About

Dr. Fuller Bazer is a Regents Fellow, Distinguished Professor, and O. D. Butler Chair in the Department of Animal Science at Texas A&M University. He received his B.S. degree in Biology from Centenary College of Louisiana in 1960, his M.S. in Animal Science from Louisiana State University in 1963, and his Ph.D. in Animal Science from North Carolina State University in 1969. His research focuses on reproductive biology, specifically uterine biology and pregnancy, including pregnancy recognition signaling from the conceptus to the maternal uterus by interferon tau and estrogen in ruminants and pigs. He investigates the roles of uterine secretions as transport proteins, regulatory molecules, growth factors, and enzymes, as well as the endocrine regulation of their secretion. His work also encompasses the endocrinology of pregnancy, examining the roles of lactogenic and growth hormones in fetal-placental development and uterine functions. Dr. Bazer studies the mechanisms of action and potential therapeutic applications of conceptus interferons and uterine-derived hematopoietic growth factors using pigs and sheep as models for human disease.

Research topics

• Biology
• Biochemistry
• Endocrinology
• Medicine
• Cell biology
• Internal medicine
• Genetics
• Food science
• Andrology
• Computer Science
• Bioinformatics
• Molecular biology
• Biotechnology
• Chemistry
• Agronomy
• Physiology
• Animal science

Selected publications

• 62. Metabolomic Analyses of Uterine Luminal Fluid Reveals Regulatory Landscapes During the Peri-implantation Period of Pregnancy in Pigs

  Journal of Animal Science · 2026-04-01

  articleOpen access

  Abstract The peri-implantation period of pregnancy in pigs is characterized by rapid morphological transitions of the conceptus necessitating a precisely regulated uterine environment to support elongation, survival, and implantation. Uterine histotroph, composed of nutrients and signaling molecules secreted or transported by endometrial epithelia, plays a central role in mediating these events. However, dynamic metabolic remodeling of uterine luminal fluid (ULF) during early pregnancy remain poorly understood. In this study, we performed stage-resolved, untargeted metabolomic profiling of ULF collected from cyclic and pregnant gilts from Days 10 to 16 of the estrous cycle and pregnancy. A total of 206 metabolites were identified, with amino acids, fatty acids, and carbohydrates being the dominant classes. Principal component and supervised learning analyses revealed progressive divergence in ULF composition between pregnant and cyclic gilts with the most distinct profiles observed by Day 16. Notably, pregnancy induced increases in amino acids associated with mTOR signaling and trophectoderm proliferation, including arginine, glutamine, proline, lysine, and phenylalanine. KEGG enrichment analyses identified gestational age-dependent activation of pathways involved in amino acid biosynthesis, nucleotide metabolism, and phospholipid turnover. Metabolites such as phosphorylcholine, succinic acid, and asymmetric dimethylarginine increased markedly in pregnancy suggesting coordinated regulation of membrane remodeling, energy production, and nitric oxide signaling. Targeted quantification of 19 amino acids revealed both temporal and physiological status effects, with distinct glycine and serine trajectories between pregnant and cyclic ULF. Collectively, these findings define the evolving biochemical milieu of the uterine lumen and highlight key metabolic pathways likely required for conceptus development and implantation.

  PublisherOA PDFDOI

• Progesterone regulates endometrial expression of <i>SLC6A9</i> to potentially increase glycine transport to the developing pig conceptus

  Biology of Reproduction · 2025-07-13

  article

  Histotroph is regulated by P4 and paracrine factors and contains amino acids essential for porcine conceptus development. We hypothesized P4 contributes to amino acid transport during pregnancy in pigs. Ovariectomized gilts received daily P4 or corn oil (CO) injections from Days 12 through 39 post-estrus. High-performance liquid chromatography (HPLC) determined increased abundances of amino acids including glycine, in uterine flushings from P4-treated gilts. SLCs transport amino acids across membranes. rtPCR analyses revealed endometrial expression of SLC6A9 mRNA increased during the peri-implantation period of pregnancy. SLC7A8 and SLC38A1 mRNA expression also increased during that period but decreased later in pregnancy. SLC1A4, SLC1A5, and SLC7A10 mRNA expression was greatest later in pregnancy. Immunofluorescence analyses localized SLC6A9, which transports glycine exclusively, to the endometrial luminal epithelium from Day 12 through 25, uterine glandular epithelium throughout gestation, conceptus trophectoderm and endoderm between Days 15 and 20, and chorionic epithelia (CE) of interareolar and areolar CE between Days 40 and 60. Expression in interareolar regions decreased by Day 60 but remained high in the areolae. Expression of SLC6A9 was greater for endometrium from P4-treated than CO-treated pigs. These results illustrate the complexity of, and stage-dependent changes in, expression of amino acid transporters in endometria from pregnant pigs. The results suggest that transport of glycine into the uterine lumen and across the chorioallantois by SLC6A9 may be critical for delivery of this amino acid that is essential for conceptus development.

