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The Nutritive Value of Distillers’ By-Products*
The Nutritive Value of Distillers' By-Products* A. D. D'ERCOLE, W. B. ESSELEN, JR., AND C. R. FELLERS Nutrition Laboratory, Massachusetts State College, Amherst (Received for publication June 17, 1938)
as "well as protein quality assays, were made. The work was done with special reference to the use of these by-products in poultry rations. Both rat and chick methods were used in determining the vitamin B2 content and the quality of the protein.
OBJECT
The main objective of this investigation was to determine the relative feed value of distillers' grains and concentrated slop. Vitamin A, B w B2 (riboflavin), C, and D, * Contribution Number 311 of the Massachusetts Agricultural Experiment Station, Amherst.
LITERATURE REVIEW
Broughton, Frey, and Carmichael (1933) investigated an industrial alcohol by-product resulting from cane molasses fermentation. Their rat tests showed that the protein was incomplete and did not support growth. They also state that the amount of vitamin B1 present was high, although no quantitative results were reported. Investigations carried out by Tomhave (1936) showed the limitations of distillers' dried grains as a supplement for hog feeding to be due to palatability. Insko, Buckner, Martin, and Harms (1937) reported that as much as four-fifths of the corn in poultry mash may be replaced by thick distillery slop and that the thick slop may be successfully fed when mixed with an all-mash mixture in the proportion of one part of mash to two parts of thick slop. Thin slop was not a satisfactory supplement to an all-mash ration. Morrison (1936) states that while distillery slop is sometimes fed to fattening cattle, it is too watery to promote satisfactory gains in weight and should be fed with hay or other roughage in addition to at least one-third of their usual allowance of grain. Distillers' dried grains are not usually fed to swine, since they are much better suited for cattle feeding, especially dairy
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LTHOUGH distillers' by-products - have long been used as animal feeds, very little data have been reported on their nutritive value. After alcohol has been distilled from the fermented mash in the manufacture of whisky or of alcohol from grain the residue contains all of the protein, fat, fiber, and mineral matter practically unchanged. Part of this material is in solution in the liquid portion but the larger part is in the form of suspended material that can be recovered by filtering. This unfiltered material is known as thick slop. The suspended material is filtered out and dried and is known as distillers' grains. The liquid which passes through the filter is known as slop. The slop may be concentrated under vacuum to a thick syrup and is referred to in this paper as concentrated slop. Present day methods of producing distillery by-products are described in detail by Cooley (1938). This author shows that ISO tons of distillers' dried grains, with a value of from $17.00 to $30.00 per ton, may be produced daily by a distillery manufacturing approximately 100,000 gallons of 100 proof alcohol daily.
A
90
A. D. D'ERCOLE, W. B. ESSELEN, JR., AND C. R. FELLERS
cows. Investigators at the Kentucky Agricultural Experiment Station (1936) used distillery slop in hog feeding and found that as the proportion of corn to slop decreased, the carcasses became progressively softer. EXPERIMENTAL WORK
The composition of the distillers' grains and concentrated slop used in this investigation is as follows:* Concentrated Slop
percent 8.25 31.79 8.06 7.55
percent 48.25 17.51 1.12 0.10
40.29 4.06
28.40 4.62
Vitamin A Vitamin A assays were made on the distillers' grain according to the technic of Sherman and Munsell (1925). Fourteen vitamin A deficient rats were fed 1.0 gram of the sample daily for 21 days. At this time all the animals showed a marked loss of weight and severe xerophthalmia. A second test gave similar results. Since a measurable amount of vitamin A is not present in 1.0 gram of distillers' grains this feed must be considered as a poor source of vitamin A. Vitamin B1 The method used for the vitamin Bx assay was that of Chase and Sherman (1931). Twenty young rats were placed on the vitamin Bj-free diet until they exhibited a deficiency of this vitamin. Then the animals were divided into two experimental groups of seven animals each and a negative control group of six. One group was t fed 0.5 gram of distillers' grains daily and the other group was fed 0.37 gram of con* Analyses made by P. H. Smith, official state chemist.
Vitamin C The vitamin C content of the distillers' by-products was determined by the Tillmans, Hirsch, and Hirsch titration method (1932) as modified by Bessey and King (1933). There was no significant amount of vitamin C present in the grains when 5 and 10 grain samples were used. However, the slop was found to contain between 0.035 and 0.06 milligrams of ascorbic acid (vitamin C) per gram which is equivalent to 0.7-1.2 international units per gram of slop. Vitamin D The vitamin D assays were carried out according to the United States Pharmacopoeia method (1934). Because of the yeast naturally present in distillers' grains it was thought that its vitamin D content might be increased by irradiation with ultraviolet rays. Samples of the grain were irradiated by two different types of commercial ultra-violet lamps for varying periods of time. The irradiated and unirradiated samples were assayed in three series of tests, as
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Moisture Protein Ether extract (fat) Fiber Extract matter (carbohydrate) Ash
Distillers' Grain
centrated slop daily. The six negative control animals died within two weeks. The rats fed the distillers' grains made an averave weight gain of 6.0 grams per week during the five-week assay period. Those fed 0.37 gram of concentrated slop made an average gain of 6.0 grams per week. It is concluded that the distillers' grains contained at least 2 Sherman units per gram. Since the weight gains were double those suggested by Chase and Sherman, it is probable that 4.0 Sherman units of vitamin B1 per gram approximates the value of this product. The concentrated slop on this basis contained approximately 5.4 Sherman units per gram. The relatively high vitamin B± content of the slop is probably due to the large numbers of yeast cells present. These were readily demonstrated by a microscopic examination.
