Dietary inclusion of a fermented rapeseed–seaweed blend alters immunity and intestinal microbial activity but not <i>Ascaridia galli</i> burden in laying hens

The infected hens were either naturally exposed to <i>A. galli</i> contaminated litter or received oral administration of 764 embryonated <i>A. galli</i> eggs per hen at 20 weeks of age for 12 weeks.</p> <p>3. Performance was unaffected by EP199 or infection. However, hens fed the EP199 diet had a significantly lower egg production 3-12 weeks <i>post</i>-infection (pi) compared to the control group (86.1% <i>vs</i>. 90.1%, P=0.044).

There was no effect on intestinal worm burden (<i>x</i>=7.98 worms per hen) or immune competence, as assessed by mitogen activation of peripheral blood mononuclear cells (PBMC). Despite similar nutrient profiles of the two diets, the hens fed the EP199 diet had significantly higher caecal levels of specific short chain fatty acids: acetic acid (79.8 <i>vs</i>. 71.0 mmol/kg digesta; P=0.020), propionic acid (35.0 <i>vs</i>. 30.1 mmol/kg digesta; P=0.005) and n-butyric acid (17.3 <i>vs</i>. 14.7 mmol/kg digesta; P=0.015).</p> <p>4.

Compared to the control group, hens fed EP199 had a lower humoral <i>A. galli</i>-specific immune response, in terms of IgY serum titres at 10 weeks (2812 <i>vs</i>. 5291; P=0.002) and 12 weeks (10546 <i>vs</i>. 17668; P=0.025) pi. Hens fed the EP199 diet showed a significantly higher frequency of activated CD4+CD8+ T cells (28.7% <i>vs</i>. 21.9%; P=0.045).</p> <p>5. Feeding EP199 at 6% did not have an effect on severity of <i>A. galli</i> infection.

However, EP199 showed an immunomodulatory effect and altered caecal microbial activity. Infection method (experimental <i>vs</i>. natural) influenced both the worm burden and immune parameters.</p>