Antibody response in sows and piglets following vaccination against Mycoplasma hyopneumoniae, toxigenic Pasteurella multocida, and Actinobacillus pleuropneumoniae

The aim of the experimental study was to compare the humoral immune response and occurrence of adverse effects following single or multiple simultaneous vaccination of sows against Mycoplasma hyopneumonia, toxigenic Pasteurella multocida, and Actinobacillus pleuropneumoniae. In addition, passively transferred antibodies to piglets were studied until weaning at 3 weeks of age. Fever was seen in a few sows within the first 12 hours after the 1st and 2nd vaccination. No difference in the occurrence of other adverse effects was observed between groups. Antibody levels were significantly higher in vaccinated sows and their offspring compared with the control group. This was found to be independent of single or simultaneous vaccinations with the 3 vaccines. In conclusion, applying multiple vaccines simultaneously to sows appeared not to influence the occurrence of adverse effects or the sow’s serum levels of antibodies at the time of farrowing, nor the offspring’s serum levels up to 3 weeks of age.     

Comparative evaluation of virulence and pathology of Streptococcus suis serotypes 2 and 9 in experimentally infected growers

Streptococcus (S.) suis is an invasive porcine pathogen causing meningitis, septicemia, arthritis and other diseases. Studies on pathogenesis as well as vaccine trials have focused on serotype 2 strains, which are worldwide the most prevalent among invasive isolates. However, in Europe serotype 9 strains also contribute substantially to S. suis-associated invasive diseases of piglets. The objective of this study was to determine the virulence of an MRP* SLY+ serotype 9 S. suis strain in comparison to an MRP+ EF+ SLY+ serotype 2 strain. Experimental intranasal and intravenous infections of 7-8 weeks old SPF piglets were investigated with regard to clinic and pathology. In contrast to the virulent serotype 2 strain, the serotype 9 strain did not cause disease with clinical manifestations after intranasal administration. However, histological screenings of these animals revealed pathological lesions, such as mild focal suppurative meningitis. Clinical manifestations related to meningitis, arthritis and serositis could be induced by intravenous application of this serotype 9 strain. Bacteriological culture and immunohistochemistry of the brain confirmed association with the S. suis challenge strains in all cases with clinical manifestations. Interestingly, expression of MRP within meningitis lesions was demonstrated for both pathotypes via immunohistochemistry. In conclusion, this study demonstrates that MRP* SLY+ serotype 9 strains are less virulent for growers than MRP+ EF+ SLY+ serotype 2 strains. Thus, intravenous application of this serotype 9 strain is required to evaluate heterologous protection in the course of vaccine development based on serotype 2 strains in the future.     

Modification of Standard Enzymatic Protocol to a Cost‐Efficient Format for Mixed‐Linkage (1→3,1→4)‐β‐d‐Glucan Measurement

The current enzymatic assay approach (AACC International Approved Method 32‐23) for the measurement of mixed‐linkage β‐glucan in small grains was modified to a cost‐efficient and high‐throughput format without compromising the accuracy of the results. Ten barley (Hordeum vulgare L.) genotypes used in the study represented a wide range of β‐glucan content levels. A reduced reaction volume is used in the new protocol to adapt to a 96‐well plate format. The volume of key components lichenase and β‐glucosidase were reduced to 25% of the volume required in the original protocol and the cost per sample was reduced to 22% of that in the original protocol. Labor cost was also decreased to 25% of the original protocol as a result of format changes. The accuracy of the measurement from the modified protocol was comparable to the current standard enzymatic procedure. β‐Glucan measurement accuracy of the modified and original protocols were also compared using 21 oat (Avena sativa L.) samples. The results indicated that the new protocol consistently produced accurate measurements in both barley and oat.     

Effect of Physical State of Nonpolar Lipids on Rheology and Microstructure of Gluten‐Starch and Wheat Flour Doughs

To clarify the effects of solid fat and liquid oil on dough in more detail in a simpler system, gluten‐starch doughs with different gluten contents were investigated. The results from rheological measurements indicate that dough with a higher starch content has less resistance to strain and dough with a lower starch content has a rubber‐like structure. The effects of the physical state of nonpolar lipids such as fat and oil on gluten‐starch doughs and wheat flour doughs were investigated using rheological measurements and scanning electron microscopy. Fat‐containing dough had more gas cells and a very smooth gluten gel surface with few holes, which may provide higher tolerance to strain. Moreover, the fat seemed to uniformly distribute the gluten gel between the starch granules in the dough, which reduced the friction between starch granules and led to a lower storage modulus. A mechanism governing the effect of fats on loaf volume is proposed based on the phenomena observed in the fat‐containing dough.     

Effect of Physical States of Nonpolar Lipids on Rheology,Ultracentrifugation, and Microstructure of Wheat Flour Dough

In the previous study, we investigated effect of physical state of nonpolar lipids of gluten‐starch model dough. This experiment examined a real wheat flour dough system to assess the role of fat crystals in the breadmaking processes. These experiments were performed with a baking test and an investigation of wheat flour dough through rheological measurements (both large and small deformations), scanning electron microscopy, and ultracentrifugation. As a result, we found that the added oil was absorbed in the gluten structure, causing the aggregation of the gluten, which gave rise to more elastic behavior. In contrast, solid fat seemed to be distributed uniformly between the starch granules in the dough, reducing the friction between the starch granules and facilitating thin gluten gel layers. These properties lead to the lower G′ value and the increased viscous behavior, which yields an increase in loaf volume. In addition, the supposed mechanism behind the large loaf volume described in the previous study was that fat provides a uniform distribution of the dough components, and that the dough can thus expand easily, resulting in a larger loaf volume, which was supported in the wheat flour dough system. In conclusion, we found that thin, expandable gluten films and the uniform dispersion of gluten and starch granules in the dough are prerequisites for attaining better baking performance.