Ocular tissue changes associated with anterior segment opacity in lumpfish (Cyclopterus lumpus L) eye

Lumpfish use their vision to hunt prey or, in the case of aquaculture, to see and eat pelleted diets. A common anterior ocular opacity abnormality designated in the literature as “cataract” described in both farmed and wild lumpfish has not yet been characterized in detail at the pathobiological level. We describe here lens tissue changes associated with cataract in cultured and domesticated lumpfish. Methodology included gross observations, ophthalmoscopy and histology. Young adult cultured animals approaching 400 days post‐hatch presented a range of anterior segment opacities associated with lenticular abnormalities observable at a histological level. Wild aged domesticated animals also displayed cataracts characterized mainly by abnormalities of the lens observed by both ophthalmoscopy and histology. Dysplastic lesions of the lens in one aged domesticated lumpfish were accompanied with both retinal and optic nerve degeneration. These novel naturally occurring anatomical changes in lumpfish present both commonalities and unique features associated with cataract in young adult cultured animals versus aged domesticated broodstock animals.     

Case study on eye abnormalities in tank-reared hybrid walleyes (Sander vitreus×S. canadensis)

Hybrid walleye is important for recreational fisheries and is a potential aquaculture species in the north central region of the United States. Stress related to intensive culture conditions has been documented to cause eye lesions in fish. Finfish eyes do not have eyelids, hence the cornea is permanently exposed to mechanical damage and toxic substances. We documented various disorders of the eye in juvenile hybrid walleyes reared in a flow‐through tank system. Abnormalities include exophthalmia, enophthalmia, unilateral loss of globe and bilateral loss of globe. These lesions negatively affected body weight, specific growth rate and condition factor of hybrid walleyes reared in tanks.     

Effect of hypervitaminosis a on the development of ascorbic acid deficiency in underyearling rainbow trout (Salmo gairdneri R.)

The effect of hypervitaminosis A on the development of ascorbic acid deficiency was investigated in rainbow trout reared on a practical diet. Excess vitamin A (124 000 I.U./kg) in the diet, as retinyl-palmitate, did not appear to interact with ascorbic acid metabolism of the trout. This dietary level of vitamin A did not affect the occurrence of the ascorbic acid deficiency symptoms, lordosis and scoliosis. Vitamin A does not appear to be toxic to rainbow trout at the level of 124 000 I.U./kg of diet and it would appear that the development of lordosis and scoliosis was due in this case to ascorbic acid deficiency.     

Vitamin C Requirements of the Angelfish Pterophylum scalare

Abstract.— Despite a large economical value of the ornamental fish trade, little information is available on the dietary ascorbic acid requirements of these species. Ascorbic acid requirements of fishes of the cichlid family appear to vary widely. Juvenile angelfish, a widely produced ornamental cichlid, were maintained on diets containing graded levels of ascorbyl monophosphate. Liver ascorbic acid concentrations after 96 d of feeding were significantly reduced in groups receiving 120 mg or less ascorbic acid equivalents/kg diet. However, no differences in growth or mortality between groups were found, and no external signs of ascorbic acid deficiency were observed, indicating a high resistance of this species against prolonged ascorbic acid deficiency. Based on the long possible life span of angelfish in the aquarium, we proposed a conservative dietary ascorbic acid requirement of 360 mg/ kg diet, necessary to maintain maximum tissue storage of this vitamin.     

The effect of varying forms of dietary ascorbic acid on the nutrition of juvenile tilapias (Oreochromis niloticus)

An 8-week growth study was conducted to evaluate the utilisation of L-ascorbic acid (AA), the sodium salt of L-ascorbic acid (NaAA), glyceride coated L-ascorbic acid (GCAA), the barium salt of L-ascorbic acid 2-sulphate (AA2S) and ascorbyl palmitate (AP) in diets for Oreochromis niloticus. All five forms were added to the basal diet, containing no ascorbic acid (AAF) on an equimolar basis to supply 125 mg ascorbic acid/100 g of dry diet. In terms of growth, feed conversion and protein utilisation diets containing all forms of ascorbic acid performed well. Fish fed AAF performed poorly and showed clinical signs of ascorbic acid deficiency such as haemorrhage, caudal fin erosion, exophthalmia, and 7% exhibited spinal deformity. Fish fed diet AAF also exhibited depressed haematocrit, haemoglobin, hepatosomatic index and muscle and liver glycogen compared with fish fed diets containing the vitamin C forms. Total ascorbate concentrations in 10 tissues were lowest in fish fed diet AAF and lower in fish fed AA2S than for the other ascorbic acid forms. When supplied in semipurified diets on an equimolar basis the five forms of ascorbic acid evaluated supported similar performance and alleviated signs of deficiency.     

