Experimental infection of chickens by a flagellated motile strain of Salmonella enterica serovar Gallinarum biovar Gallinarum.

Salmonella enterica subsp. enterica serovar Gallinarum biovar Gallinarum (SG) causes fowl typhoid (FT), a septicaemic disease which can result in high mortality in poultry flocks. The absence of flagella in SG is thought to favour systemic invasion, since bacterial recognition via Toll-like receptor (TLR)-5 does not take place during the early stages of FT. In the present study, chicks susceptible to FT were inoculated with a wild type SG (SG) or its flagellated motile derivative (SG Fla(+)). In experiment 1, mortality and clinical signs were assessed, whereas in experiment 2, gross pathology, histopathology, systemic invasion and immune responses were evaluated. SG Fla(+) infection resulted in later development of clinical signs, lower mortality, lower bacterial numbers in the liver and spleen, and less severe pathological changes compared to SG. The CD8(+) T lymphocyte population was higher in the livers of chicks infected with SG at 4 days post-inoculation (dpi). Chicks infected with SG had increased expression of interleukin (IL)-6 mRNA in the caecal tonsil at 1 dpi and increased expression of IL-18 mRNA in the spleen at 4 dpi. In contrast, the CD4(+) T lymphocyte population was higher at 6 dpi in the livers of birds infected with SG Fla(+). Therefore, flagella appeared to modulate the chicken immune response towards a CD4(+) T profile, resulting in more efficient bacterial clearance from systemic sites and milder infection.

Evaluation of Disinfectants Used in Pre-Chilling water Tanks of Poultry Processing Plants

In poultry processing plants, disinfectants are often added to pre-chilling water tanks to reduce microbial contamination. The present study aimed at evaluating the effect of five disinfectants (acidified sodium chlorite, alkyl dimethyl benzyl ammonium chloride, chlorine dioxide, peracetic acid, and sodium hypochlorite) on the populations of food quality indicator microorganisms and on Salmonella Enteritidis (SE) in the presence and absence of organic matter. The results showed that chlorine dioxide and sodium hypochlorite did not reduce microbial carcass counts. On the other hand, acidified sodium chlorite, alkyl dimethyl benzyl ammonium chloride and peracetic acid reduced total and fecal coliform counts. Peracetic acid reduced the number of psychrotrophic microorganisms. All products were effective in reducing SE counts only in the absence of organic matter. Acidified sodium chlorite, alkyl dimethyl benzyl ammonium chloride and peracetic acid could be candidates for the replacement of sodium hypochlorite (commonly used in Brazil) in pre-chilling tanks. (AU)

Evaluation of Disinfectants Used in Pre-Chilling water Tanks of Poultry Processing Plants

In poultry processing plants, disinfectants are often added to pre-chilling water tanks to reduce microbial contamination. The present study aimed at evaluating the effect of five disinfectants (acidified sodium chlorite, alkyl dimethyl benzyl ammonium chloride, chlorine dioxide, peracetic acid, and sodium hypochlorite) on the populations of food quality indicator microorganisms and on Salmonella Enteritidis (SE) in the presence and absence of organic matter. The results showed that chlorine dioxide and sodium hypochlorite did not reduce microbial carcass counts. On the other hand, acidified sodium chlorite, alkyl dimethyl benzyl ammonium chloride and peracetic acid reduced total and fecal coliform counts. Peracetic acid reduced the number of psychrotrophic microorganisms. All products were effective in reducing SE counts only in the absence of organic matter. Acidified sodium chlorite, alkyl dimethyl benzyl ammonium chloride and peracetic acid could be candidates for the replacement of sodium hypochlorite (commonly used in Brazil) in pre-chilling tanks.

Influence of the halothane gene (HAL) on pork quality in two commercial crossbreeds.

We evaluated the effect of the halothane (HAL) gene on the quality of pork in domestic pigs. Half-carcasses from two different commercial pig (Sus domestica) crossbreeds were analyzed, 46 of which were homozygous dominant (HAL(NN)) and 69 of which were heterozygous (HAL(Nn)) for the halothane gene. The measures included backfat thickness, lean meat percentage, carcass weight, pH 24 h after slaughtering, color, and drip loss; DNA was extracted from the haunch muscle. Swine with the HAL(Nn) genotype had less backfat thickness and higher lean meat percentages than swine with the HAL(NN) genotype. Yet, swine with the HAL(Nn) genotype had lower quality meat than those with the HAL(NN) swine. The pH at 24 h was lower in HAL(Nn) swine. The meat color was paler in HAL(Nn) animals, the drip loss was greater in those animals bearing the n allele, and the amount of intramuscular fat was not related to the halothane genotype. We conclude that bearers of the recessive allele of the halothane gene produce more meat, but with quality parameters that are inferior to those sought by consumers and industry.

Influence of Chinese breeds on pork quality of commercial pig lines.

We compared carcass and meat quality of pigs from the same sire line and two different dam lines, one that included Chinese breeds and one that did not. Line A consisted of 1/4 Landrace, 1/2 Large White, 1/8 Chinese breeds (Meishan, Fengjing, Jiaxing), and 1/8 Large White, Duroc and Pietrain, and line B consisted of 1/2 Large White and 1/2 Pietrain. The animals (N = 144) were slaughtered at a live weight of 108 kg. Backfat thickness, percentage of lean meat, pH 24 h after slaughter, meat color, percentage of drip loss, and percentage of intramuscular fat were measured and compared using analysis of variance in a completely randomized design; the BioEstat 5.0 test was applied for the comparison of means at a significance level of 5% for all analyses. Backfat was significantly lower for line A (12.78 mm) than for line B (15.90 mm). The pH measured 24 h after slaughter was significantly lower in line A (5.68) compared to line B (5.84). Percent lean meat was significantly higher for line A (61.21%) compared to line B (59.72%). Percentage drip loss was significantly higher in line A (2.73%) than in line B (2.23%). Percentage intramuscular fat and meat color were not significantly different between the lines. The inclusion of Chinese breeds produced a higher percentage of lean meat and reduced fat thickness, along with increased heterosis, which are important characteristics for breeding programs.