THE EFFECT OF CONCENTRATION OF DEGUMMING SOLUTIONS OF MILK AND NACL FOR HATCHABILITY OF COMMON CARP (CYPRINUS-CARPIO L) EGGS

Two laboratory experiments were conducted with degumming of fertilized eggs of common carp (Cyprinus carpio) from artificial propagation by means of solutions of milk powder Tatra of Czech made and sodium chlor ide in filtered water in a hatchery (pH 7.3 - 7.4) for 30 minutes at a temperature of 21-degrees-C. Each experiment had four variants and th ree replications. Egg incubation took place in special downing jars wi th open tops 300 ml in volume, at a flow rate of 0.8 l/min. Water temp erature during incubation which lasted three days was 21 +/- 1-degrees -C. The amount of the fry was determined at the age of one day after h atching and expressed as percentage of sac fly hatched from the egg se t.It was found out in the first experiment that the higher concentrati ons of dissolved milk powder (5 g/1) improved the conditions for egg i ncubation due to better egg degumming, which was reflected in the stat istically highly significantly increased hatchability (P < 0.01) from the egg set (78.9 +/- 0.2 %) in comparison with lower concentrations ( 2, 1 and 0.5 g/l), when the hatchability made 54.1 +/- 2.3, 44.5 +/- 4 .4 and 37.7 +/- 1.8 %. In the second experiment, no effect of NaCl add ition at a rate of 2 g/l to the solution of milk powder at a concentra tion of 10 g/l was demonstrated as exerted on hatchability of the eggs degummed in this way (82.9 +/- 2.4 %) in comparison with the control without NaCl addition (83.6 +/- 1.7 %). On the other hand, the higher concentrations of NaCl addition (5 and 10 g/l) statistically highly si gnificantly (P < 0.01) decreased the egg hatchability (to 72.1 +/- 2.9 and 36.5 +/- 4.2 %).