The Nutritive Value of Yeast Grown on Hydrocarbon Fractions for Broiler Chicks

The Nutritive Value of Yeast Grown on Hydrocarbon Fractions for Broiler Chicks P. W. WALDROUP, C. M. HILLARD AND R. J. MITCHELL

Department of Animal Sciences, University of Arkansas, Fayetteville 72701 (Received for publication October 26, 1970)

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tion of protein concentrates apparently began in 1959 in Lavera, France, by the British Petroleum Co. (Champagnat, 1967). Reports have indicated that hydrocarbon yeast protein has excellent nutrition for pigs and chickens. Shacklady (1967) reported that this material had a metabolizable energy content of 2550 Kcal./kg., with nitrogen digestibility coefficients of 80% for chicks and 86.5% for pigs. The mean Net Protein-Utilization by rat assay of 48 yeast samples was 41 with a high of 57 and a low of 20. Supplementing with 0.3% DL-methionine raised the mean to 74 with a range of 46-92. These samples included a number which had undergone deliberately severe processing conditions (Shacklady, 1968). Feeding trials with chicks, laying hens and pigs at levels up to 20% in practical type diets have shown acceptable results with no apparent histological abnormalities (Lain, 1967; Shacklady and van der Wal, 1968; Shacklady, 1969; Cheingo et al., 1967). Trials have been conducted in this laboratory to study the feeding value of a yeast grown on high purity alkane fractions. Broiler diets similar in nutritive content to those used in commercial production were tested with different levels of hydrocarbon yeast to determine their effects on growth and performance of broiler chicks. EXPERIMENT 1

Materials and Methods. A sample of yeast grown on hydrocarbon fractions was obtained from a major petroleum company.1 1

Gulf Research and Development Co., Pittsburgh, Pa.

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EASTS have been used by man for centuries, primarily in the production of alcoholic drinks and making bread. The use of yeasts grown on carbohydrate substrates as an ingredient in the diet of man or animals dates from before the beginning of this century (Llewelyn, 1967). One of the most recent applications of yeast culture for food materials has been the development of yeast cultures which can utilize hydrocarbon fractions as a substrate. Over 100 bacteria, yeast, actinomycetes and fungi are known to grow at the expense of hydrocarbons (Foster, 1962). The utilization of gaseous hydrocarbons by soil microorganisms has been studied as a means of detecting petroleum gas emanations in prospective areas (Davies, 19S6). Mixed cultures of yeast have been grown on gas oil (Miller and Johnson, 1966a) and n-paraffins (Miller and Johnson, 1966b). Generation times of 3 to 8 hours with cell yields of 70-90% of substrate utilization were noted. The recovered cells contained 6.75 to 9.3% N with 1.9-13.4% lipid. Suitable hydrocarbon substrates for microbes are liquid normal paraffins, crude paraffinic middle distillates, and methane and natural gas. The liquid normal paraffins are preferred due to fewer residue problems and ease of handling. The fermentation is aerobic and since the substrate is not soluble in water this presents several fermentation problems (Champagnat, 1968). The resultant protein is characterized by a high lysine content and a relatively low content of methionine and cystine. Research in petroleum fermentation aimed specifically at the industrial produc-

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HYDROCARBON PROTEIN TABLE 1.—Composition of typical chick diets containing hydrocarbon yeast protein (Experiment 1) Percent of Diet

Ingredient

Total 1

0.00 29.75 0.00 5.00 53.12 6.45 2.50 1.57 0.45 0.16 0.40 0.10 0.50

15.00 14.68 0.00 5.00 54.47 5.62 2.50 0.07 1.41 0.25 0.40 0.10 0.50

30.00 11.40 0.00 0.00 45.50 7.45 2.50 0.00 1.86 0.29 0.40 0.10 0.50

0.00 20.46 5.00 5.00 60.34 4.37 2.50 0.83 0.35 0.15 0.40 0.10 0.50

15.00 13.94 5.00 5.00 45.60 5.30 2.50 0.00 1.34 0.23 0.40 0.10 0.50

30.00 6.11 5.00 0.00 47.49 6.43 2.50 0.00 1.24 0.23 0.40 0.10 0.50

100.00

100.00

100.00

100.00

100.00

100.00

As outlined by Waldroup et al. (1969).

