Browsing by Author "Petersson-Wolfe, Christina S."
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- Ability of Klebsiella spp. mastitis isolates to produce virulence factors for enhanced evasion of bovine innate immune defensesNedrow, Alicia (Virginia Tech, 2009-11-24)Klebsiella spp. are coliform bacteria that cause mastitis in dairy cattle and account for high mortality rates in infected cows leading to a significant financial loss. Recent outbreaks indicate that within farms a single strain can be responsible for clinical signs in multiple animals. Identification of the virulence of factors enabling Klebsiella spp. survival in the mammary glands of multiple animals may provide insight into host adaptation. In this study, Klebsiella spp. strains were evaluated for their ability to evade neutrophil killing, the primary immune defense in the bovine mammary gland. Our research focused on capsule and biofilm production by Klebsiella spp. when strains were grown in Luria Broth or skim milk to examine the effects on evasion of neutrophil killing. Biofilm production was not significantly related to the ability to resist neutrophil killing nor was capsule (P = 0.29). Farm (P < 0.001), media type (P < 0.005), and strain type by cow (P < 0.001) were found to play significant roles in neutrophil evasion. This suggests farm of origin, media type used, and cow all may play a role in evasion of neutrophils by Klebsiella spp. Further evaluation of virulence factor expression in different media types and the role of individual cow immune responses may provide insight into ability of Klebsiella spp. to cause outbreaks of mastitis in multiple animals.
- Abundance of Antibiotic Resistance Genes in Feces Following Prophylactic and Therapeutic Intramammary Antibiotic Infusion in Dairy CattleWilling, Brittany Faith (Virginia Tech, 2013-12-04)Prophylactic and therapeutic antibiotic treatments have the potential to increase excretion of antibiotic resistance genes (ARGs) by dairy cattle through selection pressure on the gut microbiome. The objective of these studies was to evaluate the effect of cephapirin benzathine administered prophylactically at the end of lactation and pirlimycin hydrochloride administered therapeutically during a clinical mastitis infection on the abundance and relative abundance of ARGs in dairy cow feces. For prophylactic treatment using cephapirin benzathine, nineteen end-of-lactation cows were used. Treatment cows (n = 9) received cephapirin benzathine as an intramammary infusion prior to dry-off, and control cows (n =10) received no antibiotics. All cows received an internal non-antibiotic teat sealant. Fecal grab samples were collected for each cow on d -2 (baseline, used as covariate), d 1, 3, 5, 7, and once per week until d 49. Fecal samples were collected in sterile containers, then freeze-dried and subject to DNA extraction. The abundance of ampC, blaCMY-2, ermB, sul1, tetO, tetW, integrase-specific gene int1, and 16S rRNA were quantified using quantitative polymerase chain reaction (qPCR). The genes ampC and blaCMY-2 encode resistance to ß-lactam antibiotics, ermB to macrolides, sul1 to sulfonamides, tetO and tetW to tetracyclines, and int1 a class-1 integrase gene that facilitates horizontal transfer of ARGs across bacteria. The 16S rRNA gene was used as a representation of bacterial population. Absolute abundance was defined as number of ARG copies per gram of freeze-dried feces, while relative abundance was defined as ARG copy numbers per copy of 16S rRNA gene, which is indicative of the proportion of bacteria carrying ARGs. Non-normal data were logarithmically transformed and were statistically analyzed using PROC GLIMMIX in SAS 9.2. Abundance and relative abundance of sul1 and blaCMY-2 were below the limit of quantification in most samples and therefore not suitable for statistical comparisons. The int1 gene was not detectable in any sample. There were significant interactions between treatment and day for the abundance and relative abundance of ampC, tetO, and tetW. The abundance and relative abundance of ampC increased with time in control cows while remaining constant in antibiotic treated cows through the dry period. Antibiotics may act to stabilize the gut microbiome in response to diet and housing changes. There was a significant main effect of treatment for ermB with a significantly greater proportion of bacteria carrying ermB in control cows when compared to antibiotic treated cows. The tetracycline resistance genes tetO and tetW behaved similarly with a significant treatment by day interaction for the abundance and relative abundance of both genes. The relative abundance of both tetO and tetW were greater in control cows when compared to antibiotic treated cows on days 3, 5, 7, and 14. The abundance of both tetO and tetW resistance genes increased in antibiotic treated cows from day 1 to 49. There was also a significant increase in tetW relative abundance when comparing day 1 to 49. Administering long-acting antibiotics as intramammary dry treatment changed fecal bacteria composition during the dry period perhaps by stabilizing GI bacteria through dietary and housing changes. However, the use of prophylactic dry cow treatment does not uniformly or predictably lead to changes in fecal ARGs. In a second study, after clinical mastitis detection and identification, 6 lactating dairy cows received therapeutic mastitis treatment (pirlimycin hydrochloride as an intramammary infusion). Fecal grab samples were collected from each cow on d 0, 3, 9, and 12. Collection and analytical methods were as previously described. Abundance and relative abundance of sul1 and blaCMY-2 were again below the limit of quantification and therefore not suitable for statistical comparison. The int1 gene was not detected in any sample. The abundance of 16S rRNA genes decreased with day and relative abundance ermB, tetO, and tetW increased with day. There was no significant effect of day on the relative abundance of ampC or the abundance of ampC, ermB, tetO, and tetW in feces of cows with clinical mastitis. Administering fast-acting antibiotics as therapeutic intramammary mastitis treatment to dairy cows increased the relative abundance (gene copies per 16S rRNA) of selected ARGs but not the total abundance of ARGs in feces. The use of antibiotics for prevention and treatment of bacterial infections does not uniformly or predictably increase ARGs.
