Conception Rates in Early Postpartum Ewes Bred Naturally or by Intrauterine Insemination

Warren, Jennifer E.; Kiesling, D.O.; Akinbami, Mukaila A.; Price, E. A.; Meredith, S.

doi:10.2527/jas1989.6782056x

Cited by 11 publications

(4 citation statements)

References 13 publications

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“…Because hair sheep ewes in the tropics have a short postpartum interval (Godfrey et al, 1998) and are aseasonal, they can rebreed while nursing lambs. Warren et al (1989) also reported no impact of lactation on conception rates in sheep. Wang and Dickerson (1991) used computer simulations to evaluate 3 lambing systems (annual, accelerated [3 lamb crops in 2 yr], and the STAR system [5 lamb crops in 3 yr]), and they concluded that an accelerated lambing system is best suited for breeds with a longer inherent breeding season and that the annual system is best for breeds with a short inherent breeding season.…”

Section: Resultsmentioning

confidence: 98%

Effect of weaning age on hair sheep lamb and ewe production traits in an accelerated lambing system in the tropics1

Godfrey

Weis

2016

Journal of Animal Science

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This study was designed to evaluate the impact of weaning age on lamb and ewe productivity in an accelerated lambing system. St. Croix White (STX) and Dorper × St. Croix White (DRPX) lambs were assigned at birth based on breed, gender, and litter size to be weaned at 63 (Early-1; 106 lambs and 68 ewes) or 90 d of age (Late-1; 99 lambs and 60 ewes) in Exp.1 or at 63 (Early-2; 77 lambs and 57 ewes) or 120 d of age (Late-2; 75 lambs and 56 ewes) in Exp. 2. After weaning, lambs were weighed weekly and fed a concentrate ration (2% BW·lamb·d) while grazing guinea grass pastures. In Exp. 1, weaning weight was greater ( < 0.0001) for Late-1 lambs than for Early-1 lambs (14.6 ± 0.3 vs. 11.0 ± 0.3 kg, respectively) and greater ( < 0.008) for DRPX lambs than for STX lambs (13.9 ± 0.4 vs. 11.5 ± 0.4 kg, respectively). Litter weaning weight was greater ( < 0.004) for Late-1 ewes than for Early-1 ewes (20.9 ± 0.8 vs. 17.4 ± 0.8 kg, respectively). Ewe efficiency ([ewe BW at weaning/litter weaning weight] × 100) was greater ( < 0.004) for Late-1 ewes than for Early-1 ewes (50.7 ± 1.9 vs. 42.3 ± 1.8%, respectively). Lamb weight gain between 63 and 90 d of age was lower ( < 0.03) for Early-1 lambs than for Late-1 lambs (2.7 ± 0.2 vs. 3.6 ± 0.3 kg, respectively). In Exp. 2, weaning weight was greater ( < 0.0001) for Late-2 lambs than for Early-2 lambs (18.7 ± 0.4 vs. 11.8 ± 0.4 kg, respectively) and greater ( < 0.008) for DRPX lambs than for STX lambs (16.9 ± 0.5 vs. 13.3 ± 0.5 kg, respectively). Litter weaning weight was greater ( < 0.0001) in Late-2 ewes than in Early-2 ewes (27.2 ± 1.0 vs. 17.5 ± 0.9 kg, respectively). Ewe efficiency was greater ( < 0.0001) for Late-2 ewes than for Early-2 ewes (68.1 ± 2.2 vs. 41.9 ± 2.0%, respectively). Lamb weight gain between 63 and 120 d of age was not different ( > 0.06) between Early-2 and Late-2 lambs (5.1 ± 0.2 vs. 5.6 ± 0.3 kg, respectively). In Exp. 1 and 2, ewe BW at breeding and lambing and weaning and lambing rate were not different among weaning ages of lambs ( > 0.17). The Early-1 ewes exhibited estrus earlier than Late-1 ewes (10.9 ± 0.9 vs. 13.9 ± 1.0 d, respectively) but there was no difference ( > 0.63) between Early-2 and Late-2 ewes. Weaning hair lambs at 90 or 120 d of age can be done in an accelerated lambing system with no detrimental effect on lamb or ewe productivity. Late weaning resulted in a decreased number of days that lambs received high-cost, imported feed without a reduction in growth, resulting in savings of US$6 to $15 per lamb.

