Source: TEXAS A&M UNIVERSITY submitted to
Sponsoring Institution
National Institute of Food and Agriculture
Project Status
Funding Source
Reporting Frequency
Accession No.
Grant No.
Project No.
Proposal No.
Multistate No.
Program Code
Project Start Date
Jul 6, 2012
Project End Date
Jul 5, 2017
Grant Year
Project Director
Forrest, D. W.
Recipient Organization
Performing Department
Animal Science
Non Technical Summary
There is a critical need to develop and refine technologies that will faciliate utilization of superior genetics and enhance pregnancy rates in beef cattle. The potential to produce progeny with improved performance and carcass traits is significantly accelerated when beef females are mated to elite sires via artificial inseminatio or by transfer of an embryo obtained from the mating of a genetically superior dam and sire. Inaccurate detection of estrus continues to be a major impediment to successful artificial insemination mating programs. Substantial variability in response to superstimulation protocols is an obstacle to more efficient use of embryo transfer technologies. Development of improved technologies to freeze and thaw bovine embryos that result in higher pregnancy rates would facilitate greater use of embryo transfer in the beef industry. More accurate identification of criteria associated with the selection of recipient females that can maintain pregnancy following transfer of an embryo into their uterus would improve the utilization of assisted reproductive technologies. Studies will be conducted to develop/refine technologies designed to improve accuracy of estrus detection, predictability of response to superovulation protocols, freezing and thawing of bovine embryos and selection of recipients for transfer of embryos. The expected impacts of these studies include the dissemination of new techniques for use by beef cattle producers to increase efficiency and profitability of the enterprise and to produce graduates with expertise and skills that will be in demand by the beef cattle industry.
Animal Health Component
Research Effort Categories

Knowledge Area (KA)Subject of Investigation (SOI)Field of Science (FOS)Percent
Knowledge Area
301 - Reproductive Performance of Animals;

Subject Of Investigation
3310 - Beef cattle, live animal;

Field Of Science
1020 - Physiology;
Goals / Objectives
The goal is to develop technologies that will enhance pregnacy rate in beef cattle. The objectives are to: 1) develop accurate and economical mehtods for detection of estrus in beef females; 2) evaluate superstimulation protocols that reduce management effort and improve predictability of superovulation response in donor females, 3) develop technologies to increase cryotolerance of in vitro- or in vivo-produced bovine embryos; and 4) identify criteria for selection of recipient females to enhance pregnancy rate following transfer of bovine embryos. Expected outputs include mentoring undergraduate and graduate students involved in conducting the experiments and analyzing the data. The results of this project will be disseminated thorugh conferences, workshops and research reports targeted for producer groups and extension personnel and in scientific publications. Techniques developed to increase pregnancy rate will benefit beef cattle producers, and the information, skills and technology acquired by students will enhanve their competitiveness for employment opportunities.
Project Methods
A pressure-sensitive device will be mounted to the rump of beef females to monitor the number and timing of mount events. The females will be estrous-synchronized and mated by either artificial insemination or transfer of an embryo on day 7 post-estrus. The relationship between mount events and pregnancy rate will be quantified. Donor females will be allotted to one of two follicle stimulating hormone (FSH) treatment protocols to assess the total number of ova and the number of transferable embryos recovered. In vivo- or in vitro-produced bovine embryos will be cultured for 24 hr in the presence or absence of a lipolytic agent (forskolin). Embryos will be cultured for an additional 72 hr to quantify the lipid content. Additional experiments will assess the ability of embryos with reduced lipid content to survive freezing and thawing and to determine pregnancy rate of cryopreserved embryos after transfer to recipient cows. Blood flow dynamics to uterine and ovarian organs will be quantified using color Doppler ultrasonography in beef females before and after embryo transfer. Relationships among blood flow, ovarian structures and pregnancy rate will be determined. Graduate students will acquire new skills in conducting these studies and the technologies will be transfered to beef cattle producers through workshops and conferences. Success of the project will be assessed by quantifying the percentage improvement achieved in detection of estrus, predictability in superovulation response, cryotolerance of bovine embryos and selection of recipient females that maintain pregnancy as a result of embryo transfer.

