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Technologie pro účinnou prevenci předčasného dozrávání sivena amerického (Salvelinus fontinalis Mitchill)
LUNDOVÁ, Katsiaryna
Over the past few decades, it has been determined that the period of sexual maturation in salmonids not only has a negative impact on the general condition of fish, but as a consequence reduces the profitability of the aquaculture market as a whole. This influence can manifest itself in reduced growth rate, decreased flesh quality, increased susceptibility to diseases and assumed deterioration of the function of the immune system. Based on these aspects, delaying maturity can be considered a solution to one of the main problems in the on-growth industry. Photoperiod is an important environmental factor that elicits synchronous spawning in salmonids, and thus, as scientific evidence show, it can be effectively used to manipulate the reproduction cycle of fish. The present thesis focuses on effect of various prolonged photoperiod regimes on sexual maturation, growth performance, flesh quality and general physical condition in brook trout (Salvelinus fontinalis Mitchill). In the course of the research, four different experiments were carried out using distinct strategies of the photoperiod. The aim of the first experiment was to test the effects of an artificially prolonged photoperiod using different light sources on brook trout (Chapter 2). The goal of the second experiment was to study the effect of the timing of artificially prolonged photoperiod on growth and sexual maturation of brook trout (Chapter 3). The third experiment aimed to investigate the effects of artificially prolonged non-circadian photoperiod regimes on maturity and growth rate in brook trout (Chapter 4). The fourth experiment focused on the impact of extended photoperiod on post-mortem changes, and sensory, textural and nutritional characteristics of the flesh of brook trout (Chapter 5). Over the course of this research, parameters such as preparedness for spawning, growth rate, hormone level, fillet yield and survival rate, resistance to secondary fungal disease, fin condition and colouration characteristics were studied. Flesh quality of brook trout was analysed via rigor index, pH changes, fillet contraction, gaping, flesh water loss, texture and colour, sensory analysis, and finally fat content and composition analyses. The results of this complex study revealed that the tested artificially prolonged photoperiod regimes positively influence somatic growth. In all experiments, a lower growth rate was observed in control groups, especially during spawning period. Also, it can be assumed that the use of prolonged photoperiod contributes to the delay of sexual maturation in brook trout, regardless of the sex. This statement was confirmed by the analyses of hormones level that showed a similar tendency in all parts of this study. In all of the experiments, a significantly higher number of sexually mature fish ready to spawn were found in the control groups. The results of the flesh quality testing in brook trout (Chapter 5) showed that fish exposed to artificially prolonged photoperiod had a faster progression of rigor mortis, significantly higher fillet contraction, less aftertaste, higher fat content and different fat composition compare to fish from the control groups. The results of this study shed light on the possibility of using photo-stimulation to regulate reproductive cycles and improve growth parameters and the general characteristics of brook trout. These findings can be useful for developing an economically viable culture strategy, thus raising market profitability.
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Morfologie chovaných skupin lososovitých ryb
Halačka, Karel ; Mendel, Jan ; Mareš, J.
Cílem studie bylo sledování vybraných morfologických znaků sledovaných druhů či skupin lososovitých ryb : pstruh duhový (Oncorhynchus mykiss) původem z Dánska, Itálie, Jihoafrické republiky, siven americký (Salvelinus fontinalis), siven arktický (S. alpinus), siven obrovský (S. namaycush), a jejich hybridi (S. fontinalis x S. alpinus). Sledovány byly vybrané morfologické parametry - stavba těla, hmotnost vnitřních orgánů, struktura pokožky a žáber.
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Impact of alternative feed on growth, yield and sensory evaluation of flesh of salmonids.
PFLUG, Róbert
The bachelor thesis evaluates the impact of alternative feed on growth, yield and sensory evaluation of flesh of salmonids. The technology "finishing feeding" and its impact on these indicators was evaluated by a feeding test conducted in trout farm in Annin (Klatovské rybářství a.s.). The experimental species was brook trout (Salvelinus fontinalis L.) with average weight of 156 ? 4,91 g. The test was carried out for 135 days and there were 2 diets. Diet A (rapeseed oil, RO) or B (fish oil, FO) or their combination (45RO:90FO; 90RO:45FO). Each treatment was carried out in duplicate. After 45, 90 days and at the end of the test, evaluation of production characteristics, yield and sensory evulation of fish muscle was carried out. Fish oil replacement by rapeseed oil had no effects on fish survival, growth, feed conversion and yield. After 45 days (first sensory evoluation), flesh of fish fed diet with rapeseed oil was better senzory evaluated than fish fed fish oil diet. However, the later sensory evaluation didn?t show any statistical differences among the treatments.
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Sensitivity to anesthetic clove oil different species of adult fish
ŠKEŘÍK, Jindřich
Nomenclature: Sensitivity to anesthetic clove oil different species of adult fish Sensitivity of breeding fishes of various species (Siberian sturgeon, Brook trout, Black carp- young breeding fishes) for anesthetic clove oil was probed by the tests performed at temperature in the period of stripping (apart from Brook trout and Black carp). The tests were carried out with 17 fish species- with cyprinids (Ide- golden form, Common dace, European Chub, Sneep, Barbel, Grass carp, Black carp, bighead carp), salmonids (Brown trout, Rainbow trout, Brook trout), thymallinae (Grayling), pikes (Northern pike), perches (Pike-perch), sturgeons (Siberian sturgeon, Beluga) and airbreathing catfishes (North African catfish). Using concentration of 0,03ml.l-1 (Brown trout, Rainbow trout, Brook trout, Grayling, Pike, Pike perch, Ide, Dace, Chub, Barbel and Sneep), 0,04ml.l-1 (Grass carp, Black carp, Bighead carp), 0,05ml.l-1 (North African catfish) and 0,07ml.l-1 (Siberian sturgeon, Beluga) the IIb. Phase has been achieved, which is sufficient for manipulation with fishes during stripping. The anesthesia subsided after time period of 10-17 minutes (12 species) at the majority of fishes and at others after interval of 20-26 minutes (5 species). The results confirmed concentrations recommended for salmodis and Grayling (0,025-0,03ml.l-1), sturgeons (0,07ml.l-1), and North African catfish (0,05ml.l-1). At the majority of cyprinids (apart from Grass carp, Black carp and Bighead carp), the concentration used was lower than recommended (0,04-0,05ml.l-1)
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