  PublisherDOI

• Latest trends and future prospects in gene editing, omics, and AI-based approaches for enhancing swine reproductive productivity in response to climate change

  KOBRA Reports · 2025-08-13

  articleOpen accessCorresponding

  Climate change severely threatens the reproductive potential in pigs, primarily through heat stress, as pigs struggle to regulate their body temperature.This leads to reduced feed intake, ovarian dysfunction, delayed estrus, and increased embryo mortality.At the cellular level, heat impairs mitochondrial function, disrupts hormone signaling, and inhibits placental angiogenesis, causing delayed fetal growth and higher pre-weaning mortality.These challenges exceed the capacity of traditional management approaches and require advanced biotechnological solutions.CRISPR/Cas9 gene editing has produced pigs resistant to porcine reproductive and respiratory syndrome viruses (PRRSV) and has improved thermotolerance through uncoupling protein 1 (UCP1) gene restoration.Single-cell omics has revealed that endometrial cell vulnerabilities and disrupted gene networks affect uterine receptivity and embryonic development under high-temperature conditions.Mitochondrial biomarkers, such as functional integrity and haplotype analysis, are emerging tools for selecting climate-resilient pigs.Organoid models that replicate embryo-maternal interactions provide platforms for studying thermal stress effects and test interventions.In addition, artificial intelligence (AI)-based systems enhance environmental control, predict heat stress, and optimize health and productivity.However, global regulatory frameworks for genetically edited animals remain fragmented, underscoring the need for transparent science-based policies to ensure safety and public trust.The integration of gene editing, omics, organoid platforms, and AI has led to a paradigm shift in pig reproductive management.This convergence offers precision breeding strategies and novel therapeutic targets essential for sustaining productivity and resilience in the global pig industry under accelerated climate change.

  PublisherOA PDFDOI

• Effects of dietary supplementation of creatine on fetal development in gilts at d 60 and d 90 of gestation

  Journal of Animal Science and Biotechnology/Journal of animal science and biotechnology · 2025-03-01 · 4 citations

  articleOpen accessSenior author

  BACKGROUND: The creatine-creatine kinase-phosphocreatine (Cr-CK-PCr) system maintains intracellular ratios of ATP/ADP for support of cellular functions and has been characterized at the placental-uterine interface of rodents, primates, swine and sheep, and thus may support fetal development. This study determined effects of dietary supplementation of creatine (Cr) to gestating gilts on fetal development, the number and ratio of primary and secondary muscle fibers, and on protein expression in endometrium and fetal biceps-femoris muscle, respectively in fetal pigs on d 60 and d 90 of gestation. METHODS: Reproductively mature gilts were synchronized to estrus using Matrix, observed for estrus (d 0), and artificially inseminated 12 h and 36 h later. Gilts were individually housed and fed 0.86 kg of 14% crude protein diet twice daily that meets nutritional requirements for pregnant gilts. Gilts were assigned to either basal diet control (CON) group, or Cr supplemented group (provided 30 g Cr monohydrate daily) from d 10 to either d 60 or d 90 of gestation. Gilts were euthanized and hysterectomized on either d 60 or d 90 of gestation. These protocols were completed in two replicates, as gilts were bred in spring and euthanized in summer or bred in fall and euthanized in winter (n = 20 gilts/replicate). Litter size, crown-rump length, sex, and fetal weight was recorded. Three female and male fetuses closest to mean litter weight were selected to assess effects of treatment on weight of fetal brain, kidney, liver, spleen, and biceps-femoris muscle. Data were analyzed to determine effects of treatment, days of gestation, replicate, and sex on litter size, fetal measurements, and incidence of intrauterine growth restriction. RESULTS: 0.05). CONCLUSIONS: Results suggest that dietary supplementation of Cr in gestating gilts enhanced development of select fetal organs and contribute to understanding roles of the Cr-CK-PCr system in pregnancy.

