VTechWorks Repository :: Browsing by Author "Daniels, Kristy M."

Browsing by Author "Daniels, Kristy M."

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Abundance and Localization of (Yes-associated protein) YAP in Prepubertal Bovine Mammary Tissue
Granger, Paulnisha Davida (Virginia Tech, 2018-07-09)
Most mammary development is postnatal. Mammary growth that occurs before puberty is diminutive in amount but consequential for future milk production, especially in dairy heifers. With advanced knowledge on fundamental aspects that govern prepubertal mammary development, scientists and farmers alike can ensure that heifers perform their best once they become cows. The Hippo pathway has been identified as an evolutionarily conserved pathway that regulates organ size in many animal species; it might contribute to mammary growth in dairy heifers. This pathway is mediated by yes-associated protein (YAP) and through downstream gene transcription activation, results in cell proliferation. Because YAP has never been identified in bovine mammary tissue, questions examined in this body of work mainly focused on the abundance and localization of YAP in mammary tissue of prepubertal heifers. The first trial investigated effects of in vivo estradiol administration on YAP abundance and localization in prepubertal bovine mammary epithelial and myoepithelial cells. While YAP was present in nuclei and cytoplasm of both cell types, it was also discovered that estrogen did not influence YAP abundance or location. The second research trial focused on determining the effects of in vivo estradiol blockade on YAP abundance and localization in prepubertal bovine mammary epithelial and myoepithelial cells. Similar to the first experiment, results indicate that YAP abundance and localization was not influenced by estrogen blockade. Despite not being responsive to in vivo estradiol administration (experiment 1) or estradiol blockade (experiment 2) under the conditions of our experiments, YAP was present in nearly all mammary epithelial cells and myoepithelial cells of the 21 total prepubertal heifers examined. Its presence hints at an underlying biological function but that function was not ascertained here. It will be up to the next researcher to deduce what YAP contributes to mammary growth in prepubertal dairy heifers.
Cyclical heat stress during lactation influences the microstructure of the bovine mammary gland
Perez-Hernandez, G.; Ellett, Mark D.; Banda, L. J.; Dougherty, D.; Parsons, Catherine L. M.; Lengi, A. J.; Daniels, Kristy M.; Corl, Benjamin A. (Elsevier, 2024-05-31)
This study aimed to evaluate the effect of heat stress on mammary epithelial cell (MEC) losses into milk, secretory mammary tissue structure, and mammary epithelial cell activity. Sixteen multiparous Holstein cows (632 ± 12 kg BW) approximately 100 DIM housed in climate-controlled rooms were paired by BW and randomly allocated to one of 2 treatments, heat stress (HS) or pair-feeding thermoneutral (PFTN) using 2 cohorts. Each cohort was subjected to 2 periods of 4 d each. In period 1, both treatments had ad libitum access to a common TMR and were exposed to a controlled daily temperature-humidity index (THI) of 64. In period 2, HS cows were exposed to controlled cyclical heat stress (THI: 74–80), while PFTN cows remained at 64 THI and daily DMI was matched to that of the HS cows. Cows were milked twice daily, and milk yield was recorded at each milking. Individual milk samples on the last day of each period were used to quantify MEC losses by flow cytometry using butyrophilin as a cell surface marker. On the final day of period 2, individual bovine mammary tissue samples were obtained for histomorphology analysis, assessment of protein abundance, and evaluation of gene expression of targets associated with cellular capacity for milk and milk component synthesis, heat response, cellular proliferation, and autophagy. Statistical analysis was performed using the GLIMMIX procedure of SAS. Milk yield was reduced by 4.3 kg by HS (n = 7) compared with PFTN (n = 8). Independent of treatment, MEC in milk averaged 174 cells/mL (2.9% of total cells). There was no difference between HS and PFTN cows for MEC shed or concentration in milk. Alveolar area was reduced 25% by HS, and HS had 4.1 more alveoli than PFTN. The total number of nucleated MEC per area was greater in HS cows (389 ± 1.05; mean ± SE) compared with PFTN (321 ± 1.05); however, cell number per alveolus was similar between groups (25 ± 1.5 vs. 26 ± 1.4). There were no differences in relative fold expression for GLUT1, GLUT8, CSN2, CSN3, LALBA, FASN, HSPA5, and HSPA8 in HS cows compared with PFTN cows. Immunoblotting analyses showed a decrease in abundance for phosphorylated STAT5 and S6K1, and an increase in LC3 II in HS cows compared with PFTN cows. These results suggest that even if milk yield differences and histological changes occur in the bovine mammary gland after 4 d of heat exposure, MEC loss into milk, nucleated MEC number per alveolus, and gene expression of nutrient transport, milk component synthesis, and heat-stress-related targets are unaffected. In contrast, the abundance of proteins related to protein synthesis and cell survival decreased significantly, whereas proteins associated with autophagy were upregulated in HS cows compared with PFTN cows.
Dairy Pipeline, July/August 2020
Ferreira, Gonzalo; Daniels, Kristy M.; Seekford, Zack (Virginia Cooperative Exension, 2020-06-19)
multiple KPIs exist for evaluating the management of the dairy farm, and managers should not get overwhelmed monitoring these. However, as a coin has two sides, most common KPIs have a counterbalancing KPI. Once in a while, evaluate both KPIs for a more holistic and realistic analysis of your farm management.
Dairy Pipeline, September 2017
Ceh, Carrie; Daniels, Kristy M.; Daubert, Jeremy (Virginia Cooperative Extension, 2017-09-04)
The two articles in this issue focus on colostrum and calf health, and on genomics.
Dairy Pipeline. May 2016
James, Robert E.; Spurlin, Kevin; Daniels, Kristy M. (Virginia Cooperative Extension, 2016-05-02)
This issue includes articles about the federal margin protection program for dairy farms, and about antibody concentration in colostrum in milk for calves.
