Piwre 4 - ~ o t h e r n n d 28-Day-OldLittrr Repro~enfineThird m d Fuurfli Cenera;iona of R~~~ ped On cnnned ~~~d~ Only
seeo1,d a n d t h e L' series tlie t!iirdgeneration 011 a canned food (liet,. Tlic iiurnhers 011 t h e g r a p h s rcpresentiiig t h e fcmalcs are tlie numh e r per 1itt.er of young. Figures 1 to 4 are pliotograplis of typiea1 animals 011 a diet
made iip exclusively uf canired foruds. Summary
Three pairs of young guinea pigs, nreighiiig Sroin 320 to 430 grams, and one pair 3 weeks of age, and three pairs CJf young rats, 25 days of age, weighing from 53 to 56 grains, were placed on a diet consisting wholly of canned foods sterilized By beat. The plan is to feed such animals a similar diet ovcr a iiumher of generations. The foods are not irrt~liabeilnor do the animals recrivc irradiation nor direct ra3-s of the sun. Tho ex-
perimeiit has h e n in progress about 15 rirontlis. During this time, tiic aniinals wen: mated and bred so tliat irr a little over a year tlie fifth gcncration of rats ani! tlie tliirrl gcnerat.ion of giiirioa pigs was seaoiied. 'l'liey are thriving as well as is indicatcd by any record of tliese species. Ilcproduction is as prolific as can be expected, tlic size of tlic litters is iiomial in every way, and 110 difficulty is encountered io lactatiori. Tlie rate of growth and wsight at maturity is inrich liiglm than that reported anornial. In erplaimtioii of this, it is suggestcd that either a diet more nearly tlic optimurn than usual for these species results from tire combination of foods selected, or tliere is some heretofore unrecognized advantage in a diet made up wholly of camied (cooked) foods. Tire i??ridcnccindicates that canncd foods inay supply every dietary requirement, including vitamins 13 (Bi) aiid C, so often referred to as heat labile. Literature Cited (1) Dunridson. "The Rat," Memoirs Wisini I n t . Anal. and Bioi., No. 6 , Philidclphia. 1924. (2) Eddy, Kohmae. et %I., IN". EN*. C n o x , 16, 52 (19241: 15, 1261 (1924): 1'7, 69 (1'325); IS, 85 (1926); IS, 302 (19261: 10. 202 (iwn); ai, 347 (1929); 81,869 (1929) ?a, 1015 ( 1 8 s ~ ( 3 ) Osboineand Mendel, J . Bioi. Chrm., 69, 6 6 1 (19261. ~
Salmon Oil and Canned Salmon as Sources of Vitamins A and I>' C. D. Tolle and E. M. Nelson Bmsnu
UY
P i s s n w s s , DBPAXIMINT OB COMMKRCB, A N D BUREA" OP C H ~ M Z S T A PNYD SOILS.DUPABTU~NT us ACRICULIURB.W ~ s s i n a r o a .D. C
HE present anmial proCommercial salmon oil is an important source of salmon offal, oil from canned duction of salmon oil vitamin D, but the commercial oil now produced is s a l m o n , and c o m ~ n o r c i a l in tjris coiilrtryis apnot representative in quality of the oil that can be salmon oils. proximately 300,000 galI(jns produced from the standpoint of potency of vitamins Sources of Materials (11). However, the quantity A and D. The oil now produced is used largely for of oil that can he produced technical purpo=s3 and the annual production is Samples of commercial oil approximately 3O0,OOO gallons. This quantify can be were obtained fromoilsavailgreatly exceeds this figure. There are about 500,000,000 increased threefold by using products which are now able on the market. Samples discarded. The canned salmon consumed in this of oil were prepared from the pounds of salmon c a u g h t annually in the United States country carries a vast supply of vitamin D that has canned offal of five species of and Alaska. of wlrich 25 to 30 hitherto received little, if any, recognition. s a l m o n . The offal was obtained from fresh fish, placed per cent becomes waste when the fisli is canned. The waste will yield 15 to 20 gallons of oil in tin cans. Tlie cans were evacuated and then heated in a per ton, which makes the potential production of salmon oil retort for 5 hoursat 212'F. (100'C.). When thecans arrived at the laboratory they were opened, the coiltents transferred about 1,000,000 gallons annually. In a study of the vitamin content of commercial fish oils, to a hand press and the water and oil expressed. The oil wm Nelson and Manning (8) found that a salmon oil was 50 then separated from tlie water arid suspended material, by per cent as potent in vitamin U as a medicinal cod-liver oil centrifuging. Commeri:ially canned salmon of fiw different aiid that, its vitamin A content was equal to the poorer grades species were obtained from packers. The oil was recovered of iiiedicinal cod-liver oil. Other investigations liave prc- in the same manner as from the salmon offal. viously