T;-• J- :

THE ABERNATHY SALMON DIET

Laurie G. Fowlt:r and Roger E. Burrows Bureau of Sport Fisheries and Wildlife

Salmon-Cultural Laboratory., Longview., Washington 98632

ONE OF THE CONTINliI~G PRO­GRA.M:S of the Salmon-Cultural Laboratory has been the development of nutritionally adequate yet economically feasible diets suitable for the artificial propagation of salmon (Oncorhynchus). This work was started during the 1940' s with chinook (0. tshawytscha} and sockeye (0. nerka) salmon fingerlings. The starting diets developed· consisted of beef and hog liver mixtures., and the production diets con­sisted primarily of slaughterhouse by­products and available raw fish (Burrows., Robinson., and Palmer, 1951; Robinson., Palmer, and Burrows, 1951; Robinson et al • ., 1951; Burrows et al., 1952; Newman., Palmer, and Burrows, 1954). The addi­tion of dry meals to the production diets was mostly for protein supplementation and was of minor importance.

During the 1950's., use of meats as the principal ingredients was deemphasized., except in the starter rations., because of their high cost and increasing scarcity. Furthermore_. some of the raw fish prod­ucts used as meat substitutes were indi­cated to be vectors for transmitting fish diseases (Guenther., ·watson, and Rucker, 1959; Ross_. Earp., and Wood, 1959). Be­cause of these factors, the emphasis in diet formulation was placed upon the use or high-quality dry-meal combinations, •with raw meats and pasteurized fish prod­ucts serving as supplements to the diet rather than as major components ( Combs et al •. 1955, 1962; Fowler., McCormick, and Thomas, 1964). These trials demon­strated the practicability of the meal

M>mbination used and the fact that an

THE PROGRESSIVE FISH-CULTUHIST

all-meal., ricer-fed diet produce:_; ::·csults comparable to, if not better than, the meat- meal diets.

Work was continued on the newly devel­oped meal diet to determine the opti­mum caloric and vitamin levels (Fowler., McCormick, and Thomas., 1966) and to test substitutions for, and alteration of., the basic components (Fowler and Banks., 1967). More recently the diet was made more practical by pelletizing the food into a soft., moist product that required frozen storage until fed (Fowler and Banks, 1969, 1970).

From these years of research, we have now developed a meal-oil, dry diet that is superior to any of our previous formula­tions. The diet is a simple., open formula and, depending upon particle size., can be fed to fish from time of first feeding to time of release. For the past 2 years the diet has been tested at the Salmon­Cultural Laboratory on fall chinook salmon with excellent results. It has been fed on a production basis at the Quinault National Fish Hatchery to both fall chinook and coho salmon (0. kisutch) from swim-up until time of release; and it is being fed at several other National Fish Hatcheries to fall and spring chinook salmon, coho salmon., steelhead trout (Salmo gairdneri), and Atlantic salmon (S. salar).

The objective of this piper is to review some of our experiments in the develop­ment of this diet and to present the cur­rent formulation of the Abernathy dry diet. The methods of preparing the diet, along with recommended feeding techniques, will also be discussed.

67

Compos it ion of the Diet

A satisfactory die t for salmon does not appear by chance a lone; instead, it evolves after many years of feeding trials during which individual d ietary components are combined and fed, the results are ob­served and analyzed, then components are recombined o r deleted or substituted, and the process is repeated. As stated by Phillii:;s a nd Bal zer ( 19 5 7 ), dietary ingre -die nts are sel ected on the basis of nutri­tional value, availability of the p roduct, and cost of the ingredient. Each of the components of the Abernathy diet, which inc ludes fish meal, dried whey product, cottonseed meal, wheat germ meal, a vita -min supplement, and soybean oil, has been tested in this manner in past exper iments .

