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Provozní ověření vlivu krmení raného plůdku jeseterovitých ryb obohacenými naupliemi žábronožky na jejich přežití a rychlost růstu
STARÝ, Jakub
The purpose of the experiment was to verify of the influence of enriched artemia salina on the growth and survival of American paddlefish larvae (Polyodon spathula) in operating conditions. The control group was compared with group which was fed by artemia enriched by preparation Red pepper. Control group was fed by nonenriched artemia. This preparation contained increased amount of vitamins A, C, D3 and E, but especially HUFA, mainly DHA (docosahexaenoic acid). The larvae were fed by artemia only one week and then they were fed gradually by dry mixture for larvae. After a five-day co-feeding they were fed only by dry mixture for larvae. The whole experiment was 4 weeks. In the group which was fed by enriched artemia was statistically higher average weight (247.80 +- 40.36 mg) and average length of body (31.19 +- 1.03 mm) versus the control group. Average weight of control group was 140.76 +- 23.06 mg and average lenght of body was 25,27 +- 0.73 mm. Also average survival of the two groups was statistically different at the end of the experiment. The group which was fed by enriched artemia demonstrated an average survival 15.43 +- 2.90 %, while the control group only 2.20 +- 1.92 %. Only rate of cannibalism was not influenced by enrichment of artemia. But these results, mainly survival was negatively influenced by Ichthyophthirius multifiliis, which was detected on the skin after five days of the experiment. Another parameter was average amount of individual fatty acids in the body of larvae from both groups. In the group which was fed with enriched artemia was found statistically higher level of LA (linoleic acid), LNA (-linolenic acid) and DHA. On the other hand, higher levels of ARA (arachidonic acid), EPA (eicosapentaenoic acid) and DPA (docosapentaenoic acid) was found in control group.
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Length and weight growth of early pikeperch fry fed with enriched artemia nauplii in experimental conditions
JANKOVÝCH, Antonín
The aim of our experiment was proving the suitability and effectivity of artemia nauplii enrichment in pikeperch fry rearing. 24 hour enrichment took place in 3 variants: 1. SELCO, 2. 18 (n-3) (alfa-linolenic acid) and 3. 18 (n-3) + vitamin C. Original intention was initializing fry feeding with different types of enriched artemia metanauplii. Due to excessive size of artemia after 1 day enrichment (Artemia franciscana) (in comparison with size of fry oral cavity) the intake of such food was not possible, thus the metodics had to be modified. From the given reason, fish were initially fed with unenriched nauplii ; firstly with dose 100 ml (4 - 8 day post hatch - dph) after that with dose 50 ml per tank (9. dph 25.4.). As soon as fry reached suitable size and was able to intake bigger size of nauplii, was in the second part feeding diferenciated (use of different types of enrichment and control group was fed with unenriched artemia). First part of experiment lasted 22 days (5.4. - 26.4.), fish must have been netted and again placed in tanks for experiment with enriched artemia. Second part of rearing varied in use of differently enriched metanauplii and lasted 8 days (27.4. - 4.5.). At the end of second part of feeding (from 1.5.) was involved co-feeding, which means combined feeding (living food and starter feed). 5.5. was experiment terminated. The highest survival was reached in group fed with artemia enriched in comercial preparate SELCO (28,67 %), second highest survival was reached in group fed metanauplii enriched in alfa-linolenic acid (27,88 %) and third highest survival was reached in group fed with alfa-linolenic acid and vitamin C enriched metanauplii (19,00 %). The highest individual fry weight at the end of experiment was reached in group fed with artemia enriched in alfa-linolenic acid and vitamin C : 306,16 +- 64,27 mg, the lowest individual weight was reached in control group : 216,9 +- 39,96 mg. The highest average total lenght (l.t.) was measured in SELCO group 30,13 +- 2,47 mm, the lowest total lenght reached fish in control group 27,37 +- 1,32 mm. In group fed with artemia enriched in vitamin C was noticed the highest percentage of starter feed intake (8 %), but simultaneously in the same group was reached the highest rate of cannibalism (6 %).
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