It was analyzed to contain 49.4% protein ( N X 6.25). The amino acid composition was determined by auto analysis and contained as percent of sample: arginine 2.04, histidine 0.91, lysine 3.50, tryptophan 0.46, phenylalanine 2.51, methionine 0.64, methionine + cystine 0.87, threonine 2.97, leucine 3.52, isoleucine 2.23, valine 2.39 and glycine 2.01. A value of 2550 Kcal. of metabolizable energy per kilogram (Shacklady, 1967) was assigned to this sample. Tryptophan was determined by the method of Spies and Chambers (1948). Diets were computer formulated to meet the minimum essential amino acid restrictions suggested by the Arkansas Agricultural Extension Service (1966). Hydrocarbon yeast protein was included in the diets at specified levels, with the remainder of the ingredients selected on a least-cost basis, using prices which were then in effect in the Northwest Arkansas area. The major objectives of this initial trial were to determine the maximum usage levels of yeast protein in high energy broiler diets and to determine if any extra growth response could be attributed to the presence of the hydrocarbon yeast protein. The influence of the physical form of the diet (mash versus pellet) was also studied as the material was fine and powdery and

might have caused problems in separation and in the general overall appearance of the feed. The experimental variables were studied in a 2 X 2 X 9 factorial arrangement. The factors considered were: (1) Mash vs. pellet form, (2) Comparison of basal diets with and without 5% Peruvian fish meal, and (3) Dietary levels of hydrocarbon yeast protein. Levels examined in this study were 0, 2.5, 5.0, 7.5, 10.0, 15.0, 20.0, 25.0, and 30.0. The combination of all experimental factors resulted in 36 experimental treatments. For the sake of brevity, only a representative portion of the diets are shown in Table 1. Each of the diets was fed to 3 replicate pens of 5 male and 5 female broiler-type chicks (Peterson X Peterson) in electrically heated battery brooders with raised wire floors for the first four weeks of the study. During the second four weeks (finishing period) the fish meal comparison was eliminated so that only 18 diets were fed during this period. This was necessary as there were not enough pens in finishing batteries to continue all of the original treatments. Since the greatest response to fish meal is usually found during the first four weeks, it was felt that more information could be gained by examining the re-

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Yeast Soybean meal Fish meal Poultry by product Yellow corn Animal fat Alfalfa meal Dicalcium phosphate Limestone DL-methionine Salt Trace minerals1 Microingredien ts

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P. W. WALDEOUP, C. M. HILLARD AND R. J. MITCHELL TABLE 2.— Body weights of chicks fed diets with hydrocarbon yeast -L {Experiment 1) Body weight (grams) 1

% Yeast

56 day

28 day Mash

Pellet

Av.

1 3 4 3 ab < , 1371 a b 1390 a 1288"- f ab

Mash

Pellet

Av.

0 2.5 5.0 7.5 10.0 15.0 20.0 25.0 30.0

539ab0 534bc 539abc 549abc 533bo 531bc 494 d 486 d 439 e

5 6 3 aa b 566 567° 554abc 552abo 563ab 554abc 552abc 523°

551 a 550 a 553 a 55 l a 543ab 547" 524 b c 519"d 48 l

1315 1 '-" mi"-1* 1336"- d 1353"-°f 1291°1300 b - e 1242 ef 1254 0f 1219 r

1354 « 1309 bb - ee 1312 1266 d - f 1314"-*

1328 a b 1352" 1363 a 132 l a b 1323 a b 1305 b c 1278 b o 1260° 1266°

Av.