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Section: Resultsmentioning

confidence: 98%

Effect of weaning age on hair sheep lamb and ewe production traits in an accelerated lambing system in the tropics1

Godfrey

Weis

2016

Journal of Animal Science

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“…Greater fertility also has been reported in ewes after intrauterine insemination at the uterotubal junction adjacent to the previously gravid than the previously nongravid uterine horn (Akinbami et al, 1996). However, in ewes induced into estrus 31 or 32 d postpartum, fertilization and conception rates were greater after intrauterine insemination near the uterotubal junction than after natural mating (Warren et al, 1989). The latter authors suggested that a detrimental uterine environment or a change in sperm transport restricted early postpartum conception.…”

Section: Discussionmentioning

confidence: 99%

Effect of the previously gravid uterine horn and postpartum interval on follicular diameter and conception rate in beef cows treated with estradiol benzoate and progesterone.

Bridges

Taft²,

Lewis³

et al. 2000

Journal of Animal Science

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An experiment was performed to evaluate the effect of the side of ovulation with respect to the previously gravid uterine horn on fertility of cows inseminated at one of two periods postpartum. All cows were treated with an intravaginal progesterone insert for 7 d and received estradiol benzoate (2 mg, i.m.) at the time of device insertion, prostaglandin F2alpha (25 mg, i.m.) at the time of device removal, and estradiol benzoate (1 mg, i.m.) 30 h after device removal. All cows were inseminated 28 to 30 h after the second treatment with estradiol benzoate, regardless of observed estrus. Cows treated in Period 1 received inserts at 16 to 20 d postpartum and were inseminated at 25 to 29 d postpartum. Cows treated in Period 2 received inserts at 26 to 30 d postpartum and were inseminated at 35 to 39 d postpartum. Diameter of the largest follicle at insert removal was greater in cows treated in Period 2 (10.1 +/- 0.3; mm +/- SEM) than in cows treated in Period 1 (9.1 +/- 0.3; P < .05). Diameter did not differ with the side of ovulation in respect to the previously gravid uterine horn. Diameter was greater in cows 5 to 9 (10.3 +/- 0.3) than in cows 3 to 4 (9.0 +/- 0.3) or 10 to 13 (9.4 +/- 0.6) yr of age (P < .01). The proportion of cows that ovulated from the ovary contralateral to the previously gravid uterine horn was greater (P < .05) than of those that ovulated from the ipsilateral ovary, and the incidence of ovulation was reduced in cows 3 to 4 yr of age (P < .01). Conception rate tended to be greater for ovulation from the ipsilateral compared with the contralateral ovary, relative to the previously gravid uterine horn (P < .10) and for ovulation from the right than the left ovary (P < .06). Conception rate was less if cows ovulated a follicle that was < 9 mm than a follicle > or = 9 mm in diameter at insert removal (P < .01) and was greater in cows inseminated in June than in April or May (P < .05). In conclusion, in cows in which estrus was synchronized at 25 to 39 d postpartum, ovulation from either the ovary ipsilateral to the previously gravid uterine horn, or the right ovary, tended to increase fertility.

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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: 93%

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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Conception Rates in Early Postpartum Ewes Bred Naturally or by Intrauterine Insemination

Cited by 11 publications

References 13 publications

Effect of weaning age on hair sheep lamb and ewe production traits in an accelerated lambing system in the tropics1

Effect of weaning age on hair sheep lamb and ewe production traits in an accelerated lambing system in the tropics1

Effect of the previously gravid uterine horn and postpartum interval on follicular diameter and conception rate in beef cows treated with estradiol benzoate and progesterone.

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

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