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T H E NUTRITIVE VALUE OF DISTILLERS' BY-PRODUCTS
shown in Table 1. From this data it is evident that there is a small amount of vitamin D, or some antirachitic substance, normally present in distillers' grain. It is also shown that the vitamin D content of distillers' grain may be increased to some extent by irradiating the material for 30 minutes. Such a long irradiation period would probably not be practical in commer-
animals serving as negative controls. One group of rats received 0.5 gram of distillers' grain daily while the other group was fed 0.5 gram of concentrated slop daily as a supplement. Those fed the grain made an average weight gain of 3.6 grams per week and the group receiving the concentrated slop gained an average of 4.5 grams per week during the test period of five weeks.
Sample
Level fed
Number of rats
Average degree of calcification
I.U. per gram
2.0 1.0 95.0
grams 0.250 0.500 1.009 0.028
8 8 8 8
0.95 1.20 1.15 1.30
0.075 0.075
5 5
1.75 0.85
13.3
5 5 5 5 10
0.40 0.30 0.30 0.25 1.70
—
Positive control
0.075 0.075 0.075 0.075 0.028
95.0
Type 1 Lamp Irradiated 10 min Irradiated 10 min Irradiated 30 min Irradiated 30 min Positive control
0.056 0.037 0.056 0.037 0.028
10 10 10 10 10
0.42 0.05 0.45 0.025 1.39
95.0
Distillers' grain Positive control Type 1 Lamp Irradiated 10 min Type 2 Lamp Irradiated 10 min. Irradiated 6 min. Irradiated 2 min
cial practice. It would appear that there is sufficient antirachitic substance in distillers' by-products to be of some slight value in the feeding of poultry and farm animals. Vitamin B2 (Riboflavin) Both the Bourquin-Sherman rat method (1931) and the Norris, Wilgus, Ringrose, Heiman, and Heuser chick method (1936) were employed in determining the vitamin B2 content of distillers' grain and concentrated slop. Twenty vitamin B2-deficient rats were divided into two experimental groups of eight animals each with the remaining four
In terms of Sherman-Bourquin units of vitamin B2 it is concluded that the distillers' grain contained approximately 2.4 units per gram, whereas the concentrated slop contained 3.0 units per gram. Thus, both of these products are good sources of vitamin B2 and should be valuable additions to poultry and livestock diets in this respect. The vitamin B2 chick assay method determines the relative growth promoting vitamin B2 content of feedstuffs based upon the gain in weight produced over the negative control diet by adding 5 to 15 percent of the supplement under study to the basal diet, the protein content of the diet being kept constant at 25 percent. Dried pork
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TABLE 1.—Vitamin D content of distillers' by-products
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A. D. D'ERCOLE, W. B. ESSELEN, JR., AND C. R. FELLERS TABLE 2.—Composition of experimental diets used in vitamin B% chick assays
Ingredient
Positive control
Distillers' grain
Concentrated slop
Dried buttermilk
per cent
per cent
per cent
per cent
per cent
60.0 20.0 IS. 5 2.0 1.0 0.5 1.0
57.0 20.0 16.2 2.0 1.0 0.5 1.0 2.3
51.5 20.0 14.0 2.0 1.0 0.5 1.0
44.5 20.0 16.0 2.0 1.0 0.5 1.0
51 1 20 0 13.4 2 0 1 0 0 5 1 0
10.0 15.0
. ...
