The study presents an evaluation of morphological and histometric parameters of the thyroid gland of slaughtered cattle (29 cows, 10 bulls, 7 heifers and 4 calves). The thyroid gland of bulls contained 34.7% of large follicles while their content in cows and heifers was 32.6% and only 19.2%, respectively. The average follicle length was 162.0±19.8 μm in bulls, 153.5±24.8 μm in cows and 122.4±10.1 μm in heifers. The highest thyreocytes were found in heifers and bulls (9.45±1.17 and 9.42±1.50 μm, respectively) and the lowest in cows (8.46±2.13 μm). A positive relationship was determined between the iodine content of the thyroid gland and the percentage of large follicles (r = 0.55) while the relationship between iodine content and thyreocyte height was negative (r = -0.21). In the thyroid gland of older cows medium and large follicles with low cubic to flat thyreocytes were dominant. Some follicles contained necrotic thyreocytes and the cytoplasm contained lipofuscin. The results suggest the influence of an increased iodine content in the thyroid gland on follicle size and thyreocyte height.

The aim of this study was to evaluate histometric and biochemical properties of the thyroid gland of sheep supplemented with high doses of iodine. The study was conducted on ewes (n = 12) and gimmers (n = 12) of Sumava mountain sheep; each group was subdivided into two groups (group A and B) of six animals. Feed of group A was supplemented with 3 mg iodine/kg of dry matter; group B was given 5 mg iodine/kg dry matter. The iodine in feed mineral supplement was in the form of calcium iodide. The ewes were at first carrying, subsequently lambing, lactating and finally remained barren. The experiment ended after 11 months, when all animals were slaughtered and a sample of the thyroid gland was taken for histometric examination and determination of iodine content by modified colorimetric method. Prior to the slaughter, blood samples were collected for determination of thyroidal hormones and the thyroid-stimulating hormone in blood serum. Thyroid glands of sheep from group B showed higher thyroid weight, larger follicles, higher percentage of large follicles and lower follicular cells compared to groups A. Normal or lower content of triiodothyronine and thyroxine, lower content of their free fractions and bordering or elevated concentrations of thyroid-stimulating hormone were detected in blood serum of all four groups. This trend can signalize the tendency of lowering activity of the thyroid gland. The results of this long-term study show impacts of higher iodine intake on the structure and function of the thyroid gland in sheep.

The aim of this study was to analytically determine the content of iodine, copper, zinc and manganese in the yolk of consumer eggs in Bohemia in 2007 and 2008. Investigated eggs originated from six so called intensive farms with large flocks (118 eggs) and twelve backyard farms or small-flock establishments (136 eggs) from three administrative regions in Czech Republic. Eggs from intensive farms were obtained directly from the establishments, while eggs from backyard farms were purchased from private farmers. Spectrophotometric Sandell-Kolthoff method was used for determination of iodine content in egg yolk, while Cu, Zn and Mn levels were determined by the flame absorption spectrophotometric method (AAS). The average content in fresh egg yolk from intensive farms was determined to 0.9 ± 0.2 for iodine, 8.4 ± 2.1 of copper, 29.8 ± 6.9 of zinc and 1.2 ± 0.3 of manganese, all in mg·kg−1, as compared to yolk content from backyard farms with 0.4 ± 0.04 mg·kg−1 of iodine, 10.8 ± 2.9 of copper, 32.5 ± 6.9 of zinc and 1.5 ± 0.3 of manganese. Average content of copper, zinc and manganese was lower in egg yolks from intensive farms (P < 0.01) as compared to the egg yolks from backyard farms, while iodine content on the other hand was lower in eggs from backyard farms (P < 0.01).

PEKSA ZDENĚK, TRÁVNÍČEK JAN, KONEČNÝ ROMAN, JELÍNEK FRANTIŠEK, DUŠOVÁ HANA, VOLFOVÁ KATEŘINA, VRBOVÁ ANETA, ZÁBRANSKÝ LUBOŠ, FALTA DANIEL, PÁLKA VÁCLAV: The eff ect of iodine and strumigens long-term foodborne intake on histometrical parameters of thyroid gland in gimmers. Acta Universitatis Agriculturae et Silviculturae Mendelianae Brunensis, 2013, LXI, No. 5, pp. 1365-1369 In 2010 and 2011 two experiments on gimmers of Šumava mountain sheep were performed. The fi rst experiment was carried out on 12 animals (experimental period was 11 months); control group was fed with 3 mg I*kg −1 in dry matter per day and experimental group was fed with 5 mg I*kg −1 in dry matter per day. The second experiment lasted 10 months and it was carried out on 12 animals. Feed ration for control group contained 10 mg I*kg DM −1 . Feed ration for experimental group contained 10 mg I*kg DM −1 too; moreover it included rapeseed meal and 1 g of sodium nitrate. The aim of the fi rst experiment was focused on impact of high iodine intake on structure of thyroid gland. The aim of the second experiment was to discover eff ect of strumigens during high iodine intake on structure of thyroid gland. The animals were slaughtered a er the experiment and there was executed the dissection of thyroid gland. The samples of thyroid gland were processed during classic paraffi n method and dyed with haematoxylin and eosin. For fi nding of histometrical parameters was used program Leica IM 500 Version 4.0. The length, the width and the area of follicles were measured. The follicles were divided into three groups a er this procedure (by the length); in each group were measured 20 thyreocytes. In group with intake 5 mg I*kg DM −1 (experiment from year 2010): higher weight of thyroid (p < 0.01), signifi cant higher (p < 0.05) proportional representation of large and medium follicles, signifi cantly (p < 0.05) higher average size of follicles, demonstrably lower (p < 0.05) height of epithelium were found. There were not found any diff erences in monitored parameters between the groups from experiment which was carried out during the year 2011. A er comparing results from the both experiments signifi cantly higher percentage representation of large follicles a signifi cantly lower representation of small follicles, distinctly higher average size and higher height of epithelium in all size categories, in groups with iodine intake 10 mg I*kg DM −1 was found (from second experiment -year 2011).

The study aimed at defining the immunity risks connected with high iodine supplementation in ewes and their lambs. The feed ration for control group (C) of ewes (n=6) contained 3.1 mg of iodine per kilogram of dietary dry matter and for experimental group (E) of ewes (n=6) 5.1 mg of iodine per kilogram of dietary dry matter. The animals were fed the diets for 8 months. Parallelly with different iodine supplementation, some immunological parameters (percentage of γ-globulins, concentration of immunoglobulin G, and white blood cell count) were examined in ewes and their lambs. The difference in the average concentration of immunoglobulin G between the ewes of group C and E was not significant during the experiment. A significant decrease (P<0.01) in the concentration of immunoglobulin G from 19.6 mg/mL before the experiment to 9.8 mg/mL on day 60 of the experiment was demonstrated in the ewes of group E. The average percentage of γ-globulins in the whole period after parturition was lower in the ewes of group E than in group C. The concentration of immunoglobulin G and the percentage of γ-globulins in lambs from dams in group E was continually lower (P<0.01) for the entire period of 1-30 d and demonstrated immunological risks of the excessive intake of iodine. The obtained results document a dangerous influence of high iodine intake on immunity in the prenatal period in ewes and mainly in the postnatal period in their lambs.