Effect of weaning pre‐ or post‐mating on performance of spring‐mated ewes and their lambs in New Zealand

deNicolo, G.; Morris, S. T.; Kenyon, P. R.; Morel, P. C. H.

doi:10.1080/00288233.2006.9513716

Cited by 17 publications

(10 citation statements)

References 20 publications

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“…The current experiment indicated that aseasonal reproductive performance is low (August, 45-54%; November, 41-49%; January, 39-68%). These results are similar to the findings of other studies where aseasonal breeding has occurred: Smith et al (1988a) achieved conception rates of 30-52% August-, october-and December-bred ewes, Knight et al (1989b) anddeNicolo et al (2006) reported pregnancy rates from 47-55% and 33-36%, respectively, in December-bred ewes, and Morris et al (1993) reported pregnancy rates of 64-76% in January-bred ewes.…”

Section: Discussionsupporting

confidence: 89%

“…A conclusion that can be drawn from both this current experiment and that reported by deNicolo et al (2008c) is that increasing lamb weaning weight (particularly those born outside of the normal spring lambing period) may be a practical method for improving the lamb output of accelerated and out-ofseason lamb production systems. Delaying weaning and breeding ewes while they are still suckling lambs has previously been shown to be an effective means of increasing lamb weaning weight without affecting reproductive performance in spring-bred ewes (deNicolo et al 2006).…”

Section: Discussionmentioning

confidence: 99%

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Ewe reproduction and lambing performance in a five period mating system

deNicolo

Morris

Kenyon

et al. 2008

New Zealand Journal of Agricultural Research

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Section: Discussionsupporting

confidence: 89%

Section: Discussionmentioning

confidence: 99%

Ewe reproduction and lambing performance in a five period mating system

deNicolo

Morris

Kenyon

et al. 2008

New Zealand Journal of Agricultural Research

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“…De Nicolo et al (2006) reported that weaning of springborn lambs at ram introduction at 69 days postpartum did not improve fertility compared with ewes that continued to lactate for an additional 21 days when ewes in both groups were treated with CIDR and eCG; pregnancy rates averaged only 35%. Whiteman et al (1972) reported that only 23% of lactating Dorset, Rambouillet and Dorset × Rambouillet crossbred ewes managed in a twice-yearly lambing system in Oklahoma lambed again following spring lambing and 60 days of ram exposure beginning on April 20 (i.e.…”

Section: Discussionmentioning

confidence: 99%

“…These systems all recommend early weaning of lambs in order to improve fertility in spring matings, but early weaning is often not consistent with forage-based lamb production. Attempts to breed lactating ewes in spring have consistently been disappointing (Bourke, 1964;Whiteman et al, 1972;Cognie et al, 1975;Pope et al, 1989), and use of hormone or light manipulation to improve spring fertility has generally not been successful in lactating ewes (Restall et al, 1978;de Nicolo et al, 2006;Martemucci and D'Alessandro, 2010). Selection to improve ewe fertility in a crossbred (50% Dorset, 25% Rambouillet, 25% Finnish Landrace) sheep population mated in May and June at Virginia Tech (37°N latitude) resulted in significant selection response (Notter and Cockett, 2005) and correlated increase in duration of the breeding season (Vincent et al, 2000;Notter et al, 2011;Goff et al, 2013).…”

Section: Introductionmentioning

confidence: 99%

Strategies for rapid rebreeding of lactating ewes in the spring

Goff

Notter

Vanimisetti

et al. 2014

Animal

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Rapid rebreeding of winter-and spring-lambing ewes is essential if ewes are to lamb more than once per year, but fertility of lactating ewes is often low and early weaning of lambs may be undesirable in forage-based production systems. Selection to improve fertility in spring matings has been successful and led to development of ewes with a reduced seasonal anestrus. Potential for rapid rebreeding of lactating out-of-season breeding (OOS) ewes was tested in three studies. In Experiment 1, effects of short-term lamb removal on rebreeding was evaluated over 2 years using 71 January-lambing OOS ewes. At an average of 63 days postpartum, 36 ewes had lambs removed for 72 h, and all ewes were joined with rams. Circulating progesterone levels indicated that 74% of ewes ovulated before lamb separation; 91% of ewes mated within 5 weeks of ram exposure, 85% were diagnosed as pregnant and 75% lambed. The average interval between lambings was 225 days. In contrast to results observed in cattle, none of the measured variables was affected by lamb separation ( P > 0.20). Experiment 2 compared rebreeding performance of 24 OOS and 23 St. Croix ewes that lambed in January and averaged 60 days postpartum at ram introduction. More OOS ewes ovulated, mated and became pregnant during the first 21 days of ram exposure (83.3%, 58.3%, and 41.7%, respectively; P < 0.001) compared with St. Croix ewes (26.1%, 0%, and 0%, respectively). After 39 days of ram exposure, pregnancy rates still favored OOS ewes (66.7% v. 39.1%; P = 0.06), but the percentage of ewes that lambed did not differ ( P > 0.20) between OOS (47.8%) and St. Croix ewes (34.8%). In the third study, 34 March-lambing OOS ewes were exposed to rams on May 3 at an average of 40 days postpartum to characterize their reproductive performance. After 39 days of ram exposure, 52.9 ± 8.7% of the ewes had mated, and 38.2 ± 8.5% were diagnosed as pregnant. However, only 20.6 ± 7.0% of the ewes produced viable lambs, suggesting a high level of uterine insufficiency. Spring fertility of lactating OOS ewes in these studies was one of the highest reported in the literature and indicated that selection for fertility in spring mating would improve reproductive performance in accelerated lambing programs. However, exposure of lactating OOS ewes to rams at 30 to 50 days postpartum was associated with high prenatal lamb mortality.

