The aim of this study was to evaluate the growth performance, gastrointestinal function and health status of turkeys fed diets supplemented with synbiotic preparations, as compared with commercial probiotic feed additives. The experiment lasted for 15 weeks. The research material comprised 600 female BIG 6 turkeys (6 treatments, 5 replicates, 20 birds per replicate). The turkeys from the control group (I) received a diet without additives. Groups II and III received a basal diet with the addition of probiotic BioPlus 2B or Cylactin at 0.4 g/kg diet, respectively. In groups IV, V and VI turkeys were fed diets with synbiotic preparations S1 (L. reuteri, L. plantarum, L. pentosus, S. cerevisiae + inulin), S2 (L. reuteri, L. plantarum, L. pentosus, S. cerevisiae, L. rhamnosus + inulin) and S3 (L. reuteri, L. plantarum, L. pentosus, S. cerevisiae, L. rhamnosus, L. paracasei + inulin) at 0.5 g/kg diet, respectively. The following parameters were monitored: growth performance, carcass quality, the chemical composition of meat, the structure (length, weight, villus height, crypt depth) and functional parameters (pH, viscosity) of selected segments of the gastrointestinal tract, and the health status of birds (lysozyme, gamma-globulins, ceruloplasmin and total protein). Dietary supplementation with probiotics and synbiotics contributed to an increase in the final body weights of turkeys, a decrease in the feed conversion ratio and an increase in values of the European Production Efficiency Factor (p ≤ 0.05). Synbiotics improved the immune status of birds by increasing serum gamma-globulin levels and decreasing ceruloplasmin activity at 8th week of age (p ≤ 0.05). Synbiotics and probiotics also contributed to a decrease in crop and caecal pH (p ≤ 0.05). The analysed additives had no effect on carcass dressing percentage, carcass quality characteristics or the chemical composition of breast muscles. The tested synbiotics as well as commercial probiotics can be valuable feed additives, improving the growth performance and immune status of turkeys.
Keywords: Blood composition; carcass quality; gastrointestinal tract; health indicators; performance traits; probiotics; synbiotics; turkeys.