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Nutritional Qualities of Stabilized and Raw Rice Bran for Chicks
Nutritional Qualities of Stabilized and Raw Rice Bran for Chicks R. N. SAYRE,' L. EARL,2 F. H. KRATZER,2 and R. M. SAUNDERS1 Western Regional Research Center, Agricultural Research Service, US Department of Agriculture, Albany, California 94710 and Department of Avian Science, University of California, Davis, California 95616 (Received for publication October 28, 1985)
1987 Poultry Science 66:493-499 INTRODUCTION
Large quantities of rice bran are available in many parts of the world as a by-product of the rice milling industry. Much rice bran is used as animal feed and a small portion is extracted for oil production. The fat-free residue is also available for feeding. Hull-free rice bran contains many nutrients, such as 20% oil, 15% protein, 45% nitrogen-free extract, vitamins, and minerals. Conversely, rice bran has been reported to contain protease inhibitors and hemagglutinins (Barber and Benedito de Barber, 1978; Benedito de Barber and Barber, 1978). Digestive disorders have been reported when bran containing deteriorated oil was fed (Yokochi, 1972; Subrahmanyan, 1977). Due to the potential for edible oil production from rice bran, a process was developed to stabilize the bran and prevent enzymatic hydrolysis of the oil (Randall et al, 1985). This stabilization process heats the freshly milled bran in an extrusion cooker to 130 C. The hot extruded bran is maintained at near 100 C on
'Western Regional Research Center. department of Avian Science.
493
an insulated holding belt for 3 min prior to cooling in an ambient air stream. The processed rice bran is in the physical form of small, free flowing flakes with a low microbiological load. Lipolytic enzymes are permanently inactivated (Randall et al., 1985), and the extracted bran residue retains the flake form thereby reducing dust and fines. These changes from raw rice bran suggested improved utilization of rice bran as a food or feed ingredient. Feeding studies were conducted to compare stabilized and raw rice bran.
MATERIALS AND METHODS
Experiments were designed to test the effects of stabilization, extraction, and storage on the nutritional quality of rice bran. Hybrid meat strain, male chicks were placed on experimental diets at 1 day of age and were fed for 25 days. Four experiments (A through D) were conducted at approximately 6-week intervals. Each treatment was replicated by four pens of six birds each in each experiment. Replicate pens were randomly positioned in electrically heated batteries with raised wire floors. Rice bran for all four experiments was collected at one time from one stabilization run.
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ABSTRACT Rice bran either raw or processed in an extrusion cooker at 130 C was fed to meat strain chickens for 25 days after hatch. Either full fat or hexane-extracted rice bran was placed in the diet at the equivalent of 60% full fat bran. Raw full fat bran for one diet was stored at -23 C until fed, whereas rice bran for all other diets was stored at 32 C. Four experiments were conducted at 6-week intervals. Free fatty acid (FFA) content in oil from raw rice bran stored at the elevated temperature reached 81% by the start of the final experiment whereas FFA in stabilized bran oil remained at about 3%. Chickens fed stabilized rice bran made significantly greater gains than chickens fed raw bran diets. Feed efficiency was superior for chickens fed either full fat or extracted stabilized bran compared with full fat bran stored at either 32 or -23 C. Feed conversion for extracted raw bran was intermediate between stabilized bran and full fat raw bran. Raw bran stored at 32 C (with elevated FFA content) tended to produce lower gains than the frozen raw bran. Analysis of the combined data from all four trials indicated that raw bran held at 32 C produced the lowest gains among all of the diets. (Key words: rice bran, chicken, nutrition, growth)
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SAYRE ET AL.
spleen were measured. The free fatty acid (FFA) content of the oil was measured as described by Randall et al. (1985). Experimental data were subjected to analysis of variance (ANOVA), and when an interaction was found, the interaction mean square was used as the error term. Pen means for weight gain were used for ANOVA of the combined experiments. Means different at the 5% level of probability were identified by Duncan's multiple range test (Steel and Torrie, 1960). Weight gain and feed consumption data are presented on a per bird basis. Feed data were calculated on an "as is" moisture basis, but recalculation checks on dry basis did not produce any significant changes in relationship among the treatment effects. RESULTS
Full fat rice bran used in these experiments contained 21% extractable lipid on a dry weight basis. Lipid in the solvent extracted bran was reduced to .03%. The FFA contents of oil in the three full fat bran samples at the beginning of each experiment are presented in Table 4. Only a small increase of FFA (<2%) took place in frozen raw bran (Treatment 1), and there was essentially no change of FFA in oil from
TABLE 1. Composition of the commercial chick starter-control diet Ingredient
(%) Corn Soybean meal Cottonseed meal Meat and bone meal Limestone Phosphate NaCl DL Methionine Vitamin and mineral mix 1 Yeast mix Fat Total
60.43 25.33 5.17 3.58 .84 1.92 .32 .08 1.25 .83 .25 100.00
1 Premix provides per kilogram diet: vitamin A, 9,000 IU; vitamin D 3 ; 2,800 ICU; vitamin E, 10 mg; menadione SBC, 3.4 mg; vitamin B 1 2 , .013 mg; niacin, 34 mg; riboflavin, 4.5 mg; Ca pantothenate, 9 mg; folic acid, .6 mg; pyridoxine, 2.3 mg; thiamine HC1, 1.3 mg; choline CI, 400 mg; manganous oxide, 316 mg; zinc oxide, 264 mg; iron sulfate, 189 mg; copper sulfate, 19 mg; KI, 14 mg; cobalt carbonate, 1 mg; selenium, .1 mg; ethoxyquin, 125 mg.
