Kansas State University
1.
Fountain, Tara.
Evaluating
factors influencing pregnancy in beef cows and evaluating factors
at weaning influencing ability to pass breeding soundness
examination in beef bulls.
Degree: MSin Biomedical Sciences, Department of Clinical
Sciences, 2020, Kansas State University
URL: http://hdl.handle.net/2097/40882 
The common thread of this research was to identify
factors that improve efficiency and subsequent profitability for
cow-calf producers. The objective of the literature review was to
evaluate factors, such as nutrition, breed, season of birth,
exposure to cycling females and hormones that influenced puberty in
peri-pubertal bulls. Finding factors that influence puberty are
important for both for seedstock producers and commercial
cattlemen. Bulls that attain puberty earlier have a higher
likelihood of passing the breeding soundness examination by the
time of marketing.
The objective of the first study was to
determine if factors such as herd size, breeding season length,
body condition of cow at mid-gestation, or the timing of breeding
season affected the likelihood of pregnancy at the end of the first
21-day interval and at the end of the breeding season. Data were
collected by convenience sampling from herds (n=241) consisting of
8,217 head located in the Midwest and Great Plains regions of the
US from 2012 to 2017. Pregnancy diagnosis data were recorded in
either 20- or 21-day intervals. A logistic regression model was
used to evaluate the effect of the relevant factors (herd size
category, breeding season length category, body condition score
category, and timing of breeding season category) on the
probability of pregnancy status at two different time-points
(21-day and end of breeding season). Overall, an average 53.6% of
cattle across all herds were pregnant by the end of the first
21-day interval, and an average 85.2% of cattle across all herds
were pregnant by the end of the breeding season. Herds with short
or medium breeding season lengths (<63 days or 63-84 days) had
increased probability of pregnancy (65% and 58%, respectively) for
the first 21-day interval compared to herds with a long breeding
season (49%). Cows in thin body condition at the time of pregnancy
diagnosis had reduced probability of having become pregnant during
both the first 21-day interval (44%) and the entire breeding season
(64%) when compared to cows in moderate (62%, 86%) and fleshy (66%,
91%) condition. Herds with less than 50 head had reduced
probability of pregnancy (51%, 78%) as compared to medium sized
(50-99 head) herds (63%, 84%) for both the 21-day interval and
overall breeding season. Herds that started the breeding season in
the fall had higher probability of pregnancy at the end of the
breeding season (88%) as compared to spring start dates (82%).
Management factors such as breeding season length, body condition
score, herd size, and timing of breeding season had significant
impacts on the probability of pregnancy. In the future, more
research needs to be conducted to evaluate the economic impacts of
these management choices.
The focus of the next study was
identifying bulls at a young age with higher likelihood of passing
a breeding soundness examination as yearlings. Finding these bulls
at weaning may improve management options to optimize production
efficiency and profitability. The objective of this study was to…
Advisors/Committee Members: Robert L. LarsonBradley J. White.Subjects/Keywords: Efficiency;
Fertility; Breeding
Soundness Examination; Pregnancy
Interval
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APA (6th Edition):
Fountain, T. (2020). Evaluating
factors influencing pregnancy in beef cows and evaluating factors
at weaning influencing ability to pass breeding soundness
examination in beef bulls. (Masters Thesis). Kansas State University. Retrieved from http://hdl.handle.net/2097/40882
Chicago Manual of Style (16th Edition):
Fountain, Tara. “Evaluating
factors influencing pregnancy in beef cows and evaluating factors
at weaning influencing ability to pass breeding soundness
examination in beef bulls.” 2020. Masters Thesis, Kansas State University. Accessed January 20, 2021.
http://hdl.handle.net/2097/40882.
MLA Handbook (7th Edition):
Fountain, Tara. “Evaluating
factors influencing pregnancy in beef cows and evaluating factors
at weaning influencing ability to pass breeding soundness
examination in beef bulls.” 2020. Web. 20 Jan 2021.
Vancouver:
Fountain T. Evaluating
factors influencing pregnancy in beef cows and evaluating factors
at weaning influencing ability to pass breeding soundness
examination in beef bulls. [Internet] [Masters thesis]. Kansas State University; 2020. [cited 2021 Jan 20].
Available from: http://hdl.handle.net/2097/40882.
Council of Science Editors:
Fountain T. Evaluating
factors influencing pregnancy in beef cows and evaluating factors
at weaning influencing ability to pass breeding soundness
examination in beef bulls. [Masters Thesis]. Kansas State University; 2020. Available from: http://hdl.handle.net/2097/40882
University of Saskatchewan
2.
Cowan, Vanessa E.
INVESTIGATION OF THE SUBCLINICAL TOXICOLOGICAL EFFECTS OF ERGOT ALKALOID MYCOTOXIN (Claviceps purpurea) EXPOSURE IN BEEF COWS AND BULLS.
