Enhancement of Defense-Mechanisms in Broilers After Administration of Biological Feed Supplements

Veterinarni Medicina 39, 1994, 321-328

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 group P2 (n = 30) received 0.9% dried cow's colostrum and 0.9% dried brewer'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 mashes 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 samples and phagocytic activity of leucocytes was determined. Samples of the thyme, bursa Fabricii, spleen, ileocecal valve, Meckel's diverticulum, gonads, suprarenal glands and Harder's gland were subjected to histological examination. 22-day chickens of all three groups were vaccinated with Newcastle disease (the vaccine Avipest, Mevak Nitra) and the levels of specific antibodies in blood serum were determined on days 33, 46 and 56. 0.5% alga supplement to feed ration increased the live weight of experimental broilers at the end of the second week of life only (p < 0.05). On the 21st and 33rd day of life, phagocytic activity of leucocytes increased significantly (p < 0.01) in these individuals, while in the second month of life development of the intestinal lymphatic tissue and Harder's gland was largely stimulated. Combination of algae with other biological additives did not significantly influence the live weight of broilers, but it enhanced the above-mentioned effect on the phagocytic activity and lymphatic tissue development. Besides, a significant increase in specific antibodies as a reaction to Newcastle disease vaccination was demonstrated on day 33 in this experimental group (p < 0.05). The hematological values nor cholesterol levels were influenced by the biological supplements to any larger extent. The growth of bursa Fabricii and spleen was not significantly influenced either even though the differences were increasing with age in favor of the experimental birds

FULL PAPER on request
« back