Application of Controlled Reproduction to Sheep Flocks in Newfoundland

Shrestha, J. N. B.; Ainsworth, L.; Heaney, D. P.; Smith, A. N.

doi:10.4141/cjas82-083

Cited by 3 publications

(2 citation statements)

References 4 publications

(4 reference statements)

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“…The corresponding values for ewes treated with PGF2 a were 63% and 1.3. In Newfoundland, field trials carried out over 3 years with commercial flocks showed that acceptable reproductive performance can be achieved after treatment with FGA-sponges and PMSG (111). Overall fertility was 76% from matings at the synchronized estrus and 94% to matings at the synchronized plus subsequent estruses during the normal breeding season.…”

Section: Manipulation Andmentioning

confidence: 99%

Research and technology for increasing the efficiency and output of lamb production systems

Canada¹

1987

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Section: Manipulation Andmentioning

confidence: 99%

Research and technology for increasing the efficiency and output of lamb production systems

Canada¹

1987

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“…The greater than expected fertility observed for control group treated with vaginal sponges could also be explained by the photoperiodic preparation of the rams. In fact, the fertility rate in hormonal synchronized control ewes, around 76%, is much greater than the rate normally observed for seasonal sheep breeds, such as Arcott Rideau, treated with sponges during this period of the year at similar latitudes (Shrestha et al, 1982;F. W. Castonguay, unpublished data).…”

Section: Performance Of Ewes Under the Photoperiod Regimenmentioning

confidence: 99%

Accelerated lambing achieved by a photoperiod regimen consisting of alternating 4-month sequences of long and short days applied year-round1

Cameron¹,

Malpaux²,

Castonguay³

2010

Journal of Animal Science

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the World Wide Web at:The online version of this article, along with updated information and services, is located on www.asas.org at Bibliotheque De L'Univ. Laval Section Des Acquisitions on September 10, 2010. jas.fass.org Downloaded from ABSTRACT: The objective of this work was to evaluate the reproductive performance of ewes exposed to a photoperiodic regimen consisting of continuous alternating 4-mo periods of long days (LD: 16 h of light/d) and short days (SHD: 8 h of light/d) in an accelerated lambing program of 3 lambings in 2 yr. A total of 211 prolific Rideau Arcott ewes were assigned to the photoperiodic treatment, whereas 37 ewes were maintained under natural annual variation in day length (control group). Ewes under the photoperiod regimen were divided into 4 subgroups (A, B, C, D). All these groups of ewes were exposed to the same light regimen, but the LD and SHD light sequences were staggered by 2 mo to permit the evaluation of the effect of time and season of mating on performance of the ewes treated with the photoperiod. The control ewes were treated with intravaginal sponges in the out-of-season breeding periods (conventional approach). Each group of ewes was studied over 3 reproductive cycles. Two groups of rams exposed to alternating 2-mo sequences of LD and SHD were used for mating. The short mean interval between ram introduction and conception for the groups exposed to artificial photoperiod (9.4 d) confirmed the effectiveness of the treatment to induce intense sexual activity. For the 12 breeding periods studied (8 in outof-season and 4 in sexual season), fertility rate of the ewes treated with photoperiod, mated at various times of year, was 91.6%, which is comparable with the fertility normally seen in the natural breeding season. The number of lambs born/ewe remained constant across reproductive cycles and was greater in photoperiodtreated groups (2.81 vs. 2.27 for photoperiod and control groups, respectively; P = 0.0002). Groups exposed to photoperiod treatment obtained better fertility rate than the control group in out-of-season breeding (91.1 vs. 76.3%; P = 0.016). Ewes managed under the photoperiod regimen produced 1.38 lambings/yr and 69% of them lambed 3 times in 2 yr. Overall, the ewes in the photoperiodic treatment produced annually 3.78 lambs/ ewe. The reproductive performances achieved throughout the years indicate that the photoperiodic program tested, consisting of continuous alternating 4-mo periods of LD and SHD, allows control of the annual reproductive cycles in ewes.

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Genetic basis of variation in reproductive performance. (2) Genetic correlation between gestation length and prolificacy in sheep

Shrestha

Heaney

1990

Animal Reproduction Science

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Application of Controlled Reproduction to Sheep Flocks in Newfoundland

Cited by 3 publications

References 4 publications

Research and technology for increasing the efficiency and output of lamb production systems

Research and technology for increasing the efficiency and output of lamb production systems

Accelerated lambing achieved by a photoperiod regimen consisting of alternating 4-month sequences of long and short days applied year-round1

Genetic basis of variation in reproductive performance. (2) Genetic correlation between gestation length and prolificacy in sheep

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