- Adoptively transferred maternal colostral cells impact immune status and development in dairy calvesNeal, Stephanie Mary (Virginia Tech, 2013-09-25)Mortality and decreased weight gain resulting from infection and disease in dairy calves is a problem within the dairy industry. Colostrum is the sole source of maternal immunity for the calf, having a substantial impact on health and survival. To date, colostrum quality is determined by concentration of antibodies. Colostrum also contains proteins and cells, which may enhance immune development in the neonate. Our goals were to determine the impact of colostral immune cells on (1) immune status during the first month of life and (2) immune development over time. To determine the impact of adoptively transferred colostral immune cells, calves were fed either whole colostrum (WC) or cell-free colostrum (CFC) at birth. During the first month of life, calves fed CFC had decreased numbers of CD4+ T cells when compared to WC-fed calves. However, CFC-fed calves had a greater percentage of monocytes during the first month of life. To determine the influence of colostral immune cells on immune development, cellular blood parameters were measured in response to two series of vaccinations (A and B). After vaccination series A, CFC-fed calves had decreased numbers of B cells when compared to WC-fed calves. After vaccination series B, CFC-fed calves had decreased levels of interleukin-2 gene expression and numbers of CD4+ and gamma delta T cells when compared to WC-fed calves. This study demonstrates that colostral immune cells impact immune status and development in dairy calves.
- Antibiotic resistance gene abundance in feces of calves fed pirlimycin-dosed whole milkLittier, Heather Melissa (Virginia Tech, 2015-08-31)Exposure to antibiotics has the potential to increase the incidence and proliferation of antibiotic resistance genes (ARG) in the gut and fecal microbiome. Non-saleable, antibiotic-containing milk from cows treated with antibiotics (waste milk) is commonly fed to dairy calves but the effects of ingestion of antibiotics at an early age on the gut microbiome and the development of ARG in the naive gut are not well understood. Pirlimycin, a lincosamide antibiotic acting against Gram positive bacteria through inhibiting protein synthesis by binding to the 50S ribosome, is commonly used as mastitis therapy. Lincosamides are also considered highly important in human medicine, often used against Staphylococcus aureus and Clostridium difficile infections. Emerging microbial resistance to pirlimycin is of concern for both animal and human health. The objective of this study was to determine the effect of early lincosamide antibiotic exposure on the abundance of ARG in feces of milk-fed calves. Eight female Holstein calves were blocked by age, paired by block, and randomly assigned to pasteurized whole milk (control; n = 4) or milk containing 0.2 mg/L of pirlimycin (treatment; n = 4). Calves were enrolled after receiving two colostrum feedings and were fed 5.68 L of pasteurized whole milk, treatment, or control, divided into two daily feedings, from d 1 to d 50 of age. After weaning calves were fed non-medicated starter grain ad libitum. Fecal samples were collected weekly until 85 d of age and freeze-dried. DNA was extracted using QiaAmp® Fast DNA Stool Mini Kit and qPCR was used to quantify the absolute abundance (gene copies/g of wet feces) and relative abundance (gene copies/copies of 16S rRNA genes) of erm(B), tet(O), tet(W) and 16S rRNA genes. Data was analyzed using PROC GLIMMIX in SAS. Abundance of 16S rRNA genes, tet(O) and tet(W) were not different between control and pirlimycin-fed calves nor were the relative abundance of tet(O) (mean = 0.050 tet(O) copies/16S rRNA genes) or tet(W) (0.561 tet(W) copies/16S rRNA genes). While abundance of erm(B) was higher in pirlimycin-fed calves compared to control calves (6.46 and 6.04 log gene copies/g wet feces; P = 0.04) the relative abundance of erm(B) (0.273 gene copies/16S rRNA genes) in feces of calves was not influenced by treatment. There was an effect of day (P < 0.10) for absolute abundance of tet(O), tet(W), and erm(B) indicating that the levels change with time as the fecal microbiome develops. This study suggests that feeding pirlimycin-containing non-saleable milk to growing calves may increase environmental loading of erm(B), which codes for resistance to highly important macrolide and lincosamide antibiotics. Additional research is needed on effects of feeding waste milk to calves on other fecal ARG and on the post-excretion and post-application fate of these genes.
