Biomedical subjects

J S Hogan

Publications and source records attributed to J S Hogan.

At least 55 records · Page 3Linked to original sources

PubMed1994

Effect of dietary fat and vitamin E on alpha-tocopherol and beta-carotene in blood of peripartum cows.

Nonlactating cows were fed diets containing 88% grass forage and 12% concentrate (DM basis). Starting 14 d prior to anticipated calving, the concentrate was changed to provide 0 or 200 g of supplemental fat and 0 or 890 IU of supplemental vitamin E daily. Following parturition, cows were fed for 14 d a 50% concentrate diet that provided the same amounts of supplemental fat and vitamin E that were fed during the dry period. Plasma was sampled and analyzed for alpha-tocopherol and beta-carotene. Supplemental dietary fat elevated plasma concentrations of both nutrients during the peripartum period. Supplemental dietary vitamin E elevated concentrations of alpha-tocopherol during that period. Dietary fat also increased concentrations of plasma cholesterol. When alpha-tocopherol and beta-carotene were expressed per unit of plasma cholesterol, fat supplementation did not affect concentrations. Dietary treatments did not influence concentrations of alpha-tocopherol in blood neutrophils and did not affect intracellular kill of bacteria by neutrophils. Essentially no beta-carotene was found in the neutrophils. For colostrum, dietary vitamin E increased concentrations of alpha-tocopherol and decreased concentrations of beta-carotene.

Animal Feed↗

PubMed1994

Efficacy of dry cow therapy and a Propionibacterium acnes product in herds with low somatic cell count.

Dry cow therapy and a Propionibaterium acnes product were evaluated in four commercial herds with low SCC. Cows were randomly assigned within herds to treatment groups of approximately 90 cows receiving dry cow therapy, P. acnes, dry cow therapy plus P. acnes, or no treatment in a factorial arrangement. Each lactating quarter of cows that received dry cow therapy was infused via the teat duct with 300 mg of cephaprin at drying off. Cows that received P. acnes were infused intravenously with .4 mg of killed P. acnes at drying off, 7 to 10 d prepartum, and within 7 d after calving. A second prepartum injection of P. acnes immunostimulator was administered to cows that did not calve within 10 d after the first prepartum injection. Dry cow therapy enhanced bacteriological cures of IMI by Staphylococcus aureus and Corynebacterium bovis at drying off. Dry cow therapy reduced incidence of new IMI by environmental streptococci and C. bovis that originated during the dry period. Cows treated with P. acnes alone had a greater incidence of new IMI by Gram-negative bacilli originating during the dry period than did cows in the other treatment groups. Incidence of clinical mastitis at calving was greater for cows receiving no treatment than for cows receiving dry cow therapy, P. acnes, or dry cow therapy plus P. acnes.

Adjuvants, Immunologic↗

PubMed1993

Association of abnormal uterine discharge with new intramammary infection in the early postpartum period in multiparous dairy cows.

The association of abnormal uterine discharge with the development of intramammary infection (IMI) was studied in 62 multiparous Holstein cows during the nonlactating period and from lactation days 3 through 30. Duplicate milk samples were obtained from each mammary gland at approximately day 30 of the nonlactating period. Milk samples for bacteriologic culture also were obtained from each gland from all cows at the end of the previous lactation, at parturition, and on a minimum of 7 additional dates during the first 30 days of lactation. Beginning after parturition and continuing once weekly for 4 weeks, each cow was examined, using a vaginal speculum to visually estimate the quantity of abnormal uterine discharge in the vagina. Additionally, uterine swab specimens were obtained for aerobic bacteriologic culture. Cows were allotted to groups on the basis of the maximal amount of abnormal uterine discharge observed at any 1 of the 4 examinations. Cows in group 1 had normal discharge or < 30 ml of abnormal discharge; in group 2, > or = to 30 ml of abnormal discharge, observed only on examination by vaginal speculum; and in group 3, > or = to 30 ml of abnormal discharge visible externally. A difference was not detected in the development of new IMI in the nonlactating period between cows that subsequently developed uterine discharge and those that did not. Although significant differences were not found, a tendency for lactating cows with abnormal uterine discharge to be at increased risk for developing new IMI was observed.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1993

Characteristics of coagulase-negative Staphylococci isolated from bovine intramammary infections.

