Previous Page Table of Contents Next Page



2.1 Dietary essential amino acid deficiency

Although all fish examined to date display reduced growth when fed essential amino acid (EAA) deficient diets, Table 1 shows the additional gross anatomical deficiency signs which have been reported under experimental conditions with juvenile fish fed rations deficient in one or more particular EAA's.

Table 1. Reported essential amino acid (EAA) deficiency signs in fish
Limiting EAAFish speciesDeficiency signs1
LysineOncorhynchus mykissDorsal/caudal fin erosion (1,2), increased mortality (2)
 Cyprinus carpioIncreased mortality (3)
MethionineO. mykissCataract (4,5,14)
 Salmo salarCataract (6)
TryptophanO. mykissScoliosis2 (7–10), lordosis 2 (7,10), renal calcinosis (8), cataract (7,9), caudal fin erosion, decreased carcass lipid content (9); elevated Ca, Mag, Na and K carcass concentration (7)
  Scoliosis (11)
 Oncorhynchus nerkaScoliosis (12,13), cataract (13)3
 Oncorhynchus keta Oncorhynchus kisutchScoliosis (12)
MiscellaneousC. carpioIncreased mortality and incidence of lordosis observed with dietary deficiencies of leucine, isoleucine, lysine, arginine and histidine (3)

1 1-Walton, Cowey & Adron (1984),
2-Ketola (1983),
3-Mazid et al. (1978),
4-Walton,Cowey & Adron (1982),
5-Poston et al. (1977),
6-Barash, Poston &Rumsey (1982),
7-Walton et al. (1984),
8-Kloppel & Post (1975),
9-Poston &Rumsey (1983),
10-Shanks, Gahimer & Halver (1962),
11-Halver & Shanks (1960),
12-Akiyama et al. (1985),
13-Akiyama, Mori & Murai (1986),
14-Cowey et el.(1992)
2Curvature of the vertebral column
3 Reported incidence of scoliosis and cataract increased with decreasing andincreasing water temperature, respectively (13)

Under practical farming conditions dietary EAA deficiencies may arise from various routes, including:

Poor feed formulation due to the use of disproportionate amounts of feed proteins with natural specific EAA deficiencies. Table 2 presents the chemical score and limiting EAAs of some selected food proteins available to the fish feed compounder. For the sake of comparison chemical scores have been calculated for individual protein sources with reference to the mean dietary EAA requirements of rainbow trout (O. mykiss) and common carp (C. carpio) as given by Ogino (1980). Compared to fish meal, which has a well balanced EAA profile, the majority of protein sources presented have amino acid imbalances which render them unsuitable as a sole source of dietary protein for fish. For example, the deficiency of methionine in plant proteins, yeast, meat and bone meal, blood meal, and hydrolysed feather meal; the deficiency of lysine in oilseeds, hydrolysed feather meal and algae; the deficiency of threonine in some oilseeds and pulses; and the deficiency of tryptophan in fish silage. It is clear from the above that during feed formulation special care must be given to the choice of feedstuffs used so that the desired overall dietary EAA profile is obtained.

Dietary imbalances may also arise from the presence of disproportionate levels of specific amino acids; including leucine/isoleucine antagonisms, and to a lesser extent arginine/lysine and cystine/methionine antagonisms. For example, blood meal is a rich source of valine, leucine and histidine, but is a very poor source of methionine and isoleucine. However, in view of the antagonistic effect of excess leucine on isoleucine, animals fed high dietary levels of blood meal suffer from an isoleucine deficiency caused by an excess of dietary leucine (Taylor, Cole & Lewis, 1977). Although similar antagonisms have also been reported for cystine/methionine (use of hydrolysed feather meal; Ichhponani & Lodhi, 1976) and arginine/lysine (Harper, Benevenga & Wohlhueter, 1970) in terrestrial farm animals, they have not been reported to occur in fish fed synthetic amino acid diet combinations (Robinson, Wilson & Poe, 1981).

