Calm Merino ewes have a higher ovulation rate and more multiple pregnancies than nervous ewes
In 1990, two selection lines of Merino sheep were established for low and high behavioural reactivity (calm and nervous temperament) at the University of Western Australia. Breeding records consistently showed that calm ewes weaned 10% to 19% more lambs than the nervous ewes. We hypothesise that cal...
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Elsevier
2017-01-01
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| Series: | Animal |
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| Online Access: | http://www.sciencedirect.com/science/article/pii/S1751731117000106 |
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| author | E. van Lier K.W. Hart C. Viñoles B. Paganoni D. Blache |
| author_facet | E. van Lier K.W. Hart C. Viñoles B. Paganoni D. Blache |
| author_sort | E. van Lier |
| collection | DOAJ |
| description | In 1990, two selection lines of Merino sheep were established for low and high behavioural reactivity (calm and nervous temperament) at the University of Western Australia. Breeding records consistently showed that calm ewes weaned 10% to 19% more lambs than the nervous ewes. We hypothesise that calm ewes could have a higher ovulation rate than nervous ewes and/or calm ewes could have a lower rate of embryo mortality than nervous ewes. We tested these hypotheses by comparing the ovulation rate and the rate of embryo mortality between the calm and nervous lines before and after synchronisation and artificial insemination. Merino ewes from the temperament selection lines (calm, n=100; nervous, n=100) were synchronised (early breeding season) for artificial insemination (day 0) (intravaginal sponges containing fluogestone acetate and eCG immediately after sponge withdrawal). On day-17 and 11 ovarian cyclicity and corpora lutea, and on days 30 and 74 pregnancies and embryos/foetuses were determined by ultrasound. Progesterone, insulin and leptin concentrations were determined in blood plasma samples from days 5, 12 and 17. Ovarian cyclicity before and after oestrus synchronisation did not differ between the lines, but ovulation rate did (day-17: calm 1.63; nervous 1.26; P<0.01; day 11: calm 1.83; nervous 1.57; P<0.05). Ovulation rate on day 11 in nervous ewes was higher than on day-17. Loss of embryos by day 30 was high (calm: 71/150; nervous: 68/130); but nervous ewes had a lower proportion (15/47) of multiple pregnancies compared with calm ewes (30/46; P<0.01). Reproductive loss between days 30 and 74 represented 7.3% of the overall loss. Temperament did not affect concentrations of progesterone, but nervous ewes had higher insulin (32.0 pmol/l±1.17 SEM; P=0.013) and lower leptin (1.18 μg/l±0.04 SEM; P=0.002) concentrations than calm ewes (insulin: 27.8 pmol/l±1.17 SEM; leptin: 1.35 μg/l±0.04 SEM). The differences in reproductive outcomes between the calm and nervous ewes were mainly due to a higher ovulation rate in calm ewes. We suggest that reproduction in nervous ewes is compromised by factors leading up to ovulation and conception, or the uterine environment during early pregnancy, that reflect differences in energy utilisation. |
| first_indexed | 2024-12-14T13:59:49Z |
| format | Article |
| id | doaj.art-a1f5d7a53a2242abadb982ab5886ef5c |
| institution | Directory Open Access Journal |
| issn | 1751-7311 |
| language | English |
| last_indexed | 2024-12-14T13:59:49Z |
| publishDate | 2017-01-01 |
| publisher | Elsevier |
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| series | Animal |
| spelling | doaj.art-a1f5d7a53a2242abadb982ab5886ef5c2022-12-21T22:58:44ZengElsevierAnimal1751-73112017-01-0111711961202Calm Merino ewes have a higher ovulation rate and more multiple pregnancies than nervous ewesE. van Lier0K.W. Hart1C. Viñoles2B. Paganoni3D. Blache4Departamento de Producción Animal y Pasturas, Facultad de Agronomía, Universidad de la República, Avda. Garzón 780, Montevideo 12900, Uruguay; Estación Experimental Facultad de Agronomía Salto, Facultad de Agronomía, Universidad de la República, Ruta 31, km 21, Salto 50009, Uruguay; School of Animal Biology M085, UWA Institute of Agriculture M082, The University of Western