- Aseptic Technique for Milk Sampling and Teat InfusionsSwartz, Turner; Petersson-Wolfe, Christina S. (Virginia Cooperative Extension, 2016-04-08)Discusses bovine mastitis and a technique for monitoring for the disease.
- Associations between preweaning calf feeding behaviors with age at first calving and lactational performance using an automatic calf feederSwartz, Turner; Petersson-Wolfe, Christina S. (American Dairy Science Association, 2022-12-14)The objective of this retrospective observational study was to determine whether preweaning calf behaviors and milk replacer (MR) intake from an automatic calf feeder were associated with age at first calving and first-lactation performance. Calves were housed in groups with access to an automatic calf feeder for 7 wk with a maximum milk allowance of 1,800 g/d of MR (12 L/d). Outcomes of interest included age at first calving (n = 137), first-lactation mature-equivalent 305-d (ME305) milk yield (n = 132), and first-lactation ME305 energy-corrected milk (ECM) yield (n = 132). Linear models included the fixed effects of the daily means of unrewarded visits, rewarded visits, drinking speed, and MR intake. Furthermore, breed, disease diagnosis, season of birth, and age of the calf when it was first introduced to the automatic calf feeder were included in all models. The genetic parameter for milk yield (predicted transmitting abil- ity for milk) was included in models related to lactational performance. Feeding behaviors and milk replacer intake were not associated with age at first calving. Unrewarded visits to the automatic calf feeder were associated with ME305 milk and ECM yields. As mean daily unrewarded visits increased by 1, first-lactation ME305 milk yield and ME305 ECM yield increased by 319 kg and 224 kg, respectively. No other feeding behavior was significantly associated with first-lactation ME305 milk or ECM yields. In conclusion, unrewarded visits were positively associated with first-lactation performance, but external validation is still needed.
- Bacillus spp.: A Practical Summary for Controlling MastitisSwartz, Turner; Petersson-Wolfe, Christina S. (Virginia Cooperative Extension, 2016-04-11)Discusses some of the characteristics of Bacillus pathogens, and the methods for controlling and treating mastitis caused by these pathogens.
- Changes in Activity and Milk Components Around the Onset of Peripartum Diseases in Dairy CowsGriffith, Abigail Susanne (Virginia Tech, 2014-08-23)Activity and milk components were examined around disease onset in the periparturient period. Cows were monitored for daily rest bouts, rest duration, rest time, and step activity from -21 to +30 d relative to calving. Lactose concentration, fat to protein ratio (F:P), and milk yield were monitored. Diseases analyzed were assisted calving, mastitis, subclinical ketosis (SK), and a multiple disease category (MULTI) for animals who experienced more than one disease. Rest bouts decreased (d 0), step activity increased (d 0), and rest duration decreased (d -1) in animals that experienced assisted calving compared to controls. Mastitic cows showed fewer rest bouts (d -4, -3, -2, -1, and 0), increased activity (d -4, -2, and -1), decreased rest time (d -6, -5, -4, and -2), and decreased milk yield (d -4, -2, -1, 0) compared to controls. Cows with SK showed increased activity (d -5, -4, -3, and -2), decreased rest duration (d -7, -6, -5, -4, and -3), rest time (d -7, -6, -5, -4, -3, and -2), milk yield (d -4, -3, -2, -1, and 0) and lactose concentration (d -3, -2, -1, and 0) compared to controls. Animals categorized as MULTI showed increased activity (d -6, -5, -4, -3, and -2), increased F:P (d -2, -1 and 0), decreased rest time (d -5, -4, -3, and -2), and decreased lactose concentration (d -6, -5, -4, -5, -3, -2, -1, and 0) compared to controls. Deviations in activity and milk components could be used to proactively manage herd health.