shown that oil from salmori contains vitamins A For a number of years cod-liver oil has been a recogiriaed and D ( I , 3,5). Manning, Nclson, and Tolle (8) found that source of vitamins A and D. Examination of t,hirty-seven the vitamin U content of menhaden fish oil is irifluerrced samples of medidnal cod-liver oil, for the Food and Drug in part by t!ie heat treatment to which the oil is subjected Administration, United States Department of Agriculture,* in the process of production. Because of the large potential has shown tlrat only two of these oils varied more than 25 production of salmon oil arid the possibility of improving per cent in vitamin 11 potency from one of the samples the quality of the oil by proper production methods, this chosen as a staiidard of reference. Some of these oils were product has been studied further. The studies herein re- found t,o be fully six times as potent as others in vitamin A. ported were designed to obtain further information wit11 The cod-liver oil used for comparison in t h e studies aas respect. to tlie vitamin content of oil prepared carefully from representative of the average medicinal cod-liver oil in vitamin U potency and considerably above the average in vitamin Presenicd l>eloorrthe Division of Biulopical Received June 1, 1931 A potency. Cheminfiy at the 81% Meeting oi the Ameiiesn Chemical Society, Indian-
T
j
spoiis. Ind..
March 30 t o April 3, 1931.
8
Nelson, E. M., unpublished data.
INDUSTRIAL B N D ENGINEERING CHEMISTRY
September, 1931
1067
VITAMIN A IN OILS FROM OfFAL OF DIFFERENT SPECIES OF SALMON
Chart 1
Chart 2
VITAMIN A IN OILS FROM CANNED SALMON OF DIFFERENT SPECIES
I
Chart 3
Chart 4
Biological Tests
average starting weight in all the groups, the group which contained the animal having the maximum weight also contained the animal having the minimum weight a t the time of weaning. Attention is called to the fact that all of the animals in this group were put upon the curative tests before their weights had become stationary. The average weights a t the time of weaning and a t the beginning of the curative period are indicated, and average weights a t regular intervals during the 5-week test period are plotted. In the remaining charts the results have been summarized by plotting composite growth curves. The curves shown in Chart 2 summarize the results of feeding 10 mg. daily of oil from the offal of salmon of different species as a source of vitamin A. Each curve is a composite representing the average performance of six rats, and the animals in each group are comparable as to parentage and sex. The portion of the curves indicated by a broken line indicates the average change in weight from the time of weaning until curative tests were begun. It is apparent that the oils vary widely in their vitamin A potency and there was a rather striking correlation between depth of color and vitamin potency. The oils which showed a distinct reddish cast, such as chinook and sockeye, contained much more vitamin A than chum, which had practically no red color and gave practically no response when fed at a 10-mg. level. The other oils, intermediate in color, were also intermediate in vitamin potency. Oil 10 was fed a t a 50-mg. level in subsequent tests, a t which level it produced fully as good growth as 10 mg. of oil 11. Each vertical line intersecting the last two curves indicates a point a t which an animal died. A number of preliminary tests were made on commercial salmon oils before the level was established a t which the desired response could be obtained. The results obtained on oils 6 and 7 in these tests are shown in the two curves
Curative tests for vitamin A were conducted in the same manner as described by Nelson and Manning (8). Albino rats weighing approximately 40 to 45 grams were placed upon an A-deficient ration until stores of vitamin A had been depleted. When they showed distinct symptoms of ophthalmia, the curative tests were begun. This occurred in 21 to 26 days from the time of weaning. Their vitamin A storage had been controlled by the technic described by Nelson (7) which has proven more satisfactory to the authors than the common practice of keeping the stock ration low in vitamin A a t all times when the young animals are to be used in vitamin A tests. The A-free ration had the following composition : Alcohol extracted casein.. . . . 18 Yeast.. . . . . . . . . . . . . . . . . . . 8 Salt Mixture I V ( 9 ) . . . . . . . . Agar.. . . . . . . . . . . . . . . . . . . . .
