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Articles by L.J. Richardson
Total Records ( 2 ) for L.J. Richardson
  J.S. Bailey , A. Rolón , P.S. Holt , C.L. Hofacre , J.L. Wilson , D.E. Cosby , L.J. Richardson and N.A. Cox
  Although vaccination against Salmonella has been used more frequently in broiler breeders in recent years, there is limited information in the literature demonstrating the immunological response of combinations of live and killed whole cell vaccines. The present research assesses the immunological response generated by three different vaccination protocols. Treatment vaccines consisted of a live Aro-A mutant commercial Salmonella Typhimurium (ST) vaccine (Fort Dodge Animal Health) and a commercially prepared killed vaccine consisting of a pool of Salmonella serovars Berta (D1), Heidelberg (B) and Kentucky (C2). Three vaccination treatments using live, killed or a live-killed combination plus a non-vaccinated control were evaluated. Serum (SER), Crop Lavage (CL), Gut Lavage (GL), hatchling serum and egg yolk were tested for specific IgA and IgG anti-Salmonella Enteritidis (SE) or Salmonella Typhimurium lipopolysaccharide (SELPS or STLPS, respectively) antigen by indirect ELISA. Immunological response was stronger on STLPS than SELPS. IgA of SER and CL were short-lived peaks after the first killed vaccine, with Optical Densities (OD) greater than 1.000. A short-lived peak of IgG of CL on STLPS (OD>1.500) was also observed. Strong GL IgG after first live and both killed vaccine events were observed (OD>1.000), with the response to the killed preparation enduring longer. SER IgG responses observed after killed vaccination lasted throughout 40 wks of age with no demonstrable differences between treatments. Hatchling serum and egg yolk IgA were negligible and IgG was comparable among all treatments throughout time. Results confirm that killed antigen is vital in eliciting adequate IgG in serum and gut. Live vaccination with Aro-A mutant ST vaccine enhances gut IgG and possibly aids in conferring adequate immunity during the breeder's first wks of life
  J.A. Cason , R.J. Buhr , L.J. Richardson and N.A. Cox
  External and internal persistence of inoculated Salmonella and spread to uninoculated broiler chicks in the same pens were studied by sampling ceca and rinses of feathered carcasses in two experiments. Half of the day-old chicks in pens were orally inoculated with a nalidixic-acid-resistant strain of Salmonella Typhimurium at three levels of inoculum (0.1 mL delivering approximately 4 X 102, 104, or 106 cfu). At 3, 6, and 8 weeks of age, equal numbers of inoculated and non-inoculated pen mates were individually electrocuted and rinsed in 400 mL of diluent, after which ceca were removed aseptically, with a total of 654 chickens sampled in the two experiments. There were no differences in Salmonella incidence between inoculated and non-inoculated birds at any age, so the marker Salmonella was well distributed within pens. Total incidence was 70%, 86%, and 83% at the 102, 104, and 106 inoculum levels, respectively. Considering both cecal and rinse samples, incidence was 81%, 84%, and 72% at 3, 6, and 8 weeks of age respectively. There were 95 positives in the cecal samples only, 149 positives in the rinses only, and 277 positives in both ceca and rinse samples, so sampling either ceca or carcass rinses alone underestimated the total incidence of the marker Salmonella.
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