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Raw bran was collected from the hopper of the extruder during operation and within 10 min after milling. Raw bran was placed in -23 C storage within 5 hr after milling. Portions of both raw and stabilized rice bran were extracted with hexane at about 65 C in a recirculating extractor. The control diet (Table 1) and ingredients for the basal mixture (Table 2) to be added to the 60% rice bran diets were obtained prior to the start of the first experiment and stored at 2 C until the diets were mixed at the start of each experiment. Metabolizable energy (ME) of rice bran was measured by the method of Chami et al. (1980). Crude protein was calculated as Kjeldahl N x 5.95 (Juliano, 1972). Six treatments were used (Table 3) and the equivalent of full fat rice bran made up 60% of all diets except the control. When extracted rice bran was used, soybean oil was added to replace the extracted rice bran oil. Raw rice bran was used in Treatment 1 and was stored at -23 C until mixed into the diet. The diet was then stored at -23 C until placed in the feeders. Raw rice bran for Treatment 2 was stored at 32 C until mixed with the complete diet at the beginning of each experiment. The mixed diet was stored at ambient temperature. Extracted raw bran was used in Treatment 3 and stored the same as in Treatment 2 until mixed. After mixing, the diet was stored at -23 C until placed in the feeders in order to prevent enzymatic hydrolysis of the added soybean oil. Stabilized, full fat rice bran was used in Treatment 4, and stabilized, extracted rice bran with added soybean oil was used in Treatment 5. Rice bran and mixed diets for both of these treatments were stored as indicated for Treatment 2. The control diet in Treatment 6 was a commercial chick starter, which was used for a standard among experiments rather than for comparison with the rice bran diets. Rice bran used in the experiments contained 3090 kcal/kg apparent ME, 12.8% protein, and 7.0 crude fiber. The stabilization process did not affect the ME value. Rice bran diets were calculated to contain 2940 kcal/kg ME, 22.4% protein, and 5.8% crude fiber. Bulk density of these diets was .6 g/ml. The control diet contained 3,050 kcal/kg ME, 22.0% protein, and 4.0% crude fiber. The bulk density of this diet was .7 g/ml. Individual bird weights and feed consumption per pen were determined twice weekly. At the termination of each experiment, the birds were killed and weights of the liver, pancreas, and
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STABILIZED AND RAW RICE BRAN TABLE 2. Composition of the basal mixture added to 60% rice bran diets Ingredient
(%) Soybean meal Meat and bone meal Soybean oil NaCl Corn DL-Methionine Vitamin and mineral mix 1
15.00 15.00 2.50 .20 6.15 .15 1.00
Total
40.00
stabilized bran (Treatment 4). The FFA in raw full fat bran stored at 32 C (Treatment 2) was already high at the start of the second experiment and increased only slightly between Experiment C and D. Raw, full fat, high temperature storage
TABLE 3. Composition and storage temperatures of the experimental rations
Ingredient
Ingredient storage temperature
Treatment
(C)
Raw rice bran Raw rice bran Extracted raw rice bran Stabilized rice bran Extracted stabilized rice bran Soybean oil Basal mixture Control diet Mixed diet storage temperature, C % Protein % Crude fiber Metabolizable energy, kcal/kg Bulk density, g/ml
-23 32 32 32 32
2 2
602
60 48
60 40
40
12 40
40
12 40
2
100 -23
24
23
24
24
24
22.4
22.0
5.8
4.0
2,940
3,050
1 1 , Rawbran in frozen storage; 2, raw bran in high temperature storage; 3, raw bran oil extracted;4, stabilized bran in high temperature storage; 5, stabilized bran oil extracted; and 6, control diet. 2
Percent of diet.
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1 Premix provides per kilogram diet: vitamin A, 6,000 IU; vitamin D 3 , 1,200 ICU; vitamin E, 136.25 mg; choline CI, 800 mg; niacin, 70 mg; Ca pantothenate, 15 mg; menadione Na bisulfite, 4 mg; riboflavin, 8 mg ; biotin, 75 Mg; folic acid, 2 mg; vitamin B 1 2 , 10 Mg; pyridoxine, 4 mg; ethoxyquin, 187.5 mg; MnSO„, 250 mg; MgS0 4 , 2 g; ZnO, 70 mg; FeS0 4 • 7 H 2 0 , 32.7 mg; CuS0 4 -5 H 2 0 , 10 mg; NaMo0 4 , 2 mg; Co-Acetate, .6 mg; Na2 Se0 3 , .1 mg; KI, 2 mg.
bran (Treatment 2) used in Experiment D had a pungent, almost sour odor at room temperature. After drying overnight at 110 C the odor was not rancid. Stabilized full fat bran (Treatment 4) had developed a somewhat strong odor by the start of Experiment D and after being dried overnight at HOC, it had a definite rancid odor. Storage of full fat rice bran at 32 C and the associated changes in oil quality over the nearly 5-month period required for the four experiments did not appear to have a major influence on chick weight gain or feed consumption. There was no progressive change among experiments in either of these factors from the first to the last experiment. Within experiments, some changes with time were observed among treatments from the first to the last experiment. Birds in Treatment 2, which were fed raw rice bran stored at elevated temperature (32 C), had gains and feed consumption similar to those in Treatment 1 (frozen raw bran) for Experiment A (Tables 5 and 6) when the FFA content in both diets was similar (Table 4). However, both gain and feed consumption tended to be lower for Treatment 2 than for Treatment 1 in the three subsequent experiments when the FFA content of the bran oil had reached a high level.
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SAYRE ET AL. TABLE 4. Free fatty acid content of oil in rice bran of Treatments 1, 2, and 4 Treatment
Experiment
1
A B C D
4.9* 5.1 7.3 6.6
2.7 3.4 3.3 3.4
9.2 62.9 77.8 80.9
1 1, Raw bran in frozen storage; 2, raw bran in high temperature storage; 4, stabilized bran in high temperature storage. 2
Expressed as percent oleic acid.