  PublisherOA PDFDOI

• Uterine histotroph and conceptus development. V. Comparative analyses of arginine-mediated transcriptomic reprogramming in conceptus trophectoderm of pigs and sheep

  Biology of Reproduction · 2025-10-07 · 1 citations

  articleOpen access

  In ungulates such as pigs and sheep, blastocyst elongation is essential for implantation, driven by coordinated trophoblast proliferation, cytoskeletal remodeling, and nutrient signaling. L-arginine (Arg), a conditionally essential amino acid enriched in uterine histotroph during early pregnancy, plays a key role in conceptus development; however, its genomic effects on the trophectoderm are poorly defined. Therefore, we investigated Arg-responsive transcriptomic changes in porcine (pTr2) and ovine (oTr1) trophectoderm cells using RNA-seq and integrative pathway analyses. Arg significantly stimulated proliferation in both cell types in a non-linear, dose-dependent manner, with maximal effects at 0.2 mM, consistent with physiological levels. Transcriptomic profiling identified 2723 and 5369 differentially expressed genes in pTr2 and oTr1 cells, respectively, encompassing genes involved in cell proliferation, metabolism, cytoskeletal remodeling, and implantation. Canonical pathway and upstream regulator analyses revealed both conserved and species-specific responses to Arg, including shared activation of actin cytoskeleton and adrenomedullin signaling and suppression of p53 signaling. Species-specific enrichment of cholesterol biosynthesis (pigs) and interferon signaling (sheep) further highlighted divergent strategies for pregnancy recognition. Comparative analyses identified 615 commonly regulated differentially expressed genes and highlighted O-linked N-acetylglucosamine transferase as a conserved upstream regulator, implicating nutrient-responsive O-GlcNAcylation in trophectoderm function. Arg promoted gene programs supporting mitosis, oxidative phosphorylation, and extracellular matrix remodeling while repressing pathways related to apoptosis and pluripotency. These results advance understanding of how Arg activates conserved transcriptional networks to support trophectoderm proliferation and differentiation, while also fine-tuning species-specific pathways aligned with pregnancy recognition and implantation of conceptuses in sheep and pigs.

  PublisherOA PDFDOI

• Impact of dietary supplementation of L-citrulline to meat goats during gestation on reproductive performance

  Journal of Animal Science and Biotechnology/Journal of animal science and biotechnology · 2025-01-05 · 2 citations

  articleOpen accessSenior author

  BACKGROUND: Meat goat production is a worldwide industry with products such as meat, milk, soap, and fiber being produced. There are approximately 2.6 million meat goats in the United States. For breeding female ruminants, early pregnancy loss is estimated to be 30% within the first month of gestation. Extracellular L-citrulline (a precursor to L-arginine) is not degraded by ruminal microbes due to the lack of uptake. L-Arginine and thus L-citrulline, have beneficial impacts on placentation and, subsequently, fetal-placental development and survival. This study aimed to determine the impact of feeding L-citrulline to meat goats during gestation to improve reproductive success. Meat goats were fed either a control (CON) or L-citrulline (CIT) supplemented diet from d 12 to 82 of gestation. Blood samples were collected and sera were subjected to high-performance liquid chromatography analyses to quantify the abundance of amino acids. Pregnancy rates were determined on d 30, 61, and 90 of gestation, and litter weight, individual birth weights, and 90 d adjusted weaning weights were collected. RESULTS: The concentrations of citrulline, ornithine, and arginine were greater in CIT does compared to CON does, but there was no difference in pregnancy rates between CON and CIT does. Birth weight was greater for male kids born as singles when compared to females, but this phenotype was not observed for kids born as twins or triplets. Further, males born to CON does had greater 90 d adjusted weaning weights than females, but this was not observed in the CIT group. Female kids born to CON and CIT Boer goats had heavier 90 d adjusted weaning weights than those born to Spanish or F1 Boer-Spanish does. CONCLUSION: This study provides proof of concept that feeding dietary L-citrulline increases concentrations of citrulline and arginine in blood of gestating meat goats. However, further studies are needed to understand the cellular mechanisms impacted by feeding this supplement. Regardless, this study demonstrated that feeding L-citrulline has the potential to increase reproductive performance in gestating ruminants.