Fish '.'v'.Ieal

Fish meal s are high in protein and generally are an excellent source of pro­tern fo r fish growth. Several fish meals have been tested as components of the . .\bernathy diet. Our experiments indicate that the fish meal must be of high qu ality. and that fish c arcass meals are superior to fillet-scrap m eal s . Herring, sal mon, hake, dogfis h, and turbot meal s have all proved satisfactory and equal to eacJ; other when fed on an isoprotein basis, provided that they have a crude protein of not less than 70 percent. The l ipid content should be less than 12 percent, and the water content l ess than 7 percent. Fish meals with higher oil and water have generally been more rancid and of poorer quality than other meals \\·e have tested. The rancidity, as measured by the thio -barbituric acid (TBA) method (Yu and Sinnhuber, 1957), shoul d have a value of less t han -lO .

Dried :.Vlilk Products

Dried milk products have long been­recognized as good sources of protein in fish diets. In our experiments, we originally used dried skim milk to com­ple ment the animal protein furnished by the fish meal. Our tests also indicated

68

that dr i_ed buttermilk wa_s equal to drie<;la,a s ktm mtlk tf fed on an tsoprote i n basis .. The high cost of these two products, how ­ever, was prohibitive.

Dried whey product, a byproduct of the cheese indu s try, has been used increas­ingly in fish diets during recent year s . It is defined as partly delactosed whey with a guaranteed protein analys is of not l ess than 15 percent. Although the pro­tein content is considerably l ower than than that of e ither dried skim milk or dried buttermilk, it i s chiefly l actal­bumin and is reported to be of higher protein quality than casein (Morrison, 1949). The vitamin content of dried whey product is usually higher than that of e ither dried skim milk or dried butter ­mil k. Dried whey product has been shown to contain an unidentified growth factor when fed to some of the higher animals . It also acts in the capacity of a pellet binder .

Our tests have indicated that i t i s mor e economical to substitute dried whey prod­uct for dried skim milk in the Abernathy diet if the lower protein of the whey prod­uct is compensated for by increasing the amount of fish meal. The combination of dried whey product and fish meal appar ­ently produces a better growth · increase than a combination of dried skim mil k and fish meal, probably because of the better quality of protein in the fish meal.

Wheat Germ Meal

Wheat germ meal is available com­merciall y in either high (25 percent and over) o r low (2 0 percent and lower) pro-tein content, depending upon the manu­facturing process . Our t ests have indi­cated that the protein of wheat germ meal is readily availabl e to fi sh. In addition to the protein, good- qual ity wheat germ meal is high in oil w'h1ch is an excellent sourc e of vitamin E. Wheat germ meal is also rich in some of the B- complex vitamins . We recommend that the wheat germ meal used in the Abernathy diet should have a protein content of not less than 25 percent and a lipid content of no.....,__ less than 8 percent. . • ..

. APRIL 19 71

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-,, -.; ....... .... . .. ... -_ : ..... . ~ ...... .

Cottonseed Meal

Cottonseed meals can be purchased· with either high or low protein cont~nt, depending upon the amount of hulls in the finished meal. In our tests, we have found no measurable differences among cottonseed meals of different protein con­tents., provided that they are fed on an isoproteiJ'l• basis. We believe, however, that we get a better-quality meal, which receives better manufacturing care, if we specify a meal with a protein content of not less than 50 percent. High-protein cottonseed meals are usually prepared by the pre-press, solvent-extraction proc­ess. Such meals have the least chance of pesticidal c_ontamination.

Vitamin Supplement

All fish diets are supplemented with a purified vitamin supplement or with ingre­dients containing high levels of natural vitamins. Both types of supplementation have advantages. Naturally occurring vitamins are the most economical means of supplying vitamins, and this type of vitamin appears to be more stable than synthetic vitamins when incorporated into a diet. Vitamin supplementation, how­ever, makes it possible to add specific vitamins and at much more concentrated levels than occur naturally in feed ingre­diets.