Coagulase-negative Staphylococci (CNS) isolated from 86 different bovine intramammary infections (IMI) were investigated for their plasmid content, antimicrobial resistance, and infection characteristics. Plasmids were isolated from 30.2% of CNS. Number of plasmid bands ranged from 1 to 5. With the exception of tetracycline resistance, the presence of plasmids was not related to antibiotic resistance. Staphylococcus chromogenes was the CNS most frequently isolated from bovine IMI. Intramammary infections were of long duration (mean = 222 days) and resulted in a low incidence of clinical mastitis (8.1% of IMI). The greatest percentage of IMI (55%) were detected in heifers with 57% of these IMI first detected at calving. A total of 56% of IMI originated during the dry period in second lactation or older cows. The number of plasmid-positive CNS IMI was greater (P < 0.05) in multilactational cows when compared to heifers. The presence of a plasmid-positive CNS had no influence on duration of IMI, origin of IMI, clinical status of the infection, and elimination of IMI.

Animals↗

PubMed1993

Environmental mastitis.

Environmental mastitis affects all dairy farms and generally is the major mastitis problem on modern, well managed dairy farms. Control measures effective against contagious pathogens are of little value in controlling of environmental pathogens. Control of environmental mastitis is achieved by reducing exposure of teat ends to environmental pathogens and by maximizing the resistance of the cow to intramammary infection. Significant sources of environmental pathogens are organic bedding materials, manure covered alleyways, and wet or damp areas in barns, exercise lots, or pastures. Milking time hygiene can influence teat-end exposure. In general, exposure is minimized when all areas of the environment are clean, cool, and dry. Resistance is maximized by providing a stress-free environment that minimizes teat-end injury, and by feeding balanced diets sufficient in vitamin E and selenium. Antibiotic therapy during lactation or the dry period is of little value in the control of environmental mastitis in dairy herds, with the exception of preventing environmental streptococcal infection during the early dry period. Effective vaccines may help reduce the impact of environmental mastitis in the near future.

Animals↗

PubMed1993

Vitamin E as an adjuvant in an Escherichia coli J5 vaccine.

Vitamin E was tested as an adjuvant in an Escherichia coli (O111:B4) J5 vaccine. Twenty cows were assigned to five groups of 4 cows. Cows in four groups were vaccinated with an E. coli J5 bacterin containing 5 ml of 10(9) boiled cells/ml. Vaccinations were at drying off, 30 d after drying off, and within 48 h after calving. Vaccine adjuvants differed among groups. The four treatment adjuvants were 5 ml of Freund's incomplete adjuvant, 5 ml of vitamin E, 2.5 ml of Freund's plus 2.5 ml of vitamin E, and 5 ml of PBS. Cows in the fifth group were unimmunized controls. A front mammary quarter of each cow was challenged by infusion of 10 micrograms of E. coli J5 lipopolysaccharide approximately 4 wk into lactation. Vitamin E alone enhanced serum IgM titers but had no effect on milk IgM or serum and milk IgG titers. The mixture of Freund's plus vitamin E resulted in peak IgG titers in serum and milk comparable with that of Freund's alone. Persistency of IgG titers in cows immunized with the Freund's plus vitamin E mixture was greater than the persistency of titers for cows immunized with the vaccine containing Freund's alone as the adjuvant. The mixture of Freund's plus vitamin E had a synergistic effect in reducing severity of systemic clinical signs.

Adjuvants, Immunologic↗

PubMed1993

Growth responses of coliform bacteria to recombinant bovine cytokines.

Growth responses of 10 coliform isolates to recombinant bovine cytokines were measured in vitro. Six Escherichia coli and four Klebsiella pneumoniae isolates obtained from bovine IMI were tested for growth responses to recombinant bovine interleukin-1 beta, interleukin-2, and interferon-gamma. Cytokines were tested at 10(4), 10(3), 10(2), and 10 U/ml of media. Media used were a synthetic tissue culture medium, a chemically defined synthetic bacterial growth medium, and UHT sterilized milk. Bacterial counts in the synthetic tissue culture medium and UHT milk increased slightly as concentration of interferon-gamma in the media increased. Recombinant bovine interferon-gamma increased bacterial populations during the log growth phase but did not affect the number of bacteria in stationary growth phase. Bacterial growth responses were not related to either interleukin-2 or interleukin-1 beta concentrations in any of the three media. Bacterial growth responses to cytokines were not related to differences in either serum susceptibility, growth of isolates in dry cow secretion, duration of IMI from which isolates were obtained, or bacterial species.

Animals↗

PubMed1993

Role of vitamin E and selenium in host defense against mastitis.