  PublisherOA PDFDOI

• SPARC expression in the mouse decidua, placenta, and fetus: correlations with SPP1 expression

  Placenta · 2025-06-17 · 1 citations

  article
  PublisherDOI

• 95 The microbiomes of reproductive tissues in cyclic and early gestation gilts

  Journal of Animal Science · 2025-06-01

  articleOpen access

  Abstract During early gestation, the conceptus is undergoing elongation and begins to signal maternal recognition of pregnancy (day 12) with implantation occurring at approximately day 15. Additionally, luteolysis occurs in cyclic gilts at approximately day 13 of their estrous cycle. Further, there is limited research examining the reproductive microbiomes during these periods. Therefore, this study characterized the bacterial communities associated with the mucosal surfaces of the vagina, cervix, and uterus in both pregnant and cycling gilts. Duroc x Landrace x Yorkshire gilts (n=17) free of physical, health or reproductive-related issues were euthanized and hysterectomized during the preimplantation (D11) and implantation (D15) stages of pregnancy as well as cyclic (Pregnant D11, n=7; Pregnant D15, n=5; Cyclic D14/15, n=5). Sterile swabs were used to collect, in duplicate, samples from the mucosal surface of each tissue for storage in microcentrifuge tubes at -80°C until sequencing. For uterine and cervical tissues, a 1 cm incision was made in the same location, exposing the endometrium and cervical mucosa. The sterile swab was rotated 8 times and immediately placed in a microcentrifuge tube. For vaginal sampling, a sterile swab was inserted 6 inches past the vulva and rotated 8 times. Bacterial DNA extraction and genome sequencing targeting the V4 hypervariable region of the 16S rRNA gene was conducted by FERA Diagnostics and Biologicals Corp. Statistical analyses were conducted using the GLM procedure in SAS. Across all reproductive tissues, the phylum Bacteroidetes differed by pregnancy status with less relative abundance in cyclic gilts compared to D11 and D15 gilts (9.68 ± 1.71% vs 11.51 ± 1.11% and 15.91 ± 1.17%, respectively; P&amp;lt; 0.01). Within this phylum, the relative abundance of genus Prevotella was the greatest at D15 compared to D11 and cyclic (4.91 ± 0.59% vs. 3.27 ± 0.57% and 2.15 ± 0.87%, respectively; P&amp;lt; 0.05). The phylum Actinobacteria differed by pregnancy status with a greater relative abundance in cyclic gilts compared to D11 and D15 gilts (13.1 ± 1.66% vs. 5.53 ± 1.08% and 6.72 ± 1.13%, respectively; P&amp;lt; 0.01). Within this phylum, the relative abundance of genus Corynebacterium was greater in cyclic gilts compared to D11 and D15 gilts (5.22 ± 0.60% vs. 2.52 ± 0.39% and 2.83 ± 0.41%, respectively; P&amp;lt; 0.01). There were numerous bacteria that differed by tissue type with Campylobacter, Bacteroides, Porphyromonas, Actinobacillus, Anaerococcus, Peptoniphilus, and Fusobacterium being greater in relative abundance in the vagina compared to the cervix and uterus (P&amp;lt; 0.05). These results suggest that microbial communities differ among components of the reproductive tract and by pregnancy status. The differences observed between the reproductive microbiome of pregnant versus cyclic gilts could be influenced by signals from the conceptus.

  PublisherOA PDFDOI

• Dietary Supplementation with L-Citrulline Between Days 1 and 60 of Gestation Enhances Embryonic Survival in Lactating Beef Cows