Effects of bodyweight and plane of nutrition on mitogenic capacity of mammary extracts in cell culture, mammary growth and development, and protein expression profiles of mammary tissue in Holstein heifers
Daniels, Kristy M. (Virginia Tech, 2004-12-16)
Mammary gland samples from a large serial-slaughter Holstein heifer nutrition trial were used to determine the effects of stage of development and nutritional management on mitogenic activity of mammary extracts and mammary parenchymal composition. Stage of development and nutritional management of heifers had minimal effects on the mitogenic capacity of mammary extracts, and no significant effects on tissue composition. Two-dimensional proteome maps of heifer mammary extracts were constructed for heifers weighing 200 and 350 kg, respectively at slaughter. Proteins altered by stage of development and/or nutrition were quantified and identified; 820 total protein spots were analyzed. The expression of 131 protein spots differed by dietary treatment only. Stage of development altered the expression of 108 protein spots. Twenty-two protein spots were excised from gels for mass spectrometry analyses. Database searches for proteins with shared primary amino acid sequences were used to identify the proteins. Possible roles of these proteins in mammary development were described. In summary, heifers can be reared on high planes of nutrition without impairing mammary development, but mechanisms governing nutritional and temporal control of mammary development demand further investigation.
Effects of Milk Replacer Composition on Measures of Mammary Development in Holstein Heifer Calves
Daniels, Kristy M. (Virginia Tech, 2008-04-15)
This study was to evaluate effects of milk replacer (MR) composition on: mass and composition of mammary parenchyma (PAR) and fat pad (MFP), growth hormone (GH)/insulin-like growth factor-I (IGF-I) axis gene expression, and putative mammary epithelial stem cells. The hypothesis was that diet during the pre-weaning period alters the development, persistence, or activity of populations of putative mammary epithelial stem cells, possibly through involvement of GH/IGF-I axis molecules. Twenty-four newborn heifers were fed one of four MR diets: CON (20% CP, 21% fat MR fed at 441 g DM/d), HPLF (28% CP, 20% fat MR fed at 951 g DM/d), HPHF (27% CP, 28% fat MR fed at 951 g DM/d), and HPHF+ (27% CP, 28% fat MR fed at 1431 g DM/d). Animals were harvested on d 65 of life and mammary tissue was subjected to biochemical, molecular, and histological examination. By design, the effects of diet were evaluated at a common chronological age, but not necessarily at the same physiological age (body weight). Results from heifers reared on CON were compared to the average results from heifers reared on the other 3 diets. The second comparison evaluated the effect of increased fat in MR when protein content and intake were the same. The final comparison evaluated the effect of increased intake of a high-fat, high-protein MR. Neither diet composition nor nutrient intake in pre-weaned heifers affected PAR weight, PAR composition, GH/IGF-I axis gene expression, or putative mammary epithelial stem cell abundance when assessed at a common chronological age. Changes in MFP size and composition were observed, but no diet effect on GH/IGF-I axis gene expression in MFP was observed. This suggests nutrition is not critical for regulating the expression of local GH/IGF-I axis components or stem cell populations in the developing heifer mammary gland.
Environmental, Biochemical, and Dietary Factors that Influence Rumen Development in Dairy Calves
Ceh, Carrie Ann (Virginia Tech, 2019-07-12)
The dairy industry today is beginning to dedicate more focus on the growth of the calf from birth to first breeding to better improve the milk production as well as the overall performance of the individual cows. While the development of the rumen is one of the most vital contributors to the performance of the calf, it remains unknown what molecular mechanisms are responsible for the development of the rumen, and more specifically the proliferation of rumen epithelial cells. The objectives of this study were to investigate the existing data on rumen development through meta-analysis and to explore the effects of sodium butyrate and lipopolysaccharide (LPS) on rumen development in calves through experiment. In the first study a meta-analysis was performed to summarize the literature on calf performance and derive equations that relate rumen (e.g., rumen pH, reticulorumen weight, papillae area) and non-rumen factors (e.g., feed composition, form of feed, housing) to animal performance (e.g., intake of milk replacer (MR), starter, and forage; average daily gain (ADG); and feed efficiency). We looked at four different relationships to further investigate the connections between rumen, non-rumen, and performance factors. In the first and second relationships of interest, the effect of dietary and environmental variables on rumen variables and performance variables were examined, respectively. The third relationship of interest was how rumen variables influenced performance variables. The final relationship of interest was investigating the additive effects of the rumen, dietary, and environmental variables on the performance variables. Forward selection, multiple regression was used to derive equations to select variables that explained variation in the response variable in each model. Results showed that the variation in calf ADG was explained by daily forage intake, calves that were weaned, total starter intake, and total MR intake (concordance correlation coefficient (CCC) = 0.976). The variation in feed to gain ratio was explained by the weight of the ruminal contents, daily forage, MR, and starter intakes, percent of starter in the diet, and total starter intake (CCC = 0.992). The variation in daily forage intake was explained by the percent of the diet that was starter or MR (CCC = 0.998). The variation in daily starter intake was explained by the percent of acid detergent fiber in the starter, a pelleted starter (versus a texturized), diets including starter and forage (versus a milk replacer only diet), and the percent of the diet that was MR (CCC = 0.998). The variation in daily MR intake was explained by the percent of the diet that was starter, final body weight, ruminal propionate concentration, and daily starter intake (CCC = 0.918). Based on these analyses, although dietary and environmental factors are closely associated with calf performance, ruminal factors such as volatile fatty acid (VFA) concentration and ruminal contents appear to have additional, additive influences on calf performance. In the second study, 24 Holstein bull calves were challenged with oral doses of LPS and sodium butyrate. The hypothesis here was that LPS and sodium butyrate would instigate rumen cell proliferation independently and additively. Calves were assigned to one of four treatments: control (CON; n=5), butyrate (BUTY; n=5), LPS only (LPS-O) (n=6), or LPS plus butyrate (LPSB; n=6). All treatments were administered orally twice daily consisting of either: 0.9% saline (CON); 11 mM sodium butyrate (BUTY); LPS ranging from 2.5 to 40 µg/kg metabolic body weight (BW0.75, LPS), or both butyrate and LPS (LPSB). Calves were fed milk replacer (22% CP, 20% fat, as-fed) and starter (20% CP, 3% fat, as-fed) based on metabolic BW, or about 12% BW of MR and 3% BW of starter. Feed intake, fecal and respiratory scores, and rectal temperature were recorded daily. Calf BW, hip height, jugular blood samples, and rumen content samples (via oroesophageal tube) were collected weekly. Calves were weaned at 6 wk of age and euthanized at 8 wk of age, whereupon ruminal weights and ruminal samples for papillae area and epithelial thickness were collected. Blood and rumen samples were analyzed for concentrations of beta-hydroxybutyrate, glucose, LPS-binding protein, and VFA. Data were analyzed as a 2x2 factorial with the repeated effect of week. Three non-orthogonal contrasts (CON versus the average of all other treatments; LPS-O versus LPSB, and LPSB versus BUTY) were investigated. Feed intake, health measures, and blood metabolites did not differ by treatment. Calf BW increased by week (P < 0.0001). Irrespective of week, LPS calves weighed more and had higher ADG than BUTY calves (P = 0.020). Irrespective of week, withers height was greater in LPS compared to CON (P = 0.006). Rumen pH and rumen VFA concentrations did not differ by treatment but did decrease and increase, respectively, with week in conjunction with increased starter intake. Total empty forestomach (P = 0.014) and reticulorumen weights (P = 0.012) were greater in LPSB compared to BUTY. Overall, LPS and sodium butyrate appeared to have synergistically affected some, but not all rumen measurements without affecting calf growth, intake, or health. Results from the meta-analysis emphasize the importance of continuing to focus on the solid feed intake of the calf from birth through weaning. Implications from the LPS study are imperative to other dairy scientists who will attempt to further study the effects of LPS on the rumen.