516 b

555"

530

1294 b

1328 a

1310

Means having the same superscript do not differ significantly ( P = 0 . 0 5 % ) .

sponse to pelleting rather than the fish meal comparison. Individual chick weights and pen feed consumption were obtained at 4 and 8 weeks of age. The screens in the batteries were examined and scored for accumulation of droppings. Birds were examined for accumulation of feces around the vent; however, this did not appear to be a problem in this study and no differences were noted among groups of chicks. The data were subjected to the analysis of variance as outlined by Steel and Torrie (1960) with significant differences between treatment means determined by the multiple range test of Duncan (1955). Where statistically significant differences are noted, they indicate probability levels of at least 95%. Results. No differences were noted in performance that could be related to the presence or absence of fish meal in the diets or to any interaction of fish meal and yeast levels. Therefore, the data from the two basal diets were combined for brevity. At the end of the first four weeks of feeding, it was observed that broiler chicks fed diets with hydrocarbon yeast protein at levels of up to 15% in all-mash diets or up to 25% in pelleted diets grew as well as chicks fed the basal diet with no yeast (Table 2). At higher levels, reductions in weight gains

TABLE 3.—Efficiency of feed utilization of chicks fed diets with hydocarbon yeast protein [Experiment 1) Feed:Gain Ratio 1

%

0-28 days

Yeast Mash

Pellet

0 2.5 5.0 7.5 10.0 15.0 20.0 25.0 30.0

1.51ab 1.45 a b 1.49 a b 1.44 a 1.47 a b 1.49 aa bb 1.55 1.52 a b 1.68"

1.52 a b 1.55 b 1.48ab 1.48 a b 1.52 a b 1.45 aa bb 1.47 1.48 a b 1.52 a b

Av.

1.51

1.50

1

0-56 days Av. 52 a S0» 48" 46 a 50" 47 aa 51 50" 60 b 1.50

Mash

Pellet

Av.

1.94 a b 1.89" 1.92 a 1.91 a 1.99 a b 1.94 a b 1.96 a b 2.04b 2.06b

1.95 a b 1.98 aa b 1.88 1.97 a b 1.96 a b 1.92 aa b 1.94 1.98 a b 1.98 a b

1.95ab 1.94aa b 1.90 1 94ab 1.98 a b 1 . 9 3 aa bb 1.95 2.01b 2.02b

1.95

1.96

Means having the same superscript do not differ significantly (P = 0 . 0 5 % ) .

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were noted. A significant yeast level X pelleting interaction was observed in which chicks accepted higher levels of yeast in pelleted diets than in all-mash diets. It was felt that this was due primarily to problems associated with feed intake as the bulkiness of the diet was markedly increased as the hydrocarbon yeast level was increased. This factor was the subject of a later trial in this communication. The response to pelleting appeared to be related at least in part to the bulky, fluffy nature of the diets containing higher levels of yeast. The feed efficiency data (Table 3) indicate that chicks fed up to 25 percent yeast in all-mash feeds and up to 30 percent yeast in pelleted feeds had similar efficiency of feed conversion as did chicks fed diets with lower levels or the unsupplemented basal diets. This indicates that the reduction in body weight gains at higher levels of yeast feeding were more likely associated with reduced feed intake at higher levels of yeast incorporation. In regard to statistical analysis of feed utilization, differences were noted for yeast level and a yeast level X pelleting interaction. Both appeared to be related primarily to the lowered performance of the chicks fed the allmash diets with 30% yeast. The floor screens were evaluated on a numerical basis. A score of 1 indicated vir-

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HYDROCARBON PROTEIN

TABLE 4.—Accumulation of excreta on floor screens by chicks Jed diets with hydrocarbon yeast protein (Experiment 1) Screen Score1'2 % Yeast Mash

Pellet

Ave.

0 2.5 5.0 7.5 10.0 15.0 20.0 25.0 300.0

1.00* 1.00* 1.00" 1.00* 1.17*b 2.00° 2.50 d 3.17= 3.33=

1.00" 1.00* 1.00* 1.00* 1.50b 2.00° 3.33= 3.83' 4.00'

1.00" 1.00" 1.00* 1.00* 1.33b 2.00" 2.92 d 3.00= 3.67=

Av.

