Genetic parameters of spontaneous  spring ovulatory activity  in Mérinos d'Arles sheep

Hanocq, Éric; Bodin, Loýs; Thimonier, J.; Teyssier, Jacques; Malpaux, Benoît; Chemineau, Philippe

doi:10.1051/gse:19990105

Cited by 12 publications

(20 citation statements)

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“…Spontaneous ovulation in early spring in the MA ewe has been studied [11], and this trait was found to have a significant heritability (h 2 ϭ 0.20) in a model taking into account several physiological parameters such as weight and age of animals. This study and that of other authors [19,20] suggest the existence of a common overall factor involved in the control of reproductive seasonality.…”

Section: Discussionmentioning

confidence: 99%

“…The experimental animals, for which pedigree information was available over 5 generations involving 3044 animals, had been used in a previous experiment in which the genetic value of spontaneous spring ovulatory activity was determined [11]. These ewes were part of the experimental flock of the Domaine du Merle located in the Southeast of France (43.5ЊN).…”

Section: Choice Of Experimental Animals and Management Conditionsmentioning

confidence: 99%

“…Thus blood samples were collected from 293, 326, and 314 ewes over 1, 2, and 3 yr, respectively. The experimental ewes in which polymorphism was assessed were selected from among these 933 ewes for their genetic value, which takes into account their own ovulatory activity adjusted by environmental parameters and that of their relatives [11]. Two groups of 36 ewes, a ''low group'' (L) and a ''high group'' (H), were chosen as the most extreme ewes based on their genetic value for spring spontaneous ovulatory activity.…”

Section: Choice Of Experimental Animals and Management Conditionsmentioning

confidence: 99%

“…Some ewes completely cease ovulatory activity, whereas others show isolated ovulations during anestrus or continue to cycle throughout the year [9,10]. In the Mérinos d'Arles breed, raised in southern France, the presence of spontaneous ovulatory activity during spring in about 30% of ewes is a repeatable trait under genetic influence [11], suggesting that alleles of specific genes control the presence or absence of spontaneous spring ovulations.…”

Section: Introductionmentioning

confidence: 99%

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Association Between Expression of Reproductive Seasonality and Alleles of the Gene for Mel1a Receptor in the Ewe1

Pelletier¹,

Bodin

Hanocq

et al. 2000

Biology of Reproduction

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To determine whether a link exists between reproductive seasonality and the structure of the gene for melatonin receptor Mel(1a), the latter was studied in two groups of Mérinos d'Arles (MA) ewes previously chosen for their genetic value, which took into account their own out-of-season ovulatory activity adjusted by environmental parameters and that of their relatives. The genomic DNA of 36 ewes found regularly cycling in spring (group H) and that of 35 ewes never cycling in spring (group L) during the 2-3 yr before the present study was prepared, and the cDNA corresponding to almost all exon II was amplified and checked for the presence of MnlI restriction sites. The presence (+) or absence (-) of an MnlI site at position 605 led to genotypes "++", "+-", and "--", whose frequencies differed significantly (P < 0.001) between the H and L groups: 52.8%, 47.2%, and 0% vs. 28.5%, 42.9%, and 28.5%, respectively. Sequencing of exon II cDNA in group L ewes with genotype -- showed the presence of only one allele - with 4 mutations, while that in ewes with genotype ++ showed different types of alleles unrelated to the H or L groups. These + alleles exhibited a combination of 1 to 7 of the 8 mutations recorded in the part of exon II studied. The genotyping of 29 ewes from the more seasonal Ile-de-France breed indicated that 38% of animals had a -- genotype and exhibited the same mutations as in the MA ewes. Finally, a comparison of (125)I-melatonin binding to membrane preparations of pars tuberalis showed a lower number of binding sites (P < 0. 0005) in MA ewes with genotype ++ than in those with genotype -- (43. 2 +/- 4.4 vs. 75.4 +/- 8.4 fmol/mg protein in genotype ++ and genotype --, respectively). In conclusion, the data show an association between genotype -- for site MnlI at position 605 and seasonal anovulatory activity in MA ewes.

