Authors:B. Kucska, T. Feledi, Á. Adorján, and T. Molnár
This study investigated the effects of three different commercial diets on the growth, feed utilization, and product quality of pike (Esox lucius). The first diet had low lipid (12%) and low protein (37%) (diet A) content, the second diet had low lipid (12%) and high protein (52%) content (diet B), the third diet had higher lipid concentration (15%) and high protein content (52%) (diet C). Two hundred and seven pike were stocked in an experimental RAS (Recirculating Aquaculture System) and were fed ad libitum for the duration of the nine week trial. Specific growth rates, feed conversion rates, protein utilization, as well as body composition and somatic indices were calculated. Fish fed with diets B and C had significantly better SGR (Specific Growth Rate) and FCR (Feed Conversion Rate) than fish fed with diet A. The higher dietary lipid concentration does not cause significantly better protein utilization. Moreover, it had a negative effect on the product quality by increasing the body lipid concentration and the visceral fat deposition.
Authors:G. Szabó, T. Müller, M. Bercsényi, B. Urbányi, B. Kucska, and Á. Horváth
Experiments were carried out on the sperm cryopreservation of artificially induced eels. The effects of several extenders and two cryoprotectants on the motility of spermatozoa were investigated. The highest post-thaw motility was observed with the combination of Tanaka's extender and DMSO as cryoprotectant. Further dilution after thawing resulted in complete loss of motility in samples frozen in presence of DMSO while sperm frozen with methanol as cryoprotectant retained its motility after further dilution.
Authors:T. Molnár, B. Kucska, A. Szabó, J. Biró, M. Bercsényi, and Cs. Hancz
A feeding experiment was conducted on northern pike, Esox lucius L. (123.6±33.3 g initial body weight) applying graded dietary fish oil supplementation resulting three dietary fat levels (without supplementation: 6.2% fat and 11.7, 17.4% fat levels with supplementations) in a recirculation system. Feed consumption, feed efficiency and protein utilization of pike was not affected by the treatment. Whole body lipid content analysis showed that the composition of pike was significantly affected by the increasing level of fish oil supplementation, although no relationship was detected between the dietary and the fillet lipid content, as well as the protein content of fish bodies. High docosahexaenoic acid (DHA, C22:6n-3) proportions were found in the muscle lipids (groups fed fish oil supplementation), as compared to the dietary fatty acid compositions suggesting that with dietary fish oil supplementation the dietary precursors (mainly EPA) enable pike to convert long chain highly unsaturated fatty acids, especially DHA; resulting high DHA: EPA ratios in the fillet.