The Abernathy diet is supplemented with a vitamin mixture composed of sev­eral of the B-complex vitamins as well as vitamins C and E. The B-complex por­tion of the supplement is a modified and greatly reduced version of that recom­mended by Halver and co-workers ( 1960) and is considerably lower than supple­ments specified in other fish rations. Our tests have shown that deletion of the B­complex supplement from the diet pro­duced results comparable to those when the supplement was added. The indica­tions were that the naturally occurring vitamins in the naturally occurring vita­mins in the basal meal ingredients used in the Abernathy diet were adequate under

"ur test conditions. The present low

THE PROGRESSIVE FISH-CULTURlST

supplementation level of B-complex vita­mins serves as a possible safety factor in case of an inadvertent use of poor­quality meal in the basal meal mixture., which may result in an inadequate supply of natural vitamins. The additional B­complex vitamin supplement may also be needed in case of an increased vitamin requirement due to certain stress factors the fish may encounter while in the hatch­ery environment.

Two other vitamins, alpha tocopherol (E) and ascorbic acid (C), have proved to be necessary in the Abernathy diet. Since the basal dietary ingredients do not pro -vide these vitamins in large enough quan­tities, we have added them at relatively high levels. Vitamins E and C act as anti­oxidants and make the diet more stable. Our tests have shown that diets without antioxidant protection produce fish that make poor growth and have anemia. Other workers have also shown that vitamins E and Care dietary requirements. Woodall and his co-workers (1964) showed that under certain conditions chinook salmon required alpha tocopherol. Poston (1966) reported the need for vitamin C to prevent scoliosis and lordosis.

Soybean Oil

In the Abernathy diet, soybean oil serves principally as a caloric source. It has proved to be the most efficient of the vegetable oils we have tested, which include corn, cottonseed, peanut., and safflower.

Fish oils have also been tested but have been no more efficient than soybean oil. Fish oils have the disadvantage of being more rancid; they also have the possibility of greater contamination with pesticides.

Several grades and qualities of soy­bean oil are commercially available. We recommend use of a fully refined soybean oil. This grade is a little more costly than other grades., but it has less chance of being contaminated with pesticides. We also recommend that the oil be stabilized by the addition of O. 01 percent each of the antioxidants., butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT).

68

TABLE 1 . - - [-'o rmula Eor the Abe rna thy d r y die t ..

-------------------------[ng r edient Percent Type

Fi sh carcass meal1 -- ­

Dried whey product--­Wneat germ meal- ----­Cottonseed meal---- --

44 . 5 Salmo n, dog fi s h , ha ke , her rin g , o r t urbot . 1 7 . 0 16.5 15 . 0

No t less than 15 pe rcent prote in (Foremost o r equa l). Not less than 25 percent prote in and 8 percent lipid . Not l ess than 50 pe r ce nt protein.

Soyb ean oil---------- 6.0 Fu l ly r ef ined soybean o il (Na tiona l Soybean Proces­sors Associa tio n Code) with 0 . 01 percent BHA and 0 . 01 percent BHT added.

Vitamin supplement--- 1 . 0 See table 2. lTo have protein content of mor e than 70 perce nt, lipid less tha n 12 percent, water

less tha n 7 percent , a nd a T.B.A. va lue oE less than 40.

Present Diet Composition

Unlike other fish diets, the Abernathy diet is rather simplified, being based on oniy a few ingredients. It is formulated to contain approximately 45 percent protein and to have an available caloric conte nt (Phillips and Brockway, 1959 ) of about 3, 200 calories per k ilogram of diet, while the protein calories range from 50 to 55 percent of the total. The current fo r mula for granule or pelle t s izes 3 / 64 inch in diameter and l arger- is shown in table l; the vitamin mixture i s shown i n table 2. The starter and 2 / 64-inch granule sizes

TABLE 2 . --Abernathy vita;nin supplement

Ingredient

Thi am ine mo nonitrate- -----­Riboflavin---- ----------- - ­Pyridoxine hydr ochlo rid~--­Niacin----- -- -------------­d- Panto thenic acid--------­Inositol-- ---- - - ---- - -----­Biotin----- - --- - -- - -- -----­Fo lic acid- --- -- - ------- --­DL Alpha-t ocophe r o l a cetate

