Blood analysis is a very important and powerful diagnostic tool in animal health and welfare control. It is routinely performed in higher vertebrates, for which reference values are well established, but fish hematology still needs further research. Many intrinsic and environmental factors have profound impact on fish hematological values, making determination of reference values difficult. Additionally, fish blood usually requires the addition of an anticoagulant agent, because of short clotting times. The choice of anticoagulant is vital for obtaining reliable blood test values. In the present study, the impact of two common anticoagulants, K 2 EDTA (1.8 mg/ml) and lithium heparin (18 I.U./ml), on hematological values of farmed brown trout Salmo trutta spawners during the spawning season was investigated. Results of basic hematological analysis, such as packed cell volume (PCV), hemoglobin concentration (HGB), red blood cell count (RBC), mean corpuscular hemoglobin (MCH), mean corpuscular volume (MCV), mean corpuscular hemoglobin concentration (MCHC), and white blood cell count (WBC), were compared between these two compounds. Statistically significant differences were observed in PCV, MCV, and MCHC, whereas HGB, RBC, MCH, and WBC showed no such differences. These results suggest that lithium heparin gives more reliable results, because red blood cells in K 2 EDTA-treated samples have a tendency to swell. It is worth noting that ethylenediaminetetraacetic acid salt did not induce sample hemolysis in the present study.

Ulcerative dermal necrosis (UDN), a disease of unknown etiology affecting salmonids, has been observed in some rivers in the north of Poland since 2007. Fish affected by UDN die, inter alia, as a result of secondary infection caused by water molds from the Saprolegnia genus. UDN is considered to be an important factor affecting the decline of Polish salmonid populations observed in recent years. Patterns of secondary infection and differences between sexes in UDN-affected wild, adult sea trout (Salmo trutta m. trutta) during the 2014 and 2015 spawning season have been described on the basis of photographic documentation and image analysis. Male fish are most commonly infected in the dorsal region, while females in the head and tail areas. When comparing the infection patterns in both sexes, it is clear that large areas of flanks are significantly more frequently infected in males than in females. The dorsal half of the tail fin is most commonly affected by pathological changes in females. These findings are discussed in relation to various factors predisposing salmonids to Saprolegnia spp. infections during the spawning season. The presented infection patterns can be helpful in preliminary diagnosis of early stages of secondary infection with Saprolegnia spp. in UDN-affected salmonids.

Fusarium infections have been reported in aquatic animals, but are still poorly investigated in wild salmonids. The aim of the study was to determine the impact of the fungi and their toxins on the health status of brown trout ( Salmo trutta morpha trutta ) migrating from the Baltic Sea to the freshwater. Individuals from the wild brown trout population exhibiting ulcerative skin lesions were collected from the Słupia River in Poland and subjected to microbiological, histopathological, and hematological examinations, as well as toxicological analysis for a presence of mycotoxins. The results of microflora isolation from the brown trout skin samples revealed the presence of conditionally pathogenic bacteria and fungi classified by molecular techniques as Fusarium spp. Toxicological analysis allowed for detection of zearalenone (ZEN) in the liver, kidney, and gastrointestinal tract of the fish. In several cases, there was α-zearalenone (α-ZEL) identified at trace levels in the liver, as well as sterigmatocystin and enniatin B at low levels in the kidney and the liver. Histopathological examination revealed the presence of fungal hyphae disrupting the epidermis and penetrating into the necrotic dermis and hypodermis. The decreased values of the blood parameters, i.e., hemoglobin concentration (HGB), packed cell volume (PCV), mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), and white blood cell count (WBC), were indicative of osmoregulation failure being a consequence of the skin damage. The results of the study provide new information regarding Fusarium sp . infection in brown trout and serve as the basis for further research on the potential impact of the fungi and their mycotoxins on the Baltic salmonid population, including their role in ulcerative dermal necrosis. Electronic supplementary material The online version of this article (10.1007/s12550-020-00395-8) contains supplementary material, which is available to authorized users.

Blood tests were performed on 150 females sea trouts Salmo trutta m. trutta L. during four spawning seasons (2014–2017). Fish were caught on a Polish Angling Association trapping point, the Słupia River, Słupsk (northern Poland). The blood for analysis was drawn from caudal vein of 56 healthy and 94 UDN (Ulcerative Dermal Necrosis) – infected females. Fish were divided into three groups: (1) healthy, with no visible signs of UDN, (2) sick, with up to 10% skin damage and (3) agonal, where more than 10% of body surface was infected. Statistically important decrease in red blood cell count (RBC), hemoglobin concentration (HGB) and hematocrit (HCT) were found between sick and agonal fish groups. Concentration of total plasma protein and albumin decreased, in relation to fish health deterioration. Blood urea nitrogen (BUN) had an inverse proportionality to total plasma protein and albumin concentration. Based on decrease of RBC, HGB and HCT due to UDN symptoms development a decrease in fish condition was observed. Significantly higher urea concentrations observed in agonal fish may indicates respiratory and excretory systems failure.

As a regional product, Koryciński cheese is one of the most important cheeses in the Podlasie region of Poland. In this study, the influence of technological processes, such as ripening, on shaping the organoleptic characteristics of cheese was determined. Korycin-type cheeses are produced from cow’s milk according to traditional technology. The ripening process lasted 466 h at 5 °C, 10 °C, and 15 °C. The aging temperature had a decisive influence on the number of esters and organic acids formed, which were analyzed by gas chromatography–mass spectrometry (GC/MS). The organoleptic properties of the cheeses were also related to the ripening temperature.

The aim our study was qualitative and quantitative analysis of white blood morphometric elements of peripheral blood (determining the quantity, blood cells dimension and several hematological values) in White Stork chicks. One of the aims was to indicate whether the sex relevantly influences the variety of the examined white blood indicators. White blood cells parameters of 53 White Stork chicks, with molecularly marked sex, was examined. Blood samples were collected in southern Poland (around Krapkowice town, near Opole city). Lymphocytes of White Storks (mean 37% for females and males) were identified as round cells with dark purple non-lobed, eccentrically positioned nucleus. Among the whole population we differentiated small lymphocytes: with diameters of 5.31 ± 0.65 μm in males and 5.57 ± 0.59 μm in females, and large lymphocytes with a diameter of 8.10 ± 0.66 μm and 8.28 ± 0.74 μm, respectively in females and males. Monocytes (mean 8% for female and males) were the largest leukocytes found in the blood film of White Stork, measuring 13.40 ± 0.97 μm for males and 13.09 ± 1.05 μm for females in diameter. The cytoplasm was abundant and it stained blue-gray, very often contained vacuoles. Heterophils (mean 42.7%) were the largest in granular leukocytes group. They were round and 11.14 ± 0.65 μm for males and 11.01 ± 0.48 μm for females in diameter. The nucleus of heterophils was lobed, usually with two or three lobes. The cytoplasm contained brick-red, elongated granules. Eosinophils (mean 9.44%) were round cells, with a diameter of 10.72 ± 0.49 μm and 10.97 ± 0.53 μm, respectively in males and females. The nucleus was lobed and mostly stained clear blue and contained red-orange, round or rod-shaped granules. Basophils (mean 1.84%) were round and contained dark blue granules, with average of 9.56 ± 0.78 and 9.13 ± 0.84 μm in diameter, for males and females. The nucleus was usually non-lobed. The H/L ratio was 4/4 for both sexes. No significant differences in levels and types of leukocytes between male and female juvenile storks have been observed.