— 11.0
liver was used as a standard and has been given the value of 100 Cornell chick units of vitamin B2 per gram by Norris, Wilgus, Ringrose, Heiman, and Heuser (1936). Sixty day-old Hubbard Strain New Hampshire chicks were placed on the basal diet for two weeks and at the end of that time they were divided into five groups of 12 chicks each. The groups were then fed their respective rations as shown in Table 2, and were weighed each week during the four-week assay period. At the end of this period the average gain in weight of each group over the negative control group, fed the basal diet only, was compared with the gain over the negative control group obtained by feeding the reference dried pork liver. Thus the gain obtained by including the material being tested in the basal diet can be expressed in terms of the amount of dried pork liver producing an equivalent TABLE 3.-—Results
Product
Negative control (basal diet only) Positive control (dried pork liver)
gain. On dividing this value by the percentage of the test material used, and multiplying by 100, the potency of the carrier in vitamin B2 is determined and expressed in relation to dried pork liver as containing 100 units of this vitamin per gram. In this test distillers' grain and concentrated slop were assayed and compared with dried buttermilk as a source of vitamin B2. The results are presented in Table 3. Distillers' grain, concentrated slop, and dried buttermilk, containing 14.0, 15.6, and 1S.3 units of vitamin B2 per gram, respectively, may be considered as good sources of this vitamin. Norris, Wilgus, Ringrose, Heiman, and Heuser (1936) consider materials containing 16 or more Cornell chick units of vitamin B2 per gram as primary sources of this vitamin. As has been noted by the above authors and others, some leg paralysis and gizzard
of vitamin B% chick assays
Feeding level of ration
Av. total wt. at 6 weeks
per cent
grams 269 468 391 471 419
2.3 10 IS 11
Av. gain wt. over negative control
Cornell chick units per gram
grams
units 0 100 14 15.6 15.3
199 122 202 241
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Ground yellow corn Wheat flour middling Vitamin-free casein Steamed bone meal Pulverized limestone Iodized salt... . Cod liver oil. Dried pork liver Distillers' grain Concentrated slop Dried buttermilk
Negative control
T H E NUTRITIVE VALUE OF DISTILLERS' BY-PRODUCTS
PROTEIN QUALITY
The quality or "completeness" of the protein of the distillers' by-products was determined with both rats and chicks. The
rat method for comparing protein quality was that of Daniel and McCollum (1931). Three groups of rats, six in a group, were used in this experiment. The control group was fed 10 percent protein from casein, and distillers' grain was fed at two protein levels, namely 10 and 15 percent. The diet of the 10 percent protein level contained 35.5 percent of distillers' grain and the 15 percent protein diet contained 53.2 percent. The rats receiving distillers' grain as the sole source of protein at both levels slowly lost weight, whereas the case in control animals made good growth. After six weeks the rats on the 15 percent protein level from distillers' grain were placed on a diet in which 7 percent of the protein was derived from the grain and 8 percent from skimmilk powder. On this diet the animals made a normal growth comparable to those on the 10 percent casein diet. It is concluded that when fed in amounts up to about 40 percent of the total protein in the diet, distillers' grain may be used as a satisfactory protein supplement for rats. The distillers' by-products were not used in the chick protein quality tests as a sole source of protein, as was done in the rat experiment, but rather as a supplementary source of protein for growing chicks. This method was used because chick rations are normally varied in character and contain several different sources of protein. The method used was patterned after that of Cleveland and Fellers (1934). The New England College Conference Chick Mash was used as a control. The distillers' grain and concentrated slop were incorporated into a modification of this mash, leaving out the meat scrap in the experimental diets completely, and making such changes in the fish meal and dried skimmilk content as would allow for a total protein content of 18 percent in the diet. The distillers' by-products contributed about onethird of the total protein.
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erosion occurred in the experimental chicks, irrespective of the diets which they were fed. However, these conditions are not related to vitamin B2 but are caused by a deficiency of other specific factors. Jukes (1937) has fpund that the basal vitamin B2-diet of Norris, Wilgus, Ringrose, Heiman, and Heuser (1936) is deficient not only in vitamin B2 but also in the "filtrate factor" and the anti-gizzard erosion factor. According to Jukes (1937) one chick unit of vitamin B2 is approximately equivalent to a modified Bourquin-Sherman unit of this vitamin. The discrepancy between the rat and chick tests in determining the vitamin B2 content of distillers' by-products is thought to be due to the presence of the "filtrate factor" in these products. In view of the fact that the basal diet of Norris and co-workers (1936) is deficient in both vitamin B2 and the "filtrate factor" the presence of the latter in substances being assayed would induce a greater growth in the chicks than was due to vitamin B, alone. Since this investigation was completed, Jukes (1937) has reported that brewers' yeast is a relatively rich source of the filtrate factor, hence it is possible that distillers' by-products may contain a considerable amount of the filtrate factor because of their yeast content. In the above assay for vitamin B2 Hubbard Strain New Hampshire chicks were used rather than White Leghorns, as have been used by previous workers because in New England heavy birds such as these or Rhode Island Reds are raised more than Leghorns or other light weight birds. We believe that results obtained employing these heavy birds are more applicable to rations for poultry in New England.
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A. D. D'ERCOLE, W. B. ESSELEN, JR., AND C. R.
FELLERS
TABLE 4.—Composition of chick rations used in protein quality experiment
Ingredient
Corn meal Wheat middlings Wheat Bran Meat scrap
DistiUers' coned, slop constituting 7% of the total protein
Distillers' grains constituting 7% of total protein
per cent 29.54 14.77 14.77 14.77 7.39 3.69 7.39 3.70 2.21 .74 1.03
per cent 1.4 14.77 14.77 14.77
per cent 23.01 14.77 14.77 14.77
4.00 2.61 3.7 2.21 .74 1.03 40.00
5.0 3.7 2.21 .74 1.03 20.00
Thirty of the M.S.C. Strain Rhode Island Red day-old chicks* were distributed into three groups 10 to a group, and fed their respective rations as in Table 4. The chicks were weighed at weekly intervals. The results were rather clear cut, and after four weeks the experiment was discontinued. Table S shows conclusively that distillers' by-products are a poor supplementary source of protein in chick feeds, at least at so high a level as one-third of the total protein of the diet. It was noted that the concentrated slop, at the level fed, definitely reduced the palatability of the ration. This probably accounts in part for the poor weight gains observed in the chicks on this ration. In the amounts fed, the distillers' by-products appeared to have *The M.S.C. Strain Rhode Island Red chicks were supplied through the courtesy of the Poultry Department, Massachusetts State College.