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Section: Discussionmentioning

confidence: 99%

Section: Choice Of Experimental Animals and Management Conditionsmentioning

confidence: 99%

Section: Choice Of Experimental Animals and Management Conditionsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Association Between Expression of Reproductive Seasonality and Alleles of the Gene for Mel1a Receptor in the Ewe1

Pelletier¹,

Bodin

Hanocq

et al. 2000

Biology of Reproduction

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“…Rather, the annual reproductive rhythm was highly variable among individuals. In domestic sheep, genetics factors have been shown to affect the characteristics of reproductive seasonality [50,51]. Therefore, the fact that some LP ewes did not show a clear rhythm of reproductive activity might be due to the existence of great genetic variation among the females of this breed with respect to photoperiod cues, a result of the selection process to which domestic sheep breeds are subject.…”

mentioning

confidence: 98%

Endogenous Circannual Cycles of Ovarian Activity and Changes in Prolactin and Melatonin Secretion in Wild and Domestic Female Sheep Maintained under a Long-Day Photoperiod1

Gómez-Brunet¹,

Santiago-Moreno²,

Campo³

et al. 2008

Biology of Reproduction

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The present study examines the ovulatory activity of wild and domesticated ewes subjected to either a constant photoperiod of long days (16L:8D) or natural changes in daily photoperiod for 16 mo. The aim was to determine whether an endogenous reproductive rhythm controls seasonal reproductive activity in these sheep, and how the photoperiod might affect this. The effects of long-day photoperiods on long-term changes in prolactin and melatonin secretion were also evaluated. The two species showed changes in reproductive activity under the constant photoperiod conditions, suggesting the existence of an endogenous rhythm of reproduction. This rhythm was differently expressed in the two types of ewe (P < 0.05), with the domestic animals exhibiting much greater sensitivity to the effects of long days. A circannual rhythm of plasma prolactin concentration was also seen in both species and under both photoperiod conditions, although in both species the amplitude was always lower in the long-day animals (P < 0.01). The duration of the nocturnal melatonin plasma concentrations reflected the duration of darkness in both species and treatments. The peak melatonin concentration did not differ between seasons either under natural or long-day photoperiods.

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Early evidence of sheep lambing de-seasoning in the Western Mediterranean in the sixth millennium BCE

Tornero

Balasse

Bréhard

et al. 2020

Sci Rep

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Today, sheep farmers in the Western Mediterranean de-season their ewes to achieve autumnal births. This strategy contrasts sharply with spring lambing further north, and provides benefits in terms of out-of-season availability of animal products. These competences are closely linked to specific sheep physiology and favorable Western Mediterranean climatic conditions. It is not known exactly how far back in the past the ability to de-season Mediterranean sheep breeds extends. This study shows that this practice existed seven millennia ago in Southern France, at an early stage of the major agricultural expansion of the Neolithic into the Western Mediterranean. To achieve this reproductive management regime, three prerequisites were required: (i) the ability of sheep to give birth in autumn, constituting early evidence for the genetic selection of specimens with prolonged reproductive fertility; (ii) intentional management of female and male interactions within the herd, which would have required good knowledge of the timing of the fertility cycle in ewes, and; (iii) adequate pasture resources to support lactation in the autumn, possibly favored by autumnal rains, substantiating previous paleoclimatological data for the existence of a Mediterranean-type precipitation regime at that time. Moreover, we also show that winter foddering of sheep occurred, using forest resources, and that this maintained good body weights for spring mating. These findings add pivotal information about shepherding practices and the socioeconomic abilities of Early Neolithic communities, which allowed for the extension of their areas of influence from the Eastern Mediterranean area to the West during the Early Neolithic agricultural expansion in Europe.

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Genetic parameters of spontaneous spring ovulatory activity in Mérinos d'Arles sheep

Cited by 12 publications

References 12 publications

Association Between Expression of Reproductive Seasonality and Alleles of the Gene for Mel1a Receptor in the Ewe1

Association Between Expression of Reproductive Seasonality and Alleles of the Gene for Mel1a Receptor in the Ewe1

Endogenous Circannual Cycles of Ovarian Activity and Changes in Prolactin and Melatonin Secretion in Wild and Domestic Female Sheep Maintained under a Long-Day Photoperiod1

Early evidence of sheep lambing de-seasoning in the Western Mediterranean in the sixth millennium BCE

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