Progress 10/01/13 to 09/30/14

Target Audience: Reproductive physiologists and livestock producers. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided? Undergraduate and graduate students acquired valuable experience in collection of ejaculates, spermatozoa purification, isolation of RNA from spermatozoa, andquantitative reverse transcription of spermatozoa RNA. in addition, trainees learned proper techniques for blood sample collection by venipuncture, castration, endocrine assays, tissue processing and gene expression protocols. Professional development included presentation of results and networking with colleagues in seminars, conferences and scientific meetings. How have the results been disseminated to communities of interest? Results of these studies have been published in refereed journals and presented in oral platform or poster sessions to scientists at professional conferences. What do you plan to do during the next reporting period to accomplish the goals? Studies using the goat model to ascertain pre-natal and post-natal gonadal development will be completed. These results should provide additional insight into the mechanisms responsible for ontogeny of spermatozoa gene expression. Studies are in progress to quantify the relationship of anti-mullerian hormone concentration with fertility in donor and recipient bovine females.

What was accomplished under these goals? Procedures to isolate dense spermatozoa are being used with increasing frequency in assisted reproductive technologies. Dense spermatozoa have improved motility, morphology, chromatin integrity and fertilizing ability compared to less dense spermatozoa. Spermatozoa mRNAs have been identified as a potential indicator of male fertility. An experiment was conducted to determine whether differences in selectedmRNAs existedbetween dense and less dense stallion spermatozoa. Protamine 1 and Heat shock protein A8 mRNAs did not differ in stallion spermatozoa sorted on density. Surprisingly, lower concentrations of mRNAs encoding for sperm specific calcium channel 1, ornithine decarboxylase antizyme 3, aromatase and estrogen receptor alpha were detected in the dense compared with the less dense stallion spermatozoa. These results are the first to indicate that thesemRNAS are lower in dense than in less dense spermatozoa in any livestock species. The current results are incontrast to reports in human males in which levels of four ofthe mRNAsassessed were enhanced in spermatozoa from fertile compared with infertle men.Assessment of selectedmRNAs in spermatozoa may facilitate enhanced pregnancy rateswhen in vitro fertilization techniques are employed to produce geneticallyvaluable bovine embryos for transfer into recipient females.


  • Type: Journal Articles Status: Published Year Published: 2014 Citation: Ing,N.H., Forrest,D.W., Love,C.C., and Varner,D.D. (2014). Dense Spermatozoa in Stallion Ejaculates Contain Lower Concentrations of mRNAs Encoding the Sperm Specific Calcium Channel 1, Ornithine Decarboxylase Antizyme 3, Aromatase, and Estrogen Receptor Alpha than Less Dense Spermatozoa. Theriogenology, 82:347-353.
  • Type: Journal Articles Status: Published Year Published: 2014 Citation: Ing,N.H., Forrest,D.W., Riggs,P.K., Loux,S., Love,C.C., Brinsko,S.P., Varner,D.D., and Welsh,T.H.Jr. (2014). Dexamethasone Acutely Down-Regulates Genes Involved in Steroidogenesis in Stallion Testes. Journal of Steroid Biochemistry and Molecular Biology, 143:451-459.
  • Type: Journal Articles Status: Accepted Year Published: 2014 Citation: Faucette,A.N., Maher,V.A., Gutierrez.M.A., Jucker,J.M., Yates,D.C., Welsh,T.H.Jr., Amstalden,M., Newton,G.R., Nuti,L.C., Forrest,D.W., and Ing,N.H. (2014). Temporal Changes in Histomorphology and Gene Expression in Goat Testes During Postnatal Development. Journal of Animal Science, (In Press).

Progress 01/01/13 to 09/30/13

Target Audience: Reproductive physiologists and livestock producers. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided? Training of graduate students included instruction in collection of blood samples, hormone analyses, castration procedures, tissue processing and gene expression protocols. Professional development involved presentation of results at conferences, seminars and scientfic meetings. How have the results been disseminated to communities of interest? Results have been published in refereed journals and presented to scientists at professional conferences. What do you plan to do during the next reporting period to accomplish the goals? Experiments to investigate additional mechanisms whereby stress-related hormones may adversely impact fertility using an equine model are ongoing. Additional studies to ascertain biomarkers of fertility in donor and recipient beef females will be conducted.

What was accomplished under these goals? Pregnancy rate in beef cattle can be affected by stress that induces release of hormones such as glucocorticoids. Elucidation of mechanisms involved in stress-related reduction in fertility can facilitate development of strategies to mitigate the adverse impacts of stress on reproductive performance. A study was conducted to assess the effects of two injections of a synthetic glucocorticoid (dexamethasone) or saline (control) in the equine male. Administration of dexamethasone suppressed serum testosterone concentration for 10 days. Semen traits were not affected by treatment during the two-week interval until testes were harvested by castration for gene expression assessment in the testicular parenchyma. Two of the eight gene products analyzed (heat shock protein DNAJC4 and sperm-specific calcium channel CATSPER1 mRNAs) were depressed by more than 60% in the dexamethasone-treated compared to the control stallions. This work providesthe first evidence that an elevation in a stress-related hormone resulted in a decrease in expression of two germ cell genes 14 daysfollowing treatment. This knowledge should enhanceour understanding of mechanisms that influence fertility in response to stressors in donor and recipient females in embryo transfer programs.


