiment; no suppleme...

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Effects of progesterone and Pregnant Mare Serum (PMS) adminsitration in the anoestrous ewe. I. Oestrus, ovarian changes, and gonadotrophic potency of the pituitary gland

Cited by 9 publications

References 0 publications

Effect of Oestrogen on Oestrous Behaviour and Its Variation With Season in the Ewe

Effect of Oestrogen on Oestrous Behaviour and Its Variation With Season in the Ewe

The Induction of Breeding Activity in Lactating Ewes During Anoestrus

The induction of pregnancy in the anoestrous ewe by hormonal therapy V. Progesterone-pregnant mare's serum therapy on Clun forest maiden sheep and general conclusions

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