Australia, Crawley, WA 6009, AustraliaSchool of Animal Biology M085, UWA Institute of Agriculture M082, The University of Western Australia, Crawley, WA 6009, Australia; Ewetopia Consulting, Narrogin, WA 6312, AustraliaSchool of Animal Biology M085, UWA Institute of Agriculture M082, The University of Western Australia, Crawley, WA 6009, Australia; INIA Tacuarembó, Ruta 5 Km 386, Tacuarembó 45000, UruguaySchool of Animal Biology M085, UWA Institute of Agriculture M082, The University of Western Australia, Crawley, WA 6009, Australia; Department of Agriculture and Food Western Australia, 3 Baron-Hay Court, South Perth, WA 6151, AustraliaSchool of Animal Biology M085, UWA Institute of Agriculture M082, The University of Western Australia, Crawley, WA 6009, AustraliaIn 1990, two selection lines of Merino sheep were established for low and high behavioural reactivity (calm and nervous temperament) at the University of Western Australia. Breeding records consistently showed that calm ewes weaned 10% to 19% more lambs than the nervous ewes. We hypothesise that calm ewes could have a higher ovulation rate than nervous ewes and/or calm ewes could have a lower rate of embryo mortality than nervous ewes. We tested these hypotheses by comparing the ovulation rate and the rate of embryo mortality between the calm and nervous lines before and after synchronisation and artificial insemination. Merino ewes from the temperament selection lines (calm, n=100; nervous, n=100) were synchronised (early breeding season) for artificial insemination (day 0) (intravaginal sponges containing fluogestone acetate and eCG immediately after sponge withdrawal). On day-17 and 11 ovarian cyclicity and corpora lutea, and on days 30 and 74 pregnancies and embryos/foetuses were determined by ultrasound. Progesterone, insulin and leptin concentrations were determined in blood plasma samples from days 5, 12 and 17. Ovarian cyclicity before and after oestrus synchronisation did not differ between the lines, but ovulation rate did (day-17: calm 1.63; nervous 1.26; P<0.01; day 11: calm 1.83; nervous 1.57; P<0.05). Ovulation rate on day 11 in nervous ewes was higher than on day-17. Loss of embryos by day 30 was high (calm: 71/150; nervous: 68/130); but nervous ewes had a lower proportion (15/47) of multiple pregnancies compared with calm ewes (30/46; P<0.01). Reproductive loss between days 30 and 74 represented 7.3% of the overall loss. Temperament did not affect concentrations of progesterone, but nervous ewes had higher insulin (32.0 pmol/l±1.17 SEM; P=0.013) and lower leptin (1.18 μg/l±0.04 SEM; P=0.002) concentrations than calm ewes (insulin: 27.8 pmol/l±1.17 SEM; leptin: 1.35 μg/l±0.04 SEM). The differences in reproductive outcomes between the calm and nervous ewes were mainly due to a higher ovulation rate in calm ewes. We suggest that reproduction in nervous ewes is compromised by factors leading up to ovulation and conception, or the uterine environment during early pregnancy, that reflect differences in energy utilisation.http://www.sciencedirect.com/science/article/pii/S1751731117000106embryoprogesteroneinsulinleptinOvis aries |
| spellingShingle | E. van Lier K.W. Hart C. Viñoles B. Paganoni D. Blache Calm Merino ewes have a higher ovulation rate and more multiple pregnancies than nervous ewes Animal embryo progesterone insulin leptin Ovis aries |
| title | Calm Merino ewes have a higher ovulation rate and more multiple pregnancies than nervous ewes |
| title_full | Calm Merino ewes have a higher ovulation rate and more multiple pregnancies than nervous ewes |
| title_fullStr | Calm Merino ewes have a higher ovulation rate and more multiple pregnancies than nervous ewes |
| title_full_unstemmed | Calm Merino ewes have a higher ovulation rate and more multiple pregnancies than nervous ewes |
| title_short | Calm Merino ewes have a higher ovulation rate and more multiple pregnancies than nervous ewes |
| title_sort | calm merino ewes have a higher ovulation rate and more multiple pregnancies than nervous ewes |
| topic | embryo progesterone insulin leptin Ovis aries |
| url | http://www.sciencedirect.com/science/article/pii/S1751731117000106 |
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