1. Influence of hydrocolloidial silver nanoparticles on gastro-intestinal microflora and immune status of broiler chickens Charlotte Lauridsen a, Ricarda Engberg a, Lane Pineda b & André Chwalibog b a Aarhus University, Department of Animal Science, Tjele, Denmark b University of Copenhagen, Department of Basic Animal and Veterinary Sciences, Frederiksberg, Denmark Introduction Nanoparticles of silver (AgNano) have antimicrobial properties, which may be used in poultry production as an alternative to the use of antibiotic growth promoters. The purpose of the present study was to investigate effects of AgNano provided at 0, 10, 20 ppm in the pre-hatch period via in ovo injection or during the post-hatch period via drinking water on microbial profile of ileum and caecum and on immune status of broiler chickens. AU Department of Animal Science Faculty of Science and Technology AARHUS UNIVERSITY Results Age had strong influence on most of the analysed variables. Microbial profile (Table 1): -Broilers of AgNano injected eggs had lower numbers of lactic acid bacteria and higher numbers of enterococci in ileum -Boilers of AgNano injected eggs had lower number of lactose negative entero bacteria, and an increased acetic and succinic acid concentration in caecum. Immune status (Figure 1): -IgG tended to decrease with increasing doses of AgNano in the drinking water, when eggs were injected -Broiler obtained from non-injected had the highest IgG concentrations at the lowest dose of AgNano Materials and Methods -Fertile Ross eggs (#204) were divided into 4 treatment groups, i.e., in ovo injection of 10 or 20 ppm, or no injection (“0 ppm” or “sham”). -During the post-hatch period, birds receiving no AgNano in ovo were provided with AgNano via the drinking water (0, 10, or 20 ppm AgNano). Birds that were in ovo injected with 10 or 20 ppm AgNano received the same concentrations via drinking water. In total, the six treatments were repeated six times. -During two repetitions, blood, ileal and caecal samples were obtained from chickens at day 22 and 36 of age. -Plasma was analysed for immunoglobulins G and M -The composition of the microflora (i.e., enumeration of selected bacteria, pH, and concentration of short chained fatty acids) were determined Conclusion & Perspective Although some influences of in ovo injection with AgNano on the microbial profile were observed, the application of AgNano had only minor effects on the measured variables. The results regarding the immune system indicate that studies regarding the impact of AgNano on broiler immune function should involve a challenge model to stimulate the immune defense and the antimicrobial function of AgNano. No injectio n In ovo injection Ileum Lactic acid bac. (log cfu/g)8.78.3 Enterococci (log cfu/g)5.56.0 Caecum Lac. neg. entero bac. (log cfu/g) 5.65.2 Acetic acid (mmol/kg)69.878.3 Succinic acid (mmol/kg)7.610.7 Figure 1: Effect of increasing doses of AgNano during the post-hatch period on the IgG and IgM plasma concentration of broilers obtained from eggs, which were either injected or not injected with AgNano. Table 1: Variables on microbial of broilers where significant differences were obtained between in ovo injection or not with AgNano. Acknowledgement This research was financially supported by the Danish Strategic research Council under the Programme Commission on Strategic Growth Technologies.