Dietary EAA deficiencies may arise from excessive heat treatment of feed proteins during feed manufacture. For example during fish meal manufacture excessive heat treatment has been shown to markedly reduce protein digestibility and biological value due to the destruction of amino acids by oxidation or through the formation of linkages between individual amino acids which are more resistant to digestion (McCallum & Higgs, 1989; Pike, Andorsdottir & Mundheim, 1990). The free epsilon amino groups of lysine are particularly susceptible to heat damage, forming addition compounds with non-protein molecules (reducing sugars) present in the foodstuff (Cockerell, Francis & Halliday, 1972). In addition to decreased EAA availability, toxic substances such as gizzerosine (2-amino-9-(4-imidazolyl)-7-azanonanoic acid) may also be produced from heat treated fish meals containing free histidine and histamine (Okayaki et al., 1983; Watanabe et al. 1987). Although gizzerosine is reported to cause gizzard erosion (GE) in chicks, toxicological signs of rainbow trout fed comparable heat treated whole fish meals containing high levels of histidine and histamine included decreased stomach wall thickness, pycanosis and necrosis of gastric gland cells (Watanabe et al. 1987).

Table 2. Chemical score and limiting essential amino acids of selected protein sources 1
Chick pea164*8963*1041191101138672100166129Met
Mung bean159*11054*48*1271211249479114123123Cys
Cow pea165*10361*59*11611611610075127134129Cys
Yellow lupin266*8120*126117125859464*117192135Met
Lima bean28411057*741351181251067211298106Met
Broad bean37710330*41*115118981187798160118Met
Haricot bean18010343*67*1201211188392127104129Met
Palm kernel262*113941339589727841*98225311Lys
Potato protein meal58912563*96128120112149747373118Met
Leaf protein meal68412757*56*112120122129719096141Cys
Spirulina maxima2871362*30*15911810512355*75111165Cys
Bakers dried yeast49311663*85139112911088610689141Met
Torulopsis utilis49411854*81144981371178410486118Met
Bacterial SCP7971348959*115107115138718384118Cys
Whole hen's egg8771251001301321099798789296135Thr
Fish muscle9839898851081108011710112197135Phe
Fish meal (herring)4761271097811710780958996111123Thr
Fish meal (white)4811061049312110981949094116129Thr
Fish protein concentr.28311011863*12710985103929095153Cys
Fish silage10981227272101129120949812110859*Trp
Whole shrimp meal2839710985112106951058673134106His
Meat and bone meal47712859*891091138860*8610015088Met
Blood meal469*15833*52*24*16212469*8921462*123IIs
Liver meal27613572891051211091067198105153Lys
Poultry byproduct meal476125811411321238060*7187134112Tyr
Hydrolyzed feathers49116424*289131124788633*50*14776Met
Earthworm meal111079910652*11212484108791259882Cys
House fly larvae12751037252*96901282187712782147Cys

1 Scores based on comparison with the mean essential amino acid requirements of rainbow trout and common carp (Ogino, 1980). Mean EAA requirement (expressed as% of total EAA) being: threonine 10.6, valine 9.5, methionine 5.4, cystine 2.7, isoleucine 7.5, leucine 13.5, phenylalanine 9.5, tyrosine 6.5, lysine 16.8, histidine 4.8,arginine 11.6 and tryptophan 1.7
2 Source: 1-Kay (1979), 2-Gohl (1980), 3-Bolton & Blair (1977), 4-National Research Council (1983), 5-Tunnel Avebe Starches Ltd (UK), 6-Cowey et al. (1971), 7-Methanobacter methylotrophus Unpublished data, 8-Cowey & Sargent (1972), 9-Connell & Howgate (1959), 10-Jackson, Kerr & Cowey (1984), 11-Tacon, Stafford& Edwards (1983), 12-Spinelli (1980)
* Limiting essential amino acids (present below 30% mean fish requirement)

2.2 Toxic amino acids

Nutritional pathologies may arise from the consumption of feed proteins containing toxic amino acids or their derivatives. Feed proteins containing toxic amino acids which have been reported to have a negative effect on fish growth and feed efficiency (including eventual fish death) include the plant legumes Leucaena leucocephala (toxic nonprotein amino acid - mimosine; Jackson, Capper & Matty, 1982; Wee & Wang, 1987) and Sesbania grandiflora and Canavalia ensiformis (toxic amino acid - L-canavanine; Martinez-Palacios et al. 1988, Olvera et al. 1988).

In addition to the non-essential amino acids, certain EAA (ie. leucine) have also been reported to exert a toxic effect in fish when present in dietary excesses (Hughes, Rumsey & Nesheim, 1984; Robinson, Poe & Wilson, 1984). For example, the reported toxicity signs for a dietary excess of leucine (13.4% of diet) in rainbow trout (O. mykiss) included scoliosis, deformed opercula, scale deformities, scale loss, and spongiosis of epidermal cells (Choo et al. 1991).

Previous Page Top of Page Next Page