Serologic Response of Gnotobiotic Pigs Challenged with Actinobacillus Pleuropneumoniae Serotype 5 or Actinobacillus Suis Field Isolates

Three studies, a pilot study with conventional early-weaned pigs and two studies with gnotobiotic pigs were completed. The piolot study indicated that conventional pigs could be challeneged with at least 107 colony forming units (cfu) or Actinobacillus pleuropneumonia (APP) or Actinobacillus suis (A suis) without developing clinical signs. No serological response was detected in these pigs. In the first gnotobiotic study, nine pigs were used: 3 control, 3 APP or 3 A. suis. The two groups of challened pigs failed to respond clinically or serologically to the intial callenege of 106 cfu or either APP or A. suis but the APP pigs did respond clinically and serologically to a second challenge of 107 cfu. A second study with twenty gnotobiotic pigs was completed. Eight pigs were assigned to the Actinobacillus pleuropneumoniae (APP) serotype 5 group; eight pigs were assigned to the Actinobacillus suis (A. suis) group and 4 pigs were assigned to the control group. Each group of gnotobiotic pigs were challenged with 107 colony forming units (cfu) of either APP or A. suis. In both gnotobiotic studies, serological tests indicated that the hemolysin neutralization test (HNT) specificity was poor as it was unable to discriminate between APP or A. suis infections. The HNT test detected more APP positive animals than any other test and detected APP infected animals one-month post challenge. In the first gnotobiotic study, APP infected pigs were detected at one-two weeks post challenge with the APP5 ELISA developed by the University of Montreal (ELISA-M). ELISA-M was a more sensitive test than the APP5 ELISA developed by Oxford Laboratories (ELISA-O). In the second gnotobiotic study, the ELISA-M and ELISA-O failed to detect any APP 5 infected animals. In both gnotobiotic studies, the complement fixation test failed to detect any animals and was insensitive to APP infections

Studies on Salmonella Infections in Pigs with Emphasis in Food Safety Applications

During the past year, studies have been conducted in the following areas: 1. the seasonal variations in environmental fecal Salmonella in pigs prior to shipment for slaughter 2. identification of groups of pigs that might be at risk for becoming infected with Salmonella 3. comparison of culture and the Danish MIX-ELISA for detection of Salmonella on pig farms 4. efficacy of SC54 vaccination of pigs at one day of age 5. the comparison of culture and the Danish MIX-ELISA for the detection of Salmonella in carcasses at slaughter 6. the impact of Salmonella infections on performanc

Effects of supplemental zinc amino acid complex on gut integrity in heat-stressed growing pigs

Heat stress (HS) jeopardizes livestock health and productivity and both may in part be mediated by reduced intestinal integrity. Dietary zinc improves a variety of bowel diseases, which are characterized by increased intestinal permeability. Study objectives were to evaluate the effects of supplemental zinc amino acid complex (ZnAA) on intestinal integrity in heat-stressed growing pigs. Crossbred gilts (43±6 kg BW) were ad libitum fed one of three diets: (1) control (ZnC; 120 ppm Zn as ZnSO4; n=13), (2) control+100 ppm Zn as ZnAA (Zn220; containing a total of 220 ppm Zn; n=14), and (3) control+200 ppm Zn as ZnAA (Zn320; containing a total of 320 ppm Zn; n=16). After 25 days on their respective diets, all pigs were exposed to constant HS conditions (36°C, ∼50% humidity) for either 1 or 7 days. At the end of the environmental exposure, pigs were euthanized and blood and intestinal tissues were harvested immediately after sacrifice. As expected, HS increased rectal temperature (P⩽0.01; 40.23°C v. 38.93°C) and respiratory rate (P⩽0.01; 113 v. 36 bpm). Pigs receiving ZnAA tended to have increased rectal temperature (P=0.07; +0.27°C) compared with ZnC-fed pigs. HS markedly reduced feed intake (FI; P⩽0.01; 59%) and caused BW loss (2.10 kg), but neither variable was affected by dietary treatment. Fresh intestinal segments were assessed ex vivo for intestinal integrity. As HS progressed from days 1 to 7, both ileal and colonic transepithelial electrical resistance (TER) decreased (P⩽0.05; 34% and 22%, respectively). This was mirrored by an increase in ileal and colonic permeability to the macromolecule dextran (P⩽0.01; 13- and 56-fold, respectively), and increased colonic lipopolysaccharide permeability (P⩽0.05; threefold) with time. There was a quadratic response (P⩽0.05) to increasing ZnAA on ileal TER, as it was improved (P⩽0.05; 56%) in Zn220-fed pigs compared with ZnC. This study demonstrates that HS progressively compromises the intestinal barrier and supplementing ZnAA at the appropriate dose can improve aspects of small intestinal integrity during severe HS

Studies on Salmonella Infections in Pigs with Emphasis in Food Safety Applications

During the past year, studies have been conducted in the following areas: 1. the seasonal variations in environmental fecal Salmonella in pigs prior to shipment for slaughter 2. identification of groups of pigs that might be at risk for becoming infected with Salmonella 3. comparison of culture and the Danish MIX-ELISA for detection of Salmonella on pig farms 4. efficacy of SC54 vaccination of pigs at one day of age 5. the comparison of culture and the Danish MIX-ELISA for the detection of Salmonella in carcasses at slaughter 6. the impact of Salmonella infections on performance</p

The effects of zinc amino acid complex supplementation on the porcine host response to Lawsonia intracellularis infection

Abstract Lawsonia intracellularis is among the most important enteric pathogens of swine and antibiotic alternatives are needed to help mitigate the negative effects of infection. Zinc is an essential trace mineral known to be crucial for maintaining intestinal barrier function and proper immune response. In this study, we investigated the porcine host response to L. intracellularis infection when supplemented with a zinc-amino acid complex, a form of zinc that can lead to greater bioavailability when compared to traditional inorganic forms of zinc. Our results show that a zinc-amino acid complex supplementation with a final concentration of 125 ppm of zinc in feed significantly (p < 0.05) decreased the number of animals with lesions and severity of lesions caused by L. intracellularis. Animals supplemented with the zinc-amino acid complex also exhibited a significantly (p < 0.05) earlier onset of seroconversion as well as an increased number of T cells in infected and non-infected intestinal tissue. This study demonstrated that this zinc-amino acid complex aids the host in responding to L. intracellularis infection and may be a new approach to help minimize negative effects of disease