Responses of Juvenile Golden Shiner Notemigonus crysoleucas Fed Semipurified or Practical Diets With or Without Supplemental Ascorbic Acid

A 12-wk feeding trial was conducted in a flow-through system to determine whether juvenile golden shiner Notemigonus crysoleucas have a dietary requirement for ascorbic acid. Triplicate groups of 30 fish each weighing 0.44 g initially were fed semi-purified (casein) diets supplemented with 0 or 250 mg ascorbic acid/kg, or practical (fish meal) diets supplemented with 0 or 250 mg ascorbic acid/kg. The form of ascorbic acid used was L-ascorbyl-2-polyphosphate. Survival was higher in fish fed the semi-purified diet with 250 mg ascorbic acid/kg than in those fed the unsupplemented semi-purified diet, while weight gain did not differ between treatments. Weight gain was higher in fish fed the practical (fish meal) diet supplemented with 250 mg ascorbic acid/kg than in those fed the unsupplemented practical diet, while survival did not differ between treatments. No other signs of ascorbic acid deficiency were observed, but fish fed the casein diets had skin and fin erosion indicative of a possible bacterial infection. Whole-body concentrations of ascorbic acid (total, reduced, and percent of reduced ascorbic acid) were higher in fish fed semi-purified or practical diets supplemented with 250 mg ascorbic acid/kg than in fish fed unsupplemented diets. Golden shiners appear to require a dietary source of ascorbic acid for growth or survival, depending on experimental conditions. The two main differences in the study were in diet composition (semi-purified versus practical diets) and apparent health status of fish fed the different diet types. Additional studies are needed to define requirements further.     

Degenerative retinopathy in captive Atlantic menhaden,Brevoortia tyrannus (L.)

Abstract. Blindness developed in Atlantic menhaden, Brevoortia tyrannus (L.), within 4 weeks of captivity in an indoor open culture system. Ophthalmoscopic changes indicative of retinal degeneration were substantiated by the absence of retinal electrical activity as measured by conventional electroretinography. Results of histological evaluation suggest that photo-receptor degeneration, occurring initially in the rods of the central retina, was the primary abnormality. With chronicity, all retinal layers degenerated, and marked pigment proliferation developed. Other pathological changes included uveal vascular engorgement, vitreal and anterior chamber haemorrhage, and cataracts. With the exception of dermal hyperpigmentation, no systemic abnormalities were consistently observed. Phototoxicity is the suspected cause of this degenerative retinopathy.     

'Broken-Skull Disease' in African Catfish Clarias gariepinus is Related to a Dietary Deficiency of Ascorbic Acid

Abstract.— Diets containing 0. 23, 46, 69, 92, and 185 mg ascorbic acid/kg of diet were fed to African catfish Clarias gariepinus juveniles (average initial weight, 19.9 g) for 20 wk in glass aquaria. Fish fed diets supplemented with 0 or 23 mg ascorbic acid/kg showed overt signs of broken-skull disease, such as hemorrhages along the spinal column and inflammation of dorsal skull bone followed by broken skull and death. They also had significantly lower vertebral collagen content and had significantly higher mortality than fish fed 46 mg or more ascorbic acid/kg of diet. Results from this study indicate that a dietary deficiency of ascorbic acid can cause broken-skull disease and high mortality in African catfish. A concentration of 46 mg ascorbic acid/kg of diet will prevent this anomaly and allow optimum synthesis of vertebral collagen.     

The Weaver syndrome in cattle. Clinical, biochemical and pathologico-anatomic studies in a Braunvieh/Brown Swiss cow with bovine progressive degenerative myeloencephalopathy

The clinical signs and pathological lesions, consistent with Bovine Progressive Degenerative Myeloencephalopathy (BPDME), are described in a heifer. The animal was an 18-month-old Braunvieh-/Brown Swiss crossbreed with 50% Brown Swiss. Both the sire as well as the dam were related to the bull "B.". The only neurological signs were a posterior ataxia. Mobility and coordination of the front legs were normal. The CK activity of the cerebrospinal fluid was enhanced. There was a moderate to severe degeneration of the white matter consisting of marked axonal degradation and distension and degradation of myelin sheats in all parts of the spinal cord as well as in the medulla oblongata. The lesions were more severe in the descending than in the ascending tracts.     