Degree: 2020, University of Saskatchewan
URL: http://hdl.handle.net/10388/13087
In my dissertation, I examine the effects of ergot alkaloid mycotoxins on vascular and reproductive systems in beef cows and bulls. Ergot alkaloids are toxic secondary metabolites produced by the pathogenic plant fungus Claviceps purpurea. Ergot alkaloids are commonly occurring adulterating toxins in livestock feed and constitute a great concern for the health of animals that consume such feeds. Consumption of these toxins can cause a broad suite of pathophysiological effects. Relevant and up-to-date scientific information on ergotism in livestock is largely unavailable to address this growing issue. The purpose of this research was to better characterize and understand the effects of ergot alkaloids in Canadian beef cattle and to ascertain concentrations at which these effects may occur.
In my first two chapters, beef cows were fed increasing concentrations of ergot alkaloids over a short-term (Chapter 2) and long-term (Chapter 3) basis. As ergot alkaloids have a well-known vasoactive effect, hemodynamics of different arteries were evaluated with ultrasonography (B-mode and Doppler). In both studies, concentration-dependent, subclinical physiological changes in hemodynamics were observed in the caudal artery. These results are significant as a common end-stage manifestation of ergot alkaloid mycotoxicosis is the ischemic necrosis of the tail of exposed cattle. Further, these results indicate that subclinical changes occur at concentrations below current Canadian permissible values. Therefore, vascular changes appear to be the more sensitive indicator of ergot exposure than plasma prolactin changes in cows. Plasma or serum prolactin concentration is an accepted biomarker of ergot alkaloid exposure in livestock.
To address the lack of pharmacokinetic information available on ergot alkaloids in cattle, I conducted two oral pharmacokinetics studies and attempted to develop an analytical method to detect ergot alkaloids in bovine plasma (Chapter 4). Although the method was promising for spiked plasma, ergot alkaloids were not detected in plasma samples collected from ergot-exposed cows. Likely, low oral bioavailability explained the lack of detection of ergot alkaloids in plasma from ergot-exposed cattle. An important practical conclusion of this work is that blood samples from suspected poisoning cases will not be clinically useful.
In my last research chapter (Chapter 5), adult beef bulls were fed diets containing ergot alkaloids for one spermatogenic cycle (i.e., 61 days) to assess the potential negative effects of ergot exposure on sperm production or function. Results of this study indicated that ergot exposure had, at most, a subtle effect on bull sperm endpoints. However, plasma prolactin was affected by treatment. Spermatogenesis is not a sensitive endpoint for ergot exposure in adult bulls. Overall, this work answered questions related to ergot alkaloid exposure that are practically important. This work will enable policy makers to make scientifically-based decisions on guidelines for ergot alkaloids in…
Advisors/Committee Members: Blakley, Barry, Singh, Jaswant, Wickstrom, Mark, Alcorn, Jane, McKinnon, John, Anzar, Muhammad.Subjects/Keywords: ergot alkaloids; mycotoxin; bull; cow; vasoconstriction; breeding soundness; LC-MS/MS; Claviceps purpurea
Record Details
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Share »
Record Details
Similar Records
Cite
« Share
❌
APA ·
Chicago ·
MLA ·
Vancouver ·
CSE |
Export
to Zotero / EndNote / Reference
Manager
APA (6th Edition):
Cowan, V. E. (2020). INVESTIGATION OF THE SUBCLINICAL TOXICOLOGICAL EFFECTS OF ERGOT ALKALOID MYCOTOXIN (Claviceps purpurea) EXPOSURE IN BEEF COWS AND BULLS. (Thesis). University of Saskatchewan. Retrieved from http://hdl.handle.net/10388/13087
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Chicago Manual of Style (16th Edition):
Cowan, Vanessa E. “INVESTIGATION OF THE SUBCLINICAL TOXICOLOGICAL EFFECTS OF ERGOT ALKALOID MYCOTOXIN (Claviceps purpurea) EXPOSURE IN BEEF COWS AND BULLS.” 2020. Thesis, University of Saskatchewan. Accessed January 20, 2021.
http://hdl.handle.net/10388/13087.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
MLA Handbook (7th Edition):
Cowan, Vanessa E. “INVESTIGATION OF THE SUBCLINICAL TOXICOLOGICAL EFFECTS OF ERGOT ALKALOID MYCOTOXIN (Claviceps purpurea) EXPOSURE IN BEEF COWS AND BULLS.” 2020. Web. 20 Jan 2021.
Vancouver:
Cowan VE. INVESTIGATION OF THE SUBCLINICAL TOXICOLOGICAL EFFECTS OF ERGOT ALKALOID MYCOTOXIN (Claviceps purpurea) EXPOSURE IN BEEF COWS AND BULLS. [Internet] [Thesis]. University of Saskatchewan; 2020. [cited 2021 Jan 20].
Available from: http://hdl.handle.net/10388/13087.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Council of Science Editors:
Cowan VE. INVESTIGATION OF THE SUBCLINICAL TOXICOLOGICAL EFFECTS OF ERGOT ALKALOID MYCOTOXIN (Claviceps purpurea) EXPOSURE IN BEEF COWS AND BULLS. [Thesis]. University of Saskatchewan; 2020. Available from: http://hdl.handle.net/10388/13087
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Open Access Theses and Dissertations