  • Type: Journal Articles Status: Published Year Published: 2013 Citation: Luksovsky, J., Craig, T.M., Bingham, G.M., Cyr, T., and Forrest, D. (2013). Determining Treatment to Control Two Multi-drug Resistant Parasites on a Texas Horse Farm. Journal of Equine Veterinary Science 33:115-119.
  • Type: Journal Articles Status: Accepted Year Published: 2014 Citation: Ing, N., Brinsko, S., Curley, K., Forrest, D., Love, C., Hinrichs, K., Vogelsang, M., Varner, D., and Welsh, T. (2014). Dexamethasone Acutely Regulates Endocrine Parameters in Stallions and Subsequently Affects Gene Expression in Testicular Germ Cells. Andrologia (Accepted)
  • Type: Theses/Dissertations Status: Published Year Published: 2013 Citation: Thorne, J.W. (2013) Fertility of beef recipients following a fixed-time embryo transfer protocol that includes follicle stimulating hormone diluted in hyaluronan. Thesis. Texas A&M University, College Station. 73p.

Progress 07/05/12 to 12/31/12

OUTPUTS: Activities included conducting and analyzing experiments along with mentoring two graduate students involved in this project. Events included presentation of these results at one national and one international professional conference to inform scientists of research results. In addition, results were disemminated to beef cattle producers and allied industry personnel at the Annual Texas A&M Beef Cattle Short Course. Products included the enhancement of methods to select cattle for more efficient production and the graduation of one doctoral student in Animal Science. PARTICIPANTS: David Forrest served as the Principal Investigator and coordinated project design and implementation. Gordon Carstens served as a Co-Investigator and directed the studies to elucidate the relationships among feed efficiency and reproductive traits in bulls. Partner organizations included Ovagenix located in Bryan, TX, Bioniche Animal Health in Bogart, GA, and JBS Five Rivers Cattle Feeding LLC in Greeley, CO. Collaborators included scientists located at Texas AgriLife Research Centers in Overton and Uvalde, TX along with scientists at Oklahoma State University and The Ohio State University. Two graduate students received training associated with this project. A.N. Hafla conducted the bull research as a component of her Ph.D. dissertation. J.W. Thorne conducted the embryo recipient research as a component of his M.S. thesis. Both graduate students experienced professional development through presentation of research results at professional meetings. TARGET AUDIENCES: One target audience consisted of scientists, industry professionals and students who are interested in the fundamental mechanisms that regulate the reproductive processes that are responsible for successful conception and gestation. Another target audience included beef cattle producers who are interested in incorporating management practices to increase reproductive efficiency. Efforts to deliver the results from this project included seminars, classroom teaching, presentations at professional society meetings and presentations at producer meetings. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.

A meta-analysis of five postweaning performance trials and three breed types expanded our knowledge of relationships between feed efficiency and bull fertility traits. Inclusion of feed efficiency into a selection index does not appear to adversely affect pubertal development or potential fertility of bulls. These results allow beef cattle producers increased confidence in incorporating efficiency of gain into selection practices without compromising pregnancy rate of females mated to the more efficient bulls. A hormone administration protocol hypothesized to enhance luteal function in bovine embryo transfer recipient females failed to increase number or size of corpora lutea and did not result in a higher pregnancy rate. Further investigation of varying dose, timing or diluent of the hormone will be required before this technology will merit transfer to the beef cattle industry.


  • Hafla, A.N., Lancaster, P.A., Carstens, G.E., Forrest, D.W., Fox, J.T., Forbes, T.D.A., Davis, M.E., Randel, R.D., and Holloway, j.W. 2012. Relationships between feed efficiency, scrotal circumference, and semen quality traits in yearling bulls. J. Animal Science 90:3937-3944.
  • Thorne, J.W., Looney, C.R., Hasler, J.F., Hockley, D.K., and Forrest, D.W. 2012. Fertillity of beef recipients following a fixed-time embryo transfer protocol which included follicle stimulating hormone diluted in hyaluronan. Reproduction, Fertility and Development Special Issue 25(1):229-230. (abstract).