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“…However, information differs, as it has been reported that weaning improved (Mandiki et al, 1990;Camacho-Ronquillo et al, 2008), or has no advantages (Warren et al, 1989;deNicolo et al, 2006) on the reproductive responses of ewes to hormonal treatments.…”

Section: Oestrus Synchronization In Postpartum Autumn-lambing Ewesmentioning

confidence: 99%

Oestrus synchronization in postpartum autumn-lambing ewes: effect of postpartum time, parity, and early weaning

Ungerfeld

Sánchez-Dávila²

2012

Span. j. agric. res.

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Three experiments were performed to determine the effect of postpartum time interval, the influence of parity (primimarous vs multiparous), and lamb weaning on the response of postpartum ewes to oestrus synchronization/induction treatments during the breeding season. In the Experiment 1 ewes were treated with an 8-days medroxyprogesterone priming and 350 IU of eCG, starting 14-18 (EPP), 24-30 (MPP), or 42-48 (LPP) days postpartum. More EPP than LPP ewes were marked by rams (p < 0.05), but conception rate was similar. In Experiment 2, 36 primiparous and 47 multiparous ewes that lambed during autumn received a 12-days medroxyprogesterone treatment followed by the introduction of rams. Ewes that came into oestrus, and that had a corpus luteum on Day 5 was greater in multiparous than in primiparous ewes (p = 0.04 and p = 0.03 respectively). Pregnancy rates on Day 35 and on Day 90 were similar. Experiment 3 was conducted with 26 ewes that remained with their lambs suckling during all the experiment, and 26 that were weaned ~27 days after birth, 3 days before the introduction of the rams. There were no differences on the percentage of ewes that came into oestrus, or the conception rate. We concluded that in postpartum ewes that had lambed during the breeding season: (1) is possible to induce fertile oestrus during early postpartum; (2) the early response was greater in multiparous rather than in primiparous ewes, although after a 35 d-breeding period differences disappeared and (3) weaning lambs early before stimulation did not improve the response.Additional key words: intensive breeding; lactation; postpartum anoestrous; progestagen; sheep. ResumenSincronización de celos en ovejas posparto que paren en otoño: efecto del intervalo posparto, la paridad y el destete temprano Se realizaron 3 experimentos para determinar el efecto del tiempo posparto, de la paridad (primíparas-multíparas) y el destete sobre la respuesta de ovejas posparto a una sincronización/induccción de celos durante la estación reproductiva. En el Experimento 1 se trató a las ovejas con medroxiprogesterona durante 8 días y eCG (350 IU), a los 14-18 (EPP), 24-30 (MPP), o 42-48 (LPP) días posparto. Más ovejas EPP que LPP (p < 0,05) manifestaron celo, siendo la tasa de concepción similar. En el Experimento 2 se utilizaron 36 ovejas primíparas y 47 multíparas que parieron durante otoño, y recibieron un tratamiento con medroxiprogesterona seguido de la introducción de carneros. El porcentaje de ovejas en celo, y ovejas que ovularon a los 5 días fue mayor en las multíparas que en las primíparas (p = 0,04 y p = 0,03 respectivamente); la tasa de preñez fue similar. En el Experimento 3 se utilizaron 26 ovejas que permanecieron con sus corderos lactando durante todo el experimento, y 26 que fueron destetados a ~27 días posparto, 3 días antes de la introducción de los carneros. No hubo diferencias en los porcentajes de ovejas en celo, ni en la tasa de concepción. Se concluyó que en ovejas postparto que parieron durante la estación reproductiva: (1) fue ...

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Effect of weaning pre‐ or post‐mating on performance of spring‐mated ewes and their lambs in New Zealand

Cited by 17 publications

References 20 publications

Ewe reproduction and lambing performance in a five period mating system

Ewe reproduction and lambing performance in a five period mating system

Strategies for rapid rebreeding of lactating ewes in the spring

Oestrus synchronization in postpartum autumn-lambing ewes: effect of postpartum time, parity, and early weaning

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