4 2
Dextrinized corn starch.. . . 67 Peanut o i l . . . . . . . . . . . . . . . . 1
One-sixteenth of the yeast used had been exposed to the rays of a quartz mercury-vapor lamp and it had been shown that this quantity of the irradiated product carried an adequate amount of vitamin D. The oils to be tested were diluted with peanut oil so that 0.1 cc. of the diluted oil carried the desired daily dose. This quantity of oil was measured into a glass dish with a pipet and placed before the animals. Chart 1 shows the response of six rats from six different litters, all fed the same level of salmon oil. I n this group there was the largest variation in weight a t the time of weaning and also the greatest difference in gain in weight during the period of vitamin A depletion of any of the groups. The oil feeding was begun a t the point indicated by a short vertical line intersecting the growt'h curve and consisted of 10 mg. per day of salmon oil KO. 8, obtained from the offal of pink salmon. Most of the animals weighed 40 to 45 grams a t the time of weaning. To maintain a uniform
1068
INl>USTRIil I, A ~ V D ENGINEERING CHEMISTRY
Vol. 23,
No. 9
PISUPS 1-Siectloned Rad11 Stained w i t h Silver Nitrate Showing Ilealing Induced by Comrnerffsl Snlmon 011s with Cod-User (HI Controls
at the extreme right of Chart 3. Tlie rernaiiiiiig tests on cotnmercial oils were carried out in one experiment on comparable animals. In vitamin A potency, these oils are all within the range of the oils prepared from canned offal. The significance of the broken portions of the curves is explained in the preceding paragraph. The oils from commercially canned salmon of different species are not a particularly good source of vitamin A. These oils were first fed at a level of 10 mg. per day, but there was practically no response so that all of the oils were subsequently fed at a level of 50 nip. daily. The results obtained &re shown in C h a t 4. Vitamin D tests were condocted in exactly the same
manner as previously described (8). The results obtained by line t e s b are shown by photographic representations. Tlie tests were made by using a litter of rats, feeding onehalf of the litter 0.1 per cent of cod-liver oil during the curative period and the other half of the litter the desired level of the oil under examination. The bone of one animal, which was representative of the response obtained with salmon oil, was photographed. The results of the teds are given in Figures I, 2, and 3. As shown in Figure 1, of the three comrnereial salmon oils tested for vitamin D, two, 2 and 7, were found to have approximately the same vitamin D potency as a medicinal cod-liver oil, whereas the third contained xi,out one-half
September, 1931
.
