D. Caldwell

Evaluation of disinfectants commonly used by the commercial poultry industry under simulated field conditions

The correct usage of disinfectants is an important component of a successful biosecurity program. The objective of this study was to determine the effect of time, temperature, and organic matter (OM) on disinfectant efficacy. Staphylococcus aureus and Salmonella Typhimurium were used to represent gram-negative and gram-positive bacteria commonly found in commercial poultry housing. The first study evaluated the effect of temperature (4, 20, 32, or 43 degrees C) and time (1, 2, 3, 4, 6, 8, 12, 16, 20, 24, and 30 wk) on the efficacy of disinfectants diluted to working concentrations. The second study determined the effect of OM on the efficacy of working concentrations of freshly prepared disinfectants against the bacteria. For the third study, we compared the bactericidal properties of freshly prepared disinfectants and 30-wk-old disinfectants in the presence of OM. Quaternary ammonium-, chlorhexidine-, phenolic-, and binary ammonium-based solutions represented disinfectants commonly used within the poultry industry. In the first study, all of the disinfectants were effective against S. aureus and Salmonella Typhimurium regardless of treatment. However, the phenolic compound had reduced (P <or= 0.05) efficacy against Salmonella Typhimurium after 6 wk of storage at the highest temperature of 43 degrees C and after 16 wk at the second highest temperature of 32 degrees C. All of the disinfectants were effective against S. aureus regardless of temperature treatment. In the second study, the addition of sterile chicken litter had deleterious effects on all 4 classes of disinfectants against Salmonella Typhimurium. Of the disinfectants tested, the phenolic compound retained efficacy against S. aureus. In the third study, the presence of OM significantly reduced (P <or= 0.05) the efficacy of the 30-wk-old quaternary ammonium and phenolic compound against Salmonella. The fresh quaternary ammonium and binary compound achieved a greater kill (P <or= 0.05) of Staphylococcus, relative to the 30-wk-old disinfectant. These results emphasize the need to use fresh disinfectants and that OM should be removed before disinfection.

Immune response of broiler chickens fed different levels of arginine and vitamin E to a coccidiosis vaccine and Eimeria challenge

One-day-old broiler chicks (n = 300) were orally vaccinated (Coccivac-B) and divided into 6 groups to evaluate Arg at 3 levels of supplementation, 0, 0.3, or 0.6% [normal level (NARG), medium level (MARG), or high level (HARG), respectively], and 2 levels of vitamin E (VE), 40 or 80 IU/kg of feed (VE40 or VE80, respectively), in a factorial experiment. Birds were reared in floor pens with fresh pine shavings and provided a corn-soybean-based diet and water ad libitum. At d 14, all chickens were orally challenged with a mixture of Eimeria field isolates (Eimeria acervulina, Eimeria maxima, and Eimeria tenella). In vitro heterophil and monocyte oxidative burst (HOB and MOB, respectively) was measured at d 21 from cells isolated from peripheral blood. Antibody levels (IgG, IgM, and IgA isotypes, ELISA) and NO were measured at d 14 and 28. The HOB was lower in birds fed the VE40 diets but was increased with the MARG and HARG treatments, whereas birds fed the VE80 diet had a higher HOB irrespective of Arg level. Birds fed the VE80 diet had high levels of MOB, which was not further improved by Arg, whereas birds fed the VE40-MARG diet had the highest MOB response. Plasma NO was not affected by diet at d 14, but at d 28, plasma NO was higher in birds fed the VE80-MARG or the VE40-NARG diet and lower in birds fed the VE80-NARG or the VE40-MARG diet. Birds fed the VE40-HARG or VE80-MARG diet had the highest IgG levels at d 14, but at d 28, birds fed the VE80-MARG diet had the highest IgG levels. The IgM concentration was lower in birds fed NARG levels irrespective of VE levels at d 14, but at d 28, IgM levels were higher in birds fed the VE40-HARG or the VE80-MARG feed. The IgA concentration was not consistently affected at d 14 or 28. These results suggest that Arg and VE fed at levels higher than those recommended by the NRC may play complementary roles on the innate and humoral immune response against an Eimeria challenge, potentially improving vaccine efficacy and response to field infections.

Evaluation of probiotic administration on the immune response of coccidiosis-vaccinated broilers

Probiotics are nonpathogenic bacteria that can promote bird health by reducing pathogen colonization. Researchers have previously demonstrated that the avian immune response can be modulated with probiotics, which may provide a mechanism for the reported reductions in pathogens. We examined phagocyte oxidative burst and cell proliferation of vaccinated broilers administered probiotics. We hypothesized that the combination of probiotic bacteria and a vaccine would affect immune function. Two studies were conducted to evaluate this interaction in broilers. Treatments consisted of a negative control, probiotic, vaccine, or a probiotic + vaccine. Peripheral blood was collected on d 7, 14, and 21 of age. Heterophils and monocytes were evaluated for oxidative burst and lymphocytes were assayed for proliferation. In study 1, heterophil oxidative burst was higher (P ≤ 0.05) in each treatment that received probiotic on d 14 when compared with the negative control. On d 21, an enhanced (P ≤ 0.05) heterophil oxidative burst was observed in the probiotic treatment when compared with the other treatments. On d 14, monocyte oxidative burst was greater (P ≤ 0.05) in the probiotic + vaccine treatment when compared with all other treatments. An increase (P ≤ 0.05) in lymphocyte proliferation was observed among all treatments on d 7 when compared with the negative control. Both vaccine treatments had significant lymphocyte proliferation on d 14 when compared with the negative control. In study 2, the probiotic treatment was associated with greater levels in heterophil oxidative burst on d 7 when compared with all other treatments. On d 21, an increase (P ≤ 0.05) in heterophil oxidative burst was seen in the vaccine treatment when compared with the negative control. On d 7, increased (P ≤ 0.05) monocyte oxidative burst was observed in the vaccine treatment when compared with the negative control. No significant differences were observed in lymphocyte proliferation in any of the treatment groups. These data suggest that probiotics can modulate the immune response and may play a role in vaccination.