no deleterious laxative effect on the chicks. The chick data are in close agreement with the results obtained with rats in showing that the protein of distillers' grain is not complete and that it cannot be used as a sole primary source of protein in feeds. Similar results were reported by Broughton, Frey, and Carmichael (1933). SUMMARY A summary of the vitamin content of distillers' grain and concentrated slop is presented in Table 6. These materials are good sources of vitamins Bx and B2 (riboflavin). These substances also appear to contain a small amount of vitamin D-like or antirachitic substance, which can be increased by irradiation with ultra-violet light. However, it is felt that such a process would not be practical for commercial production. Distillers' by-products contain
TABLE 5.—Weight gains in chicks fed distillers' by-products so as to furnish 33 percent of the total protein {18 percent) Ration
N. E. College Conference Ration Distillers' grains to furnish § of total protein Distillers' coned, slop to furnish \ of total protein.
7 days
14 days
21 days
28 days
wt. grams
wt. grams
wt. grams
wt. grams
82 60 68
135 89 89
280 139 102
325 185 173
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Dried skimmilk Alfalfa meal Limestone Salt Cod liver oil Distillers' coned, slop Distillers' grains
Control ration N.E. College conference chick mash
T H E NUTRITIVE VALUE OF DISTILLERS' BY-PRODUCTS TABLE 6.-—Summary
Determination Vitamin A Vitamin D (irradiated 30 min.) Vitamin C Vitamin B Vitamin B2 (rat) Vitamin B2 (Cornell chick). . .
95
of vitamin results
Distillers' Grain
Distillers' Slop
international units per gram less than 1.4 2.0 13.3 none found 2 Sherman units 2.4 Sherman units 14.0 chick units
international units per gram less than 1.4
CONCLUSIONS
From this study of the nutritive value of distillers' grain and concentrated slop, it is felt that the addition of 10 to IS percent of distillers' grain or concentrated slop to poultry rations will provide a good source of vitamin B1 and B2 (riboflavin). These two vitamins are essential for optimum poultry growth and reproduction. It is emphasized that distillers' by-products should be a very economical source of these two vitamins in poultry or livestock rations. Because of their high ash content, distillers' by-products are likewise good sources of minerals. Dried buttermilk was also found to be a good source of vitamin B2. LITERATURE CITED
Bessey, O. A., and C G. King, 1933. The distribution of vitamin C in plant and animal tissues and its determination. Jour. Biol. Chem. 103: 687. Bourquin, A., and H. C. Sherman, 1931. Quantitative determination of vitamin G (B 2 ). Jour. Am. Chem. Soc. 53:3501. Broughton, L. B., P. W. Frey, and B. E. Car-
michael, 1933. An industrial alcohol by-product stock food. Md. Agr. Expt. Sta. Bull. No. 349. Chase, E. F., and H. C. Sherman, 1931. A quantitative study of the determination of the antineuritic vitamin Bj. Jour. Am. Chem. Soc. 53 :3506. Cleveland, M. M., and C. R. Fellers, 1934. Comparison of laboratory and practical tests for determining the nutritive values of fish meals. Trans. Am. Fish. Soc. 64:293. Cooley, T. C , 1938. Distillery by-products. Ind. Eng. Chem. 30:615-621. Daniel, E. P., and E. V. McCollum, 1931. Studies on the nutritive value of fish meals. U. S. Bur. Fish Investigational Rept. No. 2. Insko, W. M., Jr., G. D. Buckner, J. H. Martin, and A. Harms, 1937. Distillery slop in chick rations. Ky. Agr. Expt. Sta. Circ. 46. Jukes, T. H., 1937. Biological assay of lactoflavin with chicks. Jour. Nutr. 14:223-233. Kentucky Agricultural Experiment Station, 1936. Forty-ninth annual report. Part I, 16-17. Morrison, F. B., 1936. Feeds and feeding. 20th Ed. pp. 399-400. Morrison Publishing Co., Ithaca, N.Y. Norris, L. C , H. S. Wilgus, Jr., A. T. Ringrose, V. Heiman, and G. F. Heuser, 1936. The vitamin G requirements of poultry. N.Y. (Cornell) Agr. Expt. Sta. Bull. No. 660. Sherman, H. C , and H. E. Munsell, 1925. Quantitative determination of vitamin A. Jour. Am. Chem. Soc. 47:1639. Tillmans, J., P. Hirsch, and W. Hirsch, 1932. The reduction capacity of plant foodstuffs and its relation to vitamin C. Ztschr. Untersuch. Lebensm. 63:1. Tomhave, A. E., 1936. Dried distillers' and dried brewers' grains for growing fattening pigs. Del. Agr. Expt. Sta., Bull. No. 205:19. United States Pharmacopoeia X. Interim revision announcement No. 2. A 1934 revision of the text and assays for cod liver oil. 11 p.
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little or no vitamin A. The concentrated slop contains some vitamin C-like material but this vitamin is not required in livestock or poultry nutrition. The present investigation checks the results of previous workers in showing that the protein of distillers' by-products does not possess good growth promoting properties and is of value largely as a supplementary protein.
