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United States Department of Agriculture

Agricultural Research Service

Research Project: REDUCING COST OF EFFICIENT BEEF PRODUCTION Title: Effects of adrenocorticotropic hormone and flunixin meglumine on pregnancy retention in beef cows

Author
item Geary, Thomas

Submitted to: Journal of Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 2, 2011
Publication Date: January 1, 2012
Citation: Geary, T.W. 2012. Effects of adrenocorticotropic hormone and flunixin meglumine on pregnancy retention in beef cows. Journal of Animal Science 90:207-211.

Interpretive Summary: Pregnancy loss in beef cattle after d 28 of gestation is variable, but has been reported to be as high as 14% and has been related to transportation or handling stress. The objective of this study was to mimic a stress response in cows during early pregnancy by activation of the hypophyseal-adrenal axis using ACTH administration and determine the effects of this stress response on pregnancy maintenance. A secondary objective was to determine if pregnancy losses related to stress were mediated via prostaglandin F'' release and whether the prostaglandin synthesis inhibitor flunixin meglumine would attenuate the stress response and suppress serum PGF concentrations to prevent pregnancy loss. Forty non-lactating beef cows that were 34 ± 0.33 d pregnant were used for this study. Cows were randomly assigned to receive ACTH (0 or 0.5 IU/kg BW, i.m.) at 0 and 2 h of the study and flunixin meglumine (0, 1.1, or 2.2 mg/kg BW, i.m.) at 0 h in a 2 x 3 factorial. Blood samples were collected from all cows at 0 h and every 30 min for 4 h to measure serum cortisol and PGF metabolite (PGFM) concentrations. Rectal temperature was collected for each cow at 0, 120, and 240 min. Pregnancy exams were conducted 31 and 58 d after treatment using ultrasound and fetal heartbeat as an indicator of fetal viability. Serum cortisol concentration was affected (P < 0.01) by ACTH, time, and the interaction of ACTH by time, but not flunixin meglumine or any other interactions. Cortisol concentrations increased in serum of ACTH treated cows immediately after ACTH treatment and remained elevated throughout the 4 h sampling period. Serum PGFM concentration was not affected by ACTH or any interactions with ACTH, but was affected (P < 0.01) by flunixin meglumine, time, and the interaction of flunixin meglumine by time. Regardless of dosage (1.1, or 2.2 mg/kg BW), flunixin meglumine decreased serum PGFM concentrations in both ACTH and control cows for the duration of the study. Although ACTH treatment induced a prolonged stress response, none of the cows used in this study lost a pregnancy. We conclude that activation of the hypophyseal-adrenal axis did not cause pregnancy loss in cows during early gestation and that flunixin meglumine treatment suppressed PGFM concentrations in cows, but did not improve pregnancy maintenance. The stress response (as measured by cortisol concentration) induced by ACTH administration exceeded the level of stress that has been reported for cows in the literature. The fact that none of the cows lost a pregnancy suggests that stressors are not a major cause of late embryonic/early fetal pregnancy loss in cattle.

Technical Abstract: Pregnancy loss in beef cattle after d 28 of gestation is variable, but has been reported to be as high as 14% and has been related to transportation or handling stress. The objective of this study was to determine effects of ACTH administration on mimicking a stress response and whether this response would affect pregnancy maintenance. A secondary objective was to determine if a single injection of the prostaglandin synthesis inhibitor Flunixin Meglumine would attenuate the stress response and suppress serum PGF concentrations to prevent pregnancy loss. Forty non-lactating beef cows that were 34 ± 0.33 d pregnant were used for this study. Cows were randomly assigned to receive ACTH (0 or 0.5 IU/kg BW, i.m.) at 0 and 2 h of the study and flunixin meglumine (0, 1.1, or 2.2 mg/kg BW, i.m.) at 0 h in a 2 x 3 factorial. Blood samples were collected from all cows at 0 h and every 30 min for 4 h to measure serum cortisol and PGF metabolite (PGFM) concentrations. Rectal temperature was collected for each cow at 0, 120, and 240 min. Pregnancy exams were conducted 31 and 58 d after treatment using ultrasound and fetal heartbeat as an indicator of fetal viability. Serum cortisol concentration was affected (P < 0.01) by ACTH, time, and the interaction of ACTH by time, but not flunixin meglumine or any other interactions. Cortisol concentrations increased in serum of ACTH treated cows immediately after ACTH treatment and remained elevated throughout the 4 h sampling period. Serum PGFM concentration was not affected by ACTH or any interactions with ACTH, but was affected (P < 0.01) by flunixin meglumine, time, and the interaction of flunixin meglumine by time. Regardless of dosage (1.1, or 2.2 mg/kg BW), flunixin meglumine decreased serum PGFM concentrations in both ACTH and control cows for the duration of the study. Although ACTH treatment induced a prolonged stress response, none of the cows used in this study lost a pregnancy. We conclude that activation of the hypophyseal-adrenal axis did not cause pregnancy loss in cows during early gestation and that flunixin meglumine treatment suppressed PGFM concentrations in cows, but did not improve pregnancy maintenance.

Last Modified: 12/28/2014
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