1.79*

2.07 b

1.93

1

Screen scores ranged from 1 to 4 with the higher score indicating a more severe accumulation. 2 Means having the same superscript do not differ significantly (P = 0.05%).

efficiency of feed utilization among any of the diets with yeast in comparison to the basal control diet, although the chicks fed the diets with 25 or 30% yeast had the poorest efficiency of conversion (Table 3). No problem was encountered with the accumulation of feces on the screens in the finishing pens. The larger mesh size of the floor screens allowed the droppings to fall through easily with no accumulation. There did not appear to be any difficulty with feces adhering to the vent or feathers. Mortality was variable throughout the diets and could not be related to yeast level in the feeds. It was not considered excessive, with an average livability of 97.2 percent. EXPERIMENT 2

Materials and Methods. The objective of this study was to study further the nutritive value of petroleum yeast protein in broiler diets. The yeast was included in the diets at levels of 0, 2.5, 5.0, 7.5, 10.0 and 15%. The remainder of the ingredients were selected by least-cost linear programming. In contrast to the first experiment, the maximum amount of poultry by-product meal accepted was 2.5% of the diet to allow for a greater yeast-for-soybean meal comparison. One series of diets was designated the soy basal series and contained no fish meal. The second series of diets was designated the fish basal series and contained 5% of Peruvian fish meal. The combination of the 6 yeast levels and 2 basal diets resulted in 12 experimental feeds. These 12 feeds were then offered to the chicks in both all-mash and pelleted form for a total of 24 experimental treatments. The composition of a representative portion of the diets is shown in Table 5. Each treatment consisted of two replicate pens of 5 male and 5 female day-old broiler type chicks (Peterson X Peterson). The chicks were distributed at random into pens in electrically heated battery brooders

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tually no adhering feces, 2 a mild accumulation, 3 heavy accumulation, 4 a severe accumulation. The results of the screen scores (Table 4) indicate that pelleting the diets resulted in higher screen scores. Since chicks fed pelleted diets consumed more feed, especially at higher levels of yeast inclusion, this was to be expected. In relation to yeast content of the diet, no problem was encountered until levels greater than 15% yeast were fed. At 8 weeks of age, chicks fed the allmash diets with up to 15% hydrocarbon yeast protein grew as well as those fed the control diet (Table 2). There was some question as to the maximum effective level in pelleted feeds, as the weight of chicks fed the 25% level of yeast was reduced significantly below that of the control group, but the weight of chicks fed the diet with 30% yeast was statistically equal to that of the control group. These data again point out the effectiveness of pelleting in improving performance. Chicks fed pelleted diets with or without yeast were consistently superior in weight gains to those fed all-mash feeds. There were no significant differences in

P. W. WALDROUP, C. M. HILLARD AND R. J. MITCHELL

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TABLE 5.—Composition of typical chick diets containing i drocarbon yeast protein (Experiment 2) Percent of Diet

Ingredient

Total 1

0.00 32.44 0.00 2.SO 52.07 6.96 2.50 1.82 0.52 0.19 0.40 0.10 0.50

7.50 24.73 0.00 2.50 53.54 6.40 2.50 1.08 1.00 0.25 0.40 0.10 0.50

15.00 16.98 0.00 2.50 53.86 6.05 2.50 0.33 1.49 0.29 0.40 0.10 0.50

0.00 23.20 5.00 2.50 59.21 4.90 2.50 1.09 0.42 0.18 0.40 0.10 0.50

7.50 15.93 5.00 2.50 59.56 4.54 2.50 0.34 0.91 0.22 0.40 0.10 0.50

15.00 13.84 5.00 2.50 55.68 5.30 2.50 0.00 1.34 0.24 0.40 0.10 0.50

100.00

100.00

100.00

100.00

100.00

100.00

As outlined in Table 1.

with raised wire floors. At four weeks of age the chicks were transferred to unheated finishing batteries. The experimental diets and tap water were supplied ad libitum throughout the trial. Individual chick weights and group feed consumption were determined at four and eight weeks of age. The data were statistically analyzed as previously described. Results. The results of this study were in agreement with those of the first experiment. Chicks fed diets containing up to 15% hydrocarbon yeast grew as well or better than chicks fed the control diet. Again, the data for the corn-soy and fish meal diets were combined as there was no significant response to the presence of fish TABLE 6.—Body weights of chicks fed diets with hydrocarbon yeast protein {Experiment 2) Body weight (grams) 1

%

28 day

Yeast

56 day

Mash

Pellet

Av.

Mash

Pellet

Av.

