Ovarian and Estrous Activity Throughout the Year in Pregnant and Nonpregnant Ewes Selected for Extended Breeding Season

Dufour, J. J.; Fahmy, M. H.; Adelakoun, V.; Matton, P.

doi:10.4141/cjas82-129

Cited by 6 publications

(5 citation statements)

References 7 publications

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“…In the present study, and in those of Hulet et al (1914) and Dufour et al (1982), the sexual activity of the ewes during the summer following a long trip were different from that of the succeeding summer' In this study most of the ewes developed follicles Can. J. Anim.…”

Section: The Comparable Estimate Reported Bycontrasting

confidence: 52%

“…The present data suggest that the extension of the breeding season in this sample took place toward the end rather than at the beginning, since the two breeding seasons began almost a month later than that of 28 July reported earlier by Dufour (1914) and Dufour et al (1982) for two earlier studies on the DLS population' Since lambing in the preceding season interferes with the resumption of ovarian activity, many ewes would not benefit from this extended breeding activity towards the end of their season. Ewes which lamb and wean early may have a chance of resuming cycling activities before starting their anestrous period (Dufour et al 1982).…”

Section: The Comparable Estimate Reported Bysupporting

confidence: 39%

See 1 more Smart Citation

The Breeding Season and Ovulation Rate of DLS Ewes as Determined by Laparoscopy

Fahmy¹,

Dufour²

1986

Can. J. Anim. Sci.

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Section: The Comparable Estimate Reported Bycontrasting

confidence: 52%

Section: The Comparable Estimate Reported Bysupporting

confidence: 39%

The Breeding Season and Ovulation Rate of DLS Ewes as Determined by Laparoscopy

Fahmy¹,

Dufour²

1986

Can. J. Anim. Sci.

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“…No breed groups had more than 50% of ewes cycling in June or July. Dufour et al (1982) reported that a composite breed (DLS: ¹⁄₂ Dorset, ¹⁄₄ Leicester, ¹⁄₄ Suffolk) had a longer breeding season than any of the component purebreds. The DLS ewes began cycling Figure 4.…”

Section: Discussionmentioning

confidence: 99%

“…Patterns of estrous behavior were reported to be highly repeatable across years, and two ewes cycled continuously for the entire 4-yr period. Dufour et al (1982) reported that two of 29 DLS ewes cycled continuously from May 1 through the summer, but both had stopped cycling by April of the next year.…”

Section: Discussionmentioning

confidence: 99%

Duration of the seasonal anestrus in sheep selected for fertility in a fall-lambing system.

Vincent

McQuown

Notter

2000

Journal of Animal Science

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Crossbred ewes (1/2 Dorset, 1/4 Rambouillet, and 1/4 Finnsheep) from a flock being selected for spring fertility, defined as ability to lamb following ram exposure in May and June in Virginia (37 degrees N latitude), were used to study the duration of the seasonal anestrus. In the first 3 yr of the study (1992, 1993, and 1995), mature ewes were divergently selected based on EBV for fertility, and the duration of anestrus was measured by continuously exposing the ewes to vasectomized rams equipped with marking harnesses from mid-January until approximately August 1. Only ewes that had lambed in the previous fall were used to ensure that ewes were in a comparable physiological state, and the same rams remained with the ewes in each year to avoid induction of estrus by introduction of novel rams. The duration of anestrus in high-fertility ewes (n = 26; mean fertility EBV of 12.6%) was 28.4 d, which was significantly less than the 70.2 d of anestrus observed for low-fertility ewes (n = 15; mean fertility EBV of .3%). Five high-fertility ewes did not exhibit a period of anestrus. The regression of number of days of anestrus on fertility EBV was -2.15 +/- .72 d/%. In yr 4 (1997), 11 high-fertility and two low-fertility ewes were evaluated. None of these ewes exhibited a clear seasonal anestrus; six unequivocally cycled continuously. Between January 23 and July 31, the mean duration of anestrus for these ewes was only approximately 11 d. The duration of anestrus for high-fertility ewes seems to be the shortest reported for temperate sheep breeds.

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“…Few studies have been reported on the characteristics of occurrence of first oestrus in sheep but there is some evidence as in this study that the trait is heritable (Dufour, Fahmy, Adelakoun, and Matton, 1982). Few studies have been reported on the characteristics of occurrence of first oestrus in sheep but there is some evidence as in this study that the trait is heritable (Dufour, Fahmy, Adelakoun, and Matton, 1982).…”

Section: The Heritability Values Inmentioning

confidence: 53%

Prolificacy and 50-day lamb weight of ewes in the Cambridge sheep breed

et al. 1986

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The paper describes the results of the analysis of over 3000 records of Cambridge sheep kept on 11 farms over a 12-year period. The heritability of the number of lambs born per ewe increased from a low value for the 1-year-old ewes to a high value for the 3-year-old ewes; the multiple age value for 2-, 3-and 4-year-old ewes was 0-33 (s.e. 0-121). Heritability estimates for number of lambs surviving were lower, but showed the same trend of increasing values with increasing ewe age. This trend in heritability was also evident for the mean 50-day lamb weight, as a trait of the ewe, which had a multiple age value of 0-20 (s.e. 0-151). The estimates of heritability of various measures of early lamb mortality were relatively low. Date of first oestrus showed a variable heritability although the multiple age value was 0-42 (s.e. 0-149).Prolificacy was strongly correlated with various measures of early lamb mortality although the correlation with the final number of lambs weaned was positive. Prolificacy was positively correlated with the ewe's mature weight and the ewe's date of first oestrus and the genetic correlation with mean 50-day lamb weight was slightly positive.The effect of increases in prolificacy on numbers of lambs weaned was markedly curvilinear with maximum numbers of lambs weaned at an intermediate level of prolificacy. j •! Sire within year of birth of ewe J J J J

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Ovarian and Estrous Activity Throughout the Year in Pregnant and Nonpregnant Ewes Selected for Extended Breeding Season

Cited by 6 publications

References 7 publications

The Breeding Season and Ovulation Rate of DLS Ewes as Determined by Laparoscopy

The Breeding Season and Ovulation Rate of DLS Ewes as Determined by Laparoscopy

Duration of the seasonal anestrus in sheep selected for fertility in a fall-lambing system.

Prolificacy and 50-day lamb weight of ewes in the Cambridge sheep breed

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