Z. Svobodova et al., Values of haematological indices of wels (Silurus glanis L.) in relationship to the level of nutrition during the pre-spawning period, ACT VET B, 67(4), 1998, pp. 235-242
The goal of this paper was to evaluate the effect of different nutrition le
vels on condition and health expressed by means of selected haematological
indices of both males and females of wels (Silurus glanis L.) during the pr
e-spawning period. For 2 months of the pre-spawning period, brood wels were
separated into groups reared similarly but with different level of nutriti
on. The ratio of fodder fish biomass : wels biomass in 1995 was 3.2:1 in ma
le group A; 1.1:1 in male group B; 2.6:1 in female group C and 0.9:1 in fem
ale group D; while in 1997 this ratio was kept 2.3:1, 0.7:1 and 0.2:1 in fe
male groups A, B and C, respectively.
Prior to the anticipated reproduction, haematological examination considere
d red blood count indices (red blood count - RBC, haematocrit - PCV, haemog
lobin - Hb, mean corpuscular volume - MCV, mean corpuscular haemoglobin - M
CH, mean corpuscular haemoglobin concentration MCHC, erythrocyte sedimentat
ion rate) and white blood count indices (leukocyte count - Leuko, leukogram
me), along with concentration of total protein in blood plasma (TP). Altoge
ther, 15 males and females were checked in 1995 while 18 females were check
ed in 1997.
Both males and females which had been reared during the 1995 and/or 1997 pr
e-spawning period with higher level of nutrition reached expressively highe
r relative weight gain and significantly higher total protein (TP) in blood
plasma (P < 0.05; P < 0.01) compared to those with lower level of nutritio
n. Moreover, significantly higher PCV, Hb and MCH (P < 0.05) were found in
group of females with higher nutrition level in 1995, compared to those wit
h a lower one. A significantly higher percentage of lymphocytes (P < 0.05),
as well as a lower percentage of granulocytes and their developmental form
s (P < 0.05) were found in a group of females with higher nutrition level i
n 1997 compared to those with lower nutrition levels. No significant differ
ences were found in other haematological indices among the respective group
s of brood wels. Results gained report for a more favourable condition of b
rood wels reared at higher nutrition level (ratio of fodder fish biomass :
wels biomass 2.3:1 - 3.2:1) during the pre-spawning period and a higher non
-specific disease resistance may be anticipated also. Relationships between
nutrition level and values of production, haematological and reproductive
characters of the fish under study were discussed.