- Coagulase-Negative Staphylococci and Staphylococcus hyicus: A Practical Summary for Controlling MastitisSwartz, Turner; Petersson-Wolfe, Christina S. (Virginia Cooperative Extension, 2016-04-11)Discusses some of the characteristics of CNS (Coagulase-negative staphylococci) and Staphylococcus hyicus, and ways to prevent and control mastitis caused by these pathogens.
- Corynebacterium bovis: A Practical Summary for Controlling MastitisSwartz, Turner; Petersson-Wolfe, Christina S. (Virginia Cooperative Extension, 2016-04-11)Describes Corynebacterium bovis, a pathogen that can spread to the mammary glands of cattle, means of monitoring and use of post-milking disinfectants.
- Dairy Pipeline, April 2022Swartz, Turner; Petersson-Wolfe, Christina S.; Daubert, Jeremy (Virginia Cooperative Extension, 2022-04-30)The April 2022 issue includes the articles "Can mastitis during pregnancy affect the next generation?" by Turner Swartz and Christina Petersson-Wolfe, and "Biosecurity on your dairy farm -- Revisted" by Jeremy Daubert.
- Dairy Pipeline, March 2017Petersson-Wolfe, Christina S.; Ferreira, Gonzalo; Martel, Cynthia (Virginia Cooperative Extension, 2017-02-28)This issue has two articles. The first article discusses monitoring the status of farm debt, while the second one provides information about potential pathogens in cattle manure.
- Dairy Pipeline, May 2020Petersson-Wolfe, Christina S.; Mason, Garland (Virginia Cooperative Extension, 2020)How the CARES Act helps dairy producers. Farm Bureau-Virginia ha developed an excellent repository of resources related to COVID-19 at https://www.safb.com/FarmerResources. AgrAbility COVID-19 Notice. AgrAbilty Virginia is here to support farmers as they face distinct challenges during this time. Farmers are older and therefore more susceptible to the corona virus
- Dairy Pipeline, November-December 2017Petersson-Wolfe, Christina S.; Daubert, Jeremy (Virginia Cooperative Extension, 2017-11-03)This issue contains two articles. The first examines the use of antibiotics with dairy cattle, while the second is a brief discussion about lifelong learning and its importance for dairy farmers.
- Dairy Pipeline, October 2019Petersson-Wolfe, Christina S.; Hanling, Haylee (Virginia Cooperative Extension, 2019)Newsletter on current events in the dairy industry in Virginia
- Dairy Pipeline, October 2022Petersson-Wolfe, Christina S.; Galyon, Hailey (Virginia Tech Dairy Science Extension, 2022-10)Articles include "Understanding your milk culture reports" by Christina Petersson-Wolfe and "The influence of climate change-induced nutritional stress on dairy cattle" by Hailey Galyon.
- Dairy Pipeline. April 2013Martel, Cynthia; Petersson-Wolfe, Christina S. (Virginia Cooperative Extension, 2013-04-03)Discusses pasture management and a grant targeting mastitis control and milk quality improvement.
- Dairy Pipeline. April 2014James, Robert E.; Petersson-Wolfe, Christina S. (Virginia Cooperative Extension, 2014-03-26)Stresses the importance of cleaning colostrum containers for healthy calves, and discusses milk quality in Virginia.
- Dairy Pipeline. April 2015James, Robert E.; Petersson-Wolfe, Christina S.; Kanevsky-Mullarky, I.; Martel, Cynthia (Virginia Cooperative Extension, 2015-03-30)The articles in this issue of Dairy Pipeline include: The Truth about Staph. Aureus; Spring Cleaning!; and Dairy Pipeline, Activities.
- Dairy Pipeline. April 2017Callan, Peter L.; Cayford, Eleonor Marilyn; Cockrum, Rebecca R.; Petersson-Wolfe, Christina S. (Virginia Cooperative Extension, 2017-03-30)This issue includes an article examining inbreeding depression problems in dairy cattle, and an ongoing genomic evaluation effort compared to the traditional use of pedigrees. There is also an article highlighting the International Dairy Federation World Summit