0.7-1.2 5.4 Sherman units 3.0 Sherman units 15.6 chick units
as "well as protein quality assays, were made. The work was done with special reference to the use of these by-products in poultry rations. Both rat and chick methods were used in determining the vitamin B2 content and the quality of the protein.
OBJECT
The main objective of this investigation was to determine the relative feed value of distillers' grains and concentrated slop. Vitamin A, B w B2 (riboflavin), C, and D, * Contribution Number 311 of the Massachusetts Agricultural Experiment Station, Amherst.
LITERATURE REVIEW
Broughton, Frey, and Carmichael (1933) investigated an industrial alcohol by-product resulting from cane molasses fermentation. Their rat tests showed that the protein was incomplete and did not support growth. They also state that the amount of vitamin B1 present was high, although no quantitative results were reported. Investigations carried out by Tomhave (1936) showed the limitations of distillers' dried grains as a supplement for hog feeding to be due to palatability. Insko, Buckner, Martin, and Harms (1937) reported that as much as four-fifths of the corn in poultry mash may be replaced by thick distillery slop and that the thick slop may be successfully fed when mixed with an all-mash mixture in the proportion of one part of mash to two parts of thick slop. Thin slop was not a satisfactory supplement to an all-mash ration. Morrison (1936) states that while distillery slop is sometimes fed to fattening cattle, it is too watery to promote satisfactory gains in weight and should be fed with hay or other roughage in addition to at least one-third of their usual allowance of grain. Distillers' dried grains are not usually fed to swine, since they are much better suited for cattle feeding, especially dairy
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LTHOUGH distillers' by-products - have long been used as animal feeds, very little data have been reported on their nutritive value. After alcohol has been distilled from the fermented mash in the manufacture of whisky or of alcohol from grain the residue contains all of the protein, fat, fiber, and mineral matter practically unchanged. Part of this material is in solution in the liquid portion but the larger part is in the form of suspended material that can be recovered by filtering. This unfiltered material is known as thick slop. The suspended material is filtered out and dried and is known as distillers' grains. The liquid which passes through the filter is known as slop. The slop may be concentrated under vacuum to a thick syrup and is referred to in this paper as concentrated slop. Present day methods of producing distillery by-products are described in detail by Cooley (1938). This author shows that ISO tons of distillers' dried grains, with a value of from $17.00 to $30.00 per ton, may be produced daily by a distillery manufacturing approximately 100,000 gallons of 100 proof alcohol daily.
A
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A. D. D'ERCOLE, W. B. ESSELEN, JR., AND C. R. FELLERS
cows. Investigators at the Kentucky Agricultural Experiment Station (1936) used distillery slop in hog feeding and found that as the proportion of corn to slop decreased, the carcasses became progressively softer. EXPERIMENTAL WORK
The composition of the distillers' grains and concentrated slop used in this investigation is as follows:* Concentrated Slop
percent 8.25 31.79 8.06 7.55
percent 48.25 17.51 1.12 0.10
40.29 4.06
28.40 4.62
Vitamin A Vitamin A assays were made on the distillers' grain according to the technic of Sherman and Munsell (1925). Fourteen vitamin A deficient rats were fed 1.0 gram of the sample daily for 21 days. At this time all the animals showed a marked loss of weight and severe xerophthalmia. A second test gave similar results. Since a measurable amount of vitamin A is not present in 1.0 gram of distillers' grains this feed must be considered as a poor source of vitamin A. Vitamin B1 The method used for the vitamin Bx assay was that of Chase and Sherman (1931). Twenty young rats were placed on the vitamin Bj-free diet until they exhibited a deficiency of this vitamin. Then the animals were divided into two experimental groups of seven animals each and a negative control group of six. One group was t fed 0.5 gram of distillers' grains daily and the other group was fed 0.37 gram of con* Analyses made by P. H. Smith, official state chemist.
Vitamin C The vitamin C content of the distillers' by-products was determined by the Tillmans, Hirsch, and Hirsch titration method (1932) as modified by Bessey and King (1933). There was no significant amount of vitamin C present in the grains when 5 and 10 grain samples were used. However, the slop was found to contain between 0.035 and 0.06 milligrams of ascorbic acid (vitamin C) per gram which is equivalent to 0.7-1.2 international units per gram of slop. Vitamin D The vitamin D assays were carried out according to the United States Pharmacopoeia method (1934). Because of the yeast naturally present in distillers' grains it was thought that its vitamin D content might be increased by irradiation with ultraviolet rays. Samples of the grain were irradiated by two different types of commercial ultra-violet lamps for varying periods of time. The irradiated and unirradiated samples were assayed in three series of tests, as
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Moisture Protein Ether extract (fat) Fiber Extract matter (carbohydrate) Ash
Distillers' Grain
centrated slop daily. The six negative control animals died within two weeks. The rats fed the distillers' grains made an averave weight gain of 6.0 grams per week during the five-week assay period. Those fed 0.37 gram of concentrated slop made an average gain of 6.0 grams per week. It is concluded that the distillers' grains contained at least 2 Sherman units per gram. Since the weight gains were double those suggested by Chase and Sherman, it is probable that 4.0 Sherman units of vitamin B1 per gram approximates the value of this product. The concentrated slop on this basis contained approximately 5.4 Sherman units per gram. The relatively high vitamin B± content of the slop is probably due to the large numbers of yeast cells present. These were readily demonstrated by a microscopic examination.
