The Use of Progesterone in the Synchronization of the Estrual Periods in a Group of Ewes and the Effect on their Subsequent Lambing Records

O'mary, C. C.; Pope, A. L.; Casida, L. E.

doi:10.2527/jas1950.94499x

Cited by 29 publications

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“…This was chosen on the basis of (a) the known data on cytological changes in the corpus luteum late in dioestrus, and (6) the interval which ensues between the cessation of progesterone treatment and the onset of oestrus in either the cyclic or the anoestrous ewe in which ovulation occurs as the result of either endogenous or injected gonadotrophin [e.g. Dutt & Casida, 1948;O'Mary, Pope & Casida, 1950;Dutt, 1952Dutt, , 1953Robinson, 1952, 19546].…”

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confidence: 99%

The Behavioural and Vaginal Response of the Spayed Ewe to Oestrogen Injected at Various Times Relative to the Injection of Progesterone

Moore¹,

Robinson²

1957

Journal of Endocrinology

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confidence: 99%

The Behavioural and Vaginal Response of the Spayed Ewe to Oestrogen Injected at Various Times Relative to the Injection of Progesterone

Moore¹,

Robinson²

1957

Journal of Endocrinology

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“…Fertility from natural service was variable; the factors causing the variation were not obvious. Fertility has been variable, though generally low in numerous other studies in which ewes (Dutt & Casida, 1948; O'Mary, Pope & Casida, 1950;Hunter, 1954; Robinson, 1956Robinson, , 1960, cows (Willett, 1950; Ulberg, Christian & Casida, 1951;Trimberger & Hansel, 1955;Nellor & Cole, 1956;Ulberg & Lindley, 1960), and sows (Baker, Ulberg, Grummer & Casida, 1954) have been inseminated at the first heat after progesterone suppression of oestrous cycles. It is conceivable, however, that there might be an optimum doseinterval relationship for progesterone which will give a high degree of syn¬ chronization accompanied by high fertility.…”

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Oestrus, Ovulation and Fertility Following Suppression of Ovarian Cycles in Merino Ewes by Progesterone

Lamond¹,

Bindon²

1962

Reproduction

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Summary. Progesterone was administered to Merino ewes in February (early breeding season) and May (mid-breeding season) for 2 weeks. The period from the final progesterone injection to the onset of oestrus, the duration of oestrus, and fertility after hand mating were observed. The approximate time of ovulation was also determined in the February experiment.The duration of oestrus was 10 to 50 hr; ovulation took place near the end of oestrus. The period from the last injection to the onset of oestrus, and the fertility of the ewes were influenced by dose, interval between consecutive progesterone injections, the time of day that the injections were given, and the stage of the breeding season. Variability in onset of oestrus (indicating the degree of synchronization of oestrus) was least when the final injections were given in the morning.The results clearly show that normal levels of fertility may be achieved after synchronization of oestrus in Merino ewes with progesterone.

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“…A considerable degree of control over the time of ovulation in the cyclic ewe may be obtained by the daily injection of 10 mg. progesterone, followed by cessation of treatment (Dutt & Casida, 1948;O'Mary, Pope & Casida, 1950;Hunter, 1954;Gordon, 1958;Robinson, 1956Robinson, , 1958. The efficiency of this control appears improved by the injection of 500 i.u.…”

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The time of ovulation and efficiency of fertilization following progesterone and pregnant mare serum treatment in the cyclic ewe

Robinson

1961

J. Agric. Sci.

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A factorial experiment designed to determine the time of ovulation relative to oestrus and to the cessation of progesterone treatment in cyclic maiden ewes, and subsequent fertilization of ova, is described. Seventy-two ewes were used. Factors were: (a) type of service (natural v. A.I with fresh undiluted semen v. A.I. with semen diluted 1:1 with heated cows' milk); (b) frequency of progesterone (daily v. every 2 days); (c) post progesterone withdrawal treatment (500 i.u. PMS v. no PMS); (d) week of treatment (3 successive weeks); and (e) days within weeks (2 successive days). Insemination was carried out on the third day after cessation of progesterone without reference to the results of teasing with vasectomized rams.Progesterone (20 mg.) administered every 2 days was as effective as 10 mg. administered daily for suppression of ovulation. PMS resulted in a highly significant increase (P < 0·001) in the numbers of ewes which ovulated and which exhibited oestrus after progesterone, and in the number of fertile ewes (P < 0·05).There was a considerable spread of time of onset of oestrus and of ovulation. This was unaffected by any treatment. Most ewes were served 24–96 hr. (peak 48–84 hr.) and ovulated 48–108 hr. (peak 72–108) after cessation of progesterone. The time relationships of oestrus, ovulation and ovum transport appeared normal.

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The Use of Progesterone in the Synchronization of the Estrual Periods in a Group of Ewes and the Effect on their Subsequent Lambing Records

Cited by 29 publications

References 0 publications

The Behavioural and Vaginal Response of the Spayed Ewe to Oestrogen Injected at Various Times Relative to the Injection of Progesterone

The Behavioural and Vaginal Response of the Spayed Ewe to Oestrogen Injected at Various Times Relative to the Injection of Progesterone

Oestrus, Ovulation and Fertility Following Suppression of Ovarian Cycles in Merino Ewes by Progesterone

The time of ovulation and efficiency of fertilization following progesterone and pregnant mare serum treatment in the cyclic ewe

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