( 10 , 500 I.U . )------ ----­Ascorbic acid---------- -- -­Carrier1 ------------ - ------

Total----------------

Amount (g r a:ns)

0 . 15 .69 . 30

4. 77 .68

13.65 • 03 . 10

10.50 25 . 50

397.23

45 3.60 1 May be whea t ;n iddling s o r co ttonseed

mea l siz ed to pass throJ gh a U. S. Sieve No. 30 .

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have more oil, as noted in a l ater section of this report. Though the formula is desigr,ed for a dry feed, it can be made into a moist pellet by the addition of water.

Methods of Pellet Preparat ion

Currently the _..\.bernathy diet is being prepared a nd fed in three different fo rms, the mois t pellet and two types of dry pel­l et. Each type of pellet requires a differ -ent manufacturing process.

Moist P e llet

The m oist pellet, a s its name implies, has water added to produce a soft pellet. The diet ingredients are combined with 25 percent or less water, which produces a doughlike mixture. A binder, carboxy­methy l-cellulose , is also added at the rate of 2 percent to preve nt the finished pel-lets from disint(.grating too rapidl y w hile be ing fed . Pellets are m ade by putti ng the dou ghy m ixture through a macaroni-type extruder which c an be equipped with dies of different hole sizes . A knife attach­ment cuts the e xtrusion_s into the desired lengths . Hublou and his co - workers (1959) first used this method for preparation of the Oregon pelleted diet. · .Pellet.s of 2/64-inch diameter are the smallest possible, and even this size presents manufacturing problems which increase their cost. This size o f pellet som e times is too large for first - fe e ding fish, and a special starter diet must be used before pellet s are fed . ..

APRIL 1971

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. ~: ~--,r·:· ,f_~.:... . . After preparation the pellets must be

lle=iuick-frozen artd ·kept in frozen storage. They usually are thawed before being fed. This type of pellet has several obvious disadvantages: it must be stored frozen, requires time and effort to thaw, and is difficult to adapt to automated feeding sys -terns because of soft, moist consistency.

Dravo-'Type Ory Pellet

One method of preparing the Abernathy diet as a dry pellet involves . a pelleting process used in the fertilizer and chemi­cal industries. As described by Decker and Pigott ( 19 6 7), this method require s a Dravo pelletizing disc that rotates at an angle of approximately 45° . The diet ingredients are fed onto the rotating disc and, at the same time, a fine mist of water is sprayed ontc the falling meal. The combination of droplets of water, meal, and agitation causes the feed to roll and form - several sizes of pellets. The pellets, immediately after coming off the disc, contain between 20 and 30 per -cent moisture . Before the pellets can be screened and graded, they must be dried. Drying is a costly procedure, tending to increase the price of the feed made by this process.

Pressure-Type Dry Pellet

The Abernathy diet is prepared also by the more conventional method of pressure or compaction pelleting. The mixed diet ingredients are forced through a die which extrudes a pellet that is dense and has a polished, shiny surface . The pellets may be crumbl ed or cracked to produce granules, then graded to size by screen­ing. Any fines resulting from the crumbl­ing process are recycled and repelletized. Steam may be added to facilitate pelleting, but it s hould be dry s t eam (defined as steam under an input pressure of 90 to 110 pounds per square inch and which has passed through an expansion chamber to remove excess moisture) . The amount of steam added should not increase the temperature of the diet ingredients more

... han 30° F . The temperature of extruded

THE PROGRESSIVE F' fSH- CU LTURIST

pellets should not exceed 18 0° F., and should be cooled to 9 0° F. or less immedi­ately after pelleting and before sacking or crumbling.