Feed consumption (Table 6) by birds in Treatment 1 (frozen raw bran) was similar to Treatments 4 and 5 (stabilized bran) through all four experiments. Pooled data for all experiments indicated that birds fed raw bran stored at 32 C consumed less feed than birds fed stabilized bran and that less full fat, raw bran was consumed when stored at 32 C than when stored frozen. Consumption of extracted raw bran (Treatment 3) was similar to both of the other two raw bran containing diets but less than diets containing stabilized bran. The cumulative quantity of feed required per unit gain of bird weight (Table 7) was significantly less for Treatments 4 and 5 (stabilized rice bran diets) than for the other treatments. Birds fed the extracted raw rice bran diet (Treatment 3) had an intermediate feed efficiency. Both full fat raw bran diets (Treatments 1 and
TABLE 5. Influence of treatments on body weight gain per bird (g) in Experiments A, B, C, and D and in combined experiments Experiment Treatment1
A
B
C
D
Combined
1 2
463 463 474 540 572 616 ± 17
460 414 444 576 551 554 ± 23
483 451 500 581 613 633 ± 17
514 437 501 572 607 608 ± 14
480c 441 d 480c 568b 586ab 603a ± 9
3 4 5 6 SE2
Means followed by different superscripts are different (P<.05). 1
1 , Raw bran in frozen storage;2, raw bran in high temperature storage;3, raw bran oil extracted;4, stabilized bran in high temperature storage; 5, stabilized bran oil extracted; and 6, control diet. 2
Pooled standard error of the mean.
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Cumulative weight gains (Table 5) were similar for both the stabilized full fat rice bran and stabilized extracted rice bran (Treatment 4 and 5) diets. The three raw bran diets produced significantly lower weight gains than Treatments 4, 5, and 6. Treatments 1 and 3 with either frozen or extracted raw bran were similar, whereas Treatment 2, with raw rice bran stored at high temperature, produced the lowest cumulative gains (P<.05) when all experiments were combined. When gains were calculated on a daily basis, the results were similar except for the 4-day period prior to the final weight measurement. During this final period the rate of gain for both of the stabilized bran diets dropped slightly and the rate of gain for birds on the high temperature storage, full fat raw rice bran increased to be the same as the other two raw rice bran treatments.
STABILIZED AND RAW RICE BRAN
497
TABLE 6. Effect of treatments on feed consumption per bird (g) in Experiments A, B, C, and D and in the combined experiments
Treatment 1 1 2 3 4 5 6 SE 2
A
B
C
D
860 861 841 857 893 1,175 ± 19
827 773 772 899 835 1,038 ± 34
883 815 848 939 958 1,263 ± 24
963 824 851 921 936 1,149 ± 29
Combined 883bc 818d 828cd 904 b 905b l,156 a ± 20
a—d
2) were similar in feed efficiency and required the greatest amount of feed per unit gain of any of the bran diets. The control diet, which produced gains similar to diets containing stabilized bran, was similar to the full fat, raw bran diets in feed efficiency. When feed efficiency was calculated on a periodic basis, efficiency improved during the latter part of the experiment for diets containing raw bran, and all diets containing rice bran were similar in feed efficiency during the last 4 days of the experiment. Liver weight, as percentage of live weight, was significantly lower in Treatment 5 (extracted, stabilized bran) than in all other treatments (Table 8), and Treatment 4 (stabilized bran) resulted in significantly lower liver
weights than Treatments 1, 2 (raw, full fat bran, low and high temperature storage), and 6 (control). Diets containing raw full fat bran produced significant pancreatic hypertrophy compared with stabilized rice bran diets; Treatment 2 (raw, full fat, high temperature storage) caused the greatest increase. Treatment 5 with extracted stabilized rice bran produced the smallest pancreas weights. Treatments did not affect spleen weights (data not shown). DISCUSSION
Although storage time and FFA accumulation did not show a marked progressive effect from experiment to experiment on chick performance,
TABLE 7. The effect of treatments on feed per unit gain in Experiments A, B, C, and D and for the combined experiments Treatment 1
A
1 2 3 4 5 6 SE2
1.86 1.86 1.78 1.58 1.56 1.91 + .04
B 1.80 1.87 1.75 1.56 1.52 1.88 + .06
C
D
Combined
1.83 1.81 1.70 1.62 1.56 2.00 ± .04
1.86 1.90 1.70 1.61 1.54 1.89 ± .05
1.84 b 1.86 a b 1.73 c 1.59 d 1.55 d 1.92" ± .02
a—d Means followed by different superscipts are different (P<.05). 1 , Raw bran in frozen storage; 2, raw bran in high temperature storage; 3, raw bran oil extracted; 4, stabilized bran in high temperature storage; 5, stabilized bran oil extracted; and 6, control diet. 2 Pooled standard error of the mean. 1
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Means followed by different superscripts are different (P<.05). 1 , Raw bran in frozen storage; 2, raw bran in high temperature storage; 3, raw bran oil extracted; 4, stabilized bran in high temperature storage; 5, stabilized bran oil extracted; and 6, control diet. 2 Pooled standard error of the mean. 1
498
SAYRE ET AL. TABLE 8. The influence of treatments on liver and pancreas weight
Treatment 1
Liver weight
1 2 3 4 5 6 SE 2
32.7a 32.4 a 31.7ab 31.3 b 29.0 C 32.6 a ± .4
Pancreas weight (g/kg live weight) 3.64 b 3.90 a 3.49 c 3.13 d 2.95 e 3.44 c ± .05
' 1, Raw bran in frozen storage; 2, raw bran in high temperature storage; 3, raw bran oil extracted; 4, stabilized bran in high temperature storage; 5, stabilized bran oil extracted; and 6, control diet. 2
Pooled standard error of the mean.