Water-soluble vitamin requirements of tilapia: ascorbic acid (vitamin C) requirement of Nile tilapia, Oreochromis niloticus (L.)

Abstract. The quantitative dietary ascorbic acid requirements of fingerling Nile tilapia, Oreochromis niloticus L., were assessed by feeding seven diets containing graded supplements of this vitamin (0, 50, 75, 100, 125, 300 and 400mg/100g dry diet) to triplicate groups of fish for 12 weeks. Fish fed the diet devoid of ascorbic acid exhibited significantly ( P < 0·01) poorer growth and higher condition factor. Food conversion and protein efficiency ratios were improved with increasing dietary ascorbic acid level up to 125mg/100g of dry diet. Protein utilization, haematocrit, haemoglobin level and tissue ascorbate concentrations were depressed in fish fed the ascorbic-acid-free diet. Tissue ascorbate concentrations, especially for liver, were highly correlated with dietary ascorbic acid level. Fish fed the ascorbic-acid-free diet exhibited deficiency signs including erratic and convulsive swimming, anorexia, lethargy, caudal fin erosion, skin haemorrhages and mortality. Based on the nutritional and pathological parameters investigated, the recommended dietary inclusion level is 125mg/100g dry diet, which is equivalent to a net requirement (after processing and storage) of 42mg/100g diet.     

Effect of ascorbic acid supplement in vitro onrainbow trout sperm viability

We evaluated motility and fertilizing ability of rainbow trout Oncorhynchus mykiss semen obtained from fish fed diets without ascorbic acid and a diet supplemented with 870 mg kg^{minus 1} of ascorbyl monophosphate. Semen was stored in vitro on ice (0 °C) during 14 days. The spermatozoa from the supplemented group had the highest motility and lowest decline in fertilizing ability after storage. Lack of a positive effect of exogenous vitamin C on semen in fish deficient in ascorbic acid (milt was supplemented with 50 mg l^–1 of ascorbic acid) suggests that the positive effect of ascorbic acid on semen quality is related to its long-term effects during spermatogenesis.     

Effects of season and dietary ascorbic acid on some biochemical characteristics of rainbow trout (Oncorhynchus mykiss) semen

During the reproductive season, rainbow trout spermatozoa are stored in the sperm ducts for several months. There is no sperm production at this time since spermatogenesis is completed before spawning. To leam more about characteristics of semen during such a long storage, we analyzed changes in protein concentrations, anti-proteinase activity in seminal plasma and sperm aspartate aminotransferase activity during an extended reproductive period during which fish were fed diets supplemented with various ascorbic acid concentrations. Seminal plasma protein concentration and anti-proteinase activity declined toward the end of the reproductive season. These phenomena may be related to oncoming proteolytic events leading to degradation of the sperm. Protein concentrations and anti-proteinase activities were strongly correlated within groups of different ascorbic acid supplementations and several sampling dates (r=0.6–0.9 in most cases, p<0.05). Ascorbic acid deficiency resulted in a decrease in both parameter levels as compared to levels in groups with vitamin C supplement (p<0.08). Deficiency also resulted in lower stimulation of aspartate aminotransferase by an exogenous pyridoxal 5-phosphate in comparison to fish fed vitamin C-supplemented diets (p<0.05). These results support earlier studies suggesting a protective role of ascorbic acid toward maintaining sperm quality.     

Stability of L-ascorbic acid (vitamin C) and its forms in fish feeds during processing,storage and leaching

The stability of several forms of L-ascorbic acid to processing, storage and leaching was investigated. Percentage retention of ascorbic acid after processing was increased with increasing dietary ascorbic acid level. Ascorbic acid 2-sulphate (AA2S) and glyceride-coated ascorbic acid (GCAA) were more stable than ascorbic acid (AA) and its sodium salt (NaAA). The stability of AA, NaAA, GCAA and AA2S under different storage conditions was, in descending order; freezer (−20°C), refrigerator (5–8°), room temperature in black bags (22–24°C), and room temperature in clear bags (22–24°C). Leaching of dietary ascorbic acid increased with increasing immersion time and water temperature. Evaluation of stability of each ascorbic acid form suggested that GCAA is to be preferred for use in fish feeds.     

