ENHANCEMENT OF DEFENSE-MECHANISMS IN BROI LERS AFTER ADMINISTRATION OF BIOLOGICAL FEED SUPPLEMENTS

The trial involved broilers from the 4th to the 56th day of life. The first group P1 (n = 30) received commercial mashes with supplements of 0.5% biomass of fresh-water algae (Chlorella vulgaris). The second gr oup P2 (n = 30) received 0.9% dried cow's colostrum and 0.9% dried bre wer's yeasts in addition to the algae (0.2%). All the ingredients came from fluid-bed drying at temperatures maximally 50-degrees-C. Control group K (n = 30) consisted of broilers which received commercial mash es only. At the age of 21, 33 and 56 days, 10 birds of each group were killed, and basic hematological values were determined in the blood s amples and phagocytic activity of leucocytes was determined. Samples o f the thyme, bursa Fabricii, spleen, ileocecal valve, Meckel's diverti culum, gonads, suprarenal glands and Harder's gland were subjected to histological examination. 22-day chickens of all three groups were vac cinated with Newcastle disease (the vaccine Avipest, Mevak Nitra) and the levels of specific antibodies in blood serum were determined on da ys 33, 46 and 56. 0.5% alga supplement to feed ration increased the li ve weight of experimental broilers at the end of the second week of li fe only (p < 0.05). On the 21st and 33rd day of life, phagocytic activ ity of leucocytes increased significantly (p < 0.01) in these individu als, while in the second month of life development of the intestinal l ymphatic tissue and Harder's gland was largely stimulated. Combination of algae with other biological additives did not significantly influe nce the live weight of broilers, but it enhanced the above-mentioned e ffect on the phagocytic activity and lymphatic tissue development. Bes ides, a significant increase in specific antibodies as a reaction to N ewcastle disease vaccination was demonstrated on day 33 in this experi mental group (p < 0.05). The hematological values nor cholesterol leve ls were influenced by the biological supplements to any larger extent. The growth of bursa Fabricii and spleen was not significantly influen ced either even though the differences were increasing with age in fav or of the experimental birds.