there did appear to be some negative effect. Most of the formation of FFA took place between Experiments A and B with only small changes thereafter. These effects were small compared with the increase in weight gain resulting from the stabilization process. Hussein and Kratzer (1982) found that addition of ethylenediaminetetraacetate to freshly milled raw rice bran retarded oil hydrolysis and significantly increased chick weight gain. They attributed the increased gain to retardation of FFA formation. Reports from tropical climates indicated that degraded oil in stored raw rice bran caused digestive disturbances when fed to livestock (Yokochi, 1972; Subrahmanyan, 1977). Conversely, Scott et al. (1976) stated that hydrolitic rancidity did not interfere with the nutritional value of fat, and Kratzer and Payne (1976) reported similar gains from chicks fed rice bran containing widely varying amounts of FFA. These findings indicate that some additional factors independent from FFA accumulation may be responsible for growth retardation resulting from consumption of deteriorating rice bran. Possibly mycotoxins may develop under certain storage conditions and they may be reduced or destroyed by treatments that also prevent oil breakdown. The lower liver weights in birds fed stabilized bran, particularly extracted stabilized bran, indicate that the stabilization process may either prevent some stimulus for tissue hypertrophy or reduce fat deposition in the liver. However, none of the livers appeared to be fatty and no unhealthy appearing livers could be associated with any particular treatment. Majun and Payne
(1977) reported that liver weight of laying hens fed autoclaved rice bran were significantly lower than those from hens fed raw rice bran. The consistent finding of reduced pancreatic weight in birds fed stabilized bran compared with those of birds fed raw bran is in agreement with the finding of Kratzer et al. (1974) that autoclaving prevented a large proportion of the pancreatic hypertrophy produced by raw rice bran. Pancreatic weight appeared to be associated with the amount of processing to which the bran had been subjected. Extracted raw bran produced a lower weight than full fat bran, and extraction of stabilized bran further reduced pancreatic weight below that resulting from stabilizing alone. The pancreatic weight of birds fed stabilized bran was even lower than that of birds fed the control diet. Kratzer and Payne (1977) reported that trypsin inhibitor was somewhat resistant to denaturation and retained a portion of its original activity after heat treatments sufficient to destroy growth limiting factors. Their conclusion was that growth retardation components in rice bran were not related to trypsin inhibitor and pancreatic hypertrophy. The greater weight gains produced by stabilized bran compared with raw bran were even more impressive, considering that the 60% stabilized bran diets produced gains similar to the 60% corn, commercial chick starter diet. This gain was produced on 20% less feed than the control diet, resulting in a significant improvement in the feed:gain ratio. Cumulative feed efficiency of rice bran diets for the first 25 days after hatch reflected treatment effects on pancreatic weight. Extracted raw bran was inter-
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Means followed by different superscripts are different at the 5% level of probability.
STABILIZED AND RAW RICE BRAN
ACKNOWLEDGMENTS
This work was supported in part by funding from the AID Office of Nutrition through an OICD RSSA Agreement, SEA-12-14-50016478. The authors express their appreciation to R. Fong and J. Labat for technical assistance and to B. Mackey for advice in statistical analysis of data. Reference to a company or product named by the Department is only for purposes of information and does not imply approval or recommendation of the product to the exclusion of others that may also be suitable.
REFERENCES Barber, S., C. Benedito de Barber, M. J. Flores, and J. J. Montes, 1978. Toxic constituents of rice bran. I. Trypsin inhibitor activity of raw and heat-treated bran. Rev. Agroquim. Tecnol. Aliment. 18(l):80-88. Benedito de Barber, C , and S. Barber, 1978. Toxic constituents of rice bran. II. Hemagglutinating activity of raw and heat-treated bran. Rev. Agroquim. Tecnol. Aliment. 18(l):89-94. Chami, D. B., P. Vohra, and F. H. Kratzer, 1980. Evaluation of a method for determination of true metabolizable energy of feed ingredients. Poultry Sci. 59:569571. Hussein, A. S., andF. H. Kratzer, 1982. Effect of rancidity on the feeding value of rice bran in chickens. Poultry Sci. 61:2450-2455. Juliano, B. O., 1972. Page 38 in: Rice Chemistry and Technology. D. F. Houston, ed. Am. Assoc. Cer. Chem., St. Paul, MN. Kratzer, F. H., L. Earl, and C. Chiaravanont, 1974. Factors influencing the feeding value of rice bran for chickens. Poultry Sci. 53:1795-1800. Kratzer, F. H., and C. G. Payne, 1977. Effect of autoclaving, hot-water treating, parboiling and addition of ethoxyquin on the value of rice bran as a dietary ingredient for chickens. Br. Poult. Sci. 18:475^182. Majun, G. K., and C. G. Payne, 1977. Autoclaved rice bran in layer's diets. Br. Poult. Sci. 18:201-203. Randall, J. M., R. N. Sayre, W. G. Schultz, R. Y. Fong, A. P. Mossman, R. E. Tribelhorn, and R. M. Saunders, 1985. Rice bran stabilization by extrusion cooking for extraction of edible oil. J. Food Sci. 50:361364. Scott, M. L., M. C. Nesheim, and R. J. Young, 1976. Nutrition of the Chicken. M. L. Scott and Assoc, Ithaca, NY. Steel, R.G.D., and J. H. Torrie, 1960. Principles and Procedures of Statistics. McGraw-Hill Book Co., Inc., New York, NY. Subrahmanyan, V., 1977. Improved method of processing and milling of paddy for production of more rice and oil in Tamil Nadu. Paddy Processing Res., Tiruvarur, India. Yokochi, K., 1972. Rice bran processing for the production of rice-bran oil and rice-bran protein meal. ID/WG 120/9 UNIDO, Vienna.
Downloaded from http://ps.oxfordjournals.org/ at Kainan University on April 22, 2015
mediate between stabilized bran and the full fat, raw bran. Inspection of the feed per unit gain at different periods in the experiment and, to some extent, the daily gain indicated that some changes in feed utilization were taking place near the end of the 25-day feeding period. After 18 days, feed efficiency began to improve for all three raw bran diets when calculated for individual weight periods. During the last 4 days of the experiment, all rice bran diets were similar in feed efficiency. This change was more the result of a change in rate of gain than from a change in feed consumption. Rate of gain for all the raw bran diets increased, and the greatest increase was found in Treatment 2, the full fat raw bran stored at high temperature. The reason for the weight gain change registered during the last few days by the raw bran is unknown. Apparently the more mature chick was able to overcome the growth inhibitory factors present in the raw bran.