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T H E NUTRITIVE VALUE OF DISTILLERS' BY-PRODUCTS
shown in Table 1. From this data it is evident that there is a small amount of vitamin D, or some antirachitic substance, normally present in distillers' grain. It is also shown that the vitamin D content of distillers' grain may be increased to some extent by irradiating the material for 30 minutes. Such a long irradiation period would probably not be practical in commer-
animals serving as negative controls. One group of rats received 0.5 gram of distillers' grain daily while the other group was fed 0.5 gram of concentrated slop daily as a supplement. Those fed the grain made an average weight gain of 3.6 grams per week and the group receiving the concentrated slop gained an average of 4.5 grams per week during the test period of five weeks.
Sample
Level fed
Number of rats
Average degree of calcification
I.U. per gram
2.0 1.0 95.0
grams 0.250 0.500 1.009 0.028
8 8 8 8
0.95 1.20 1.15 1.30
0.075 0.075
5 5
1.75 0.85
13.3
5 5 5 5 10
0.40 0.30 0.30 0.25 1.70
—
Positive control
0.075 0.075 0.075 0.075 0.028
95.0
Type 1 Lamp Irradiated 10 min Irradiated 10 min Irradiated 30 min Irradiated 30 min Positive control
0.056 0.037 0.056 0.037 0.028
10 10 10 10 10
0.42 0.05 0.45 0.025 1.39
95.0
Distillers' grain Positive control Type 1 Lamp Irradiated 10 min Type 2 Lamp Irradiated 10 min. Irradiated 6 min. Irradiated 2 min
cial practice. It would appear that there is sufficient antirachitic substance in distillers' by-products to be of some slight value in the feeding of poultry and farm animals. Vitamin B2 (Riboflavin) Both the Bourquin-Sherman rat method (1931) and the Norris, Wilgus, Ringrose, Heiman, and Heuser chick method (1936) were employed in determining the vitamin B2 content of distillers' grain and concentrated slop. Twenty vitamin B2-deficient rats were divided into two experimental groups of eight animals each with the remaining four
In terms of Sherman-Bourquin units of vitamin B2 it is concluded that the distillers' grain contained approximately 2.4 units per gram, whereas the concentrated slop contained 3.0 units per gram. Thus, both of these products are good sources of vitamin B2 and should be valuable additions to poultry and livestock diets in this respect. The vitamin B2 chick assay method determines the relative growth promoting vitamin B2 content of feedstuffs based upon the gain in weight produced over the negative control diet by adding 5 to 15 percent of the supplement under study to the basal diet, the protein content of the diet being kept constant at 25 percent. Dried pork
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TABLE 1.—Vitamin D content of distillers' by-products
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A. D. D'ERCOLE, W. B. ESSELEN, JR., AND C. R. FELLERS TABLE 2.—Composition of experimental diets used in vitamin B% chick assays
Ingredient
Positive control
Distillers' grain
Concentrated slop
Dried buttermilk
per cent
per cent
per cent
per cent
per cent
60.0 20.0 IS. 5 2.0 1.0 0.5 1.0
57.0 20.0 16.2 2.0 1.0 0.5 1.0 2.3
51.5 20.0 14.0 2.0 1.0 0.5 1.0
44.5 20.0 16.0 2.0 1.0 0.5 1.0
51 1 20 0 13.4 2 0 1 0 0 5 1 0
10.0 15.0
. ...
