The objective of this study was to reveal potential production and met
abolic risks in laying hens with targeted production of consumer eggs
with high iodine content. A trial lasted 74 days and was conducted in
four groups of hens (n = 11) of laying type Hisex Brown. All groups of
hens had a free choice of complete feed mixture for laying hens - N-1
. These iodine additions per 1 kg of feed mixture were applied to expe
rimental groups: 3.5 mg to group B, 1.3 and 10.0 mg to group C, 7.0 an
d 15.0 mg to group D. Hen weight (Tab. I), and feed and water intake (
Tab. II) were determined during the trial. Iodine content in yolk (Tab
. III) was determined colorimetrically after alkaline digestion. These
methodical principles were used to determine blood parameters: hemogl
obin content in blood as hemoglobin cyanide(Fig. 1), leukocyte counts
in blood - microscopically in Burker chamber (Fig. 2), plasma choleste
rol - reaction with acetic anhydride (Fig. 4), total protein biuret re
action (Fig. 3), protein fractions - electrophoresis on cellulose acet
ate foils (Tab. IV), triiodothyronine - RIA (Tab. IV). Iodine suppleme
nts significantly (P < 0.01) stimulated an increase in iodine concentr
ation in yolk, ranging from 2 303 +/- 691 in control group A to 23 592
+/- 9 436 mu g/kg of fresh matter after an addition of 15 mg I/kg of
feed. Significantly higher feed consumption (P < 0.01) in groups C and
D receiving the highest additions of iodine was accompanied by a sign
ificant decrease in water intake (P < 0.01). Iodine load was followed
by a significant decrease in hemoglobin content (P < 0.01) only at the
intake of 15 mg I per kg of feed. The character of changes in leukocy
te counts and protein content in blood plasma in experimental groups d
id not differ very much from the control group under iodine load. A si
gnificant increase in gammaglobulin content (P < 0.01) was observed af
ter additions of more than 7 mg I per kg of feed. Plasma cholesterol c
ontent increased significantly (P < 0.01) only after an addition of 15
mg I per kg of feed. Triiodothyronine content in blood plasma was inc
reasing after additive iodine intake while the difference from control
group was significant (P < 0.01) after additions of more than 7 mg I
per kg of feed. A significant decrease in hemoglobin content and an in
crease in cholesterol content in blood plasma following an addition of
15 mg of iodine, accompanied by higher of gamma-globulin and triiodot
hyronine concentrations after the additive intake of 7-15 mg iodine pe
r kg of feed, suggest a metabolic action of iodine that should be stud
ied in greater detail with respect to production of iodine-enriched eg
gs.