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Maternal antibodies (matAb) can protect avian embryos and young birds after hatching against vertically transmitted pathogens. In birds, maternal IgY in egg yolk is transferred across the yolk sac through the FcRY receptor to passively immunize chicks. High-affinity binding occurs at pH 6, and does not occur at pH greater than 8.0. This study aimed to evaluate the influence of enrofloxacine, florfenicol, and ceftiofur on maternal IgY concentration in the yolk sac and serum of newly hatched chicks. In this study 184 one-day-old chicks were administered enrofloxacine, florfenicol, or ceftiofur in recommended doses according to the currently recommended treatment schedule. The yolk sac and blood were collected daily from day 1 to day 5 (yolk sac) or 7 (blood) of the experiment. Then, the samples were subjected to radial immunodiffusion investigation. The experiment showed that the concentration of IgY in serum on day 3 after the administration of ceftiofur and florfenicol was higher than that in the control group or the enrofloxacine group. It was also shown that after enrofloxacine treatment the level of IgY was higher in the yolk sac on day 4 of the experiment and lower in serum on day 5 of the experiment compared with the corresponding levels of IgY in the ceftiofur and florfenicol groups. These results suggest that the administration of enrofloxacine, florfenicol, and ceftiofur might influence the efficiency of matAb transfer from the yolk sac to the bloodstream of chicks.
Yolk is a source of nutrients for developing embryos and for early fish larval stages that lack the ability to feed actively. Thanks to abundant networks of capillaries, yolk sacs are responsible for larval respiration before the development of gills, and in some fish species they are also the site of primary hematopoiesis. Fish yolk sac shapes and sizes differ among species. Cold-water fish with long periods of embryonic and larval development have larger yolk sacs as compared to those of warm-water species. Yolk comprises free amino acids, proteins, lipids, and minerals that are taken up by developing organisms through the yolk syncytial layers. Free amino acids and proteins are utilized before lipids. Yolk nutrients are divided between growth and energy production. The efficiency of yolk utilization for growth is higher in embryos, and then decreases with the increase in larval locomotion. The rate of yolk resorption depends mainly on water temperature, but it can also be modified by other environmental factors such as the availability of exogenous food or water that is contaminated with toxic compounds.
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