Limitations to Female Reproductive Efficiency

Niekerk, C.H. van

doi:10.1016/b978-0-408-10633-7.50040-x

Cited by 12 publications

(5 citation statements)

References 25 publications

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“…The evidence concerning the effect of lactation on post-partum ovarian activity appears inconclusive (Hunter 1968a, 6;Van Niekerk, 1979) although a delaying effect on the appearance of the first post-partum oestrus has been claimed (Barker & Wiggins, 19646). The relatively short rebreeding intervals (39-1 and 43-7 days) obtained with lactating ewes in the present investigation suggest that lactation is of only limited importance as a delaying factor.…”

Section: Resultsmentioning

confidence: 52%

Post-partum intervals to oestrus and conception in Yankasa sheep

Osinowo

Ekpe

1985

J. Agric. Sci.

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Section: Resultsmentioning

confidence: 52%

Post-partum intervals to oestrus and conception in Yankasa sheep

Osinowo

Ekpe

1985

J. Agric. Sci.

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“…This agrees with Hayder and Ali (2008) in Farafra ewes that lambed in October, and involution occurred at 28.72 ± 1.0 days postpartum which is slightly shorter than ewes that lambed in February (29.42 ±1.2) and in June (33.85 ± 1.1 days). According to Van Niekerk (1976), complete uterine involution occurred in ewes mostly between 28 and 35 days after parturition. It is also in agreement with the report of Greyling (2000) and Enginler et al (2017) whom stated that complete uterine involution in slaughtered animals is 28 days, the mean involution period in single and twin saturated does to be 27.10±0.43 and 28.29±0.54 days respectively, and complete uterine involution in goats occurred within 28 days postpartum.…”

Section: Discussionmentioning

confidence: 99%

Sonographic changes during Postpartum Uterine Involution in Sahel Goats (Capra hircus)

Majama,

Zakariah,

Sanda

et al. 2023

SJVS

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The use of ultrasonography as diagnostic tool is crucial in animal reproduction especially in pregnancy diagnosis and can be useful in the assessment of postpartum uterine involution. Uterine involution in does has been described using macroscopic and histological examination post-mortem. The present study was carried out to determine the time of uterine involution in live Sahel goats by measuring the uterine diameter using ultrasonography. A total of 35 non-pregnant does were estrus synchronized using 2 intramuscular injection cloprostenol (250µg/kg) at 11 days interval. All the does that came into estrus after the second treatment were allowed to run free with five bucks. Pregnancy was determined by ultrasonography and the does were monitored until successful parturition. It was found that the diameter of the uterus decreased from 88.6-118 mm on day 1 postpartum to 80.8-88.6 mm, 55.3-80.8, 45.6-55.3, 39.0-45.6 mm and 24.0-39.0 mm diameters on days 3, 7, 14, 21 and 28 postpartum respectively. In conclusion, postpartum uterine involution in Sahel does was completed by day 28 postpartum. This finding suggests that breeding of Sahel does can be considered after 28 days postpartum, particularly, in circumstances where suckling of the kids is not practicable or desired.

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“…Although the present study indicates that GnRH, at the dose used, is incapable of inducing cyclic ovarian activity in the early postpartum ewe, the results obtained with the FGA-sponge plus PMSG treatment are encouraging. Attempts to implement exactly twicea-year lambing on a flock basis by exogenous hormone treatment, have met with varying degrees of success (Speedy et al, 1976;Thimonier and Cognie, 1977), a fact which is probably related to the multiplicity of factors that can affect the early rebreeding of ewes (Hunter 1968a,b;Van Niekerk, 1979). More information is needed to establish whether there is a biological limitation on the part of the ewe to sustain a high level of lamb production when subjected to twice-yearly lambing.…”

Section: Ovarian Response Of Ewes To a 12-day Fga-sponge + Pmsg Treatmentioning

confidence: 99%

Effect of GnRH-Induced Endogenous Luteinizing Hormone Release and Exogenous Progestogen Treatment on Ovarian Activity in the Postpartum Ewe

Ainsworth

Lachance

Labric

1982

Journal of Animal Science

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In two experiments, 64 crossbred ewes that had lambed in September or January and had their lambs removed within 24 h after birth were assigned to four groups and given the following treatments: group 1 (16 ewes)-1 ml saline, im or iv on d 10 postpartum; group 2 (24 ewes)-150 microgram/gonadotropin releasing hormone (GnRH) in 1 ml saline, im or iv on d 10 postpartum; group 3 (16 ewes)-150 microgram/GnRH in 1 ml saline, im or iv on d 10 postpartum, plus 40 mg fluorogestone acetate (FGA)-impregnated intravaginal sponges for 12 d beginning 22 d postpartum and group 4 (eight ewes)-40 mg FGA-impregnated intravaginal sponges only for 12 d beginning 22 d postpartum. Pregnant mare's serum gonadotropin (500 IU) was injected im into FGA-treated ewes at the time of sponge removal. Blood samples were collected from eight ewes in groups 1 and 2 at regular intervals up to 2 and 6 h, respectively, after treatment and analysed for luteinizing hormone (LH). Plasma progesterone (P) levels in blood collected once or twice weekly were used to monitor ovarian activity. GnRH induced a release of LH in all ewes monitored, whereas the LH levels remained unchanged in saline-treated ewes. Only 44% of the latter ewes had shown evidence of luteal activity by 50 d postpartum. The mean plasma P levels in the GnRH-treated ewes did not rise above basal preinjection values during the 14 d after treatment. In contrast, a synchronized ovulation followed by normal luteal activity was induced in 88% of the FGA-sponge-treated ewes. Of 16 ewes from group 2 slaughtered 26 d postpartum, 13 had ovaries that contained luteinized structures and uterine involution was incomplete in six ewes. These results preclude the use of GnRH as a single injection for induction of cyclic ovarian activity in the early postpartum ewe and indicate the need for progestogen treatment to initiate cyclic ovarian activity by 35 d postpartum. However, incomplete uterine involution may limit the number of ewes that can be successfully rebred at this time.

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Limitations to Female Reproductive Efficiency

Cited by 12 publications

References 25 publications

Post-partum intervals to oestrus and conception in Yankasa sheep

Post-partum intervals to oestrus and conception in Yankasa sheep

Sonographic changes during Postpartum Uterine Involution in Sahel Goats (Capra hircus)

Effect of GnRH-Induced Endogenous Luteinizing Hormone Release and Exogenous Progestogen Treatment on Ovarian Activity in the Postpartum Ewe

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