499
1987 Poultry Science 66:493-499 INTRODUCTION
Large quantities of rice bran are available in many parts of the world as a by-product of the rice milling industry. Much rice bran is used as animal feed and a small portion is extracted for oil production. The fat-free residue is also available for feeding. Hull-free rice bran contains many nutrients, such as 20% oil, 15% protein, 45% nitrogen-free extract, vitamins, and minerals. Conversely, rice bran has been reported to contain protease inhibitors and hemagglutinins (Barber and Benedito de Barber, 1978; Benedito de Barber and Barber, 1978). Digestive disorders have been reported when bran containing deteriorated oil was fed (Yokochi, 1972; Subrahmanyan, 1977). Due to the potential for edible oil production from rice bran, a process was developed to stabilize the bran and prevent enzymatic hydrolysis of the oil (Randall et al, 1985). This stabilization process heats the freshly milled bran in an extrusion cooker to 130 C. The hot extruded bran is maintained at near 100 C on
'Western Regional Research Center. department of Avian Science.
493
an insulated holding belt for 3 min prior to cooling in an ambient air stream. The processed rice bran is in the physical form of small, free flowing flakes with a low microbiological load. Lipolytic enzymes are permanently inactivated (Randall et al., 1985), and the extracted bran residue retains the flake form thereby reducing dust and fines. These changes from raw rice bran suggested improved utilization of rice bran as a food or feed ingredient. Feeding studies were conducted to compare stabilized and raw rice bran.
MATERIALS AND METHODS
Experiments were designed to test the effects of stabilization, extraction, and storage on the nutritional quality of rice bran. Hybrid meat strain, male chicks were placed on experimental diets at 1 day of age and were fed for 25 days. Four experiments (A through D) were conducted at approximately 6-week intervals. Each treatment was replicated by four pens of six birds each in each experiment. Replicate pens were randomly positioned in electrically heated batteries with raised wire floors. Rice bran for all four experiments was collected at one time from one stabilization run.
Downloaded from http://ps.oxfordjournals.org/ at Kainan University on April 22, 2015
ABSTRACT Rice bran either raw or processed in an extrusion cooker at 130 C was fed to meat strain chickens for 25 days after hatch. Either full fat or hexane-extracted rice bran was placed in the diet at the equivalent of 60% full fat bran. Raw full fat bran for one diet was stored at -23 C until fed, whereas rice bran for all other diets was stored at 32 C. Four experiments were conducted at 6-week intervals. Free fatty acid (FFA) content in oil from raw rice bran stored at the elevated temperature reached 81% by the start of the final experiment whereas FFA in stabilized bran oil remained at about 3%. Chickens fed stabilized rice bran made significantly greater gains than chickens fed raw bran diets. Feed efficiency was superior for chickens fed either full fat or extracted stabilized bran compared with full fat bran stored at either 32 or -23 C. Feed conversion for extracted raw bran was intermediate between stabilized bran and full fat raw bran. Raw bran stored at 32 C (with elevated FFA content) tended to produce lower gains than the frozen raw bran. Analysis of the combined data from all four trials indicated that raw bran held at 32 C produced the lowest gains among all of the diets. (Key words: rice bran, chicken, nutrition, growth)
494
SAYRE ET AL.
spleen were measured. The free fatty acid (FFA) content of the oil was measured as described by Randall et al. (1985). Experimental data were subjected to analysis of variance (ANOVA), and when an interaction was found, the interaction mean square was used as the error term. Pen means for weight gain were used for ANOVA of the combined experiments. Means different at the 5% level of probability were identified by Duncan's multiple range test (Steel and Torrie, 1960). Weight gain and feed consumption data are presented on a per bird basis. Feed data were calculated on an "as is" moisture basis, but recalculation checks on dry basis did not produce any significant changes in relationship among the treatment effects. RESULTS
Full fat rice bran used in these experiments contained 21% extractable lipid on a dry weight basis. Lipid in the solvent extracted bran was reduced to .03%. The FFA contents of oil in the three full fat bran samples at the beginning of each experiment are presented in Table 4. Only a small increase of FFA (<2%) took place in frozen raw bran (Treatment 1), and there was essentially no change of FFA in oil from
TABLE 1. Composition of the commercial chick starter-control diet Ingredient
(%) Corn Soybean meal Cottonseed meal Meat and bone meal Limestone Phosphate NaCl DL Methionine Vitamin and mineral mix 1 Yeast mix Fat Total
60.43 25.33 5.17 3.58 .84 1.92 .32 .08 1.25 .83 .25 100.00
1 Premix provides per kilogram diet: vitamin A, 9,000 IU; vitamin D 3 ; 2,800 ICU; vitamin E, 10 mg; menadione SBC, 3.4 mg; vitamin B 1 2 , .013 mg; niacin, 34 mg; riboflavin, 4.5 mg; Ca pantothenate, 9 mg; folic acid, .6 mg; pyridoxine, 2.3 mg; thiamine HC1, 1.3 mg; choline CI, 400 mg; manganous oxide, 316 mg; zinc oxide, 264 mg; iron sulfate, 189 mg; copper sulfate, 19 mg; KI, 14 mg; cobalt carbonate, 1 mg; selenium, .1 mg; ethoxyquin, 125 mg.
