Influence of thermal and parasitary stress on the erythrocytary hemoglobin (index M) in some culture cyprinids

The paper analyzes the variation of the M index values (Hb x 106 /E) in common carp, silver carp, bighead carp and grass carp during the winter season, as well as a function of the anti- parasitary treatments applied. The results of the polyculture growth experiments on 1 year-old common carp, silver carp and bighead carp (C1+) in preventively antiparasitary-treated ponds are discussed, along with those referring to wintering under severe hypothermal and over-density conditions of some 2 year-old common carp, silver carp and grass carp (C2+), respectively wintering under over-density conditions (15 t/ha) of some batches of 1 summer-old common carp, silver carp and bighead carp (C0+) under mild hypothermal conditions. In the first experiment, the ponds were prophylactically treated, both during populating operations (April), and during growing with 0.1 mg/l trichlorphon, in two stages, and with 2 kg/ha calcium chloride, twice a week, while the hematological evaluation of the effects was made on samples taken over (6 ex./batch) both in the end of the growing season (November) and in the following spring (April). The results obtained show that the values of index M are higher in the autochthonous species - the common carp (6.43 - 5.59), comparatively with the grass carp (6.18), bighead carp (4.83 - 6.04) and silver carp (4.43 - 4.37). The “echo” beneficial effect of the anti-parasitary treatments is more clearly evidenced by index M, comparatively with the hemoglobin values. Thus, in April, the Hb values of the treated batch were 16.7% higher than those of the reference, while index M was 35.5% higher in common carp and 4.8 - 12.8% higher in the case of silver carp and bighead carp, respectively. Under severe wintering conditions, the erythropoiesis yield visibly decreases, so that the value of index M in April is 41.5% higher in common carp and 18.1% higher in silver carp - comparatively with the reference moment (autumn)-, unlike the values obtained under mild wintering conditions, when the levels of index M are comparable with the autumn ones in common carp (104.8%) and silver carp (101.8%) while, in the case of bighead carp and, respectively, grass carp, the values remain inferior to those of the reference.