— 11.0
liver was used as a standard and has been given the value of 100 Cornell chick units of vitamin B2 per gram by Norris, Wilgus, Ringrose, Heiman, and Heuser (1936). Sixty day-old Hubbard Strain New Hampshire chicks were placed on the basal diet for two weeks and at the end of that time they were divided into five groups of 12 chicks each. The groups were then fed their respective rations as shown in Table 2, and were weighed each week during the four-week assay period. At the end of this period the average gain in weight of each group over the negative control group, fed the basal diet only, was compared with the gain over the negative control group obtained by feeding the reference dried pork liver. Thus the gain obtained by including the material being tested in the basal diet can be expressed in terms of the amount of dried pork liver producing an equivalent TABLE 3.-—Results
Product
Negative control (basal diet only) Positive control (dried pork liver)
gain. On dividing this value by the percentage of the test material used, and multiplying by 100, the potency of the carrier in vitamin B2 is determined and expressed in relation to dried pork liver as containing 100 units of this vitamin per gram. In this test distillers' grain and concentrated slop were assayed and compared with dried buttermilk as a source of vitamin B2. The results are presented in Table 3. Distillers' grain, concentrated slop, and dried buttermilk, containing 14.0, 15.6, and 1S.3 units of vitamin B2 per gram, respectively, may be considered as good sources of this vitamin. Norris, Wilgus, Ringrose, Heiman, and Heuser (1936) consider materials containing 16 or more Cornell chick units of vitamin B2 per gram as primary sources of this vitamin. As has been noted by the above authors and others, some leg paralysis and gizzard
of vitamin B% chick assays
Feeding level of ration
Av. total wt. at 6 weeks
per cent
grams 269 468 391 471 419
2.3 10 IS 11
Av. gain wt. over negative control
Cornell chick units per gram
grams
units 0 100 14 15.6 15.3
199 122 202 241
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Ground yellow corn Wheat flour middling Vitamin-free casein Steamed bone meal Pulverized limestone Iodized salt... . Cod liver oil. Dried pork liver Distillers' grain Concentrated slop Dried buttermilk
Negative control
T H E NUTRITIVE VALUE OF DISTILLERS' BY-PRODUCTS
PROTEIN QUALITY
The quality or "completeness" of the protein of the distillers' by-products was determined with both rats and chicks. The
rat method for comparing protein quality was that of Daniel and McCollum (1931). Three groups of rats, six in a group, were used in this experiment. The control group was fed 10 percent protein from casein, and distillers' grain was fed at two protein levels, namely 10 and 15 percent. The diet of the 10 percent protein level contained 35.5 percent of distillers' grain and the 15 percent protein diet contained 53.2 percent. The rats receiving distillers' grain as the sole source of protein at both levels slowly lost weight, whereas the case in control animals made good growth. After six weeks the rats on the 15 percent protein level from distillers' grain were placed on a diet in which 7 percent of the protein was derived from the grain and 8 percent from skimmilk powder. On this diet the animals made a normal growth comparable to those on the 10 percent casein diet. It is concluded that when fed in amounts up to about 40 percent of the total protein in the diet, distillers' grain may be used as a satisfactory protein supplement for rats. The distillers' by-products were not used in the chick protein quality tests as a sole source of protein, as was done in the rat experiment, but rather as a supplementary source of protein for growing chicks. This method was used because chick rations are normally varied in character and contain several different sources of protein. The method used was patterned after that of Cleveland and Fellers (1934). The New England College Conference Chick Mash was used as a control. The distillers' grain and concentrated slop were incorporated into a modification of this mash, leaving out the meat scrap in the experimental diets completely, and making such changes in the fish meal and dried skimmilk content as would allow for a total protein content of 18 percent in the diet. The distillers' by-products contributed about onethird of the total protein.
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erosion occurred in the experimental chicks, irrespective of the diets which they were fed. However, these conditions are not related to vitamin B2 but are caused by a deficiency of other specific factors. Jukes (1937) has fpund that the basal vitamin B2-diet of Norris, Wilgus, Ringrose, Heiman, and Heuser (1936) is deficient not only in vitamin B2 but also in the "filtrate factor" and the anti-gizzard erosion factor. According to Jukes (1937) one chick unit of vitamin B2 is approximately equivalent to a modified Bourquin-Sherman unit of this vitamin. The discrepancy between the rat and chick tests in determining the vitamin B2 content of distillers' by-products is thought to be due to the presence of the "filtrate factor" in these products. In view of the fact that the basal diet of Norris and co-workers (1936) is deficient in both vitamin B2 and the "filtrate factor" the presence of the latter in substances being assayed would induce a greater growth in the chicks than was due to vitamin B, alone. Since this investigation was completed, Jukes (1937) has reported that brewers' yeast is a relatively rich source of the filtrate factor, hence it is possible that distillers' by-products may contain a considerable amount of the filtrate factor because of their yeast content. In the above assay for vitamin B2 Hubbard Strain New Hampshire chicks were used rather than White Leghorns, as have been used by previous workers because in New England heavy birds such as these or Rhode Island Reds are raised more than Leghorns or other light weight birds. We believe that results obtained employing these heavy birds are more applicable to rations for poultry in New England.
93
94
A. D. D'ERCOLE, W. B. ESSELEN, JR., AND C. R.
FELLERS
TABLE 4.—Composition of chick rations used in protein quality experiment
Ingredient
Corn meal Wheat middlings Wheat Bran Meat scrap
DistiUers' coned, slop constituting 7% of the total protein
Distillers' grains constituting 7% of total protein
per cent 29.54 14.77 14.77 14.77 7.39 3.69 7.39 3.70 2.21 .74 1.03
per cent 1.4 14.77 14.77 14.77
per cent 23.01 14.77 14.77 14.77
4.00 2.61 3.7 2.21 .74 1.03 40.00
5.0 3.7 2.21 .74 1.03 20.00
Thirty of the M.S.C. Strain Rhode Island Red day-old chicks* were distributed into three groups 10 to a group, and fed their respective rations as in Table 4. The chicks were weighed at weekly intervals. The results were rather clear cut, and after four weeks the experiment was discontinued. Table S shows conclusively that distillers' by-products are a poor supplementary source of protein in chick feeds, at least at so high a level as one-third of the total protein of the diet. It was noted that the concentrated slop, at the level fed, definitely reduced the palatability of the ration. This probably accounts in part for the poor weight gains observed in the chicks on this ration. In the amounts fed, the distillers' by-products appeared to have *The M.S.C. Strain Rhode Island Red chicks were supplied through the courtesy of the Poultry Department, Massachusetts State College.
