Browsing by Author "O'Brien, Dahlia"
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- Age related differences in phylogenetic diversity, prevalence of Shiga toxins, Intimin, Hemolysin genes and select serogroups of Escherichia coli from pastured meat goats detected in a longitudinal cohort studyNdegwa, Eunice; Alahmde, Aber; Kim, Chyer; Kaseloo, Paul; O'Brien, Dahlia (BMC, 2020-07-30)Background: Little is known on significance, diversity and characteristics of gut E. coli in goats despite their importance as food animals globally. We characterized the temporal dynamics in diversity of E. coli in fecal samples from a cohort of goat kids and adult meat goats on pasture over a one-year period. Isolates were characterized based on phylogenetic grouping, virulence genes; shiga toxins 1 and 2 (Stx1&Stx2) (STEC), intimin (eaeA), hemolysin (hly) and select important sero-groups (026, 045, 0103, 0126 and 0146) using molecular methods. Results: A total of 516 E. coli isolates were screened. Prevalence of virulence genes and STEC was 65 and 56% respectively. Prevalence of virulence genes and STEC was significantly higher in goat kids less than six months (76% /66%) than adults (48% /28%). Isolates with virulence profiles of two or more genes were also higher in young goat kids (50%) than adults (20%). Entero-pathogenic E. coli (EPEC-eaeA gene only) were mostly from pre-weaned goat kids while hly gene only isolates were significantly higher in adults. The stx1, stx2 and hly genes peaked around weaning (60, 63 and 52%) respectively. Goats kids were mostly hosts to group D (59%) while adults older than one year had B1 (75%) isolates. Group D isolates were most abundant at weaning (64%) and diarrhea samples (74%). Group B2 isolates overall (6%) were mostly detected around weaning (63%) while A isolates were 4% overall. Twenty-four isolates belonged to sero-groups 026, 0103 and 0146 with 70% of the isolates detected around weaning. Nineteen of these isolates were STEC with most harboring the stx1/stx2/hly/eae (25%) profile. Most belonged to O26 sero-group (75%) and phylogroup D (75%). Conclusion: To our knowledge this is the first study to highlight longitudinal age related differences in E. coli phylogenetic diversity, abundance of virulence genes and select important sero-groups in goats. Differences detected suggest a possible role of age and weaning stress in influencing E. coli diversity in the gut of goats. The findings are relevant to both animal and public health to advise on further studies on caprine E. coli isolates as animal and human pathogens.
- Dewormer Resistance on Virginia Sheep FarmsO'Brien, Dahlia; Schoenian, Susan Gail; Whitley, Niki (Virginia Cooperative Extension, 2017-12-05)Discusses a study of dewormer resistance among nematode gastrointestinal parasites of sheep and goats, confirming that there is widespread dewormer resistance, and that training in sustainable parasite management techniques is vital.
- Enhancing reproduction performance in small ruminants. Part III. Breeding and management systemsO'Brien, Dahlia; Wildeus, Stephan (Virginia Cooperative Extension, 2019)Comparison of different kinds of breeding programs for ruminants
- Enhancing reproductive performance in small ruminants part II: Puberty and estrous cyclesO'Brien, Dahlia; Wildeus, Stephan (Virginia Cooperative Extension, 2019)Puberty and estrous cycles in ruminants. Reproductive success and failure in male and female ruminants
- Enhancing reproductive performance in small ruminants. Part IV. Breed/SelectionO'Brien, Dahlia; Wildeus, Stephan (Virginia Cooperative Extension, 2019)Sheep and goat breeds are diverse in their reproductive traits, and so to optimize reproductive efficiency it is important to consider breed seriously before starting a flock or herd
- Enhancing reproductive performance in small ruminants: Part 1. Biology of reproductionO'Brien, Dahlia; Wildeus, Stephan (Virginia Cooperative Extension, 2019)This has been designed to assist producers in enhancing reproductive performance in their herd so that overall production can be optimized to promote profitability.
- Enhancing reproductive performance in small ruminants: Part V. Nutrition and healthO'Brien, Dahlia; Wildeus, Stephan (Virginia Cooperative Extension, 2019)Small ruminant nutrition when reproducing. Best health practices including diet and vaccinations
- Enhancing reproductive performance in small ruminants: Part VI. Reproductive management techniquesO'Brien, Dahlia; Wildeus, Stephan (Virginia Cooperative Extension, 2019)Different methods for causing small ruminants to synchronize estrus
- Influence of Breed and Supplementation on Consumer Ratings of Pasture-raised Ground LambNartea, Theresa J.; Wildeus, Stephan; O'Brien, Dahlia (Virginia Cooperative Extension, 2017-12-11)Discusses consumer ratings of pasture-raised ground lamb.
- Preparing for the breeding season in meat goats and hair sheepO'Brien, Dahlia; Wildeus, Stephan (Virginia Cooperative Extension, 2018-02-20)Discusses health checks and other issues before the breeding season of goats and sheep.
- Shiga Toxin Subtypes, Serogroups, Phylogroups, RAPD Genotypic Diversity, and Select Virulence Markers of Shiga-Toxigenic Escherichia coli Strains from Goats in Mid-Atlantic USNdegwa, Eunice; O'Brien, Dahlia; Matthew, Kwame; Wang, Zhenping; Kim, Jimin (MDPI, 2022-09-15)Understanding Shiga toxin subtypes in E. coli from reservoir hosts may give insight into their significance as human pathogens. The data also serve as an epidemiological tool for source tracking. We characterized Shiga toxin subtypes in 491 goat E. coli isolates (STEC) from the mid-Atlantic US region (stx1 = 278, stx2 = 213, and stx1/stx2 = 95). Their serogroups, phylogroups, M13RAPD genotypes, eae (intimin), and hly (hemolysin) genes were also evaluated. STEC-positive for stx1 harbored Stx1c (79%), stx1a (21%), and stx a/c (4%). Those positive for Stx2 harbored stx2a (55%) and Stx2b (32%), while stx2a/stx2d and stx2a/stx2b were each 2%. Among the 343 STEC that were serogrouped, 46% (n = 158) belonged to O8, 20% (n = 67) to 076, 12% (n = 42) to O91, 5% (n = 17) to O5, and 5% (n = 18) to O26. Less than 5% belonged to O78, O87, O146, and O103. The hly and eae genes were detected in 48% and 14% of STEC, respectively. Most belonged to phylogroup B1 (73%), followed by D (10%), E (8%), A (4%), B2 (4%), and F (1%). M13RAPD genotyping revealed clonality of 091, O5, O87, O103, and O78 but higher diversity in the O8, O76, and O26 serogroups. These results indicate goat STEC belonged to important non-O157 STEC serogroups, were genomically diverse, and harbored Shiga toxin subtypes associated with severe human disease.
- Using Fecal Egg Counts On Your FarmO'Brien, Dahlia; Matthews, Kwame; Whitley, Niki; Schoenian, Susan Gail (Virginia Cooperative Extension, 2019-09-17)Discusses the use of fecal egg counts to monitor for intestinal parasites of sheep and goats.