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Registro Completo |
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Biblioteca(s): |
Embrapa Caprinos e Ovinos. |
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Data corrente: |
24/03/1998 |
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Data da última atualização: |
27/12/2013 |
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Autoria: |
DUTT, R. H.; ELLINGTON, E. F.; CARLTON, W. W. |
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Título: |
Fertilization rate and early embryo survival in sheared and unsheared ewes following exposure to elevated air temperature. |
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Ano de publicação: |
1959 |
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Fonte/Imprenta: |
Journal of Animal Science, v.18, n.4, p.1308-1318, 1959. |
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Idioma: |
Inglês |
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Conteúdo: |
Fertilization rate in ewes exposed to elevated air temperature (90° F.) on the 12th day of the cycle before breeding was significantly lower (P<0.01) than for control ewes. During two breeding seasons 92.6% of ova from control ewes were cleaved, compared to 51.9% from ewes in the hot room. The heat treatment resulted in an increase in the percentage of abnormal ova. Only 3.7% of ova from control ewes examined 3 days after breeding were classified as morphologically abnormal, compared to 44.2% from ewes in the hot room. Embryo loss, estimated as the percent of fertilized ova that died, was significantly higher in ewes exposed to the heat before breeding. For control ewes during two breeding seasons, the estimated embryo loss was 4.0% compared to an estimated loss of 91.7% for ewes exposed to the heat before breeding. When ewes were not exposed to the heated room until 8 days post-breeding, the estimated embryo loss (15.4%) was not significantly different from control ewes. Seventeen out of 20 ewes lambed when bred and exposed to the heat 8 days later, compared to only one out of 20 ewes when exposed to the heat before breeding. Fertilization rate and survival of the early embryo in ewes appear to be more susceptible to heat damage than is the 8-day embryo. Birth weights of lambs from ewes exposed to heat from the 8th through the 24th day post-breeding did not differ significantly from control lambs. Rectal temperatures and pulse rates of the ewes in the hot room were significantly increased (P<0.01) over control ewes. The hot-room sheared ewes had lower average rectal temperature and pulse rate than the unsheared ewes.
The adverse effect of heat on fertilization rate, percentage of abnormal ova and embryo loss was less severe when ewes were sheared before they were exposed to the elevated temperature. MenosFertilization rate in ewes exposed to elevated air temperature (90° F.) on the 12th day of the cycle before breeding was significantly lower (P<0.01) than for control ewes. During two breeding seasons 92.6% of ova from control ewes were cleaved, compared to 51.9% from ewes in the hot room. The heat treatment resulted in an increase in the percentage of abnormal ova. Only 3.7% of ova from control ewes examined 3 days after breeding were classified as morphologically abnormal, compared to 44.2% from ewes in the hot room. Embryo loss, estimated as the percent of fertilized ova that died, was significantly higher in ewes exposed to the heat before breeding. For control ewes during two breeding seasons, the estimated embryo loss was 4.0% compared to an estimated loss of 91.7% for ewes exposed to the heat before breeding. When ewes were not exposed to the heated room until 8 days post-breeding, the estimated embryo loss (15.4%) was not significantly different from control ewes. Seventeen out of 20 ewes lambed when bred and exposed to the heat 8 days later, compared to only one out of 20 ewes when exposed to the heat before breeding. Fertilization rate and survival of the early embryo in ewes appear to be more susceptible to heat damage than is the 8-day embryo. Birth weights of lambs from ewes exposed to heat from the 8th through the 24th day post-breeding did not differ significantly from control lambs. Rectal temperatures and pulse rates of the ewes in the hot room were signific... Mostrar Tudo |
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Palavras-Chave: |
Comportamento reprodutivo; Fertilization. |
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Thesagro: |
Endocrinologia; Fisiologia; Obstetrícia; Ovino; Reprodução. |
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Thesaurus Nal: |
Ewes; Heat exhaustion; Sheep. |
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Categoria do assunto: |
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L Ciência Animal e Produtos de Origem Animal |
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Marc: |
null
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Registro original: |
Embrapa Caprinos e Ovinos (CNPC) |
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