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Impiego delle farine di pesce in acquacoltura: valutazione degli effetti del trattamento termico sulla qualità nutrizionale della frazione proteica
No full textEffect of expanded feed with high fish oil content on growth and fatty acid composition of rainbow trout
No full textRainbow trout (Oncorhynchus mykiss) were fed three different diets for 110 days — a basal dry diet with 8.4% oil content (BD8), a basal dry diet with 11.1%; oil content (BD11) a nd an expanded diet with 20.7% oil content (ED) — to investigate the influence of high fish oil exp anded diet on fatty acid composition of muscle, and to evaluate nutritional properties of edible tissue. In fact, the experimental diets were also different in their component fatty acids, with an increasing content of OHgr3 highly unsaturated fatty acids (OHgr3 HUFA) from BD8 to ED. As regards biometrics data, the condition factor and the coefficient of fatness were higher in fish fed ED in comparison with groups BD8 and BD11 (p < 0.05 ed bd8). On the other hand, hepatosomatic index in group ed was markedly lower than those in groups bd8 and bd11 (p < 0.05 ed vs bd8 and ed vs bd11). This be explained by the lower amount of crude protein in ed or it may indicate an excess amount of essential fatty acids (EFA) in ed. As regards fatty acid composition of fish muscle, there were only slight differences in fatty acid composition of the edible tissue of fish when compared with the differences in fatty acid composition of the diets the increased amount of fish oil in ed had a positive influence on the final weight of fish (p < 0.05 ed vs bd8 and ed vs bd11), but did not affect proportionately the percentage of n-3 HUFA (20:5n-3, 22:5n-3, 22:6n-3) and therefore the derived indices of lipid quality: so it appears possible to partially substitute fish oil in the diet with other lipid as a source of dietary fat
Qualità delle proteine e dei lipidi della razione e caratteristiche nutrizionali e tecnologiche delle specie ittiche allevate
No full textProtein and lipid quality Ìn fish meal and fish feeds has been ìnvestigated. D-aspartic acid (D-Asp) content of fish meal was confirmed as a reliable marker of thermal treatment and as a promising indicator of protein quality. Cholesterol content of fish meal was quantified and cholesterol oxidation was proved to occur during storage, although in very low amount due to the protective action of antioxidant added to fish meal dunng manufactunn
Aspartic acid racemization in fish meal as induced by thermal treatment
No full textThe effect of heat treatment during fish meal processing on amino acid racemization was studied. The hydrolysis-induced racemization rate (R) and the D-isomer content in the sample before hydrolysis (I) were differentiated by means of deuterium labelling and gas chromatography-mass spectrometry (GC-MS) analysis in selected ion monitoring mode. A preliminary experiment on laboratory-made herring meals cooked at 125°C for different time intervals showed aspartic acid (Asp) as the only amino acid with significant racemization before hydrolysis. Aspartic acid racemization rate appeared to be a nearly linear function of the duration of thermal treatment (R2 = 0.93; P <0.01). Analyses were carried out on several samples of commercial fish meals from different origin. Low-temperature-dried fish meals had a D-Asp content, expressed as I = 100 [D-isomer concentration before hydrolysis I (D- + L-isomer concentration before hydrolysis)], at less than 1%, while the D-isomer content of high-temperature dried fish meals exceeded 2%. Differences between the two commercial categories were statistically significant (P < 0.001). Further studies are required in order to evaluate the effects of D-Asp in protein of fish feeds and the role of the raw material and processing parameters in inducing amino acid racemization in protein of fish meals
Racemization kinetics of aspertic acid in fish material under different conditions of moisture, pH, and oxygen pressure
No full textThe racemization kinetics of aspartic acid in heat-treated whole herring have been studied under conditions of treatment comparable to those that may occur in processing of fish meal. D-Aspartic acid content in the samples has been measured by RP-HPLC with precolumn automatic derivatization. The major parameters affecting the rate of racemization of aspartic acid k(Asp) have been demonstrated to be temperature (elevation of temperature from 95 to 120 °C resulted in an increase of k(Asp) from 0.46 to 3.39 x 10-3 min-1), moisture of the raw material (reduction of the moisture content of the raw material from 80 to 15% lowered k(Asp) measured at 95 °C from 0.46 to 0.06 x 10-3 min-1), and to a lesser extent, pH (k(Asp) at 95 °C was lowered from 0.46 to 0.37 x 10-3 min-1 following a decrease of pH from 7.0 to 4.0). No significant effects on the racemization rate of aspartic acid was observed for reducing the oxygen pressure to 0.8 %. The results from the present study show that the content of D-aspartic acid in fish material is a function of heat exposure and may be used to predict the thermal history of fish meal
Seasonal variations in fat content and fatty acid composition of male and female coregonid 'bondella' from Lake Maggiore and landlocked shad from Lake Come (Northern Italy)
