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חיפוש מתקדם
Journal of Dairy Science
Kaim, M., Institute of Animal Science, Agricultural Research Organization, Volcani Center, Bet Dagan 50250, Israel
Bloch, A., Department of Animal Science, Fac. Agric., Food Environ. Qual. S., Hebrew University of Jerusalem, Rehovot 76100, Israel
Wolfenson, D., Department of Animal Science, Fac. Agric., Food Environ. Qual. S., Hebrew University of Jerusalem, Rehovot 76100, Israel
Braw-Tal, R., Institute of Animal Science, Agricultural Research Organization, Volcani Center, Bet Dagan 50250, Israel
Rosenberg, M., Institute of Animal Science, Agricultural Research Organization, Volcani Center, Bet Dagan 50250, Israel
Voet, H., Dept. of Agric. Econ. and Management, Fac. Agric., Food Environ. Qual. S., Hebrew University of Jerusalem, Rehovot 76100, Israel
Folman, Y., Institute of Animal Science, Agricultural Research Organization, Volcani Center, Bet Dagan 50250, Israel
Two experiments examined effects of GnRH administered within 3 h after onset of estrus (OE) on ovulation and conception in dairy cows. In experiment 1, 46 cows received either saline, 250 μg of GnRH, or 10 μg of the GnRH analogue, Buserelin. Cows were observed for estrus, blood samples were collected, and ovulations were monitored by ultrasound. In controls, 76% of cows had intervals from estrus to ovulation of ≤ 30 h and 24% had intervals > 30 h. Treatment with either GnRH or GnRH analogue (data combined) increased magnitude of LH surges and decreased intervals from estrus to LH surge or to ovulation. Treated cows all ovulated ≤ 30 h after OE. Among control cows, plasma estradiol concentrations before estrus correlated positively with amplitudes of LH surges. Higher plasma progesterone was observed in the subsequent estrous cycle in GnRH-treated cows compared to control cows with delayed ovulations. Experiment 2 included 152 primiparous and 211 multiparous cows in summer and winter. Injection of GnRH analogue at OE increased conception rates (CR) from 41.3 to 55.5% across seasons. In summer, GnRH treatment increased CR from 35.1 to 51.6%. Across seasons, GnRH increased CR from 36.0 to 61.5% in cows with lower body condition at insemination and GnRH increased CR (63.2 vs. 42.2%) in primiparous cows compared to controls. Use of GnRH eliminated differences in CR for cows inseminated early or late relative to OE and increased CR in cows having postpartum reproductive disorders. In conclusion, GnRH at onset of estrus increased LH surges, prevented delayed ovulation, and may increase subsequent progesterone concentrations. Treatments with GnRH increased conception in primiparous cows, during summer, and in cows with lower body condition.
פותח על ידי קלירמאש פתרונות בע"מ -
הספר "אוצר וולקני"
אודות
תנאי שימוש
Effects of GnRH administered to cows at the onset of estrus on timing of ovulation, endocrine responses, and conception
86
Kaim, M., Institute of Animal Science, Agricultural Research Organization, Volcani Center, Bet Dagan 50250, Israel
Bloch, A., Department of Animal Science, Fac. Agric., Food Environ. Qual. S., Hebrew University of Jerusalem, Rehovot 76100, Israel
Wolfenson, D., Department of Animal Science, Fac. Agric., Food Environ. Qual. S., Hebrew University of Jerusalem, Rehovot 76100, Israel
Braw-Tal, R., Institute of Animal Science, Agricultural Research Organization, Volcani Center, Bet Dagan 50250, Israel
Rosenberg, M., Institute of Animal Science, Agricultural Research Organization, Volcani Center, Bet Dagan 50250, Israel
Voet, H., Dept. of Agric. Econ. and Management, Fac. Agric., Food Environ. Qual. S., Hebrew University of Jerusalem, Rehovot 76100, Israel
Folman, Y., Institute of Animal Science, Agricultural Research Organization, Volcani Center, Bet Dagan 50250, Israel
Effects of GnRH administered to cows at the onset of estrus on timing of ovulation, endocrine responses, and conception
Two experiments examined effects of GnRH administered within 3 h after onset of estrus (OE) on ovulation and conception in dairy cows. In experiment 1, 46 cows received either saline, 250 μg of GnRH, or 10 μg of the GnRH analogue, Buserelin. Cows were observed for estrus, blood samples were collected, and ovulations were monitored by ultrasound. In controls, 76% of cows had intervals from estrus to ovulation of ≤ 30 h and 24% had intervals > 30 h. Treatment with either GnRH or GnRH analogue (data combined) increased magnitude of LH surges and decreased intervals from estrus to LH surge or to ovulation. Treated cows all ovulated ≤ 30 h after OE. Among control cows, plasma estradiol concentrations before estrus correlated positively with amplitudes of LH surges. Higher plasma progesterone was observed in the subsequent estrous cycle in GnRH-treated cows compared to control cows with delayed ovulations. Experiment 2 included 152 primiparous and 211 multiparous cows in summer and winter. Injection of GnRH analogue at OE increased conception rates (CR) from 41.3 to 55.5% across seasons. In summer, GnRH treatment increased CR from 35.1 to 51.6%. Across seasons, GnRH increased CR from 36.0 to 61.5% in cows with lower body condition at insemination and GnRH increased CR (63.2 vs. 42.2%) in primiparous cows compared to controls. Use of GnRH eliminated differences in CR for cows inseminated early or late relative to OE and increased CR in cows having postpartum reproductive disorders. In conclusion, GnRH at onset of estrus increased LH surges, prevented delayed ovulation, and may increase subsequent progesterone concentrations. Treatments with GnRH increased conception in primiparous cows, during summer, and in cows with lower body condition.
Scientific Publication
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