ABSTRACT
Effect of Reproductive Efficiency in Regards to Workload on Peripheral Circulations of Blood Cortisol and Leptin in the Open Mare
(December, 2016)
Michaelle Kathleen Coker, B.S., Texas A&M University
Thesis Director: Dr. John Michael Mehaffey
Quarter and Paint horse mares (n= 9) were randomly assigned to 1 of 3 groups after being blocked based by expected conception date. Groups consist of mares on no work (NW), light work (LW), and moderate work (MW). Blood was taken weekly via jugular venipuncture prior to first heat cycle from each mare. Additionally, blood was taken at time of ovulation and then weekly until a 30 day (d) heartbeat was reported for the fetus. Each blood sample was assayed for leptin and cortisol concentrations, to see if cardiovascular fitness played a role in these reproductive hormones. There was a statistical difference between body weight (BW) (p-value < 0.0001) between the groups based on a week interaction. When blood leptin concentrations were observed for a successful 30d pregnancy between the groups, a statistical difference was seen between LW and MW (p-value < 0.0001). Statistical significance was seen between LW and NW (p-value = 0.0069) for serum cortisol levels for mares with successful 15d pregnancies. This study showed moderate workload could be beneficial on reproductive efficiency, while light work could be harmful to the open mare; however more research is needed.
","abstract_html":"<p>ABSTRACT</p> <p>Effect of Reproductive Efficiency in Regards to Workload on Peripheral Circulations of Blood Cortisol and Leptin in the Open Mare</p> <p>(December, 2016)</p> <p>Michaelle Kathleen Coker, B.S., Texas A&M University</p> <p>Thesis Director: Dr. John Michael Mehaffey</p> <p>Quarter and Paint horse mares (n= 9) were randomly assigned to 1 of 3 groups after being blocked based by expected conception date. Groups consist of mares on no work (NW), light work (LW), and moderate work (MW). Blood was taken weekly via jugular venipuncture prior to first heat cycle from each mare. Additionally, blood was taken at time of ovulation and then weekly until a 30 day (d) heartbeat was reported for the fetus. Each blood sample was assayed for leptin and cortisol concentrations, to see if cardiovascular fitness played a role in these reproductive hormones. There was a statistical difference between body weight (BW) (p-value < 0.0001) between the groups based on a week interaction. When blood leptin concentrations were observed for a successful 30d pregnancy between the groups, a statistical difference was seen between LW and MW (p-value < 0.0001). Statistical significance was seen between LW and NW (p-value = 0.0069) for serum cortisol levels for mares with successful 15d pregnancies. This study showed moderate workload could be beneficial on reproductive efficiency, while light work could be harmful to the open mare; however more research is needed.</p>","abstract_has_math":false,"creators":["Coker, Michaelle K"],"institution":null,"degree_name":"Master of Science - Agriculture","degree_level":"Thesis","degree_discipline":"Agriculture","degree_department":null,"school":null,"contributors":["Dr. John Michael Mehaffey","Dr. Robin Parker","Dr. Joey Bray"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2016,"date_issued":"2016-12-17T08:00:00Z","date_published":"2016-12-17T08:00:00Z","updated_at":"2026-07-24T04:30:03Z","subjects":["Mare","Reproductive Efficiency","Exercise","Workload","Leptin","Cortisol","Other Animal Sciences"],"languages":[],"rights":[],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"https://scholarworks.sfasu.edu/etds/60","outbound_label":"Repository record","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Dr. John Michael Mehaffey","Dr. Robin Parker","Dr. Joey Bray"]},{"key":"dc:creator","label":"Author","values":["Coker, Michaelle K"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.available","label":"Dc Date Available","values":["2016-12-19T08:00:00Z"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Agriculture"]},{"key":"thesis:degree_level","label":"Degree Level","values":["Thesis"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Master of Science - Agriculture"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["Mare","Reproductive Efficiency","Exercise","Workload","Leptin","Cortisol","Other Animal Sciences"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["https://scholarworks.sfasu.edu/etds/60"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["ABSTRACT
