Responsiveness to invasive pathogens, clearance via the inflammatory response, and activation of appropriate acquired responses are all coordinated by innate host defenses. Toll-like receptor (TLR) ligands are potent immune-modulators with profound effects on the generation of adaptive immune responses. This property is being exploited in TLR-based vaccines and therapeutic agents in chickens. However, for administering the TLR agonist, all previous studies used in ovo, intra-muscular or intra-venous routes that cannot be performed in usual farming conditions, thus highlighting the need for TLR ligands that display systemic immune effects when given orally (per os). Here we have demonstrated that an ulvan extract of Ulva armoricana is able to activate avian heterophils and monocytes in vitro. Using specific inhibitors, we have evidenced that ulvan may be a new ligand for TLR2 and TLR4; and that they regulate heterophil activation in slightly different manner. Moreover, activation of heterophils as well as of monocytes leads to release pro-inflammatory cytokines, including interleukin1-β, interferon α and interferon γ, through pathways that we partly identified. Finally, when given per os to animals ulvan induces heterophils and monocytes to be activated in vivo thus leading to a transient release of pro-inflammatory cytokines with plasma concentrations returning toward baseline levels at day 3.

Highlights MSP extract increased IgG anti- Bordetella titers with the highest dosage. Improved IgG anti- Bordetella transudation from the blood to the colostrum. MSP extract increased total IgA titers in the milk, 7 days after farrowing.

Background Marek’s disease (MD) is a highly contagious lymphoproliferative disease of chickens caused by an alphaherpesvirus, Marek’s disease virus (MDV). MD is presently controlled by systematic vaccination of animals, which protects efficiently against the development of clinical disease. However, MDV vaccines do not prevent the multiplication and spread of MDV field strains and may favor the emergence of strains with increased virulence. Therefore, MDV persists to be a major problem for the poultry industry and the development of new alternative strategies to control MDV is needed. Seaweed extracts have previously been shown to exert immunomodulatory and antiviral activities, especially against herpesviruses. The objective of the present study was to explore the effect of Ulva armoricana extracts on MDV infection in vitro. Results We could demonstrate that the ulvan extract as well as its vitamin-enriched formulation reduce the viral load by about 80% at 24 h post-infection in infected chicken fibroblasts at concentrations that are innocuous for the cells. We also observed a substantial decrease in MDV plaque size suggesting that ulvans impede MDV cell-to-cell spread in vitro. Moreover, we showed that ulvan extract could promote MDV reactivation in lymphoid cells. Conclusions Our data provide the first evidence that the use of the ulvan extract could be a good alternative to limit MDV infection in poultry.

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The digestive system of poultry breeders is highly solicited, especially late in the egg production period when the demand in lipids for yolk development increases. To maintain a good health status and optimal levels of egg production, the digestive system needs to be properly drained and stimulated. This study assesses the impact of the product DigestSea ® containing a sulphated polysaccharide extracted from green seaweeds named MSP ® LIPIDS , on liver physiology and laying performance of breeding turkeys in comparison with a choline and sorbitol complex. The trial was performed in two buildings, from 23 to 28 weeks of laying. One group of 2,016 turkey breeders received the choline and sorbitol complex at 1 L/1,000 L of drinking water while the test group of 2,110 turkey breeders received DigestSea ® at a dosage of 0.5 L/1,000 L of drinking water, during 2 periods, first 10 days at 23 weeks of laying and again 5 days at 27 weeks of laying. Histological evaluation of the liver was performed at the end of the trial. The results show higher egg production in the DigestSea ® group with a significant reduction of the biliary canal hyperplasia and blood capillaries leucocytosis in the portal area, associated with a statistically significant reduction of lipids overload in the liver. Overall, our results show that the use of DigestSea ® containing MSP ® LIPIDS helps maintain a high level of egg production and lower hepatic steatosis. In conclusion, the use of the product containing MSP ® LIPIDS in breeding poultry production may be beneficial to maintain animal health and production levels. Further experiments are required to determine the mechanisms of action as a reduction of lipid resorption, metabolic changes, and an increased energy demand due to improving egg production.