Performances de reproduction des brebis berrichonnes du cher, romanov et croisées. II. – Composantes de la prolificité

Ricordeau, G.; Razungles, J.; Eychenne, Francis; Tchamitchian, L.; Lajous, Daniel; Mollaret, R.

doi:10.1186/1297-9686-8-1-25

Cited by 15 publications

(3 citation statements)

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“…Sidwell and Miller (1971) reported negative heterosis in crosses of Dorset X Columbia-Southdale and Suffolk x Dorset. Specifically with regard to lambing date, our results are consistent with those of Ricordeau et al (1976) in showing additivity in breed crosses.…”

Section: Heterotic Effectssupporting

confidence: 87%

Lambing Date and Lamb Production of Spring-Mated Rambouillet, Dorset and Finnsheep Ewes and Their F1 Crosses1

Iñíguez

Bradford

Mwai

1986

Journal of Animal Science

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The reproductive performance of 255 Rambouillet (R), Dorset (D), Finnsheep (F) and F1 ewes born in 1978-1979 (group I) and 1979-1980 (group II) and managed in a semiconfinement fall/winter lambing system was evaluated through 4 yr of age of all ewes and through 5 yr for a portion of group I ewes. Ewes were with rams from approximately May 1 to late September each year, with a 2-wk break late in July/early August. Traits considered were fertility (ewes lambed/ewes exposed), lambing date, litter size, lamb survivial and 70-d lamb weights. Breeds and crossbred groups differed significantly in lambing date, with DR crossbred ewes earliest and F ewes latest. Repeatabilities for groups I and II were .31 and .22, .24 and .24 and .11 and .07 for lambing date, fertility and litter size, respectively. There was no significant heterosis in lambing date, although DR ewes in both groups I and II were superior to (D + R)/2, by about 1 wk on average. There was significant positive heterosis for fertility and traits of which fertility is a component in FR ewes in group I, but none in group II. The FD ewes showed negative heterosis for litter size, -.23 (P less than .05) for group I and -.09 for group II. The results indicate: F and FD ewes are not well adapted to the Mediterranean climate where this experiment was conducted; there is little, if any, useful heterosis in crosses among these three breeds for lambing date or other reproduction traits and RD and R ewes are most suitable of the groups tested, while late onset of the breeding season limits the usefulness of even 50% Finnsheep ewes for an autumn lambing system in this environment.

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Section: Heterotic Effectssupporting

confidence: 87%

Lambing Date and Lamb Production of Spring-Mated Rambouillet, Dorset and Finnsheep Ewes and Their F1 Crosses1

Iñíguez

Bradford

Mwai

1986

Journal of Animal Science

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“…It seems from these that LS has an additive inheritance, since heterosis was small (1.4 %). This result agrees with several other studies (10,22,28).…”

Section: Litter Size and Its Components 21 Litter Sizesupporting

confidence: 94%

“…On the other hand, individual heterosis for OR was small and negative (-0.5 %) (6). This result shows that OR is controlled by additive genes and it is in agreement with those of Land et al (22) and Ricordeau et al (28). (20) 88 87 79 67 (5) Hankahan (15)…”

Section: Ovulation Ratesupporting

confidence: 85%

Reproduction and adaptation characteristics in D’man sheep

Lahlou-Kassi

Benlamlih

Boukliq

1988

AFSci

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D’man breed (D) is found in the oasis of the subsaharian regions of Morocco and reared usually in sedentary type of management with small flocks (< 10 ewes). Preliminary field surveys showed that D is early maturing, prolific and aseasonal. Hence, a multidisciplinary research programme on D was started in 1974. This paper reports the findings of these studies and describes the approach used to (1) characterize and evaluate the performances of D in field and station, (2) study the physiological mechanism involved in its peculiar reproduction and production, (3) study the genetic basis of reproduction parameters, and (4) evaluate use of D in crossbreeding schemes to improve the productivity of other Moroccoan breeds. Results show that D is one of the rare breeds that is simultaneously early maturing, highly prolific and completely aseasonal. However, studies on water turnover and nitrogen recycling show that D is not well adapted to hot climate and poor nutrition. Its reproduction parameters are relatively independent of photoperiod and related to a low sensitivity to negative oestrogen feedback. D male is characterized by high libido and can be used for synchronizing oestruses through the »ram effect». Crossbreeding experiments with non-prolific sheep confirm the heritability of reproductive parameters. However, the genetic basis for these is not yet well known.

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