Extracellular Proteoglycan Decorin in Bovine Mammary Physiology
Tucker, Hannah L. (Virginia Tech, 2017-09-27)
The majority of bovine mammary gland research focuses on the main cell types - mammary epithelial cells and fibroblasts. However, the extracellular matrix (ECM) within the mammary gland is also of importance for its ability to regulate cell shape, proliferation, polarity, differentiation, gene transcription, protein synthesis, and secretion. Decorin is an ECM proteoglycan known to impact mammary cell proliferation in humans and rodents. Prior to this work, very little was known about decorin in bovine mammary biology. A series of bovine mammary cell culture experiments was conducted. The first experiment demonstrated existence of decorin pathway molecules in immortalized bovine mammary cells, but stopped short of demonstrating mature decorin proteoglycan deposition into the extracellular space. During the investigation it was noted that when cultured under basal conditions, intracellular decorin core protein (DCP) localization patterns appeared to be coordinated with specific phases of the cell cycle. Therefore, the objective of the second set of experiments was to characterize DCP localization patterns in bovine mammary epithelial cells (BME) at known phases of the cell cycle. The work was carried out in two sequential experiments. The hypothesis of the first experiment was that DCP accumulates in BME during S-phase of the cell cycle; the research rejected this hypothesis. The hypothesis of the second experiment, formulated after completion of the first experiment for this objective, was that DCP accumulates in BME during metaphase of the cell cycle. However, the experiment was unable to confirm of reject this hypothesis. Major findings were that both BME and mammary fibroblasts produce DCP and known decorin pathway molecules. BME produce intracellular DCP, but it is not accumulated during the S-phase of the cell cycle. However, it is still unknown if DCP is accumulated in BME during metaphase. Future research should focus on further characterization of decorin and its associated pathway molecules to learn if decorin induces proliferation or apoptosis of bovine mammary epithelial cells. This is important because number and activity of mammary epithelial cells ultimately determine milk yield in dairy cows. Fundamental knowledge gained in this research area may one day be applied at the animal-level and lead to gains in milk production efficiency by altering the cellular composition of mammary glands.
Functional and gene network analyses of transcriptional signatures characterizing pre-weaned bovine mammary parenchyma or fat pad uncovered novel inter-tissue signaling networks during development
Piantoni, Paola; Bionaz, Massimo; Graugnard, Daniel E.; Daniels, Kristy M.; Everts, Robin E.; Rodriguez-Zas, Sandra L.; Lewin, Harris A.; Hurley, Hurley L.; Akers, Robert Michael; Loor, Juan J. (2010-05-26)
Background The neonatal bovine mammary fat pad (MFP) surrounding the mammary parenchyma (PAR) is thought to exert proliferative effects on the PAR through secretion of local modulators of growth induced by systemic hormones. We used bioinformatics to characterize transcriptomics differences between PAR and MFP from ~65 d old Holstein heifers. Data were mined to uncover potential crosstalk through the analyses of signaling molecules preferentially expressed in one tissue relative to the other. Results Over 9,000 differentially expressed genes (DEG; False discovery rate ≤ 0.05) were found of which 1,478 had a ≥1.5-fold difference between PAR and MFP. Within the DEG highly-expressed in PAR vs. MFP (n = 736) we noted significant enrichment of functions related to cell cycle, structural organization, signaling, and DNA/RNA metabolism. Only actin cytoskeletal signaling was significant among canonical pathways. DEG more highly-expressed in MFP vs. PAR (n = 742) belong to lipid metabolism, signaling, cell movement, and immune-related functions. Canonical pathways associated with metabolism and signaling, particularly immune- and metabolism-related were significantly-enriched. Network analysis uncovered a central role of MYC, TP53, and CTNNB1 in controlling expression of DEG highly-expressed in PAR vs. MFP. Similar analysis suggested a central role for PPARG, KLF2, EGR2, and EPAS1 in regulating expression of more highly-expressed DEG in MFP vs. PAR. Gene network analyses revealed putative inter-tissue crosstalk between cytokines and growth factors preferentially expressed in one tissue (e.g., ANGPTL1, SPP1, IL1B in PAR vs. MFP; ADIPOQ, IL13, FGF2, LEP in MFP vs. PAR) with DEG preferentially expressed in the other tissue, particularly transcription factors or pathways (e.g., MYC, TP53, and actin cytoskeletal signaling in PAR vs. MFP; PPARG and LXR/RXR Signaling in MFP vs. PAR). Conclusions Functional analyses underscored a reciprocal influence in determining the biological features of MFP and PAR during neonatal development. This was exemplified by the potential effect that the signaling molecules (cytokines, growth factors) released preferentially (i.e., more highly-expressed) by PAR or MFP could have on molecular functions or signaling pathways enriched in the MFP or PAR. These bidirectional interactions might be required to coordinate mammary tissue development under normal circumstances or in response to nutrition.