0 2.5 5.0 7.5 10.0 15.0

5 0 5 ba ob 533abo 523 518abo 5 0 5 ba ob o 524

526ab0 497"b c 508 533ab S 1 3ab 0 549

516 b 515 b 516\ S26 a b 509 b 536 a

1437 a 1484 a 1446 a 1513" 1449 a 1475 a

1478" 1528 aa 1456 1518 a 1466 a 145 l a

1458 a 1506 a 1451" 1516 a 1458" 1463°

Av.

518

521

520

1467

1482

1475

1

Means having the same superscript do not differ significantly (P = 0 . 0 5 % )

meal in the diet or to a fish meal X yeast protein interaction. At four weeks of age, chicks fed the diets with 15% yeast protein were significantly larger than those fed the unsupplemented diet when all diets within level were combined, (Table 6). There was a pelleting X yeast level interaction which followed no particular pattern and was felt to have no meaningful effect. It did appear that slightly better performance was attained on diets containing higher levels of hydrocarbon yeast protein when the diets were pelleted, in agreement with the results of the first study. At eight weeks of age, however, there were no significant main effects or interactions observed in regard to body weight gains (Table 6). The same was true for efficiency of feed utilization at four and eight weeks of age (Table 7). Statistical analysis of the mortality data indicated that there were no significant differences among the various treatments that could be related to increases in level of hydrocarbon yeast protein. It can be concluded from the results of these two trials that single cell yeast protein grown in petroleum fractions has good nutritive quality and can be used in well balanced high energy broiler diets. Levels of 15% are acceptable in all-mash feeds.

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Yeast Soybean meal Fish meal Poultry by product Yellow corn Animal fat Alfalfa meal Dicalcium phosphate Limestone DL-methionine Salt Trace minerals1 Microingredients 1

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HYDROCARBON PROTEIN TABLE 7.—Efficiency of feed utilisation of chicks fed diets with hydrocarbon yeast protein (Experiment 2)

TABLE 8.—The response of chicks to diets containing hydrocarbon yeast protein when fed free choice or restricted (Experiment 3)

Feed:Gain Ratio1

% Yeast 0 2.5 5.0 7.5 10.0 15.0 Av. 1

W t . Gain (gm.) 2

0 -56 days

0-28 days Mash

Pellet

Av.

Mash

Pellet

Av.

1.86 1.82 1.89 1.84 1.91 1.87 1.86

1.86 1.87 1.90 1.81 1.86 1.75 1.75

1.86 1.84 1.89 1.82 1.89 1.81 1.81

2.07 2.07 2.05 2.06 2.04 2.03 2.05

2.06 2.06 2.03 2.02 2.04 2.04 2.04

2.06 2.06 2.04 2.04 2.04 2.03 2.95

No significant differences observed among treatments.

, Yeast

0 15 30 0 15 30

Feeding System 1

FF FF FF LF LF LF

7-24 days

Feed/ bird 2 (gm.)

325" 322" 275 b 263b 283 b 271"

570» 659" 534 b 479. 473° 474c

Feed/ gain 2 ratio

1.771.77* 2.00b 1.82» 1.73" 1.76 s

F F = Full-fed; LF = Limit-fed Means having the same superscript do not differ significantly (P = .05%).

EXPERIMENT 3

without yeast protein. At this time the chicks were weighed, randomly assigned to experimental compartments, and the controlled feeding started. The experiment continued until the chicks were 24 days of age at which time the trial was terminated. The data were analyzed as previously described.

Materials and Methods. The objective of this study was to determine if the reduced weight gains which occurred at high levels of yeast incorporation in the first experiment were due to reduced intake of feed or to some detrimental factor inherent in the yeast. Therefore, a controlled intake feeding trial was conducted. Three levels of yeast protein (0, IS, 30%) were incorporated into the diet of broiler chicks (Diets 1, 2 and 3 in Table 1). Each of the diets was fed on a freechoice intake basis to four battery pens of 5 male and 5 female broiler-chicks. The feed consumption of the chicks fed the diet with 30% yeast was determined each day at approximately the same time. Another series of chicks was designated as the limit-fed group. These chicks were also fed the diets with 0, IS or 30% hydrocarbon yeast but their daily intake was limited to 90% of the average consumption of the 30% full-fed group. Each of the limitfed diets was also fed to four battery pens of 5 male and S female chicks. Sufficient space was available so that all chicks could eat at once. All the diets were fed in mash form. For the first 7 days of age the chicks were full-fed a typical chick starter diet