INDUSTRIAL A N D EXGINEERING CHEMISTRY
1069
Figure 3 Sectioned Radii Stained with silver Nitrate Showing Hedine. Induced by Oils f r o m Canned Salmon w i t h Cod-Liver 011 Conrrols 14-~Chinarkm kiinr. 17-Chum or keta IS sockeye or red IS-Humpbnck m pink IR--.Coho or silver
much vitamin D. The degree of healiug induced by feeding these oils to rachitic rats a t a level of 0.1 per cent of the ration, together with the healiug produced by the same level of cod-liver oil, is shown in the photomicrographs. The number on the plate refers to the laboratory number of the oil. The prefixed letter, C, refers to the cod-liver oil control for that oil. Oil 3 was subsequently fed at higher lcvels, and it was found that 0.2 per cent of this oil in the ration induced the same degree of healing as 0.1 per cent of tlie cod-liver oil control. In the upper left hand corner of the figure arc reproductions of hones similarly prepared and stained, one showing normal calcification and tlic other the degree of rickets produced in 30 days on the diet used. As shown in Figure 2, oils from the offal of salmon of five different species were found to he excellerrt sources of vitamin l). Three of the oils, 8,9, arid 11, were fully twice as potent as R medicinal cod-liver oil; one oil, 10, about 50 per cent more potent; and another, 12, approximately equal to cod-liver oil in vitamin D. The photomicrographs show the healing induced by 0.05 per cent of salmon oil in the ration as r~mparedto 0.1 per cent of cod-liver oil, using littcrmat,e animals. As shown in Figure 3, oils obtained from commercially canned salmon are fully equal to a medicinal cod-liver oil in vitamin D potency. The oils were all fed at a level of 0.1 per cent in the ration together with littermate controls receiving the same level of cod-liver oil. Subsequent teak with lower levels of salmon oil showed that oils 15 and 18 were approximately twice as potent in vitamin D as the codliver oil. H.’
Conclusions
The results obtained show that salmon oil can be prodiict.4 which is equal to good grades of cod-liver oil in vitamin A content and approximately twice as potent as cod-liver oil in vitamin D. Commercial salmon oils now on the market show considerable variation in their nutritive value. This is due to a number of factors. Salmon oils have not been prepared particularly as a source of vitamins. The species of salmon used as a source of material will determine to a large extent the possible vitamin content of the oil. The heat treatment. to which the oil is subjected must be con-
C-Cod-liver
oil confro1
trolled to conserve maximum vitamin potency. The couditions under which the oil is stored must be considered if the oil is to retain its maximum value in feeding. The value of marine prodi1ct.s in providing vitamin 1) in the diet of the American people is not generally recognized. Amoiig the foods commonly eaten, eggs and dairy products alone are considered as carrying appreciabte quantities of this vitamin. It has been shown that oysters and clams contain vitamin D3 (4, 6 ) , and canned fish must also be considered as a source of vitamin D. Statistics show that there are approximately 300,000,000 pounds of canned salmon produced annually in this country. This fish contains from 6 to 15 per cent, of oil (Iff). From the data obtained on vitamin 2) content oE the oil in canned salmon, it is quite apparent that there is more vitamin D in the canned salmon sold in this country than in the cod-liver oil used for both human and animal feeding. Acknowledgment
The commercial oils were kindly furnished by four salmouoil producers on the Pacific coast. The samples of canned salmon were obtaiued through the kind coiiperation of E. D. Clark, director of the Northwestcru Branch of the National Canners Association, Seattle, Washington. The canned offal was prepared by Harry R. Beaxd, director of Scientific Research, New Eiigland Fish Cbmuanv. Vancouver, Canada. Literature Cited (11 Bills. 3. Btoi. C h m . , 78, 761 (1927). (21 Davinand Beach. Calif. Aw. Expt. Sla , Bxil. 414, 1 (IS26j. (31 Holmes and Pibolt. Rasion M e d . Surg J . , 198, 726 (1925). (4) loner. Murphy, and Nelson. 1x0. ENC.. Cum.. 40, 205 (18281. (51 Jone9. Nelnn. and Murphy, Ibid., 40, 648 (192R). (61 Manning. N d s n . aod Tolle, U . S. Birr. Fisheries. Inorsiiioliontrl Rae(. 3, l(19311. (71 Nelson. Srisne, 66, 212 11928). (SI N e i s n and Manning, IND EN0 Caam., 14, 1361 (19301 (9) Osboioeand Mcndel. 3. Bid Chem.. SP,. 374 (1917). . (101 Shoetrom, Cloiieli, m d C1-k. 1x0. EN