Bursal anti-steroidogenic peptide (BASP): modulation of mitogen-stimulated bursal-lymphocyte DNA synthesis

The present study examined the effects of bursal anti-steroidogenic peptide (BASP) on mitogen-induced DNA synthesis in bursa-derived B-lymphocytes in short-term culture. Partially purified extracts of chicken bursa of Fabricius tissue, containing BASP, significantly (P < 0.05) reduced DNA synthesis in bursal-lymphocytes exposed to increasing concentrations of phorbol 12,13-dibutyrate (PDB). Following these initial observations, BASP, further purified from bursal extracts using sequential rpHPLC fractionation, was observed to reduce (P < 0.05) both B-lymphocyte PDB-stimulated DNA synthesis and ovarian granulosa cell progesterone biosynthesis with bioactivity observed at similar retention times in each assay, suggesting that each bioactivity may be due to the same or similar molecules. A similar BASP-enriched fraction was not effective in altering basal levels of DNA synthesis in chick embryonic kidney cells. Subsequently, BASP was further purified by several sequential chromatographic methods including: C-18 rpHPLC (preparative rpHPLC followed by a semi-preparative rpHPLC column), cation exchange chromatography, molecular sieve HPLC chromatography, and SDS-PAGE. Biologically active material was observed at approximately 29 or 34 kDa. Protein concentration was determined and bioactivity was evaluated. Anti-proliferative effects of this partially purified BASP on bursal-lymphocytes was observed at concentrations as low as 1.6 micrograms ml-1, with complete suppression of mitogen-stimulated DNA synthesis observed at approximately 25 micrograms ml-1. This partially purified BASP was also efficacious for attenuation of ovarian granulosa cell progesterone biosynthesis at concentrations as low as 0.4 microgram ml-1, with complete suppression of gonadotrophin-stimulated progesterone biosynthesis observed at approximately 0.8 microgram ml-1. While BASP is efficacious for attenuation of both granulosa cell steroidogenesis and bursal-lymphocyte proliferation, these data suggest that BASP is much more potent with regard to anti-steroidogenic activity.

Basp-induced suppression of mitogenesis in chicken, rat and human PBL

The purpose of the present investigation was to extend previous research conducted by our laboratory which demonstrated the suppressive effects of chicken bursa of Fabricius-derived bursal anti-steroidogenic peptide (BASP) on neonatal-chick B-lymphocyte mitogenesis. To test these anti-proliferative effects on lymphocytes derived from older animals, and to evaluate the phylogenetic applicability of these findings to other species, we evaluated the ability of BASP to alter proliferative indices in peripheral blood lymphocytes derived from adult chickens, rats and humans. Data from the present series of experiments confirm and extend our previous findings and suggest an anti-proliferative effect, exerted by BASP, on pools of isolated PBL from chickens, rats and humans, when measuring 3H-thymidine incorporation following mitogenic stimulation. While the present data was derived from limited numbers of pooled PBL, these findings may be indicative of a potential extra-bursal function of BASP on lymphocyte function.

Effect of bursal antisteroidogenic peptide (BASP) on chicken embryonic pituitary secretion of growth hormone (GH) and prolactin (PRL): evaluation in a reverse hemolytic plaque assay (RHPA)

Using the reverse hemolytic plaque assay described in the present investigation, a secretagogue activity of bursal antisteroidogenic peptide (BASP) for growth hormone (GH) or prolactin (PRL) secretion was observed in chicken Day 20e pituitary cell monolayers. Partially purified BASP (ppBASP), at all concentrations evaluated (0.25 BEQ/ml, 0.75 BEQ/ml, or 1.5 BEQ/ml), induced PRL secretion by isolated lactotrophs above (P < 0.05) basal levels during the 2- and 6-hr incubation. At the 18-hr time point, neither ppBASP nor vasoactive intestinal polypeptide (VIP) was efficacious (P < 0.05) in causing an elevation in PRL-secreting cells above basal levels. ppBASP, at all concentrations evaluated (0.25 BEQ/ml, 0.75 BEQ/ml, or 1.5 BEQ/ml), caused an increase in the percentage of GH-secreting cells above (P < 0.05) basal levels during the 18-hr incubation. When evaluating the 2-hr time point alone, ppBASP, at 0.75 or 1.5 BEQ/ml, significantly (P < 0.05) elevated the percentage of GH-secreting cells to above basal levels. After the 6-hr incubation, ppBASP at 0.25 or 0.75 BEQ/ml, was efficacious in causing elevated (P < 0.05) GH secretion above basal levels. The present study indicates a secretagogue activity of BASP on PRL or GH secretion by chicken embryonic anterior pituitary cells in vitro.