Love (1968) reported that mycotoxins from Aspergillus flavus and rel ated molds will not be found in fish meals having a moisture content of 10 percent or less . Aflatoxins produced by A. flavus have been responsible for carcinomas and deaths in some species of fish. To protect against the formation of mold, we recommend that the moisture content of the finished Aber­nathy granules and pellets not exceed 8. 5 percent.

Compaction pelleting appears to be the most economical and the best method of preparing the Abernathy dry diet. It is the method most often used in the preparation of commercial trout feeds and therefore invites the greatest number of prospective bidders . This method does not require extensive drying of the pellets, as does the Dravo process . Further, the pres -sure pellet, according to our tests, has a better retention of vitamins after stor­age than the other types of pellets.

Feeding Techniques

The Abernathy diet, pelletized by the compaction or pressure method, can be made into a number of granule and pellet sizes, depending on the size and species of fish being fed. Our experience with chinook sal mon has shown that particle size plays . a major role in the acceptance or rejection of the diet and is much more crit ical in dry diets than in soft, moist die ts . Too large a dry particle will be repeatedly rejected by the fish, especially when they first start to feed or when they are being shifted to a larger pellet. Our r ecommendations for granule and pellet sizes of dry feeds to be fed to different s izes of fish are listed in table 3. The two smallest granules have additional oil, as noted.

When the fish are being shifted from a smaller to a l arger granule or pellet, the change should be granual rather than abrupt. The change may be made eithe r by mixing the different particl e s izes

71

TABLE 3 . --Recommended parti.cle si.z e s of the Abernathy die t as c o rrela t e d with fi.sh s i.ze

Granu l e or pellet size Fish size

(number of fish per po und)

St arter granu lel ---- ---- t-bre than 800. 2/64- inch granule2 ------ 800 to 500 . 3/64-inch granule------- 500 t o 200 . 4/64- inch granule----- -- 200 to 100. 6 / 64-inch g ranule-- - - - - - 100 to 80 . 6/64-inch pellet----- - -- 80 t o 50. 8 / 64-inch pellet-------- Less than 50.

1 Composed of 95 percent of the basic Abernathy formula as shown in table 1 plus 5 per cent additional soybean oil.

2 Compo sed of 98 percent of the basic formul a plus 2 percen t additional soybean oil.

together and feeding at the same time, or by feeding separate feeds of the two sizes, starting with a few feeds of the larger size and gradually increasing t his number until only t he l arger particl e is fed. This p rocedure should continue for 1 to 3 weeks, depending upon the water temperature, or until the transition is complete.

In general , when dry feeds are being fed, the number of feedings per day should be greater than when soft, moist diets are being fed. With first-feeding finger -l ings, t he oftener they are fed. the better. There i s some wastage of feed with first­feeding fish, a condition which increases the conversion rate; however, this is justifiable because a good start is of the utmost importance. For the Abernathy star ter granule, a conversion rate of 2. 0 or higher i s reasonable. Conver­sion rates for the l a r ger granul es and pellets shoul d be l ower, ranging from 1. 0 to 1. 5 .

We are still in the process of working out a feeding chart, but the one p resented in table 4 can be used as a guide, This chart is primarily for chinook salmon; other species may require more feed or less.

72

Discuss ion .. The Abernathy die t is an open formula

and is bas ed on only a few ingredients . In eithe r the moist or d r y s tate, its prepa­ration presents fe w if any problems for the commercial manufacture r . In addi­tion to being easily prepared, the diet appears to be nutritionally adequate, read­ily accepted, and highly palatabl e to the fish . The moist pellet has been fed for several years, and both types of dry pel­lets have been fed fo r more than a year. All are comparable to, if not better than, o ther diets currently be ing fed .

