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Journal of Thermal Biology
Roth, Z., Department of Animal Science, Faculty of Agricultural, Food Environ. Qual. Sci., Hebrew U., Israel
Bor, A., Agricultural Research Organization, Institute of Animal Science, Bet Dagan, Israel, Israel
Braw-Tal, R., Agricultural Research Organization, Institute of Animal Science, Bet Dagan, Israel, Israel
Wolfenson, D., Department of Animal Science, Faculty of Agricultural, Food Environ. Qual. Sci., Hebrew U., Israel
Low fertility of cattle during the cool autumn is mostly associated with exposure to thermal stress in the previous summer. This study examined carry-over effects of summer heat stress and induction of enhanced follicular turnover, on the characteristics of preovulatory follicles during autumn. Holstein cows were treated with PGF 2α and GnRH to induce six successive 9-day follicular waves during autumn. Intact cows served as controls. Follicular fluid concentrations of androstenedione were higher in treated cows, but those of IGF-I and progesterone did not differ between groups. The concentration of estradiol at the end of the treatment was higher, and the content per follicle increased with time and was numerically higher in treated cows. The volume of follicular fluid increased during the autumn and was greater in treated cows. A delayed effect of heat stress on preovulatory follicles was noted, and induction of follicular waves by GnRH was able to improve follicular characteristics in autumn. © 2004 Elsevier Ltd. All rights reserved.
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Carry-over effect of summer thermal stress on characteristics of the preovulatory follicle of lactating cows
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Roth, Z., Department of Animal Science, Faculty of Agricultural, Food Environ. Qual. Sci., Hebrew U., Israel
Bor, A., Agricultural Research Organization, Institute of Animal Science, Bet Dagan, Israel, Israel
Braw-Tal, R., Agricultural Research Organization, Institute of Animal Science, Bet Dagan, Israel, Israel
Wolfenson, D., Department of Animal Science, Faculty of Agricultural, Food Environ. Qual. Sci., Hebrew U., Israel
Carry-over effect of summer thermal stress on characteristics of the preovulatory follicle of lactating cows
Low fertility of cattle during the cool autumn is mostly associated with exposure to thermal stress in the previous summer. This study examined carry-over effects of summer heat stress and induction of enhanced follicular turnover, on the characteristics of preovulatory follicles during autumn. Holstein cows were treated with PGF 2α and GnRH to induce six successive 9-day follicular waves during autumn. Intact cows served as controls. Follicular fluid concentrations of androstenedione were higher in treated cows, but those of IGF-I and progesterone did not differ between groups. The concentration of estradiol at the end of the treatment was higher, and the content per follicle increased with time and was numerically higher in treated cows. The volume of follicular fluid increased during the autumn and was greater in treated cows. A delayed effect of heat stress on preovulatory follicles was noted, and induction of follicular waves by GnRH was able to improve follicular characteristics in autumn. © 2004 Elsevier Ltd. All rights reserved.
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