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Raw bran was collected from the hopper of the extruder during operation and within 10 min after milling. Raw bran was placed in -23 C storage within 5 hr after milling. Portions of both raw and stabilized rice bran were extracted with hexane at about 65 C in a recirculating extractor. The control diet (Table 1) and ingredients for the basal mixture (Table 2) to be added to the 60% rice bran diets were obtained prior to the start of the first experiment and stored at 2 C until the diets were mixed at the start of each experiment. Metabolizable energy (ME) of rice bran was measured by the method of Chami et al. (1980). Crude protein was calculated as Kjeldahl N x 5.95 (Juliano, 1972). Six treatments were used (Table 3) and the equivalent of full fat rice bran made up 60% of all diets except the control. When extracted rice bran was used, soybean oil was added to replace the extracted rice bran oil. Raw rice bran was used in Treatment 1 and was stored at -23 C until mixed into the diet. The diet was then stored at -23 C until placed in the feeders. Raw rice bran for Treatment 2 was stored at 32 C until mixed with the complete diet at the beginning of each experiment. The mixed diet was stored at ambient temperature. Extracted raw bran was used in Treatment 3 and stored the same as in Treatment 2 until mixed. After mixing, the diet was stored at -23 C until placed in the feeders in order to prevent enzymatic hydrolysis of the added soybean oil. Stabilized, full fat rice bran was used in Treatment 4, and stabilized, extracted rice bran with added soybean oil was used in Treatment 5. Rice bran and mixed diets for both of these treatments were stored as indicated for Treatment 2. The control diet in Treatment 6 was a commercial chick starter, which was used for a standard among experiments rather than for comparison with the rice bran diets. Rice bran used in the experiments contained 3090 kcal/kg apparent ME, 12.8% protein, and 7.0 crude fiber. The stabilization process did not affect the ME value. Rice bran diets were calculated to contain 2940 kcal/kg ME, 22.4% protein, and 5.8% crude fiber. Bulk density of these diets was .6 g/ml. The control diet contained 3,050 kcal/kg ME, 22.0% protein, and 4.0% crude fiber. The bulk density of this diet was .7 g/ml. Individual bird weights and feed consumption per pen were determined twice weekly. At the termination of each experiment, the birds were killed and weights of the liver, pancreas, and
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STABILIZED AND RAW RICE BRAN TABLE 2. Composition of the basal mixture added to 60% rice bran diets Ingredient
(%) Soybean meal Meat and bone meal Soybean oil NaCl Corn DL-Methionine Vitamin and mineral mix 1
15.00 15.00 2.50 .20 6.15 .15 1.00
Total
40.00
stabilized bran (Treatment 4). The FFA in raw full fat bran stored at 32 C (Treatment 2) was already high at the start of the second experiment and increased only slightly between Experiment C and D. Raw, full fat, high temperature storage
TABLE 3. Composition and storage temperatures of the experimental rations
Ingredient
Ingredient storage temperature
Treatment
(C)
Raw rice bran Raw rice bran Extracted raw rice bran Stabilized rice bran Extracted stabilized rice bran Soybean oil Basal mixture Control diet Mixed diet storage temperature, C % Protein % Crude fiber Metabolizable energy, kcal/kg Bulk density, g/ml
-23 32 32 32 32
2 2
602
60 48
60 40
40
12 40
40
12 40
2
100 -23
24
23
24
24
24
22.4
22.0
5.8
4.0
2,940
3,050
1 1 , Rawbran in frozen storage; 2, raw bran in high temperature storage; 3, raw bran oil extracted;4, stabilized bran in high temperature storage; 5, stabilized bran oil extracted; and 6, control diet. 2
Percent of diet.
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1 Premix provides per kilogram diet: vitamin A, 6,000 IU; vitamin D 3 , 1,200 ICU; vitamin E, 136.25 mg; choline CI, 800 mg; niacin, 70 mg; Ca pantothenate, 15 mg; menadione Na bisulfite, 4 mg; riboflavin, 8 mg ; biotin, 75 Mg; folic acid, 2 mg; vitamin B 1 2 , 10 Mg; pyridoxine, 4 mg; ethoxyquin, 187.5 mg; MnSO„, 250 mg; MgS0 4 , 2 g; ZnO, 70 mg; FeS0 4 • 7 H 2 0 , 32.7 mg; CuS0 4 -5 H 2 0 , 10 mg; NaMo0 4 , 2 mg; Co-Acetate, .6 mg; Na2 Se0 3 , .1 mg; KI, 2 mg.
bran (Treatment 2) used in Experiment D had a pungent, almost sour odor at room temperature. After drying overnight at 110 C the odor was not rancid. Stabilized full fat bran (Treatment 4) had developed a somewhat strong odor by the start of Experiment D and after being dried overnight at HOC, it had a definite rancid odor. Storage of full fat rice bran at 32 C and the associated changes in oil quality over the nearly 5-month period required for the four experiments did not appear to have a major influence on chick weight gain or feed consumption. There was no progressive change among experiments in either of these factors from the first to the last experiment. Within experiments, some changes with time were observed among treatments from the first to the last experiment. Birds in Treatment 2, which were fed raw rice bran stored at elevated temperature (32 C), had gains and feed consumption similar to those in Treatment 1 (frozen raw bran) for Experiment A (Tables 5 and 6) when the FFA content in both diets was similar (Table 4). However, both gain and feed consumption tended to be lower for Treatment 2 than for Treatment 1 in the three subsequent experiments when the FFA content of the bran oil had reached a high level.
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SAYRE ET AL. TABLE 4. Free fatty acid content of oil in rice bran of Treatments 1, 2, and 4 Treatment
Experiment
1
A B C D
4.9* 5.1 7.3 6.6
2.7 3.4 3.3 3.4
9.2 62.9 77.8 80.9
1 1, Raw bran in frozen storage; 2, raw bran in high temperature storage; 4, stabilized bran in high temperature storage. 2
Expressed as percent oleic acid.