Genetic and Maternal Factors Underlying Early Milk Production and Their Influence on Calf Health
Nin-Velez, Alexandra Irma (Virginia Tech, 2020-09-11)
The quality of early milk produced by dams is affected by various factors (i.e. breed, age, parity, environment, nutrition, management). The impact of these factors on the quality of milk then have subsequent effects on calf health and development. Producers are responsible for following guidelines in order to ensure that they feed calves optimal quality milk in order to produce a healthy animal. They can also regulate factors such as environment and nutrition of the dam in order to produce better quality early milk. However, even after maximizing these factors there is still high mortality rate among pre-weaned calves, therefore, other factors such as mode of birth and genetics need to be studied to determine impacts on early milk quality and make further improvements to calf health and decrease mortality. Two experiments were conducted in order to study the effects of maternal and genetic factors on early milk production and to determine relationships that exist with calf health. The objective of the first study was to determine the effects that the mode of delivery had on early milk composition, and on the rumen microbiome of calves. We hypothesized that mode of birth would impact early milk composition, and, in turn, influence the microbial phyla in the calf gut. The second study had three objectives: 1) establish phenotypic relationships between colostrum composition traits, milk production traits, and calf health, 2) determine impact of breed and season on colostrum production and 3) ) elucidate the genetic parameters (i.e. heritability, genotypic, and phenotypic correlations) among colostrum production and milk production We hypothesized that colostrum composition and production differ among breeds and by season and that individual components influence calf health. Additionally, we hypothesized that colostrum quality traits (i.e. Brix score and volume) are heritable. For the first study Charolaise (CHAR; n = 23) and Angus (ANG; n = 15) dams were divided into two experimental groups; dams underwent vaginal (VD; n= 25) or cesarean (CD; n= 13) deliveries. Early milk samples were collected and quantified for protein, lactose, somatic cell count, and fatty acid concentrations. After parturition calves were separated based on dams experimental group. Rumen fluid was collected from calves on d 1, 3, and 28 post-partum. Extracted DNA from fluid were used for metagenomic sequencing (ANG calves, n=11; CHAR calves, n=13). Samples were run on the HiSeq 2500 platform as paired end reads according to Ilumina's standard sequencing protocol. A regression analysis was done in SAS using PROC GLM and regressing mode of birth on milk components for d 1,3, and 28. After, milk components found to be significantly impacted by mode of birth were regressed against microbial counts. Results showed that VD dams were more likely to have increased (P  0.05) protein, solids non-fat, and lactose on d 1 and 3, but decreased (P < 0.05) urea concentrations. Similarly, short, medium, and long-chain fatty acids were increased (P  0.05) in VD d 3 milk. Changes in true protein elicited a decrease (P  0.05) in rumen fluid Actinobacteria and Proteobacteria; whereas, both solids non-fat and lactose were associated with an increased (P  0.05) response in d 1 transition milk. No significant results for d 28 of sampling were observed. Based on our results we suggest that mode of birth influences protein concentrations in early milk. However, only a slight impact on the overall dynamics of the calf rumen was observed with the microbiome remaining relatively stable on the phyla level in response to changes in protein concentration. The second study looked into relationships between colostrum composition traits, management practices, and calf health, as well as determined heritability and genetic correlations for colostrum quality traits. Values for test-day milk, protein, fat, and somatic cell count (SCS) for Holstein (HO, n= 250) and Jersey (JE, n=289) cows were obtained from the Animal Genomic and Improvement laboratory server at the USDA. Brix score, colostrum weight, dam age, parity, and 3-month season of calving were also recorded. After, colostrum samples from JE cows were sent to DHIA where compositional measurements were obtained (i.e. true protein, fat, lactose, SCS, solid non-fats). Lactoferrin concentration for JE colostrum samples was also determined via ELISA. Calf blood samples were collected within 72 h post-partum and total serum protein (TSP) quantified to determine success of passive immunity transfer. Additionally, farm staff were instructed to record colostrum source for 1st feeding (i.e. dam, mix, other), freshness for 1st feeding (frozen vs fresh), Brix score of colostrum fed, volume of colostrum fed, and birth weight. A PROC Mixed with LSMEANS was performed in SAS to determine relationships between colostrum components, test day components, and quality traits for season, breed, and the interaction between season and breed. Also, PROC Mixed with LSMEANS was used to determine relationships of calf health with environment, management, and colostrum components. Additionally, a Pearson correlation was used to determine relationships between colostrum components and quality traits. Results for Holstein and Jersey showed that both colostrum Brix and volume (P < 0.001) differed by breed. Colostrum volume (P < 0.001), lactose (P < 0.001), and lactoferrin (P = 0.002) varied significantly by season. Additionally, test day milk (P = 0.046), fat (P = 0.012), and protein (P = 0.003) varied significantly by season. Moreover, a significant season and breed interaction (P = 0.028) was observed solely for colostrum volume. Calf health models indicated that TSP, colostrum total protein and solid non-fats impacted incidence of respiratory illness, but no factor significantly impacted incidence of scours. Results for Pearson correlation indicated strong correlations between true protein and solid non-fats and Brix (r = 0.99; 0.86). Lactoferrin also had moderate negative correlations with volume and lactose (r = -0.35; -0.33). Heritability and repeatability's were calculated using BLUPF90 family of programs. A single-trait repeatability animal model was used and included a 1-vector phenotype (Brix or Colostrum weight), fixed effects (i.e. calving year, parity, 3-month season of calving, and age at calving), additive genetic variance, random permanent environment effects, and random residual effects. A series of bivariate models were used to calculate genetic correlations of Brix score and colostrum weight with test-day compositional traits. Heritability estimates results for Holstein cow Brix and colostrum weight, were 0.25 and 0.15. Jersey cow heritability estimates were 0.36 and 0.47 respectively. We also observed some significant genetic correlations with Holstein Brix score and test-day milk (-0.23), fat (0.54), and SCS (0.29) having moderate correlations. Holstein colostrum weight had a strong correlation with test-day milk (0.96). Jerseys had strong genetic correlation of Brix score with colostrum weight (-0.98). Low to moderately heritability was observed for Brix score and colostrum weight in both breeds making them receptive to genetic selection in order to improve breeding programs. In conclusion, mode of birth significantly impacted colostrum composition which had subsequent effects on abundance of rumen microbiota. Colostrum Brix and volume were impacted by breed, season, and interaction, and calf incidence of disease was impacted by colostrum composition and environment. Additionally, two factors influencing colostrum quality (Brix score and colostrum weight) were found to be low to moderately heritable and have moderate to strong genetic correlations to compositional traits. Strong significant relationships were also found between colostrum compositional traits and colostrum quality traits. Therefore, incorporating quality traits into breeding programs has the potential to influence compositional traits which, in turn, can impact calf health and development by the interactions that exist between composition and microbial abundance in the rumen.