no deleterious laxative effect on the chicks. The chick data are in close agreement with the results obtained with rats in showing that the protein of distillers' grain is not complete and that it cannot be used as a sole primary source of protein in feeds. Similar results were reported by Broughton, Frey, and Carmichael (1933). SUMMARY A summary of the vitamin content of distillers' grain and concentrated slop is presented in Table 6. These materials are good sources of vitamins Bx and B2 (riboflavin). These substances also appear to contain a small amount of vitamin D-like or antirachitic substance, which can be increased by irradiation with ultra-violet light. However, it is felt that such a process would not be practical for commercial production. Distillers' by-products contain
TABLE 5.—Weight gains in chicks fed distillers' by-products so as to furnish 33 percent of the total protein {18 percent) Ration
N. E. College Conference Ration Distillers' grains to furnish § of total protein Distillers' coned, slop to furnish \ of total protein.
7 days
14 days
21 days
28 days
wt. grams
wt. grams
wt. grams
wt. grams
82 60 68
135 89 89
280 139 102
325 185 173
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Dried skimmilk Alfalfa meal Limestone Salt Cod liver oil Distillers' coned, slop Distillers' grains
Control ration N.E. College conference chick mash
T H E NUTRITIVE VALUE OF DISTILLERS' BY-PRODUCTS TABLE 6.-—Summary
Determination Vitamin A Vitamin D (irradiated 30 min.) Vitamin C Vitamin B Vitamin B2 (rat) Vitamin B2 (Cornell chick). . .
95
of vitamin results
Distillers' Grain
Distillers' Slop
international units per gram less than 1.4 2.0 13.3 none found 2 Sherman units 2.4 Sherman units 14.0 chick units
international units per gram less than 1.4
CONCLUSIONS
From this study of the nutritive value of distillers' grain and concentrated slop, it is felt that the addition of 10 to IS percent of distillers' grain or concentrated slop to poultry rations will provide a good source of vitamin B1 and B2 (riboflavin). These two vitamins are essential for optimum poultry growth and reproduction. It is emphasized that distillers' by-products should be a very economical source of these two vitamins in poultry or livestock rations. Because of their high ash content, distillers' by-products are likewise good sources of minerals. Dried buttermilk was also found to be a good source of vitamin B2. LITERATURE CITED
Bessey, O. A., and C G. King, 1933. The distribution of vitamin C in plant and animal tissues and its determination. Jour. Biol. Chem. 103: 687. Bourquin, A., and H. C. Sherman, 1931. Quantitative determination of vitamin G (B 2 ). Jour. Am. Chem. Soc. 53:3501. Broughton, L. B., P. W. Frey, and B. E. Car-
michael, 1933. An industrial alcohol by-product stock food. Md. Agr. Expt. Sta. Bull. No. 349. Chase, E. F., and H. C. Sherman, 1931. A quantitative study of the determination of the antineuritic vitamin Bj. Jour. Am. Chem. Soc. 53 :3506. Cleveland, M. M., and C. R. Fellers, 1934. Comparison of laboratory and practical tests for determining the nutritive values of fish meals. Trans. Am. Fish. Soc. 64:293. Cooley, T. C , 1938. Distillery by-products. Ind. Eng. Chem. 30:615-621. Daniel, E. P., and E. V. McCollum, 1931. Studies on the nutritive value of fish meals. U. S. Bur. Fish Investigational Rept. No. 2. Insko, W. M., Jr., G. D. Buckner, J. H. Martin, and A. Harms, 1937. Distillery slop in chick rations. Ky. Agr. Expt. Sta. Circ. 46. Jukes, T. H., 1937. Biological assay of lactoflavin with chicks. Jour. Nutr. 14:223-233. Kentucky Agricultural Experiment Station, 1936. Forty-ninth annual report. Part I, 16-17. Morrison, F. B., 1936. Feeds and feeding. 20th Ed. pp. 399-400. Morrison Publishing Co., Ithaca, N.Y. Norris, L. C , H. S. Wilgus, Jr., A. T. Ringrose, V. Heiman, and G. F. Heuser, 1936. The vitamin G requirements of poultry. N.Y. (Cornell) Agr. Expt. Sta. Bull. No. 660. Sherman, H. C , and H. E. Munsell, 1925. Quantitative determination of vitamin A. Jour. Am. Chem. Soc. 47:1639. Tillmans, J., P. Hirsch, and W. Hirsch, 1932. The reduction capacity of plant foodstuffs and its relation to vitamin C. Ztschr. Untersuch. Lebensm. 63:1. Tomhave, A. E., 1936. Dried distillers' and dried brewers' grains for growing fattening pigs. Del. Agr. Expt. Sta., Bull. No. 205:19. United States Pharmacopoeia X. Interim revision announcement No. 2. A 1934 revision of the text and assays for cod liver oil. 11 p.
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little or no vitamin A. The concentrated slop contains some vitamin C-like material but this vitamin is not required in livestock or poultry nutrition. The present investigation checks the results of previous workers in showing that the protein of distillers' by-products does not possess good growth promoting properties and is of value largely as a supplementary protein.
0.7-1.2 5.4 Sherman units 3.0 Sherman units 15.6 chick units