Of the three type s of Abernathy pellet, we recommend that the dry , pressurized pellet be used. It appears to be the most economical. Currently it is being pro­duced for about 50 percent less than the moist pellet. Further, conversion rates are about 20 percent l ess for the dry pel ­l e t than for the moist pellet. A 70-pe rce nt savings in cost, the refore , c a n be realized by u s ing the dry, pre ssure -type pellet rather than the m o ist pe llet. Thus far, no large quantities of the rolled dry pel­let have been manufactured, and at this time no assessment of cost can be made. We believe, how ever, that the drying procedure involved in it s processing will make the rolled pe llet m o re expensive than the pressure - typ e pe llet.

Another advantage of the pressure-type pellet is that it appears to have a higher retention of vitamins after manuf?-Ct!,lre . Evidently this type of processing is less destructive of vitamins, and our chemical tests indicate a greater c a r ry through.

The Abernathy diet may be altered to some extent to mee t s pecial situations. Our tests have indicate d that, for chinook salmon, the present protein l evel of the diet is at or near . the optimum. F'or other species or conditions, however,-, ·the pro -tein or caloric intake can be decreased or increased as necessary. For example, if the growth rate of a group needs to be reduced, a bulk ingredient such as wheat middlings may be added as a percentage of the total diet . A situation like t his m ay occu r whe re the fis h a re outgrowing the capac ity of the hatc he r y water supply, ye ..

.}\PRIL 19 71

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•• TABLE 4.--Feeding chart for the Abernathy dry diet

(Amount of ~ood per day expressed as percent of body weight]

Average water temperature

oF. 2,500-1,000 1,000-300

40------------- 2.6 2.2 41----------~-- 2.7 2.3

42------------- 2.8 2.4 43------------- 3.0 2.5 44------------- 3.1 2.6 45------------- 3.2 2.8 46------------- 3.4 2.9 47------------- 3.6 3.1 48------------- 3.7 3.2 49 .--.-------· -· 3.8 3.4. 5o=--~~--~~.:.:..... ___ .;. 4.0 3.6 51----------- .. - 4.2 3.7 52------------- 4.5 3.9 53------------- 4.7 4. 1 54------------- 4.9 4.3 55------------- 5.1 4.5 56------------ · 5.3 4.6 57------------- 5.6 4.8 58------------- 5.8 s., 59------------- 6.0 5.3

60------------- 6.5 5.6

the release conditions are not optimum. Similarly, the rate of growth may need acceleration. An example of this might be a hatchery with low water temperatures and a limited growing season but also the objective of raising the largest possible fish in a given time. This maybe achieved by increasing the amount of protein in the diet by using a greater percentage of one of the high-protein meals, such as fish meal, and decreasing one of the low­protein meals, such as dried whey prod­uct. This change may increase the cost of the diet and decrease the utilization of protein, but be justifiable if large fish are necessary to produce ·higher survivals.

The vitamin supplement of the diet can also be increased to meet certain situa­tions. Some fish species may have higher requirements. Also., the vitamin intake may need to be increased at a hatchery where groups of fish are held for long

IJll>eriods, such as over winter., at low

THE PROGRESSIVE FISH-CULTURIST

Number of fish eer :eound

300-150 150-90 90-40 40-10 10-Under

2.0 1.7 1.3 0.8 0.6 2.0 1.8 1 .4 .9 .6 2.2 1. 9 1.4 .9 .7 2.2 2.0 1. 5 1.0 • 7 2.4 2., 1. 6 , .o .7 2.5 2.2 1.7 1. 0 .8 2.6 2.3 1. 8 , • 1 .8 2.7 2.4 1.8 1.2 .9 2.9 2.5 1. 9 1.2 .9 3.0 2.6 2.0 1.3 1. 0 3.2 2.8 2.1 1 .4 1.0 3.3 2.9 2.2 1. 4 1.0 3.5 3.1 2.4 1.5 1. 1 3.6 3.2 2.4 1.6 1. 2 3.8 3.4 2.5 1.7 , • 2 4.0 3.6 2.7 1.7 1. 2 4.2 3.7 2.8 1.8 1. 3 4.4 3.9 2.9 ,. 9 1 .4 4.6 4.1 3.1 2.1 1.4 4.8 4.3 3.2 2. 1 1. 5 5.0 4.5 3.4 2.2 1.6

water temperatures with corresponding low food intakes.

