A direct non‐parametric method was used to calculate reference (physiological) haematology values for farmed 10–12‐month rainbow trout of the Kamloops strain (mean weight: 330±131 g) with respect to red blood cell counts (RBCc), haematocrit values (Hct), haemoglobin concentrations (Hb), mean corpuscular volume (MCV), mean corpuscular haemoglobin (MCH) and mean corpuscular haemoglobin concentrations (MCHC). The fish in the selected reference group (n=798) were given dry pelleted diets that contained 37–47% crude protein, 7–18% crude fat and 108–300‐mg vitamin E, 1.08–5‐mg folic acid, 0.018–0.05‐mg vitamin B12, 48–64.5‐mg iron, 4.5–8.4‐mg copper and 0.18–0.24‐mg selenium supplied per kg of diet. Ethoxyquin and butylhydroxytoluol were used to protect the fat component against oxidation. The fish were kept at a stocking density of 50kg per cubic metre in tanks provided with running freshwater (dissolved oxygen 8.4–11.5 mg L−1, with O2 saturation of 77–98%) at an ambient temperature of 0.2–16°C. Blood was sampled between September and November at a photoperiod of 9–13 h:11–15 h (light:dark). Reference ranges for the preceding haematological indices were as follows in immature females (males): RBCc, 0.77–1.42T L−1 (T – tera, 1012) (0.98–1.55T L−1); Hct, 0.304–0.502 (0.34–0.546); Hb, 54–93 g L−1 (59–97 g L−1); MCV, 282–469 fL (279–434 fL); MCH, 51–86 pg (47–78 pg); MCHC, 0.15–0.22 (0.15–0.2). In males, values for RBCc, Hct and Hb were significantly higher (P=0.01 and 0.0000 respectively) and those for MCV, MCH and MCHC were significantly lower (P=0.01 and 0.0002 respectively) than in immature females. Nutritional and environmental factors affecting erythropoiesis in trout and some correlations between haematological (RBCc, Hb, Hct) and biochemical indices of the blood plasma (total protein, cholesterol) are discussed.

Mass death of farmed brook trout Salvelinus fontinalis reared in raceway culture on a commercial ¢sh farm was recorded in May. The condition was caused by natural infection with external signs of Flavobacterium columnare. Haematological analyses were carried out from peripheral blood from 10 ¢sh from each group. Anaemia was characterized by a reduced erythrocyte count and lower haemoglobin levels; the values of mean corpuscular volume and mean corpuscular haemoglobin were higher and the values of mean corpuscular haemoglobin concentration were decreased. Clinical chemistry analyses in blood plasma indicated decreased levels of total protein, glucose and total calcium and an increase in the urea level. Among the four enzymes analysed, a catalytic activity reaching multiples of the normal level was found in alanine aminotransferase, aspartate aminotransferase and lactate dehydrogenase. The catalytic concentration of alkaline phosphatase was decreased. Electrophoretic analyses of the plasma protein indicated a reduced level of albumin. The moribund ¢sh had a higher hepatosomatic index and their condition coe⁄cient after Fulton and after Clark was also higher.

Correspondence: J R í ehulka, Department of Zoology, Lilesian Museum, Na Ł draz› n|¤ okruh 33, CZ-74646, Opava, Czech Republic. AbstractRainbow trout Oncorhynchus mykiss (Walbaum) were studied for 98 days for their response to the administration of a 1% rapeseed lecithin supplement in dry pellets. Lecithin tended to stimulate erythropoiesis, which manifested itself as a higher erythrocyte count, a higher haematocrit level and higher haemoglobin concentration during the course of the trial, compared with the control group. The signi¢cant differences that were found in the haematological pro-¢le, in the parameters of nitrogen metabolism (total protein, blood nitrogen urea, uric acid, creatinine) and mineral metabolism (inorganic phosphate, total calcium) and in the activity of catalytic enzymes (alanine aminotransferase), in certain periods of the trial do not suggest any adverse e¡ects on the state of health of the ¢sh; the levels of haematological parameters remained within the range of reference values. The catalytic activity of the aspartate aminotransferase, alkaline phosphatase, lactate dehydrogenase and a-hydroxybutyryl dehydrogenase as well as the hepatosomatic index and condition factors calculated after Fulton and after Clark were unchanged. Lecithin supplement to the diet caused no clinical changes in the state of health of the ¢sh, nor were any changes ascribable to the administration of lecithin observed on the basis of the patho-anatomic and histological examination. Considering this and the good results in terms of the supporting antioxidant properties and the e¡ect on growth capacity, recorded in previous experiments, rapeseed lecithin at the tested concentration level can be recommended as a supplement to dry pellets for rainbow trout.

This study was aimed at construction of reference (physiological) value intervals determined by lower 2.5% and upper 97.5% quantiles for total plasma protein (TPP) in farmed rainbow trout, Oncorhychus mykiss (Kamloops strain), aged 10^12 months (n 5 755). Total plasma protein in male trout from raceway culture was found to be signi¢cantly greater (385 8.3 g L À 1 ) relative to females (31^51.5 g L À 1 ). Total plasma protein in trout from cage culture was signi¢cantly greater (32^54 g L À 1 ) compared with the raceway culture (31^49 g L À 1 ). Moderate productm oment correlations between TPP and cholesterol (r 5 0.8730), TPP and total calcium (r 5 0.8188), TPP and alanine aminotransferase (r 5 0.6200) and between TPP and aspartate aminotransferase (r 5 0.6430) were estimated. Proteinaemia was explained as a metabolic response to feed content, infections of bacterial or viral aetiology or to intoxications.

Rainbow trout at a weight of 223 ± 12 g (mean ± SD) were experimentally injected with a technical mixture of Delor 103 to evaluate the red blood cell indices (red blood cell count, haematocrit, haemoglobin, mean corpuscular volume, mean corpuscular haemoglobin, mean corpuscular haemoglobin concentration) and some biochemical and enzyme parameters of the blood plasma (total protein, glucose, inorganic phosphate, total calcium, sodium, alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase, lactate dehydrogenase).