No full textThe Lake Maggiore bondella Coregonus macrophthalmus use perivisceral adipose tissue for gonadal development (with particular evidence in females), and muscle far as an energy source. Females use mainly saturated fatty acids (SFA) for energy purposes, while males use monounsaturates (MUFA) also. During vitellogenesis, females can also mobilize fatty acid precursors of gonadal highly unsaturated fatty acids of the omega 3 family from muscle tissue, bur in both sexes specific retention of docosahexaenoic acid (DHA=22:6 omega 3) in muscle is evident. Landlocked shad, unlike several freshwater fishes, can utilize the liver as well as body cavity and muscle as a fat reserve depot. The perivisceral fat stored during the feeding period appears to be utilized mainly for winter energy maintenance requirements. Lipid reserves from liver and muscle are also mobilized to meet the requirements resulting from gonadal development. In particular, females seem to use liver reserves, especially 18:1 omega 9, more than males, to meet the demands of ovogenesis. In the muscle, SFA are used mainly for energy purposes. During gonadal development, specific muscular and hepatic omega 3 highly unsaturated fatty acids (omega 3 HUFA=20 : 5+22 : 5+22 : 6) and omega 6 HUFA (20 : 4+22 :4+22 : 5) retention is evident in both sexes, while fatty acid precursors of omega 3 and omega 6 HUFA are mobilized, especially from muscle tissue. (C) 1996 The Fisheries Society of the British Isle
Occurrence of free D-amino acids in milk from food-producing animals
No full textOccurrence of free D-amino acids (DAA) was quantified in raw milk from animals normally bred for food production and characterized by different digestive physiology. Free DAA were extracted from cow, sheep, goat, mare and sow milk in ethanol and proteins were precipitated by addiction of picric acid. After centrifugation the supernatant was passed through a column packed with a Dowex 50 WX8 cation exchanger resin and the amino acids were eluted with aqueous ammonia. N-trifluoroacetyl-O-isopropyl esters of amino acids were prepared and analised by capillary gas chromatography using a chiral stationary phase. The results suggest that contribution of gut bacteria and microbial protein to the occurrence of DAA in milk could be less important in monogastric animals than in ruminants
High-performance liquid chromatographic determination of polyamines in milk as their 9-fluorenylmethoxycarbonyl derivatives using a column-switching technique
No full textA high-performance liquid chromatographic method for the determination of polyamines in milk is described. Polyamines were extracted in perchloric acid and derivatized with 9-fluorenylmethoxycarbonyl chloride (FMOC-Cl). The excess of reagent was reacted with aspartic acid before the analysis on a column-switching system. Linearity of derivatization was calculated for each amine and the coefficient of regression ranged from 0.994 to 0.999. Chromatographic separation of FMOC-polyamines was achieved with a gradient elution programme of water-acetonitrile. The correlation coefficients of the standard curves in the concentration range from 0.5 to 5 nmol ml(-1) were higher than 0.991. The repeatability of the method, expressed as R.S.D. for each polyamines ranged from 3.0 to 8.6%. The percent mean recoveries at 1 nmol ml(-1) spiking level were 49+/-3, 58+/-5, 61+/-5 and 48+/-4 for putrescine, cadaverine, spermidine and spermine, respectively. The limit of detection, calculated on the basis of three times signal-to-noise ratio, was 50 pmol ml(-1) for each polyamin
High-performance liquid chromatographic determination of oxytetracycline in channel catfish (Ictalurus punctatus) muscle tissue
No full textA high-performance liquid chromatographic method for the determination of oxytetracycline in channel catfish muscle tissue is presented. Oxytetracycline is extracted three times from muscle tissue with an ethylenediaminetetraacetic acid disodium salt–McIlvaine buffer (pH 4.0) by using an Ultra Turrax. Analysis is carried out by using high-performance liquid chromatography and an acetonitrile–oxalic acid (0.05 mol l–1, pH 2.2) mixture (14 + 86, v/v) is used as mobile phase. Oxytetracycline is separated on a Lichrosorb RP-8 125 × 4.0 mm i.d. column and ultraviolet detection at 355 nm is used. The limit of quantification is 10 ng g–1 and the linearity, tested in the spiking range 20–500 ng g–1, is 0.9997. Recovery from muscle spiked at 20, 50, 100, 200 and 500 ng g–1 levels is in the range 70–80%. Precision, expressed as percentage relative standard deviation, is below 7%. The method is applied to muscle tissue from channel catfish fed on a medicated die
Effect of temperature and diet composition on residue depletion of oxytetracycline in cultured channel catfish
No full textOxytetracycline is an antibacterial agent widely used in fish farming. The normal method of administration of oxytetracycline to the fish is to mix the drug into the feed. As a consequence, the concentration of the drug in feed, together with the preparation and the composition of feed, can influence the disposition of the drug itself. An experimental study was carried out to evaluate the residue depletion of oxytetracycline from muscle tissue of channel catfish (Ictalurus punctatus) fed different medicated diets. Three hundred channel catfish were randomly divided into six tanks (50 fish per tank), maintained at water temperatures of 18 degrees C (three tanks) and 23 degrees C (three tanks). The animals were fed with three diets, differing in their energy content and composition, for the duration of the experiment oxytetracycline was added to the diets at a level of 7500 mg kg(-1) for 7 d. After cessation of the treatment, five fish from each tank were killed on days 1, 3, 8, 13, 18, 24, 30, 35 and 40. Oxytetracycline residues in muscle tissue were determined by high-performance liquid chromatography. The results indicate that the energy level and chemical composition of the medicated diets administered to channel catfish influence oxytetracycline disposition in fish, and that temperature is an important factor in conditioning the reported dietary effects. Therefore, formulation of specific diets to administer drugs to farmed fish could assure better bioavailability of the chemotherapeutant and shorter withdrawal times
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