Dietary Vitamin C Requirement of Hybrid Striped Bass Morone chrysops♀× M. saxatilis ♂

A feeding trial was conducted to determine the dietary vitamin C requirement of juvenile hybrid striped bass Morone chrysops × M. saxatilis . Fish were fed a semi-purified basal diet with 40% crude protein and an energy to protein ratio of 8 kcal/g for a conditioning period of 2 wk. This diet which was not supplemented with vitamin C contained approximately 6-mg vitamin C/kg. Following conditioning, fish (approximately 0.55 g initial weight) were stocked as groups of 20 in 38-L aquaria and fed the basal diet and experimental diets supplemented with 10, 20, 30, 45, 60, 75, or 150-mg vitamin C/kg as ascorbate polyphosphate for a period of 10 wk. Fish fed the basal diet and the diet supplemented with 10-mg vitamin C/kg exhibited signs of vitamin C deficiency including suppressed weight gain, reduced plasma and liver ascorbic acid levels, and abnormalities in isthmus cartilage formation. Plasma and liver ascorbic acid levels generally reflected dietary supplementation with the lowest levels occurring in fish fed the basal diet and higher levels in fish fed the supplemented diets. The minimum dietary requirement (±SE) based on non-linear least squares regression analysis of weight gain was 22 (±6) mg vitamin C/kg diet.     

Pathology of bacterial gill disease: sequential development of lesions during natural outbreaks of disease

Abstract. This study examines the sequential pattern of bacterial colonization and the sequential development of branchial lesions during typical outbreaks of bacterial gill disease (BGD) among four groups of commercially reared rainbow trout fingerlings, Oncorhynchus mykiss (Richardson). During a 5-month monitoring regime, prior to the onset of natural outbreaks of BGD, gill morphology of examined fish remained unaltered. Bacterial colonization of the gills was immediately preceded by several gill changes which were widely present in fish from all groups under study. These changes, which were detectable at the ultrastructural level only, included cytoplasmic blistering and degeneration of the microridges of the superficial filament epithelium, in addition to slight topographical irregularity of the filament tips suggestive of mild hyperplasia. Bacterial colonization began at these altered filament tips before spreading to more proximal regions of the filament and adjacent lamellar surfaces. Explosive increases in proportional morbidity and mortality coincided with the development of the following gill lesions: extensive bacterial colonization of lamellar surfaces, lamellar epithelial hydropic degeneration and necrosis, and lamellar oedema. In contrast, gill lesions such as lamellar fusion, epithelial hyperplasia and various metaplastic responses were detected later either as subacute (3–5 days) or chronic (7–14 days) changes. The role of epithelial necrosis as an important event during BGD is discussed as a possible mechanism leading to the development of sub-acute and chronic gill lesions.     

Role of dietary ascorbic acid in vitellogenesis in rainbow trout (Salmo gairdneri)

Adult rainbow trout which were fed a diet devoid of ascorbic acid for 21 months, including the stages of gonadal development, showed no macroscopic signs of avitaminosis C and no increased mortality compared to a control group of fish with dietary supplementation of this vitamin. Fish without dietary supplementation of ascorbic acid contained more lipid in the liver and less in the ovaries than the reference fish. The lipid metabolism of the maturing fish is thus affected when the dietary intake of ascorbic acid is very low or absent. Fish without dietary ascorbic acid became anaemic (reduced levels of haemoglobin and haematocrit) towards the end of the feeding period. The serum levels of oestradiol-17β and vitellogenin were also lower in these fish. Possible modes of action of ascorbic acid in maturing rainbow trout are discussed on the basis of the presented analytical data on ascorbic acid, gross composition, blood serum levels of oestradiol-17β, vitellogenin, total protein, albumin, cholesterol, calcium, phosphorus and haematological parameters.     

Renal -gulono-1,4-lactone oxidase activity as affected by dietary ascorbic acid in lake sturgeon (Acipenser fulvescens)

Sturgeon can synthesize -ascorbic acid (vitamin C) as they possess in their kidney -gulono-1,4-lactone oxidase, the enzyme catalyzing the last step of AA biosynthesis. The effect of increasing dietary ascorbic acid on gulonolactone oxidase activity was studied in lake sturgeon. Two-year-old lake sturgeon (body weight 253±89 g) were fed in triplicate groups with casein-based semipurified diets supplemented with either 0, 50, 250 or 1250 mg ascorbic acid/kg in the form of ascorbyl-2-monophosphate Mg for 38 days at 19.8°C. At the end of the trial, there were no significant differences in growth rate and survival among groups. Tissue total ascorbic acid concentrations increased significantly with dietary ascorbic acid. Renal gulonolactone oxidase activity was inconsistently affected by dietary treatment. These results suggested that, in sturgeon kidney unlike in the livers of ascorbic acid-synthesizing mammals, dietary ascorbic acid did not exert a negative feedback control on gulonolactone oxidase activity and thus on ascorbic acid synthesized. Using in vitro kinetics data we estimated a theoretical biosynthetic rate of ascorbic acid of 17 μmol (or 3 mg) per kilogram body weight per day at 15°C in juvenile lake sturgeon.     