Vitamin E and Se are essential nutrients that share common biological activities. Deficiencies in either of these micronutrients have been related in increased incidence and severity of mastitis. A known physiological consequence of alpha-tocopherol or Se deficiency is reduced neutrophil activity. Vitamin E and the Se-containing enzyme, glutathione peroxidase, and antioxidants that protect neutrophils from the destructive action of toxic oxygen molecules necessary for intracellular kill of ingested pathogens. Dietary supplementation of cattle with Se results in a more rapid neutrophil influx into milk following intramammary bacterial challenge and increased intracellular kill of ingested bacteria by neutrophils. Dietary supplementation of early lactation cows with vitamin E results in increased bactericidal activity by bovine blood neutrophils. Recently completed trials have shown that subcutaneous injections of vitamin E approximately 10 and 5 d prior to calving successfully elevated neutrophil alpha-tocopherol concentrations during the periparturient period and negated the suppressed intracellular kill of bacteria by neutrophils that is commonly observed at calving.

Animals↗

PubMed1992

Opsonic activity of bovine serum and mammary secretion after Escherichia coli J5 vaccination.

Six pairs of cows were used to determine the effects of immunization with an Escherichia coli (O111:B4) J5 bacterin on in vitro opsonization of a smooth heterologous strain of E. coli. One cow in each pair was either immunized with the vaccine or sham-immunized at drying off, 30 d after drying off, and at calving. Opsonizing bacteria with serum collected from vaccinated cows 21 d after calving resulted in higher mean number of intracellular bacteria per phagocytosing neutrophil than opsonizing bacteria with serum collected from control cows. Phagocytic parameters using serum collected at drying off and calving did not differ between treatment groups. A trend for enhanced opsonic activity of colostrum from vaccinates was noted. Enhanced opsonization by serum from vaccinated cows coincided with higher serum IgM titer to E. coli J5 whole cell antigen compared with controls. Serum IgG titers to E. coli J5 did not differ between groups. Colostrum IgG titers to E. coli J5 were greater at calving in vaccinated than in control cows. Colostrum and milk collected 21 d after calving from vaccinated cows had higher IgM titers to E. coli J5 than did mammary secretions from control cows. Numbers of intracellular bacteria per phagocytizing neutrophil were correlated positively with IgM titers to E. coli J5 in both serum and colostrum.

Animals↗

PubMed1992

Field trial to determine efficacy of an Escherichia coli J5 mastitis vaccine.

Efficacy of an Escherichia coli (O111:B4) J5 bacterin for preventing naturally occurring IMI and clinical mastitis was tested in a 2.5-yr field trial in a 225-cow commercial herd. Cows with odd-numbered identification were vaccinated, and cows with even-numbered identification served as unvaccinated controls for each lactation during the study. Immunizations were subcutaneous on the upper part of the rib cage just posterior to the scapula at drying off, 30 d after drying off, and at calving. Percentage of quarters infected at calving with Gram-negative bacteria did not differ between treatment groups. A total of 67% of Gram-negative bacterial IMI present at calving in control cows became clinical during the first 90 d of lactation compared with 20% in vaccinated cows. Rate of Gram-negative bacterial clinical mastitis was higher in control cows than in vaccinated cows during the first 90 d of lactation. Immunization with the E. coli J5 bacterin did not reduce level of Gram-negative bacterial IMI at calving but did reduce incidence of clinical mastitis.

Animals↗

PubMed1992

Bovine neutrophil responses to parenteral vitamin E.

Twenty-eight Holsteins were tested to determine effects of dietary and parenteral vitamin E supplementation during the dry period on plasma alpha-tocopherol and in vitro neutrophil functions at calving. Cows were assigned to one of four experimental groups receiving either supplemental dietary vitamin E, injections of vitamin E, both dietary and injections of vitamin E, or neither source of supplemental vitamin E during the dry period in a 2 x 2 factorial arrangement. Cows receiving parenteral vitamin E were injected subcutaneously with 3000 IU of vitamin E (dl-alpha-tocopherol) at 10 and 5 d prior to anticipated calving. Cows not receiving parenteral vitamin E were injected with a placebo. Experimental groups receiving dietary vitamin E during the dry period were supplemented with 1040 IU/d compared with none for controls. Cows injected with vitamin E had greater plasma alpha-tocopherol concentration 5 d after the first injection, at calving, and 1 wk after calving than did cows injected with placebo. Plasma alpha-tocopherol concentrations did not differ between dietary vitamin E treatment groups from calving through 4 wk postpartum. No interaction was found between dietary and parenteral supplementation of vitamin E on plasma alpha-tocopherol concentration. Neutrophils from cows injected with vitamin E had greater intracellular kill of bacteria at calving than did neutrophils from placebo-injected cows. Neither phagocytic index nor percentage of neutrophils phagocytizing differed between vitamin E-injected and placebo-injected cows. Dietary vitamin E during the dry period had no effect on neutrophil function at calving. Intracellular kill and plasma alpha-tocopherol were correlated at calving.