Graduate Student Literature Review: Potential mechanisms of interaction between bacteria and the reproductive tract of dairy cattle
Owens, Connor E.; Daniels, Kristy M.; Ealy, Alan D.; Knowlton, Katharine F.; Cockrum, Rebecca R. (2020-11)
Although the presence of bacteria has been characterized throughout the reproductive tracts of multiple species, how these bacteria may interact with the host has yet to be described. Previous reviews have described how pathogenic bacteria interact with the reproductive tract to cause infections such as metritis. This review aimed to summarize the knowledge related to pathogenic and nonpathogenic bacteria in various locations of the bovine reproductive tract and the possible mechanisms underlying host-microbe interactions during gametogenesis and early pregnancy. Lactic acid bacteria such as Lactobacillus seem to be beneficial in multiple areas of the reproductive tract: they have been associated with increased oocyte quality when in follicular fluid and secrete reactive oxygen species that are beneficial during placental angiogenesis. However, other bacteria, including Enterococcus, Staphylococcus, and Streptococcus, may modulate T helper cells that inhibit maternal recognition of pregnancy. Available data on the reproductive microbiome focus on variations in microbial communities and their associations with reproductive performance. However, research on these host-microbiorne interactions may provide more insight on how bacteria affect fertility.
Microbiomes of Various Maternal Body Systems Are Predictive of Calf Digestive Bacterial Ecology
Owens, Connor E.; Huffard, Haley G.; Nin-Velez, Alexandra I.; Duncan, Jane; Teets, Chrissy L.; Daniels, Kristy M.; Ealy, Alan D.; James, Robert E.; Knowlton, Katharine F.; Cockrum, Rebecca R. (MDPI, 2021-07-26)
Body systems once thought sterile at birth instead have complex and sometimes abundant microbial ecosystems. However, relationships between dam and calf microbial ecosystems are still unclear. The objectives of this study were to (1) characterize the various maternal and calf microbiomes during peri-partum and post-partum periods and (2) examine the influence of the maternal microbiome on calf fecal microbiome composition during the pre-weaning phase. Multiparous Holstein cows were placed in individual, freshly bedded box stalls 14 d before expected calving. Caudal vaginal fluid samples were collected approximately 24 h before calving and dam fecal, oral, colostrum, and placenta samples were collected immediately after calving. Calf fecal samples were collected at birth (meconium) and 24 h, 7 d, 42 d, and 60 d of age. Amplicons covering V4 16S rDNA regions were generated using DNA extracted from all samples and were sequenced using 300 bp paired end Illumina MiSeq sequencing. Spearman rank correlations were performed between genera in maternal and calf fecal microbiomes. Negative binomial regression models were created for genera in calf fecal samples at each time point using genera in maternal microbiomes. We determined that Bacteroidetes dominated the calf fecal microbiome at all time points (relative abundance ≥42.55%) except for 24 h post-calving, whereas Proteobacteria were the dominant phylum (relative abundance = 85.10%). Maternal fecal, oral, placental, vaginal, and colostrum microbiomes were significant predictors of calf fecal microbiome throughout pre-weaning. Results indicate that calf fecal microbiome inoculation and development may be derived from various maternal sources. Maternal microbiomes could be used to predict calf microbiome development, but further research on the environmental and genetic influences is needed.
Nutrient Impacts on Rumen Growth and Development
Yohe, Taylor Timothy (Virginia Tech, 2018-04-19)
Our collective knowledge of calf nutrition has evolved over the past 100+ years, but there are still areas of improvement that merit further scientific inquiry. The work described herein explored different aspects of calf nutrition with a central focus on rumen growth and development. The first study performed used 8 Holstein bull calves to determine if calf starters differing in starch and neutral detergent fiber (NDF) content would affect calf growth, intake, rumen metabolites, blood metabolites, and gross rumen measurements when fed along with milk replacer (MR). The experiment used completely pelleted calf starters consisting of ground and pelleted barley, wheat, and corn grains. Besides the high-starch starter resulting in lower rumen pH, the hypothesis that completely pelleted calf starter diets differing in NDF and starch level would alter intake, growth, rumen metabolism, and rumen measurements was not supported. However, calves fed the high-NDF starter were $5.71 less expensive per calf to raise. Findings suggest a form of feed effect in today's calf starter diets that might be of physiological and economic importance. The second study tested custom-built rumen infusion, sampling, and evacuation devices. The main objectives were to build and confirm the successful use of the devices in one Holstein bull calf at 62 days of age, which determined a liquid passage rate out of the rumen at 40.2% of ruminal fluid/h. The third and final study examined the effects of form of diet (MR only, n = 5; MR and starter, n = 6) on rumen growth and development. More specifically, isocaloric and isonitrogenous diets were fed to neonatal and ruminally cannulated Holstein calves for 6 week. The hypothesis of MR and starter calves having altered gross rumen measurements, epithelial stem and progenitor cell number, and epithelial proliferation status was supported, but hypothesized changes in volatile fatty acid (VFA) transporter abundance and VFA absorption rate were not supported. These results indicate that form of diet, even one that promotes rumen growth, does not equate to enhanced ability to absorb VFA, but there is an effect on rumen stem and progenitor cells as well as epithelial proliferation.