2

Results. When the experimental diets were offered to the chicks on an ad libitum basis, there were no significant differences in body weight gains, average feed intake, or feed:gain ratios between chicks fed the diet with no yeast and those fed the diet with 15% yeast protein. However, body weights and feed intake were significantly reduced when 30% yeast was incorporated in the diet with a concomitant increase in the feed:grain ratio (Table 8). When feed intake was reduced to 90% of that consumed by the 30% yeast group fed ad libitum, there were no significant differences among the chicks fed diets with 0, IS or 30% yeast. This would appear to indicate that the problems associated with high level feeding of hydrocarbon yeast protein are due primarily to problems associated with feed intake, such as appearance, dustiness, separation, or other factors. While it may be questionable as to

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Higher levels can be used provided the diets are pelleted to reduce the problems of bulkiness.

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P. W. WALDROUP, C. M. HILLARD AND R. J. MITCHELL

whether yeast protein would be included at levels exceeding 15% due to factors such as sticky droppings or cost of product, these data would indicate that if such problems could be solved there would be no reason why hydrocarbon yeast protein would not be an acceptable dietary ingredient for broiler diets. SUMMARY

ACKNOWLEDGEMENTS

The authors express their thanks to the Gulf Research and Development Co., Pittsburgh, Pa., for providing the hydrocarbon yeast protein and for a grant-in-aid for support of these trials. The assistance of Mrs. Zelpha Johnson in the statistical analyses is greatly appreciated.

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Three broiler feeding trials have been conducted to study the nutritive value of yeast grown on high purity alkane fractions. Levels of up to 30% yeast were incorporated into high energy broiler diets. The experimental variables included the presence or absence of 5% Peruvian fish meal, pellet or mash diet form, and free choice or controlled intake. Excellent growth and feed utilization by broiler chicks was obtained on all-mash diets with 15% yeast. When the diets were fed in pelleted form to control the bulkiness of the diet resulting from the addition of the yeast material, higher levels were accepted, although resulting in the accumulation of feces on the floor screens in the battery brooders. Controlled intake comparisons revealed that when the diets were fed at sub-optimal intake levels chicks grew as well on allmash diets with 30% yeast as did those fed a control diet with no yeast protein. This indicates that the reduced performance associated with high dietary levels of hydrocarbon yeast protein are related to factors related to feed intake.

REFERENCES Arkansas Agricultural Extension Service, 1966. Suggested restrictions for poultry rations. X2638-6-65. Champagnat, A., 1967. Proteins from petroleum. World Petroleum, 38: 64-68. Champagnat, A. 1968. The biosynthesis of protein from petroleum. I. U. P. A. C. Conference on Modern Chemistry in Industry, Eastbourne, England, pp. 1-11. Chepigo, S. V., I. D. Boiko, A. D. Gololobor, A. P. Kruychkova, G. I. Vorobyeva, P. N. Fisher, V. K. Pokrovski and N. I. Korotchenko, 1967. The production and utilization of fodder yeasts grown on petroleum hydrocarbons. Proc. Seventh World's Petroleum Congress, pp. 73-99. Davis, J. B., 1956. Microbial decomposition of hydrocarbons. Ind. Eng. Chem. 48: 1444-1448. Duncan, D. B., 1955. Multiple range and multiple f tests. Biometrics, 11: 1-42. Foster, J. W., 1962. Hydrocarbons as substrates for microorganisms. Antonie van Leeuwenhoek 28: 271-274. Laine, B., 1967. Production and utilization of BP protein concentrate. Part I. The production of hydrocarbon-grown yeasts. Second International Conference on Global Impacts of Applied Microbiology, Addis Ababa. Llewelyn, D. A. B., 1967. The production of protein concentrate biomass from hydrocarbons. Microbiology. Proceedings of Conference held in London, England, pp. 63-84. Miller, T. L., and M. J. Johnson, 1966a. Utilization of gas oil by a yeast culture. Biotechnology Bioengineering, 8: 567-S80. Miller, T. L., and M. J. Johnson, 1966b. Utilization of normal alkanes by yeast. Biotechnology Bioengineering 8: 549-565. Shacklady, C. A., 1967, Production and utilization of BP protein concentrate. Part II. The use of hydrocarbon-grown yeasts in commercial type rations for pigs and poultry. Second International Conference on Global Impacts of Applied Microbiology, Addis Ababa. Shacklady, C. A., 1968. Single cell proteins, Nutritional value application and acceptability. Yeasts from gas oil. C. I. I. A. International Symposium on New Source of Proteins in Human Nutrition, Amsterdam. Shacklady, C. A., 1969. The production and evaluation of protein derived from organisms grown on hydrocarbon residues. Proc. Nutr. Soc. 28: 91-97. Shacklady, C. A., and P. van der Wal, 1968. The use of hydrocarbon-grown yeasts in feeds for

