Professor 205C Brehm 2505 River Drive Knoxville, TN 37996-4574 (865) 974-3147 Fax: (865) 974-7297 Email: fschrick@utk.edu Research Appointment: 88% Teaching Appointment: 12%
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EDUCATION and TRAINING

B.S., Animal Science, Oklahoma State University, 1985
M.S., Animal Science (Reproductive Physiology), Clemson University, 1988
Ph.D., Animal Science (Animal Physiology), Clemson University, 1990 Postdoc, West Virginia University, 1990-1994

RESEARCH INTERESTS

My research focuses primarily on reproductive physiology and endocrinology with emphasis on environmental and management factors related to embryonic mortality and deviations in estrous cyclicity. During the past years, my laboratory has organized and performed studies in five distinct areas associated with reduced reproductive efficiency. Current fields of interest include: 1) embryonic loss associated with elevated uterine prostaglandin F 2α, 2) reduced reproductive performance associated with clinical and subclinical mastitis, 3) reproductive alterations observed in both bulls and cows grazing endophyte-infected fescue, 4) nutritional parameters affecting pregnancy rate, and 5) economical methods of estrus synchronization and timed insemination.

Embryonic Loss Associated with Elevated Uterine Prostaglandin F 2α:In performing this research, my laboratory has focused primarily on the whole animal model to determine the detrimental effects of elevated concentrations of prostaglandin F 2α on early pregnancy loss. Cattle must have a corpus luteum to maintain pregnancy; however, negative effects of prostaglandin F 2α continue to be apparent even in the presence of supplemental progestogen. The occurrence of prostaglandin F 2α release has been demonstrated in animals subjected to elevated temperatures, fescue toxicosis, clinical mastitis, negative energy balance, and embryo transfer. In vivo from beef cows suggests that the detrimental effects of prostaglandin F 2α occur before blastocyst development. In vitro data from rat and cattle embryos indicates that the negative effects of prostaglandin F 2α occur during the compaction process observed during morula development. The compaction process involves numerous tight and gap junctions, which may be disrupted by prostaglandin F 2α. Current research plans focus on determining gene expression of embryos affected by elevated prostaglandin F 2α utilizing primarily in vitro studies. My laboratory in collaboration with industry organized trials to determine the benefits of treating animals with a prostaglandin inhibitor prior to embryo transfer to improve pregnancy rates. Data from this study indicated that administration of a PGF inhibitor increased pregnancy rates by 5-10% when administered at the time of embryo transfer in beef cattle. Subsequently, we have identified receptors for PGF located on the early embryo, which lead to identification of a receptor blocker for PGF that is being tested currently with both in vitro and in vivo studies. Numerous publications have resulted from this research as well as a patent. Furthermore, we have just completed contract negotiations for future funding in this area.

Reduced Reproductive Performance Associated with Clinical and Subclinical Mastitis:This research is in collaboration with Dr. Stephen Oliver and consisted initially of retrospective analyses of herd records from the Dairy Experiment Station. Cows with clinical or subclinical mastitis during early lactation had an increase in days to first service, services per conception, and days open compared to uninfected cows or cows that had mastitis following confirmed pregnancy. Furthermore, cows that exhibited clinical mastitis during the breeding period (between first service and conception) had an increase in days open and a 2-fold increase in services per conception. Subsequent studies demonstrated a decrease in LH concentrations during clinical mastitis that may alter follicular environment and impact pregnancy rates. Furthermore, occurrence of clinical mastitis during the preovulatory period resulted in reduced estradiol concentrations, absence of an LH surge, reduction in LH pulse frequency, failure to exhibit estrus and ovulate. However, follicular development was not altered in these animals compared to controls. A final study in this area will focus on steroid concentrations and enzyme function of the preovulatory follicle in cows exhibiting clinical mastitis.

Reproductive Alterations Observed in Bulls and Cows Grazing Endophyte-Infected Fescue: It is well recognized that fescue toxicosis affects both growth and reproductive performance of cattle located in the southeastern United States. Pregnancy rates have been reported to be reduced by 3.5-5% for each 10% of infestation. Research performed in my laboratory has shown no difference between animals grazing infected fescue and controls in fetal loss after 30 days of pregnancy. Furthermore, follicular development and endocrine profiles were not altered in heifers receiving ergotamine tartrate to simulate fescue toxicosis during the estrous cycle prior to breeding. However, pregnancy rates of these animals were reduced. Other studies conducted in my laboratory indicated that follicle numbers were decreased in animals grazing fescue; although follicular developmental patterns were not altered. No differences were observed in the ability of the uterine environment to maintain pregnancy following transfer of good quality embryos into the uterus of heifers receiving ergotamine tartrate. In ongoing companion studies, single embryos recovered from heifers being fed ergotamine tartrate had similar fertilization rates but embryo quality was decreased. Furthermore, recovery of embryos on day 7 after breeding was greatly reduced in heifers administered ergotamine tartrate. Studies in bulls receiving ergotamine tartrate or actually grazing fescue have shown no differences in semen motility or morphology. However, in bulls under the influence of fescue toxicosis, both scrotal temperature and ability of semen to fertilize oocytes in vitro were reduced in three separate sets of bulls over three years. Future studies will focus on management strategies to reduce the negative effects on fertility of animals grazing tall fescue.

Nutritional Parameters Affecting Pregnancy Rate: This area of research is one of my most recent ventures and one that I feel may best benefit producers of Tennessee and the United States. It is well recognized that reduced nutrition negatively impacts reproductive performance of both dairy and beef cattle. During my graduate education, the majority of my research focused on effects of negative energy balance and body condition as related to reduced reproductive efficiency. However, these studies, as well as others, were not able to separate the detrimental effects observed during poor nutrition between two different variables: weight loss versus reduced body condition (fat content). My laboratory investigated the developmental potential of oocytes collected from cows that were either in good or poor body condition. Hormonal profiles indicated that neither group of cows were in negative energy balance and only body condition differed. Data suggested that developmental potential of oocytes from cows in good or poor body condition were equal. Fertilization rate, development to 8-cell embryos, and development to blastocyst were similar for both body condition groups. A subsequent study in vivo indicated that cows that have reinitiated cyclicity prior to weight loss had no reduction in pregnancy rates during an intensive weight loss during the breeding period. Thus, body condition of cows at calving is the most important factor relating to pregnancy success.

Economical Methods of Estrus Synchronization and Timed Insemination: For beef producers in Tennessee to become competitive, genetic improvement must become a reality. This genetic improvement can only become economical through increased use of artificial insemination. However, for artificial insemination to become an everyday management tool, improvements must be made in estrus synchronization protocols. Furthermore, timed breeding must accurately replace estrous detection to reduce labor input. My laboratory has investigated several different estrus synchronization protocols to improve conception rates associated with timed breeding. However, these protocols may be too labor intensive for the majority of interested producers. Therefore, my laboratory is currently investigating use of combining gonadotropin releasing hormone, progesterone and prostaglandin F 2α to increase conception rates at timed breeding as are several other land grant institutions. Results are routinely presented at county, state and national meetings focusing on estrus synchronization. Future projects will focus on designing management systems that will economically use estrus synchronization protocols and timed breeding as new technologies arise.

RECOGNITION OF RESEARCH EFFORTS

Recipient of the 2000 TJ Whatley Distinguished Young Scientist Award, Institute of Agriculture, The University of Tennessee

Recipient of the 1999 WF & Golda Moss Outstanding Teaching Award, Institute of Agriculture, The University of Tennessee