Phenotypic and microbial influences on dairy heifer fertility and calf gut microbial development
Owens, Connor E. (Virginia Tech, 2020-10-12)
Pregnancy loss and calf death can cost dairy producers more than $230 million annually. While methods involving nutrition, climate, and health management to mitigate pregnancy loss and calf death have been developed, one potential influence that has not been well examined is the reproductive microbiome. I hypothesized that the microbiome of the reproductive tract would influence heifer fertility and calf gut microbial development. The objectives of this dissertation were: 1) to examine differences in phenotypes related to reproductive physiology in virgin Holstein heifers based on outcome of first insemination, 2) to characterize the uterine microbiome of virgin Holstein heifers before insemination and examine associations between uterine microbial composition and fertility related phenotypes, insemination outcome, and season of breeding, and 3) to characterize the various maternal and calf fecal microbiomes and predicted metagenomes during peri-partum and post-partum periods and examine the influence of the maternal microbiome on calf gut development during the pre-weaning phase. In the first experiment, virgin Holstein heifers (n = 52) were enrolled over 12 periods, on period per month. On -3 d before insemination, heifers were weighed and the uterus was flushed. Flush pH and glucose concentration were measured. Blood was collected from coccygeal vessels on d -3, 15, 18, 21, 24, 27, and 30 relative to insemination and serum progesterone concentration was measured. Ultrasound measurements of dominant follicle diameter and corpus luteum volume. Insemination outcome was determined on d 30 using ultrasound and pregnancy was checked on d 42, 56, 70, and 84. Heifers were clustered based on outcome of insemination at d 30 (not pregnant, NP30, n = 24; pregnant, PS30, n = 28), d 84 (not pregnant, NP84, n = 24; pregnant but lost before d 84, PL84, n = 2; successfully pregnant through d 84, PS84, n = 26). Differences in phenotypes were assessed based on insemination outcome at d 30 and d 84. Weight was greater in NP30 heifer than PS30 heifers. Progesterone was greater in PS30 and PS84 heifers than NP30 or NP84 heifers on d -3 and 18 to 30 and CL volume was greater in PS30 and PS84 heifers than NP30 and NP84 heifers on d 21 and 30. To summarize, traits related to pregnancy maintenance were different in virgin Holstein heifers based on first insemination outcomes and might be able to be used to predict heifer reproductive performance. Uterine flushes were examined in a subset of heifers (n = 28) based on insemination outcome and period. This subset was also clustered based on season (spring, n = 3; summer, n = 12; fall, n = 8; winter, n = 5). From this subset of heifers, DNA was extracted from uterine flush and 16S amplicons of the V4 region underwent 250 paired-end sequencing via Illumina NovaSeq 6000. Filtered reads were clustered into operational taxonomic units using a 97% similarity and assigned taxonomy using the SSURNA Silva reference version 132. Alpha and beta diversity were measured and differences in alpha and beta diversity measurements were analyzed based on insemination outcome at d 30 or d 84 and season of breeding. Differential abundance analyses were performed at the phylum and genus taxonomic ranks based on insemination outcome at d 30 or d 84 and season of breeding. Bacterial richness was reduced in PL84 heifers than NP84 and PS84 heifers and reduced in heifers bred in spring than those bred in other seasons. Bacterial community structure was different based on insemination outcome at d 30 and d 84 using unweighted Unifrac distances and was different based on season of breeding using weighted Unifrac distances. We observed an increase of Bacteroidetes in PS30 and PS84 heifers compared to NP30 and NP84 heifers. Ureaplasma and Ruminococcus had an increased abundance in PS30 and PS84 heifers than NP30 and NP84 heifers, while Afipia and Gardnerella had an increased abundance in NP30 and NP84 heifers than PS30 and PS84 heifers. Prevotella and Ruminococcus had a reduced abundance in summer bred heifers than winter bred heifers. Proteobacteria had a moderate negative correlation with -3 d progesterone (rp = -0.42) and Actinobacteria had a moderate negative correlation with fetal growth rate (rp = -0.66). Uterine microbiome of virgin Holstein heifers differed based on insemination outcomes and season of breeding and might be a new phenotype to indicate heifer fertility. In the second experiment, multiparous Holstein cows (n = 12) were placed in individual box stalls 14 d before expected calving. Sterile swabs were used to collect samples from the posterior vagina of the dam approximately 24 h before calving, dam feces, dam oral cavity, and colostrum within 1 h after calving, and cotyledonary placenta within 6 h after calving. Calves (n = 12; bulls = 8, heifers = 4) were isolated immediately after parturition to prevent environmental contamination. Colostrum was fed to calves using a clean bottle that was assigned to the calf for the duration of the study. Calves were individually housed for 60 d until weaning. Sterile swabs were used to collect calf fecal samples at birth, 24 h, 7 d, 42 d, and 60 d of age. A subset of calf-dam pairs (n = 6; bulls = 3, heifers = 3) were selected and DNA was extracted from all samples. Amplicons covering V4-V5 16S rDNA regions were generated using extracted DNA and sequenced using 300 bp paired end sequencing via Illumina MiSeq. Sequences were aligned into operational taxonomic units using the 97% Greengenes reference database. Spearman correlations were performed between maternal and calf fecal microbiomes. Negative binomial regression models were created for genera in calf fecal samples at each time point using genera in maternal microbiomes. Metagenomes were predicted, collapsed into gene pathways and differences in predicted metagenomes were analyzed within STAMP (Statistical Analysis of Metagenomic Profiles). We determined that Bacteroidetes dominated the calf fecal microbiome at all time points (relative abundance ≥ 42.55%) except for 24 h post-calving, where Proteobacteria were the dominant phylum (relative abundance = 85.10%). Colostrum and placenta had low diversity within samples and clustered independently from fecal samples. Each maternal microbiome was a significant predictor for calf fecal microbiome during at least 2 time points. Genes for infectious disease and neurodegenerative disease were greater in colostrum and 24 h calf fecal samples compared to other samples. Results indicated that no one maternal microbiome was a major influence on calf fecal microbiome inoculation and development. Instead, calf fecal microbial development stems from various maternal microbial sources. Overall, the reproductive microbiome was predictive of heifer pregnancy outcomes and calf fecal microbial development. The virgin heifer uterine microbiome could be used to predict fertility and adaptation to heat stress, but further research including a larger group of pregnancy loss is needed. Maternal microbiomes from the reproductive tract, colostrum, oral cavity, and feces could all be used to predict calf microbial development, but more research including other maternal microbiomes and environmental microbial contributions is needed. However, the results from this dissertation indicate reproductive microbiome composition is a trait that might be predictive of dairy cattle performance.