Feed consumption (Table 6) by birds in Treatment 1 (frozen raw bran) was similar to Treatments 4 and 5 (stabilized bran) through all four experiments. Pooled data for all experiments indicated that birds fed raw bran stored at 32 C consumed less feed than birds fed stabilized bran and that less full fat, raw bran was consumed when stored at 32 C than when stored frozen. Consumption of extracted raw bran (Treatment 3) was similar to both of the other two raw bran containing diets but less than diets containing stabilized bran. The cumulative quantity of feed required per unit gain of bird weight (Table 7) was significantly less for Treatments 4 and 5 (stabilized rice bran diets) than for the other treatments. Birds fed the extracted raw rice bran diet (Treatment 3) had an intermediate feed efficiency. Both full fat raw bran diets (Treatments 1 and
TABLE 5. Influence of treatments on body weight gain per bird (g) in Experiments A, B, C, and D and in combined experiments Experiment Treatment1
A
B
C
D
Combined
1 2
463 463 474 540 572 616 ± 17
460 414 444 576 551 554 ± 23
483 451 500 581 613 633 ± 17
514 437 501 572 607 608 ± 14
480c 441 d 480c 568b 586ab 603a ± 9
3 4 5 6 SE2
Means followed by different superscripts are different (P<.05). 1
1 , Raw bran in frozen storage;2, raw bran in high temperature storage;3, raw bran oil extracted;4, stabilized bran in high temperature storage; 5, stabilized bran oil extracted; and 6, control diet. 2
Pooled standard error of the mean.
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Cumulative weight gains (Table 5) were similar for both the stabilized full fat rice bran and stabilized extracted rice bran (Treatment 4 and 5) diets. The three raw bran diets produced significantly lower weight gains than Treatments 4, 5, and 6. Treatments 1 and 3 with either frozen or extracted raw bran were similar, whereas Treatment 2, with raw rice bran stored at high temperature, produced the lowest cumulative gains (P<.05) when all experiments were combined. When gains were calculated on a daily basis, the results were similar except for the 4-day period prior to the final weight measurement. During this final period the rate of gain for both of the stabilized bran diets dropped slightly and the rate of gain for birds on the high temperature storage, full fat raw rice bran increased to be the same as the other two raw rice bran treatments.
STABILIZED AND RAW RICE BRAN
497
TABLE 6. Effect of treatments on feed consumption per bird (g) in Experiments A, B, C, and D and in the combined experiments
Treatment 1 1 2 3 4 5 6 SE 2
A
B
C
D
860 861 841 857 893 1,175 ± 19
827 773 772 899 835 1,038 ± 34
883 815 848 939 958 1,263 ± 24
963 824 851 921 936 1,149 ± 29
Combined 883bc 818d 828cd 904 b 905b l,156 a ± 20
a—d
2) were similar in feed efficiency and required the greatest amount of feed per unit gain of any of the bran diets. The control diet, which produced gains similar to diets containing stabilized bran, was similar to the full fat, raw bran diets in feed efficiency. When feed efficiency was calculated on a periodic basis, efficiency improved during the latter part of the experiment for diets containing raw bran, and all diets containing rice bran were similar in feed efficiency during the last 4 days of the experiment. Liver weight, as percentage of live weight, was significantly lower in Treatment 5 (extracted, stabilized bran) than in all other treatments (Table 8), and Treatment 4 (stabilized bran) resulted in significantly lower liver
weights than Treatments 1, 2 (raw, full fat bran, low and high temperature storage), and 6 (control). Diets containing raw full fat bran produced significant pancreatic hypertrophy compared with stabilized rice bran diets; Treatment 2 (raw, full fat, high temperature storage) caused the greatest increase. Treatment 5 with extracted stabilized rice bran produced the smallest pancreas weights. Treatments did not affect spleen weights (data not shown). DISCUSSION
Although storage time and FFA accumulation did not show a marked progressive effect from experiment to experiment on chick performance,
TABLE 7. The effect of treatments on feed per unit gain in Experiments A, B, C, and D and for the combined experiments Treatment 1
A
1 2 3 4 5 6 SE2
1.86 1.86 1.78 1.58 1.56 1.91 + .04
B 1.80 1.87 1.75 1.56 1.52 1.88 + .06
C
D
Combined
1.83 1.81 1.70 1.62 1.56 2.00 ± .04
1.86 1.90 1.70 1.61 1.54 1.89 ± .05
1.84 b 1.86 a b 1.73 c 1.59 d 1.55 d 1.92" ± .02
a—d Means followed by different superscipts are different (P<.05). 1 , Raw bran in frozen storage; 2, raw bran in high temperature storage; 3, raw bran oil extracted; 4, stabilized bran in high temperature storage; 5, stabilized bran oil extracted; and 6, control diet. 2 Pooled standard error of the mean. 1
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Means followed by different superscripts are different (P<.05). 1 , Raw bran in frozen storage; 2, raw bran in high temperature storage; 3, raw bran oil extracted; 4, stabilized bran in high temperature storage; 5, stabilized bran oil extracted; and 6, control diet. 2 Pooled standard error of the mean. 1
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SAYRE ET AL. TABLE 8. The influence of treatments on liver and pancreas weight
Treatment 1
Liver weight
1 2 3 4 5 6 SE 2
32.7a 32.4 a 31.7ab 31.3 b 29.0 C 32.6 a ± .4
Pancreas weight (g/kg live weight) 3.64 b 3.90 a 3.49 c 3.13 d 2.95 e 3.44 c ± .05
' 1, Raw bran in frozen storage; 2, raw bran in high temperature storage; 3, raw bran oil extracted; 4, stabilized bran in high temperature storage; 5, stabilized bran oil extracted; and 6, control diet. 2
Pooled standard error of the mean.