Any major alteration of the diet- -whether it be protein levels, different ingredients., or vitamin intakes- -should be tested on an experimental basis before it is used on a large scale.

Research with the Abernathy diet is continuing, and the current formula will change. Alterations will be made as other ingredients prove to be better than those in use, or as nutritional requirements of the fish being fed become better known. The present diet, however, has proved to be both economical and practical for feed­ing salmonids., and its immediate applica­tion to salmon propagation is justified.

References

Burrows., Roger E • ., L. A. Robinson., and D. D. Palmer. 1951. Tests of hatchery foods for

73

blueback salmon (Oncorhynchus nerka ) 1944-48. U. S. F'ish and Wildlife Ser­vice, Special Scientific Report- - Fish­eries No. 59, 39 p.

Burrows, Roger E., D. D. Palmer, H. W. Newman, and R. L . Azevedo. 1952. Tests of hatchery foods for

salmon, 1951. U. S. Fish and Wild­life Service, Special Scientific Re­port- - Fisheries No . 86, 24 p.

Combs, Bobby D., D. D. Palmer, J . H . Finucane, and R. E. Burrows. 1955. Tests of hatchery foods for

salmon, 1953 and 1954. U.S. Fish and Wildlife Service, Special Scien­tific Report - - Fisheries No. 160, 8 p .

W. W. Heinemann, A. E. Thomas, and

Combs, Bobby D., R. E. Burrows, L. G. Fowler, 1962. Protein

meat - meal, salmon diets.

and calorie levels of vitamin - supplemented U.S. Fish and Wildlife

Service, Special Scientific Report- -Fisheries No. 432, 7 p.

Decker, Carl D. , and G. :YI. Pigott. 1967. The development of a continu­

ous non-compacting pelleting proc­ess. Winter meeting, the American Society of Agricultural Engineers, Detroit, Michigan, Paper No. 67 - 888, 16 p.

Fowler, Laurie G., and J. L. Banks.

74

1967. Test of different components in the Abernathy salmon diet. Bureau of Sport Fisheries and Wildlife, Techni­cal Paper No . 13, 18 p.

1969 . Tests of vitamin supplements and formula changes in the Abernathy salmon diet, 1966-67. Bureau of Sport F isheries and Wildlife, Techni­cal Paper No. 26, 19 p.

1970. Tests of substitute ingredients and effects of storage in the Abernathy salmon diet, 1968. Bureau of Sport Fisheries and Wildlife, Technical Paper No . 47, 8 p .

fowle r, Laurie G., J. H. McCormick, Jr . , and A. E . Thomas. ... 1964. further' s tudies of protein and

calorie l e ve ls of meat- meal, vitamin­suppleme nted salmo n diets. U.S. fish and Wildlife Service, Special Scien­tific Report- - F isheries No. 480, 13 p.

1966. Studies of caloric and vitamin levels of salmon diets. Bureau of Sport Fisheries and Wildlife, Techni­cal Paper No . 6, 14 p.

Guenther, Raymond W., S. W. Watson, and R. R. Rucker . 1959. Etiology of sockeye salmon "vi­

rus" disease. U.S. Fish and Wildlife Service, Special Scientific Report- -Fisheries No. 296, 10 p.

Halver, John E . , E. T . Mertz, D. C . DeLong, and R. E . Chance. 1960. The vitamin and amino acid

requirements of salmon. F ifth In­dustrial Congress of Nutrition, Ab­stracts, No. 191.

Hublou, Wallace F . , Joe Wallis, T. B. McKee, D. K. Law, R. 0 . Sinnhuber, and T . C . Yu. 1959 . Development of , the Oregon pel­

let diet. Research Briefs, Fish Com­mission of Oregon, vol. 7, no. 1, p. 28 - 5 6.