Effect of Reproductive Efficiency in Regards to Workload on Peripheral Circulations of Blood Cortisol and Leptin in the Open Mare
(December, 2016)
Michaelle Kathleen Coker, B.S., Texas A&M University
Thesis Director: Dr. John Michael Mehaffey
Quarter and Paint horse mares (n= 9) were randomly assigned to 1 of 3 groups after being blocked based by expected conception date. Groups consist of mares on no work (NW), light work (LW), and moderate work (MW). Blood was taken weekly via jugular venipuncture prior to first heat cycle from each mare. Additionally, blood was taken at time of ovulation and then weekly until a 30 day (d) heartbeat was reported for the fetus. Each blood sample was assayed for leptin and cortisol concentrations, to see if cardiovascular fitness played a role in these reproductive hormones. There was a statistical difference between body weight (BW) (p-value < 0.0001) between the groups based on a week interaction. When blood leptin concentrations were observed for a successful 30d pregnancy between the groups, a statistical difference was seen between LW and MW (p-value < 0.0001). Statistical significance was seen between LW and NW (p-value = 0.0069) for serum cortisol levels for mares with successful 15d pregnancies. This study showed moderate workload could be beneficial on reproductive efficiency, while light work could be harmful to the open mare; however more research is needed.
"]},{"key":"dc:title","label":"Title","values":["EFFECT OF REPRODUCTIVE EFFICIENCY IN REGARDS TO WORKLOAD ON PERIPHERAL CIRCULATIONS OF BLOOD CORTISOL AND LEPTIN IN THE OPEN MARE"]}]}],"canonical_facts":{"dc:contributor":["Dr. John Michael Mehaffey","Dr. Robin Parker","Dr. Joey Bray"],"dc:creator":["Coker, Michaelle K"],"dc:date.available":["2016-12-19T08:00:00Z"],"dc:description.abstract":["ABSTRACT
Effect of Reproductive Efficiency in Regards to Workload on Peripheral Circulations of Blood Cortisol and Leptin in the Open Mare
(December, 2016)
Michaelle Kathleen Coker, B.S., Texas A&M University
Thesis Director: Dr. John Michael Mehaffey
Quarter and Paint horse mares (n= 9) were randomly assigned to 1 of 3 groups after being blocked based by expected conception date. Groups consist of mares on no work (NW), light work (LW), and moderate work (MW). Blood was taken weekly via jugular venipuncture prior to first heat cycle from each mare. Additionally, blood was taken at time of ovulation and then weekly until a 30 day (d) heartbeat was reported for the fetus. Each blood sample was assayed for leptin and cortisol concentrations, to see if cardiovascular fitness played a role in these reproductive hormones. There was a statistical difference between body weight (BW) (p-value < 0.0001) between the groups based on a week interaction. When blood leptin concentrations were observed for a successful 30d pregnancy between the groups, a statistical difference was seen between LW and MW (p-value < 0.0001). Statistical significance was seen between LW and NW (p-value = 0.0069) for serum cortisol levels for mares with successful 15d pregnancies. This study showed moderate workload could be beneficial on reproductive efficiency, while light work could be harmful to the open mare; however more research is needed.
"],"dc:identifier":["https://scholarworks.sfasu.edu/etds/60"],"dc:subject":["Mare","Reproductive Efficiency","Exercise","Workload","Leptin","Cortisol","Other Animal Sciences"],"dc:title":["EFFECT OF REPRODUCTIVE EFFICIENCY IN REGARDS TO WORKLOAD ON PERIPHERAL CIRCULATIONS OF BLOOD CORTISOL AND LEPTIN IN THE OPEN MARE"],"thesis:degree_discipline":["Agriculture"],"thesis:degree_level":["Thesis"],"thesis:degree_name":["Master of Science - Agriculture"]},"updated_at":"2026-07-24T04:30:03Z"}