there did appear to be some negative effect. Most of the formation of FFA took place between Experiments A and B with only small changes thereafter. These effects were small compared with the increase in weight gain resulting from the stabilization process. Hussein and Kratzer (1982) found that addition of ethylenediaminetetraacetate to freshly milled raw rice bran retarded oil hydrolysis and significantly increased chick weight gain. They attributed the increased gain to retardation of FFA formation. Reports from tropical climates indicated that degraded oil in stored raw rice bran caused digestive disturbances when fed to livestock (Yokochi, 1972; Subrahmanyan, 1977). Conversely, Scott et al. (1976) stated that hydrolitic rancidity did not interfere with the nutritional value of fat, and Kratzer and Payne (1976) reported similar gains from chicks fed rice bran containing widely varying amounts of FFA. These findings indicate that some additional factors independent from FFA accumulation may be responsible for growth retardation resulting from consumption of deteriorating rice bran. Possibly mycotoxins may develop under certain storage conditions and they may be reduced or destroyed by treatments that also prevent oil breakdown. The lower liver weights in birds fed stabilized bran, particularly extracted stabilized bran, indicate that the stabilization process may either prevent some stimulus for tissue hypertrophy or reduce fat deposition in the liver. However, none of the livers appeared to be fatty and no unhealthy appearing livers could be associated with any particular treatment. Majun and Payne
(1977) reported that liver weight of laying hens fed autoclaved rice bran were significantly lower than those from hens fed raw rice bran. The consistent finding of reduced pancreatic weight in birds fed stabilized bran compared with those of birds fed raw bran is in agreement with the finding of Kratzer et al. (1974) that autoclaving prevented a large proportion of the pancreatic hypertrophy produced by raw rice bran. Pancreatic weight appeared to be associated with the amount of processing to which the bran had been subjected. Extracted raw bran produced a lower weight than full fat bran, and extraction of stabilized bran further reduced pancreatic weight below that resulting from stabilizing alone. The pancreatic weight of birds fed stabilized bran was even lower than that of birds fed the control diet. Kratzer and Payne (1977) reported that trypsin inhibitor was somewhat resistant to denaturation and retained a portion of its original activity after heat treatments sufficient to destroy growth limiting factors. Their conclusion was that growth retardation components in rice bran were not related to trypsin inhibitor and pancreatic hypertrophy. The greater weight gains produced by stabilized bran compared with raw bran were even more impressive, considering that the 60% stabilized bran diets produced gains similar to the 60% corn, commercial chick starter diet. This gain was produced on 20% less feed than the control diet, resulting in a significant improvement in the feed:gain ratio. Cumulative feed efficiency of rice bran diets for the first 25 days after hatch reflected treatment effects on pancreatic weight. Extracted raw bran was inter-
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Means followed by different superscripts are different at the 5% level of probability.
STABILIZED AND RAW RICE BRAN
ACKNOWLEDGMENTS
This work was supported in part by funding from the AID Office of Nutrition through an OICD RSSA Agreement, SEA-12-14-50016478. The authors express their appreciation to R. Fong and J. Labat for technical assistance and to B. Mackey for advice in statistical analysis of data. Reference to a company or product named by the Department is only for purposes of information and does not imply approval or recommendation of the product to the exclusion of others that may also be suitable.
REFERENCES Barber, S., C. Benedito de Barber, M. J. Flores, and J. J. Montes, 1978. Toxic constituents of rice bran. I. Trypsin inhibitor activity of raw and heat-treated bran. Rev. Agroquim. Tecnol. Aliment. 18(l):80-88. Benedito de Barber, C , and S. Barber, 1978. Toxic constituents of rice bran. II. Hemagglutinating activity of raw and heat-treated bran. Rev. Agroquim. Tecnol. Aliment. 18(l):89-94. Chami, D. B., P. Vohra, and F. H. Kratzer, 1980. Evaluation of a method for determination of true metabolizable energy of feed ingredients. Poultry Sci. 59:569571. Hussein, A. S., andF. H. Kratzer, 1982. Effect of rancidity on the feeding value of rice bran in chickens. Poultry Sci. 61:2450-2455. Juliano, B. O., 1972. Page 38 in: Rice Chemistry and Technology. D. F. Houston, ed. Am. Assoc. Cer. Chem., St. Paul, MN. Kratzer, F. H., L. Earl, and C. Chiaravanont, 1974. Factors influencing the feeding value of rice bran for chickens. Poultry Sci. 53:1795-1800. Kratzer, F. H., and C. G. Payne, 1977. Effect of autoclaving, hot-water treating, parboiling and addition of ethoxyquin on the value of rice bran as a dietary ingredient for chickens. Br. Poult. Sci. 18:475^182. Majun, G. K., and C. G. Payne, 1977. Autoclaved rice bran in layer's diets. Br. Poult. Sci. 18:201-203. Randall, J. M., R. N. Sayre, W. G. Schultz, R. Y. Fong, A. P. Mossman, R. E. Tribelhorn, and R. M. Saunders, 1985. Rice bran stabilization by extrusion cooking for extraction of edible oil. J. Food Sci. 50:361364. Scott, M. L., M. C. Nesheim, and R. J. Young, 1976. Nutrition of the Chicken. M. L. Scott and Assoc, Ithaca, NY. Steel, R.G.D., and J. H. Torrie, 1960. Principles and Procedures of Statistics. McGraw-Hill Book Co., Inc., New York, NY. Subrahmanyan, V., 1977. Improved method of processing and milling of paddy for production of more rice and oil in Tamil Nadu. Paddy Processing Res., Tiruvarur, India. Yokochi, K., 1972. Rice bran processing for the production of rice-bran oil and rice-bran protein meal. ID/WG 120/9 UNIDO, Vienna.
Downloaded from http://ps.oxfordjournals.org/ at Kainan University on April 22, 2015
mediate between stabilized bran and the full fat, raw bran. Inspection of the feed per unit gain at different periods in the experiment and, to some extent, the daily gain indicated that some changes in feed utilization were taking place near the end of the 25-day feeding period. After 18 days, feed efficiency began to improve for all three raw bran diets when calculated for individual weight periods. During the last 4 days of the experiment, all rice bran diets were similar in feed efficiency. This change was more the result of a change in rate of gain than from a change in feed consumption. Rate of gain for all the raw bran diets increased, and the greatest increase was found in Treatment 2, the full fat raw bran stored at high temperature. The reason for the weight gain change registered during the last few days by the raw bran is unknown. Apparently the more mature chick was able to overcome the growth inhibitory factors present in the raw bran.
499