Administration, Oral↗

PubMed1992

Efficacy of an Escherichia coli J5 mastitis vaccine in an experimental challenge trial.

An Escherichia coli (O111:B4) J5 bacterin was tested for efficacy in reducing IMI and severity of clinical coliform mastitis in an experimental challenge trial. Ten cows were immunized at drying off, 30 d after drying off, and at calving. Ten control cows were not immunized. Right front quarters of all cows were infused with a heterologous strain of E. coli approximately 30 d after calving. Vaccinated cows had lower bacterial counts in milk and lower rectal temperatures than unvaccinated controls following intramammary challenge. Milk production and DMI were more depressed in controls than in vaccinated cows. Milk SCC did not differ between experimental groups. Mean serum IgG titer to whole cell E. coli J5 was significantly greater in vaccinated than in unvaccinated cows at 30 d after drying off, day of challenge, and 7 d postchallenge. Milk IgG titer to E. coli J5 was higher at challenge in vaccinated than in control cows. Vaccination with the E. coli J5 bacterin did not prevent IMI but did reduce severity of clinical signs following intramammary experimental challenge with a heterologous E. coli strain.

Animals↗

PubMed1992

Susceptibility of Escherichia coli isolated from intramammary infections to phagocytosis by bovine neutrophils.

Thirteen Escherichia coli isolated from naturally occurring IMI were tested for susceptibility to phagocytosis by bovine blood neutrophils. Isolates were opsonized in pooled serum collected from nine healthy lactating cows. Bacteria isolated from IMI first diagnosed within 3 d after calving were more resistant to phagocytosis than were isolates from IMI originating during either the first half of the dry period or later during lactation. Duration of the IMI was negatively correlated with both phagocytic index and percentage of neutrophils phagocytizing within bacterial isolates from IMI originating at calving and during lactation. Phagocytosis was independent of duration of IMI within isolates from IMI originating during the first half of the dry period. Susceptibility to in vitro phagocytosis by neutrophils was not related to O antigen serotype, encapsulation, or growth in dry cow secretion.

Animals↗

PubMed1992

Effect of supplementing periparturient cows with vitamin E on distribution of alpha-tocopherol in blood.

Holstein cows were fed 0 or 1000 IU/d of supplemental vitamin E during the dry period and injected with placebo or 3000 IU of vitamin E at 10 and 5 d prior to anticipated calving. Blood was collected at various times, starting at 60 d prepartum (dry off) and concluding 30 d postpartum, and separated into plasma, red blood cells, and neutrophils. Oral supplementation increased concentrations of alpha-tocopherol in plasma and red blood cells on 10 d, but not on 5 d prepartum. Injection of vitamin E increased alpha-tocopherol in plasma, red blood cells, and neutrophils at d 5 prior to and on the day of parturition. Concentrations of alpha-tocopherol and cholesterol in plasma were correlated, and both were at their nadir at parturition. Concentrations of alpha-tocopherol in plasma and red blood cells were correlated, but the correlation increased when plasma alpha-tocopherol was expressed per unit of cholesterol. alpha-Tocopherol in plasma and neutrophils had a low correlation. Injection of alpha-tocopherol increased its concentration in plasma, red blood cells, and neutrophils during the periparturient period. Concentration of alpha-tocopherol in plasma of periparturient cows may be limited by its low lipid content, and transport mechanisms for alpha-tocopherol may differ between red blood cells and neutrophils.

Animals↗

PubMed1991

Costs associated with selected preventive practices and with episodes of clinical mastitis in nine herds with low somatic cell counts.

