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קהילה:
אסיף מאגר המחקר החקלאי
פותח על ידי קלירמאש פתרונות בע"מ -
Delayed effect of heat stress on steroid production in medium-sized and preovulatory bovine follicles
Year:
2001
Source of publication :
Reproduction
Authors :
בראב-טל, רות
;
.
Volume :
121
Co-Authors:
Roth, Z., Department of Animal Science, Fac. Agric., Food Environ. Qual. S., Hebrew University of Jerusalem, Rehovot 76100, Israel
Meidan, R., Department of Animal Science, Fac. Agric., Food Environ. Qual. S., Hebrew University of Jerusalem, Rehovot 76100, Israel
Shaham-Albalancy, A., Department of Animal Science, Fac. Agric., Food Environ. Qual. S., Hebrew University of Jerusalem, Rehovot 76100, Israel
Braw-Tal, R.
Wolfenson, D., Department of Animal Science, Fac. Agric., Food Environ. Qual. S., Hebrew University of Jerusalem, Rehovot 76100, Israel
Facilitators :
From page:
745
To page:
751
(
Total pages:
7
)
Abstract:
During the autumn, the conception rate of dairy cattle in warm countries is low although ambient temperatures have decreased and cows are no longer exposed to summer thermal stress, indicating that there may be a delayed effect of heat stress on cattle fertility. Two experiments were conducted to examine possible delayed effects of heat stress on follicular characteristics and steroid production at two distinct stages of follicular growth: medium-sized and preovulatory follicles, 20 and 26 days after heat exposure, respectively. Lactating cows were subjected to heat stress for 12 h a day in an environmental chamber, during days 2-6 of a synchronized oestrous cycle. In Expt 1, ovaries were collected on day 3 of the subsequent cycle, before selection of the dominant follicle, and medium-sized follicles were classified as atretic or healthy. In Expt 2, on day 7 of the subsequent cycle, PGF2α was administered and preovulatory follicles were collected 40 h later. In both experiments, follicular fluid was aspirated, granulosa and thecal cells were incubated, and steroid production was determined. In healthy medium-sized follicles (Expt 1), oestradiol production by granulosa cells and androstenedione production by thecal cells were lower (P < 0.05) and the concentration of progesterone in the follicular fluid was higher in cows that had been previously heat-stressed than in control cows (P < 0.05). In preovulatory follicles (Expt 2), the viability of granulosa cells was lower (P < 0.05) and the concentration of androstenedione in the follicular fluid and its production by thecal cells were lower (P < 0.05) in cows that had been previously heat-stressed than in control cows. In both experiments, the oestradiol concentrations in the follicular fluids were not altered by heat stress. These results demonstrate a delayed effect of heat stress on steroid production and follicular characteristics in both medium-sized and preovulatory follicles; this effect could be related to the low fertility of cattle in the autumn.
Note:
Related Files :
animal experiment
Animals
animal tissue
cattle
Female
Follicular Fluid
heat stress
lactation
Steroids
עוד תגיות
תוכן קשור
More details
DOI :
Article number:
Affiliations:
Database:
סקופוס
Publication Type:
מאמר
;
.
Language:
אנגלית
Editors' remarks:
ID:
25721
Last updated date:
02/03/2022 17:27
Creation date:
17/04/2018 00:17
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Scientific Publication
Delayed effect of heat stress on steroid production in medium-sized and preovulatory bovine follicles
121
Roth, Z., Department of Animal Science, Fac. Agric., Food Environ. Qual. S., Hebrew University of Jerusalem, Rehovot 76100, Israel
Meidan, R., Department of Animal Science, Fac. Agric., Food Environ. Qual. S., Hebrew University of Jerusalem, Rehovot 76100, Israel
Shaham-Albalancy, A., Department of Animal Science, Fac. Agric., Food Environ. Qual. S., Hebrew University of Jerusalem, Rehovot 76100, Israel
Braw-Tal, R.
Wolfenson, D., Department of Animal Science, Fac. Agric., Food Environ. Qual. S., Hebrew University of Jerusalem, Rehovot 76100, Israel
Delayed effect of heat stress on steroid production in medium-sized and preovulatory bovine follicles
During the autumn, the conception rate of dairy cattle in warm countries is low although ambient temperatures have decreased and cows are no longer exposed to summer thermal stress, indicating that there may be a delayed effect of heat stress on cattle fertility. Two experiments were conducted to examine possible delayed effects of heat stress on follicular characteristics and steroid production at two distinct stages of follicular growth: medium-sized and preovulatory follicles, 20 and 26 days after heat exposure, respectively. Lactating cows were subjected to heat stress for 12 h a day in an environmental chamber, during days 2-6 of a synchronized oestrous cycle. In Expt 1, ovaries were collected on day 3 of the subsequent cycle, before selection of the dominant follicle, and medium-sized follicles were classified as atretic or healthy. In Expt 2, on day 7 of the subsequent cycle, PGF2α was administered and preovulatory follicles were collected 40 h later. In both experiments, follicular fluid was aspirated, granulosa and thecal cells were incubated, and steroid production was determined. In healthy medium-sized follicles (Expt 1), oestradiol production by granulosa cells and androstenedione production by thecal cells were lower (P < 0.05) and the concentration of progesterone in the follicular fluid was higher in cows that had been previously heat-stressed than in control cows (P < 0.05). In preovulatory follicles (Expt 2), the viability of granulosa cells was lower (P < 0.05) and the concentration of androstenedione in the follicular fluid and its production by thecal cells were lower (P < 0.05) in cows that had been previously heat-stressed than in control cows. In both experiments, the oestradiol concentrations in the follicular fluids were not altered by heat stress. These results demonstrate a delayed effect of heat stress on steroid production and follicular characteristics in both medium-sized and preovulatory follicles; this effect could be related to the low fertility of cattle in the autumn.
Scientific Publication
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