Love, Travis D. 1968 . Relation of temperature, time,

and moisture to the production of a flatoxin in fish meal. U.S. Fish and Wildlife Service, Fishery Industrial Research, vol. 4, no. 4, p . 139-142.

Morrison, Frank B. 1949 . Feeds and feeding. Morrison

Publishing Company, Ithaca, New York, 21st edition, 1207 p.

Newman, H. William, D. D. Palmer, and R. E. Burrows. 1954. Tests of · hatchery foods for

salmon, 1952 . U.S. Fish. and Wild ­life Service, Speciai Scientific Re-port- -Fisheries No . 124, 12 p. ..

·. APRIL 1971

· .. --;·_ --~-

.-..,. .. _.·;;~· ;.~ . •. :.:.... ..

-~~~:~t;·~\· :·. . .. J:::>niµ1ps:.,:iA;rthtir ·M. ,. Jr • ., and George C.

·• Balzer.;· Jf. 195:7. · :.: The nutrition of trout: V. Ingre-

dients · for trout diets. Progressive Fish-Culturi_st, vol. 19, no. 4., p. 158-167.

Phillips, Arthur ·M., Jr • ., and Donald R. Brockway. 195~. · Die_tary calories and the produc­

tion of trout· in hatcheries. Progres -sive Fish-Culturist, vol. 21., no. 1, p. 3-16.

Poston, Hugh A. 1966. Effect of dietary L-ascorbic acid

on immature brook trout. In: Cort­land Hatchery Report No. 35 for year 1966··~ · New York Conservation De­partment,. Fisheries Research Bulle -tin 30, p. 46-51.

Robinson, Leslie A • ., D. D. Palmer., and R. E. Burrows. 1951. Tests of hatchery foods for blue­

back salmon, 1949. U. S. Fish and Wildlife Service, Special Scientific Report- -Fisheries No. 60., 21 p.

Robinson., Leslie A., M. H. Payne., Jr., D. D. Palmer., and R. E. Burrows. 1951. Tests of hatchery foods for blue­

back salmon, 1950. U. S. Fish and Wildlife Service, Special Scientific Report- -Fisheries No. 63, 23 p.

Ross, A. John, B. J. Earp, and J. W. Wood. 1959. Mycobacterial infections in adult

salmon and steelhead trout returning to the Columbia River basin and other areas in 1957. U. S. Fish and Wild­life Service., Special Scientific Re­port- -Fisheries No. 332., 34 p.

Woodall., A. N • ., L. M. Ashley, J. E. Hal­ver., H. S. Olcott, and J. Van Der Veen. 1964. Nutrition of salmonoid fishes.

XIII. The a-tocopherol requirement of chinook salmon. Journal of Nutrition, vol. 84., no. 2., p. 125-135.

Yu., T. C., and Russell O. Sinnhuber. 1957. 2-Thiobarbituric acid method for

the measurement of rancidity in fish­ery products. Food Technology, vol. 11., no. 2., p. 104-108.

Visitors to the Okefenokee National Wildlife Refuge in Georgia have had to travel considerable distances by boat to see the interior of this refuge. In the future., a 5-mile wildlife drive, a 3/4-mile boardwalk, and a 30-foot observation tower deep in the swamp will enable visitors to view cypress and Spanish moss., burned-out peat bog lakes., floating masses of unusual vegetation known as "houses," and watery channels, islands, alligators, and herons.

In the spring of 1970 at the Marion (Alabama) Warmwater Fish Cultural Develop­ment Center., no losses attributable to hemorrhagic septicemia were noted in largemouth bass receiving a medicated feed. The bass were fed Oregon moist pellets medicated with oxytetracycline at a rate of about 60 milligrams per kilogram of fish per day. The antibiotic was given 10 days before and 10 days after bass were stocked into spawning ponds. Near the end of the spawning season., another 10-day feeding period was used.

" THE PROGRESSIVE FISH- CULTURIST 75