Nine dairy herds (mean size, 149 cows) with bulk-tank milk somatic cell counts of less than 300,000 cells/ml and greater than 80% of cows with Dairy Herd Improvement Association linear somatic cell counts less than or equal to 4 were selected for study. Each herd was monitored for 12 consecutive months. Duplicate quarter-milk specimens were collected from each cow for bacteriologic culturing at beginning of lactation, cessation of lactation, and at the time of each clinical episode of mastitis. Streptococcus agalactiae was never isolated and Staphylococcus aureus was isolated from less than 1% of all quarters. There were 554 episodes of clinical mastitis. During the year of study, the incidence rate of clinical mastitis varied from 15.6 to 63.7% of cows among the 9 herds. Mean costs per cow per year in herd for mastitis prevention were: $10 for paper towels, $3 for nonlactating cow treatment, and $10 for teat disinfectants. Mean cost associated with clinical mastitis was $107/episode. Approximately 84% ($90) of the costs attributed to a clinical episode were associated with decreased milk production and nonsalable milk. Costs of medication and professional veterinary fees per clinical episode varied significantly among the 9 herds. Three of the herds did not have a veterinarian treat a clinical episode of mastitis during the year of study even though 2 of these herds had the first and third highest incidence rates of clinical mastitis. When calculated on a per cow in herd basis, mean costs of $40/cow/year were attributed to clinical mastitis.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1991

Antibodies to iron-regulated outer membrane proteins of coliform bacteria isolated from bovine intramammary infections.

Expression of iron-regulated outer membrane proteins (OMP) by Escherichia coli and Klebsiella pneumoniae initially isolated from bovine intramammary infections (IMI) was investigated. Additionally, the presence of antibodies in bovine serum and mammary secretion directed against the iron-regulated OMP was examined. Outer membrane proteins were separated by sodium-dodecyl polyacrylamide electrophoresis. Detection of immunoglobulin G directed against OMP was by immunoblotting. All Gram-negative bacteria expressed iron-regulated OMP when grown in skim milk or trypticase soy broth plus iron chelator, alpha-alpha'-dipyridyl. Immunoglobulin G directed against the iron-regulated OMP, as well as the major OMP and several other proteins, was detected in serum and milk of lactating cows with or without Gram-negative bacterial IMI. Antibody against the iron-regulated OMP was detected also in colostrum, secretion from the involuted gland, and in newborn calf serum 4 days after ingesting colostrum.

Animals↗

PubMed1991

Intramammary challenge with Escherichia coli following immunization with a curli-producing Escherichia coli.

Holstein and Jersey cattle were immunized with a curli-producing strain of Escherichia coli (pCRL65/A012) or a noncurli-producing strain (pUC18/HB101) to determine differences in resistance to establishment of experimental intramammary infection. Cows (n = 6 per group) were immunized at 14 d prior to drying off, 7 d of involution, and at calving with 3 x 10(10) E. coli in Freund's Incomplete Adjuvant. At 30 d of lactation, one mammary quarter of each cow was infused with a wild strain of E. coli (727). Escherichia coli 727 was isolated from a naturally occurring intramammary infection and produced curli. All challenged quarters became infected, and all cows developed acute clinical mastitis. Geometric mean duration of intramammary infections was 6 d for both immunization groups. All infections were spontaneously eliminated within 10 d. No differences occurred between immunization groups in blood selenium and glutathione peroxidase activity, plasma selenium, number of E. coli 727 isolated from secretion after challenge, rectal temperature and SCC response, clinical status of mammary quarters, or DMI. Reduction in milk production after challenge was greater for cows immunized with E. coli pCRL65/A012. Immunization of dairy cattle with a curli-producing strain of E. coli did not protect against experimental intramammary challenge during lactation.

Animals↗

PubMed1991

Serratia species isolated from bovine intramammary infections.

Intramammary infections from which Serratia spp. were isolated were studied over a 32-mo period in a research dairy herd consisting of approximately 120 lactating cows. A total of 29 Serratia spp. intramammary infections were detected and accounted for 9% of all Gram-negative bacterial intramammary infections. Serratia marcescens was the most common Serratia spp. isolated. Origin of intramammary infections was 48.3% during the first half of the dry period, 31% during the last half of the dry period, and 20.7% during lactation. A total of 64% of intramammary infections that were first detected during the first half of the dry period persisted to calving. Geometric mean number of lactation days infected for all infections was 55. Intramammary infections that originated during the first half of the dry period were present in lactation for a significantly greater number of days compared with intramammary infections new during the last half of the dry period or lactation. A total of 48% of infections were clinical. Serratia spp. intramammary infections tended to be of long duration compared with other Gram-negative bacterial intramammary infections and were highly associated with the dry period.

Animals↗