Relationships Between Gastrointestinal Permeability, Heat Stress, And Milk Production in Lactating Dairy Cows
Ellett, Mark D.; Rhoads, Robert P.; Hanigan, Mark D.; Corl, Benjamin A.; Perez-Hernandez, Gabriela; Parsons, Catherine L. M.; Baumgard, Lance H.; Daniels, Kristy M. (Elsevier, 2024-02-29)
Heat stress (HS) is a global issue that decreases farm profits and compromises animal welfare. To distinguish between the direct and indirect effects of HS, 16 multiparous Holstein cows approximately 100 DIM were assigned to one of 2 treatments: pair fed to match HS cow intake, housed in thermoneutral conditions (PFTN, n = 8) or cyclical HS (n = 8). All cows were subjected to 2 experimental periods. Period 1 consisted of a 4 d thermoneutral period with ad libitum intake. During period 2 (P2), the HS cows were housed in cyclical HS conditions with a temperature-humidity index (THI) ranging from 76 to 80 and the PFTN cows were exposed to a constant THI of 64 for 4 d. Dry matter intake of the PFTN cows was intake matched to the HS cows. Milk yield, milk composition, rectal temperature, and respiration rate were recorded twice daily, blood was collected daily via a jugular catheter, and cows were fed twice daily. On d 3 of each period, Cr-EDTA and sucralose were orally administered and recovered via 24 h total urine collection to assess gastrointestinal permeability. All data were analyzed using the GLIMMIX procedure in SAS. The daily data collected in P1 was averaged and used as a covariate if deemed significant in the model. Heat stress decreased voluntary feed intake by 35% and increased rectal temperature and respiration rate (38.4°C vs. 39.4°C and 40 vs. 71 respirations/min, respectively). Heat stress reduced DMI by 35%, which accounted for 66% of the decrease in milk yield. The yields, and not concentrations, of milk protein, fat, and other solids were lower in the HS cows on d 4 of P2. Milk urea nitrogen was higher and plasma urea nitrogen tended to be higher on d 3 and d 4 of HS. Glucose was 7% lower in the HS cows and insulin was 71% higher in the HS cows than the PFTN cows on d 4 of P2. No difference in lipopolysaccharide-binding protein was observed. Heat stress cows produced 7 L/d more urine than PFTN cows. No differences were detected in the urine concentration or percentage of the oral dose recovered for Cr-EDTA or sucralose. In conclusion, HS was responsible for 34% of the reduction of milk yield. The elevated MUN and the tendency for elevated plasma urea nitrogen indicate a whole-body shift in nitrogen metabolism. No differences in gastrointestinal permeability or lipopolysaccharide-binding protein were observed. These results indicate that, under the conditions of this experiment, activation of the immune system by gut-derived lipopolysaccharide was not responsible for the decreased milk yield observed during HS.
Rumen volatile fatty acid molar proportions, rumen epithelial gene expression, and blood metabolite concentration responses to ruminally degradable starch and fiber supplies
Beckett, Linda; Gleason, Claire B.; Bedford, Andrea; Liebe, Douglas M.; Yohe, Taylor T.; Hall, Mary Beth; Daniels, Kristy M.; White, Robin R. (2021-08)
The objective of this work was to characterize rumen volatile fatty acid (VFA) concentrations, rumen epithelial gene expression, and blood metabolite responses to diets with different starch and fiber sources. Six ruminally cannulated yearling Holstein heifers (body weight = 330 +/- 11.3 kg) were arranged in a partially replicated Latin square experiment with 4 treatments consisting of different starch [barley (BAR) or corn (CRN)] and fiber [timothy hay (TH) or beet pulp (BP)] sources. Treatments were arranged as a 2 & times; 2 factorial. Beet pulp and TH were used to create relative changes in apparent ruminal fiber disappearance, whereas CRN and BAR were used to create relative changes in apparent ruminal starch disappearance. Each period consisted of 3 d of diet adaptation and 15 d of dietary treatment. In situ disappearance of fiber and starch were estimated from bags incubated in the rumen from d 10 to 14. From d 15 to 17, rumen fluid was collected every hour from 0500 to 2300 h. Rumen fluid samples were pooled by animal/period and analyzed for pH and VFA concentrations. On d 18, 60 to 80 papillae were biopsied from the epithelium and preserved for gene expression analysis. On d 18, one blood sample per heifer was collected from the coccygeal vessel. In situ ruminal starch disappearance rate (7.30 to 8.72%/h for BAR vs. 7.61 to 10.5%/h for CRN) and the extent of fiber disappearance (22.2 to 33.4% of DM for TH vs. 34.4 to 38.7% of DM for BP) were affected by starch and fiber source, respectively. Analysis of VFA molar proportions showed a shift from propionate to acetate, and valerate to isovalerate on TH diets compared with BP. Corn diets favored propionate over butyrate in comparison to BAR diets. Corn diets also had higher molar proportions of valerate. Expression of 1 gene (SLC9A3) were increased in BP diets and 2 genes (BDH1 and SLC16A4) tended to be increased in TH diets. Plasma acetate demonstrated a tendency for a starch by fiber interaction with BAR-BP diets having the highest plasma acetate, but other metabolites measured were not significant. These results suggest that TH has the greatest effect on shifts in VFA molar proportions and epithelial transporters, but does not demonstrate shifts in blood metabolite concentrations.