  Animals · 2025-08-15 · 1 citations

  articleOpen access

  Low fertility limits reproductive efficiency in cattle. This study was conducted with multiparous Brangus cows receiving dietary supplementation with or without L-citrulline [Cit; an immediate precursor of L-arginine (Arg)]. During the entire experimental period, cows grazed green pasture and had free access to drinking water and mineral blocks. One hundred and seven (107) cows were assigned randomly to one of three treatment groups: dried distillers grains with solubles (DDGS) without Cit supplement (n = 36); DDGS top-dressed with rumen-protected Cit product (RPAA; n = 36); or unprotected Cit product (RUAA; n = 35). After 2 months of lactation, all cows were synchronized to estrus and were bred once via artificial insemination. From Day 1 to Day 60 of gestation, cows were individually fed once daily 0.84 kg of a supplement (DDGS; control), 0.56 kg of DDGS plus 0.28 kg of RUAA (containing 0.07 kg of unencapsulated Cit), or 0.56 kg of DDGS plus 0.28 kg of RPAA (containing 0.07 kg of rumen-protected Cit). The supplemental dose of Cit was equivalent to 0.5% of the estimated daily intake of 14 kg dry matter from pasture. On Days 40 and 60 of gestation, ultrasound was used to determine pregnancy rates. Each pregnant cow had a single conceptus. On Day 60 of gestation, blood samples were obtained from the jugular vein. All cows grazed normally and appeared healthy. Birth rates for live-born calves were 22% and 35% in cows receiving DDGS alone and Cit supplementation, respectively (p &lt; 0.05). The beneficial effect of Cit was associated with increases in concentrations of Cit (+19%), Arg (+20%), ornithine (+19%), proline (+17%), and insulin (+82%) but decreases in concentrations of ammonia (–14%) in maternal plasma (p &lt; 0.05). Thus, dietary supplementation with Cit is a simple, novel, and cost-effective nutritional method to increase the reproductive efficiency of lactating beef cows.

  PublisherOA PDFDOI

• Stage of pregnancy impacts the bacterial communities of reproductive and placental tissues in gilts

  Journal of Animal Science · 2025-01-01 · 1 citations

  articleOpen access

  Bacterial communities within the female reproductive tract have previously been linked to fertility status in mammals, however, minimal research has focused on reproductive microbiota in swine. Therefore, the objectives of this study were to compare and analyze the composition and α- and β-diversity of bacterial populations of different reproductive tissues (i.e., vagina, cervix, endometrium, and chorion) and placental fluids (i.e., allantoic and amniotic) in cyclic or pregnant gilts throughout gestation. Crossbred gilts free of physical, health, or reproductive-related issues were euthanized, hysterectomized, and sampled during diestrus (n = 5; cyclic) or on day 11 (n = 11; peri-implantation), 15 (n = 10; implantation), 60 (n = 6; mid-gestation), or 90 (n = 6; late-gestation) of pregnancy. A sterile swab was rotated 8 times to collect samples from the mucosal surface of individual tissues and immediately placed in microcentrifuge tubes for storage (-80 °C) until sequencing. For allantoic and amniotic fluids, 5 mL samples were collected and placed immediately in a sterile 10 mL conical tube and stored (-80 °C) for subsequent analyses. Bacterial DNA was extracted, and genome sequencing targeting the V4 hypervariable region of the 16S rRNA gene was conducted. The relative abundance of Fusobacterium was more abundant (P < 0.05) in the vagina compared to all tissues and fluids across all days except in day 90 gilts, while the relative abundance of Lactobacillus was more abundant in allantoic fluid than the endometrium at day 60 (P < 0.05). Alpha-diversity (Shannon's and Simpson's index) was lower in amniotic fluid compared to other tissues (P < 0.05), but there were no differences in α-diversity by day of pregnancy or between cyclic and pregnant gilts (P > 0.05). Beta-diversity revealed distinct clustering by tissue type, with posterior tissues such as the vagina clustering separately from placental fluids, and by day, with cyclic, day 11, and 15 samples clustering separately from day 60 and 90 samples (P < 0.01). These findings suggest that bacterial communities within the reproductive tract are dynamic and vary by both anatomical location and stage of pregnancy in gilts.

  PublisherOA PDFDOI

Recent grants

• NIH Grant R01HD010436

  NIH · $433k · 1990

• NIH Grant R01DK046766

  NIH · $517k · 1996

• NIH Grant R01HD032534

  NIH · $1.8M · 2008

Frequent coauthors

• Thomas E. Spencer

  University of Missouri

  271 shared

• Guoyao Wu

  Texas A&M University

  222 shared

• Robert C. Burghardt

  Texas A&M University

  188 shared

• Gwonhwa Song

  Korea University

  185 shared

• Greg A. Johnson

  Mitchell Institute

  148 shared

• Whasun Lim

  Sungkyunkwan University

  118 shared

• Gregory A. Johnson

  103 shared

• M. Carey Satterfield

  Texas A&M University

  79 shared

Education

• B.S.

  Centenary College of Louisiana

• M.S.

  Louisiana State University

• Ph.D.

  North Carolina State University

Awards & honors

• Regents Fellow
• O. D. Butler Chair, Physiology of Reproduction