Effect of Source and Dietary Concentration of Ascorbic Acid on Tissue Concentrations of Ascorbic Acid in Channel Catfish

Semipurified diets containing either no ascorbic acid or supplemental amounts of 11, 22, 44 and 132 mg/kg from Gascorbic acid (AA), L-ascorbyl-2-monophosphate (AAP) or L-ascorbyl-2-sulfate (AAS) were fed to channel catfish fingerlings (13 ± 2.1 g average initial weight) in aquaria. After a feeding period of 14 wk, weight gain was measured and ascorbic acid content of liver and anterior kidney of the fish was determined. Growth was normal for fish fed all dietary levels of AA and AAP, but lower in fish fed the control and diets supplemented with all levels of AAS; however, growth improved as the concentration of AAS increased. Liver and kidney ascorbic acid increased with level of dietary supplementation in fish fed AA and AAP but only traces or no detectable levels were found in the tissues of fish fed AAS or the controls. Liver and kidney levels of ascorbic acid were significantly higher in fish fed AAP than in fish fed corresponding levels of ascorbic acid from AA. Regression of liver ascorbic acid content on diet concentration indicated that the potency of AAP for maintaining liver storage of ascorbic acid at a minimum acceptable level is 1.74 times higher than that of AA on an ascorbic acid equivalent basis. These results demonstrate that AAP and AA have similar vitamin activity for growth in channel catfish, but AAP is markedly more effective for maintaining tissue levels of ascorbic acid, and that AAS has limited vitamin activity for growth and its contribution to the tissue ascorbic acid pool is negligible.     

Depletion of ascorbic acid derivatives in fish feed by the production process

ABSTRACT:   The depletion of ascorbic acid derivatives in fish feed during the feed processing (extrusion cooking and drying) was studied at five extrusion cooking temperatures and at 85°C for 2 h dryer processing temperature. Three ascorbic acid derivatives were used: L-ascorbyl-2-mono-phosphate Mg (APM), L-ascorbic acid sodium (AAS) and L-ascorbic acid palmitic acid ester (AAP). Samples were collected after drying and ascorbic acid derivatives losses evaluated. APM was found to be quiet stable with an average retention of 88%, but AAS and AAP were unstable and the depletion was very high.     

Effects of dietary vitamin C on growth,gonad development and antioxidant ability of on‐growing gibel carp (Carassius auratus gibelio var. CAS III)

An 88‐day experiment was conducted in a flowing system to evaluate the effects of dietary vitamin C on growth, body composition, antioxidant and gonad development of on‐growing gibel carp. Triplicate tanks of gibel carp (77.2 ± 0.1 g) were randomly fed with one of seven experimental diets containing l ‐ascorbic acid of 0, 101.1, 188.5, 313.1, 444.1, 582.1 and 747.0 mg/kg, respectively. The results showed that specific growth rate (SGR) and feed efficiency (FE) of fish were not affected by dietary l ‐ascorbic acid. Dietary l ‐ascorbic acid of 444.1 mg/kg diet led to low levels (p < .05) of gonadosomatic index (GSI) and hypothalamic gonadotropin‐releasing hormone (GnRH) in on‐growing fish, as well as the early ovarian stages (Developing stages) compared with fish (Maturing stages) from the other groups. Dietary l ‐ascorbic acid supplementation increased (p < .05) the dorsal muscle collagen content, but did not affect the protein or lipid content of dorsal muscle in gibel carp. Plasma total antioxidant capacity (T‐AOC) and superoxide dismutase (SOD) activity increased (p < .05) and then remained unchanged with the increase in dietary l ‐ascorbic acid levels. Dietary l ‐ascorbic acid of 101.1 mg/kg diet improved (p < .05) plasma lysozyme activity of the fish. Broken‐line regression indicated that dietary l ‐ascorbic acid requirement of 77 g gibel carp was 223.3 or 225.0 mg/kg diet based on plasma T‐AOC or SOD activity, which was a little higher than that based on plasma l ‐ascorbic acid concentration (193.2 mg/kg).