HYDROCARBON PROTEIN growing pigs. Second World Conference on Animal Production. College Park, Maryland. Spies, J. R., and D. C. Chambers, 1948. The chemical determination of tryptophan. Anal. Chem. 20:30-39. Steel, R. G. D., and J. H. Torrie, 1960. Principles

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and Procedures of Statistics. McGraw-Hill Book Co., New York. Waldroup, P. W., W. W. Abbott, T. E. Bowen and V. E. Tollett, 1969. The influence of dietary alterations on the utilization of soft phosphate in broiler diets. Poultry Sci. 48: 578-585.

Ferritin in the Plasma of Birds With Erythroblastosis

(Received for publication October 28, 1970)

collected by cardiac puncture, using Vacu1 VIAN erythroblastosis (Eb) is a virus- tainer tubes, from birds of both sexes • induced disease of chickens charac- varying in age from 5-12 weeks old. terized by the presence of large numbers of Plasma was separated from these blood primitive red cells in the circulating blood samples by centrifugation, 1000 r.p.m. for 10 minutes in an SVB size 1, International stream (Darcel, 1960). Centrifuge. Care was taken to use birds of Preliminary studies had suggested disthe same age when comparing the techturbances in iron metabolism in Eb. When 59 niques or variables. leukemic (Eb) blood is incubated with Fe Fowl ferritin: Preparation of fowl ferrithere is incorporation into material with tin (F.F.) was undertaken in two different electrophoretic characteristics of fowl ferways. The first procedure was that of ritin instead of into hemoglobin. The Granick (1943) in which the livers were plasma of birds in the terminal stages of homogenized with 0.005M MgCl 2 and Eb shows the presence of additional plasma heated to 80°C. followed by further fraciron (Darcel and Bather, 1964) and it was tionation with ammonium sulphate. suspected that this might also be ferritin. Ferritin was also prepared by homogeThis paper shows that much of the iron nizing different tissues (liver, bone marrow, present in Eb plasma is not bound to transspleen and hemolysates) with Tris buffer ferrin and that it is likely present in mole(0.01 M pH 7.5), adding an equal volume cules of ferritin, probably coated with a of 20% sucrose (Gabuzda and Pearson, plasma protein. 1969) and recovering the ferritin by differential ultracentrifugation (Penders et al., EXPERIMENTAL 1968). Virus: Engelbreth-Holm's strain R virus In both cases tissue ferritin levels were (Eckert et al., 1956) was used to infect raised by administering subcutaneously 0.5 birds of the East Lansing Line 15 I White 2 ml. iron-dextran 24-72 hours prior to Leghorns. Birds were judged leukemic by slaughter. their symptoms and by recognition of primPlasma iron concentrates: Partial purifiitive cells in unstained blood films exam1 ined by phase microscopy. Becton, Dickinson, Clarkson, Ont. 2 Stevenson, Turner and Boyce, Guelph, Ont. Plasma samples: Blood samples were INTRODUCTION

A

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C. LE Q. DARCEL AND MOHENDRA J. G. S. MERRIMA'N Animal Pathology Division, Health of Animals Branch, Canada Department of Agriculture, Animal Diseases Research Institute (Western), Box 640, Lethbridge, Alberta, Canada