Ruminal volatile fatty acid absorption is affected by elevated ambient temperature
Bedford, Andrea; Beckett, Linda; Harthan, Laura; Wang, Chong; Jiang, Ning; Schramm, Hollie H.; Guan, Leluo; Daniels, Kristy M.; Hanigan, Mark D.; White, Robin R. (2020-08-04)
The objective of this study was to investigate the effect of short-term elevated ambient temperature on ruminal volatile fatty acid (VFA) dynamics and rumen epithelium gene expression associated with the transport and metabolism of VFA. Eight ruminally cannulated Holstein heifers (200 kg) were used in a factorial, repeated measures experiment with two treatments and two periods. During the first period, animals were provided with feed ad libitum and housed at 20 degrees C. During the second period, one group (HS) was housed at 30 degrees C and fed ad libitum. The other group (PF) was housed at 20 degrees C and pair-fed to match the intake of the HS group. During each period, animals were kept on treatment for 10 day, with sample collection on the final day. In the second period, indicators of heat stress were significantly different between PF and HS animals (P<0.05). There was a thermal environment effect on butyrate production (P<0.01) that was not associated with feed intake (P=0.43). Butyrate absorption decreased in HS animals (P<0.05) but increased in PF animals (P<0.05) from period 1 to period 2. There was a feed intake effect on BHD1 expression (P=0.04) and a tendency for a thermal environment effect (P=0.08), with expression increasing in both cases. Expression of MCT4 was affected by feed intake (P=0.003) as were all NHE genes (NHE1, NHE2, and NHE3; P<0.05). These results indicate that with low feed intake and heat stress, there are shifts in rumen VFA dynamics and in the capacity of the rumen epithelium to absorb and transport VFA.
Short-Term Adaptation of Dairy Cattle Production Parameters to Individualized Changes in Dietary Top Dress
Price, Tanner P.; Souza, Vinicius C.; Liebe, Douglas M.; Elett, Mark D.; Davis, Ty C.; Gleason, Claire B.; Daniels, Kristy M.; White, Robin R. (MDPI, 2021-12-01)
Immediate and short-term changes in diet composition can support individualized, real-time interventions in precision dairy production systems, and might increase feed efficiency (FE) of dairy cattle in the short-term. The objective of this study was to determine immediate and short-term effects of changes in diet composition on production parameters of dairy cattle fed varying amounts of top dressed commodities. A 4 × 4 replicated Latin square design was used to evaluate responses of twenty-four Holstein cows fed either no top dress (Control) or increasing amounts of: corn grain (CG), soybean meal (SBM), or chopped mixed grass hay (GH) top dressed on a total mixed ration (TMR) over four, 9-day periods. Throughout each period, top dressed commodities were incrementally increased, providing 0% to 20% of calculated net energy of lactation (NEL ) intake. Measured production responses were analyzed for each 9-d period using a mixed-effects model considering two different time ranges. Samples collected from d 3 and 4 and from d 7 and 8 of each period were averaged and used to reflect “immediate” vs. “short-term” responses, respectively. In the immediate response time frame, control fed cows had lower milk yield, milk fat yield, and milk true protein yield than CG and SBM supplemented animals but similar responses to GH supplemented animals. Milk fat and protein percentages were not affected by top dress type in the immediate term. In the short-term response time-frame, GH supplemented animals had lower DMI and milk fat yield than all other groups. Control and GH supplemented cows had lower milk yield than CG and SBM fed cows. In the immediate response time frame, FE of SBM supplemented cows was superior to other groups. In the short-term time frame, FE of GH and SBM groups was improved over the control group. Results suggest that lactating dairy cows show rapid performance responses to small (<20% NEL ) changes in dietary composition, which may be leveraged within automated precision feeding systems to optimize efficiency of production. Before this potential can be realized, further research is needed to examine integration of such strategies into automatic feeding systems and downstream impacts on individual animal FE and farm profitability.
Tissue-specific responses to oxidative fuel source preference during heat stress in lactating dairy cows
Ellett, Mark D.; Daniels, Kristy M.; Hanigan, Mark D.; Corl, Benjamin A.; Perez-Hernandez, G.; Parsons, Catherine L. M.; Melvin, J. A.; Fausnacht, D. W.; McMillan, R. P.; Baumgard, L. H.; Rhoads, Robert P. (American Dairy Science Association, 2024-09-18)
Prolonged exposure to high environmental temperatures results in an accumulated heat load that induces a heat stress (HS) response in dairy cattle. Heat stress compromises dairy farm profitability by reducing milk yield, altering milk composition, and hindering reproductive performance. The ability to alternate between carbohydrate and lipid sources for energy production is termed metabolic flexibility (Met Flex). The objective of this study was to evaluate the Met Flex of mammary, muscle, and liver tissue in lactating dairy cows under HS and thermoneutral (TN) conditions. Sixteen Holstein cows were assigned to 1 of 2 treatment groups: pair-feeding in TN conditions (PFTN) or HS conditions. All cows experienced a 4-d TN period with ad libitum intake followed by a 4-d treatment period. Heat stress cows were exposed to a temperature-humidity index (THI) ranging from 76 to 80 and the PFTN cows were exposed to a THI of 64. Milk production and health data were recorded twice daily. Semitendinosus biopsies were obtained on d 4 of each period and postmortem mammary and liver samples were obtained on d 4 of period 2. All tissue samples were assayed for Met Flex. Activity of mitochondrial (Mit) enzymes were assessed in skeletal muscle only. Four days of HS decreased milk yield, altered milk composition, and increased respiration rate and rectal temperatures. No differences in Met Flex were observed in mammary or liver tissue during period 2. However, HS, but not PFTN conditions, lowered Met Flex of skeletal muscle by 18.3% when compared with TN ad libitum feed intake conditions of period 1. No treatment differences were observed in skeletal muscle Mit enzyme activity indicating the decrease in Met Flex occurred independently of changes in Mit function. The reduction in Met Flex of skeletal muscle during HS may contribute to reduced milk yield and warrants further investigation.

Browsing by Author "Daniels, Kristy M."

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