Response of seasonally anoestrous ewes to small-dose multiple injections of Gn-RH with and without progesterone pretreatment

McLeod, B. J.; Haresign, W.; Ge, Lan

doi:10.1530/jrf.0.0650223

Cited by 105 publications

(52 citation statements)

References 11 publications

(14 reference statements)

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“…Kidding rates between 52 and 66% have been reported out-of-season using CIDR-G and eCG [12]. During the breeding season, the use of CIDR-G has been reported to produce a kidding rate of 61% with [13] and 63% without eCG [14]. Results of CGPE group in the present study showed improvement in kidding rates (88.9%) compared with those mentioned above.…”

Section: Discussionsupporting

confidence: 51%

The effects of progesterone priming on reproductive performance of GnRH-PGF2α-treated anestrous goats

2005

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-The objective of this experiment was to determine the effect of a 5-day progesterone priming prior to a GnRH-PGF 2α treatment on reproductive performance of anestrous goats. Thirtysix Mountain Black goats were randomly assigned in a 2 × 2 factorial arrangement and were administered intravaginally on day -12, either with 300 mg progesterone inserts (CGPE and CGP) or with 0 mg progesterone (GPE and GP) for 5 days. On day -6, the goats were injected with 100 µg GnRH, followed 6 days later by 15 mg PGF 2α (day 0), the time at which the goats in the CGPE and GPE groups were administered 300 IU eCG injections and those in CGP and GP groups were administered the control solution. The goats were exposed to four fertile bucks at 0 h and were checked for breeding marks at 6-h intervals for 72 h. Blood samples were collected from all goats for progesterone analysis. Progesterone concentrations increased only in CGPE and CGP during the period of device insertion but remained low in GPE and GP groups (P < 0.001). Progesterone levels at the time of GnRH injection on day -6 were basal (0.2 ± 0.04 ng·mL -1 ) among the groups and began to increase starting on day -2. Day 0 progesterone concentrations differed (P < 0.05) among groups and were significantly influenced by CIDR-G (P < 0.001). A similar proportion of goats expressed estrus and intervals to detected estrus were shorter (P < 0.05) in the CGPE and GPE groups than in GP with no difference between the CGPE, CGP and GPE or between CGP and GP groups. The number of goats ovulating based upon elevated progesterone levels on day 0 was significantly greater (P = 0.002) in CGPE (9/9) and CGP (9/9) than GPE (6/9) and GP (5/9) groups and was significantly influenced by CIDR-G (P = 0.03). All pregnant goats had elevated progesterone concentration on day 0 and none of the goats with basal progesterone levels became pregnant. Pregnancy and kidding rates, twinning percentage and the number of kids born per goat exposed were greater (P < 0.05) among goats treated with progesterone and eCG. In conclusion, progesterone priming and eCG are essential for producing higher rates of pregnancy and kidding in GnRH-PGF 2α -treated anestrous goats.

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Section: Discussionsupporting

confidence: 51%

The effects of progesterone priming on reproductive performance of GnRH-PGF2α-treated anestrous goats

2005

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“…While this may appear to be incompatible with current concepts of the need for high episode frequency to drive the final stages of follicular growth and maturation (McLeod et al, 1982b) The fact that maintaining ewes of both breeds in short days did not significantly prolong the breeding season in most cases beyond that found in the same breeds exposed to natural photoperiodic changes (Webster & Haresign, 1983) (Radford, 1961b;Wodzicka-Tomaszewska, Hutchinson & Bennett, 1967;Williams, 1974), in ewes subjected to constant light (Radford, 1961a) and in rams maintained in constant photoperiods (Howies et al, 1982), implying that in such circumstances the main importance of daylength is in entraining rather than driving the rhythm.…”

Section: Welsh Mountainmentioning

confidence: 73%

Evidence that the onset of seasonal anoestrus in the ewe may be independent of increasing prolactin concentrations and daylength

Worthy¹,

Haresign²

1983

Reproduction

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“…Although Guinness et al (1971) have claimed that silent ovulations before the first oestrus of the breeding season do not occur in the red deer hind, the phenomenon has been described in other seasonal ungulates (sheep: Walton et al, 1977; fallow deer: Asher, 1985). In the ewe it has been shown that progesterone priming is essential to ensure normal luteal function at the subsequent ovulation (McLeod et al, 1982;McLeod & Haresign, 1984). In addition, Legan et al (1985) have shown that some of the priming effects of progesterone require only low physiological concentrations of progesterone for as little as 3 days.…”

Section: Discussionmentioning

confidence: 99%

Oestrous cycles and the breeding season of the Pere David's deer hind (Elaphurus davidianus)

Curlewis

Loudon²,

Coleman³

1988

Reproduction

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Summary. Reproductive cycles were studied in a group of tame P\l=e`\reDavid's deer hinds. The non-pregnant hind is seasonally polyoestrous and, in animals studied over 2 years, the breeding season began in early August (2 August \ m=+-\ 3\m=.\3days; s.e.m., N = 9) and ended in mid-December (18 December \m=+-\5\m=.\7 days; N = 8) and early January (6 January \ m=+-\3\m=.\2days; N = 11) in consecutive years. During the anoestrous period, plasma progesterone concentrations were low (0\m=.\2\ m=+-\ 0\m=.\01 ng/ml) or non-detectable. During the breeding season, experiments were conducted to investigate synchronization of oestrus with exogenous progestagens. Oestrus occurred 32\p=n-\90h after progestagen removal. The changes in plasma progesterone concentrations which followed oestrus were similar to those seen after natural oestrus.

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Response of seasonally anoestrous ewes to small-dose multiple injections of Gn-RH with and without progesterone pretreatment

Cited by 105 publications

References 11 publications

The effects of progesterone priming on reproductive performance of GnRH-PGF2α-treated anestrous goats

The effects of progesterone priming on reproductive performance of GnRH-PGF2α-treated anestrous goats

Evidence that the onset of seasonal anoestrus in the ewe may be independent of increasing prolactin concentrations and daylength

Oestrous cycles and the breeding season of the Pere David's deer hind (Elaphurus davidianus)

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