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Effect of Grinding on Digestibility of Argentine Flint Corn
Effect of Grinding on Digestibility of Argentine Flint Corn JAMES C.
FRITZ
Bettsvitte Research Center of U. S. Department of Agriculture, Beltsville, Maryland (Received for Publication July 23, 1934)
O
MATERIAL
One hundred pounds of Argentine corn (purchased September, 1932) was set aside for the experiment. This was divided into three equal portions. One of these portions was kept without further treatment, to be fed as the whole grain. A second portion was coarsely cracked. The third portion was finely ground by repeated grinding in a cereal mill. The chemical composition of the three corn samples is given in Table 1. Five Rhode Island Red cocks were used in this study, which was conducted from February 1
Four of these birds were operated upon by W. H. Burrows of this Bureau.
11 to November 17, 1933. Paraschtschuk (1902) and Nitzescu (1918) have shown that there is no marked difference between the digestibilities obtained by hens and by cocks on the same diet. These five cocks were altered by surgical means1 so that the urine and the feces were voided separately. This was done by bringing the colon to the exterior about two inches below the cloaca. The operation has been described in detail by Paraschtschuk (1902), Katayama (1924), and others who have used this technic successfully. Katayama (1924) has shown that this operation does not change the bird's ability to digest its food. All of the birds were operated upon at least seven weeks before they were placed on experiment, and all from which data are here reported were in excellent health at all times while on experiment. Any apparent irregularity was considered sufficient cause temporarily to remove a bird from experiment. The most common cause for the removal of birds from experiment was an impacted crop. No grit was fed to these birds for at least two months prior to the beginning of the experiments, and no grit was fed during the course of the experiments. This does not, however, mean that there was no grit in the birds' gizzards. Kaupp and Ivey (1923) have shown that grit may remain in the bird's gizzard for a period longer than two months. PROCEDURE
Each bird was placed in an individual .wire cage 26 inches high, 21 inches long, and 17 inches wide. The Argentine corn
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NE of the problems which have confronted poultrymen is the question of the relative feeding values of whole and ground grains. Fields and Ford (1900), Kriiger (1925), Mangold (1928), Bartlett (1910), and others have found no significant differences in digestibility due to the state of subdivision of a grain when fed. Kaupp and Ivey (1923) found slightly better digestibility for corn meal than for whole corn. The object of this investigation was to study the effect of grinding on digestibility. Argentine flint corn was selected because it is the hardest grain that is used to any extent in animal feeding. A second reason for studying this grain was that there was no information on the digestibility of Argentine flint corn in the literature. Since this grain is being used to an increasing extent in poultry feeding, more information on its feeding value was desired.
268
POULTRY
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TABLE 1.—Chemical composition of the Argentine corn Average composition on an air-dry basis Condition of Argentine corn
Whole
Moisture
Crude protein (total Nx 6.25)
True protein (albuminoid Nx 6.25)
Ash
Ether extract
Crude fiber
Percent 9.50
Percent 11.17
Percent 10.71
Percent 1.57
Percent 5.06
Percent 1.87
Cracked
11.61
10.90
10.62
1.56
5.77
1.78
Ground
11.65
10.82
10.63
1.68
5.83
1.73
Daily weight of feed = 0.462 X (live weight)% The feed given each bird per day was force-fed, with the aid of a German silver funnel and plunger, in two equal portions, at 9:30 a.m. and at 3:30 p.m. Enemas were given twice daily, at 9:00 a.m. and at 4:00 p.m. At all other times a glass plug was kept in the artificial anus. The samples collected by means of the enemas at 4:00 p.m. one day and at 9:00 a.m., on the following day were combined. This combined sample was mixed with 10 ex. of glacial acetic acid and then dried on a boiling water bath. Records of the daily weight of the feces were kept. After the daily excretion became constant—• usually after three or four days on the experiment diet—the feces samples for eight days were collected and combined.
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was the only feed allowed the birds while on experiment, and the amount fed each bird per day was calculated from the live weight of the bird at the beginning of the digestion trial. The birds were fed at least sufficient feed for maintenance. Since the maintenance requirement is approximately proportional to the two-thirds power of the live weight, the following formula was used to calculate the daily weight of the feed, based on the report by Titus (1928) that a bird weighing 1,632 grams required approximately 64.00 grams of a normal allmash diet per day for maintenance:
The eight-day feces samples were ground, and analyzed by official methods, Association of Official Agricultural Chemists (1930), for moisture, crude protein, true protein, ash, ether extract, and crude fiber. Organic matter was calculated by subtracting the amount of ash from the total amount of dry matter. Nitrogen-free extract was calculated by subtracting from the organic matter the combined weights of crude protein, ether extract, and crude fiber. Similar determinations were made on the corn samples. From the weight and composition of the feed and feces the digestibility coefficients were calculated for each of these constituents. Data were obtained from nine digestion trials with whole Argentine corn, seven trials with cracked Argentine corn, and six trials with ground Argentine corn. Two-week intervals elapsed after a bird completed one digestion trial and before the bird was again placed on experiment. During these intervals the birds were held in the metabolism cages and fed a normal, all-mash diet, supplemented with fresh lettuce. Variance analyses of the data were made. Fisher's (1932) "z" test was used to indicate whether grinding had had a significant effect upon digestibility. The "t" test was used to test the significance of the differences between the average digestibilities of the grain in the different states of subdivision. The standard errors were calcu-
87.71 + 0.44 0.88 + 0.31
88.13 + 0.41 0.95 + 0.29
86.68 + 0.36 1.24+0.25
Organic matter
86.22±1.08 2.82 + 0.76 85.07+1.17 2.48 + 0.83
82.81 + 1.39 3.08±0.98
85.62 + 0.95 3.17 + 0.67
True protein (albuminoid N X 6.25)
84.30+1.20 4.46+0.85
83.75+1.05 2.78 + 0.74
Crude protein (total N X (6.25)
91.25 + 1.61 2.04+1.14
87.05+1.52 2.83+1.07
26.83 + 4.17 9.61 + 2.95 45.73 + 4.50 11.51 + 3.18
75.02 + 1.34 5.48 + 0.95
Ether extract
26.81 + 4.17 17.66+2.95
Ash
Average coefficients of apparent digestibility
coefficients of apparent digestibility and their standard deviations
12.67 + 2.47 4.26+1.75
5
5
6
3
3
A
B
C
D
E
86.58 + 0.88
84.81+0.88
86.22 + 0.62
86.43 + 0.68
86.75 + 0.68
Dry matter
87.64 + 0.95
86.20 + 0.95
87.58 + 0.67
87.51 + 0.73
87.73 + 0.73
Organic" matter
83.06 + 2.89 76.64±4.08 75.11 + 4.08
27.00 + 6.24 21.42 + 9.89 32.39 + 8.05
83.68 + 0.96 83.61 + 1.35 88.20+1.35
81.77±1.53 86.23±1.53
18.49±3.53
13.52 + 3.53
17.85 + 2.49
12.68±2.73 86.10 + 3.16
35.75 + 6.24
81.38+1.08
89.58 + 3.16 ' l 3 . 1 5 ± 2 . 7 3
Crude fiber
39.22 + 6.24
Ether extract 8
86.50+1.05
86.85 + 1.05
85.40+1.19
Asha
84.37 + 1.19
True protein (Albuminoid N X 6.25)
Crude protein (total N X (6.25)
90.99 + 0.56
90.02 + 0.56
91.18±0.39
90.46 + 0.43
90.22 + 0.43
* The values given in the cases of organic matter, ash, and ether extract are complicated because differences in digestibility, due to grinding, were found; and the same bird was not used an equal number of times with each corn sample.
No. trials
Average coefficients of apparent digestibility Nitrogenfree extract
90.52 + 0.39 0.68 + 0.28
91.11 + 0.36 1.16 + 0.25
90.29 + 0.31 1.01 + 0.22
14.96 + 2.01 6.10+1.42 17.36 + 2.28 7.16+1.61
Nitrogenfree extract
Crude fiber
TABLE 3.—Average coefficients of apparent digestibility, and their standard errors, obtained with individual birds {without regard to the state of subdivision of the corn)
cr
Av.
Bird
Ground
<7
86.82 + 0.56 0.95±0.40
86.88 + 0.52 1.31 + 0.34
Av.
Cracked
85.38 + 0.46 1.53 + 0.33
0"
Av.
Whole
Dry matter
Av. or
Condition of Argentine corn
TABLE 2.—Average
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TABLE 4.—Summary of digestibility coefficients for corn, with chickens, reported in the literature Average coefficients of apparent digestibility Kind" and condition of corn
Investigator
Fraps (1928, compilation) Hainan (1928) Hallnan Henning (1929) Henning Kaupp & Ivey (1923) Kaupp & Ivey Kaupp & Ivey Lehmann (?) Mangold (1928) Mangold Paraschtschuk (1902) Peters (1933) Radeff (1928) Stotz (1933) Szalagyi & Kriwusche (1918) Fritz (this paper) Fritz (this paper) Fritz (this paper)
Whole Cracked Meal White Yellow Whole Meal
Organic matter
Crude protein (Total Nx 6.25)
Crude fat
Crude fiber
Nitrogenfree extract
86.6 83.3 83.1 86.65
68.3 72.2 74.6 83.95
87.0 87.1 87.6 85.32
— — —
91.6 88.1 86.0 89.25
49.8 48.3
91.7 92.8
14.53 27.35 7.277 0.0 0.0
92.5 91.5
74.9
85.1
14.8
90.1
71.8 79.5
91.6 78.0
15.2 5.0
91.9 87.5
93.8 83.75
90.2
81.5
95.1
83.91 84.67 83.21
68.71 74.04 73.50 76.70
75.26 86.26 84.50 85.00
82.58
89.21 84.08
92.51 87.09
83.43 83.09
80.03
82.92
87.12
76.02
Negative 19.72 19.76 5.86 6.66 6.80 11.00 19.72 19.76 31.20 2.68 17.01 21.46
85.38 86.88 86.82
86.68 88.13 87.71
84.4 83.75 84.30 82.81
75.02 87.05 91.25
14.96 17.36 12.67
81.9 78.6
Whole and cracked Meal Whole yellow "Flaked" steamed Whole Ground Whole Meal bolted Meal unbolted
84.6
Whole Ground Cracked
Whole Argentine Cracked Argentine Ground Argentine
" All of the values given in the above table are for dent (Indian) corn, unless otherwise stated. This value was designated "Digestibility coefficient of chemical energy."
b
lated from the error variances used in making the "z" tests. EXPERIMENTAL DATA The average coefficients of apparent digestibility found for the three Argentine corn samples are given in Table 2, together with their standard errors and their standard deviations. The average coefficients of apparent digestibility by individual birds are summarized in Table 3. DISCUSSION Appropriate tests of the significance of the differences between the digestibilities of
89.40 88.18 87.60 85.50 91.76 85.69 84.29 88.9 b 90.29 91.11 90.52
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Bartlett (1910) Bartlett Bartlett Brown (1909) Bruggemann (1931) Briiggemann Fields & Ford (1900) Fields & Ford Fraps (1928, compilation)
Dry matter
whole, cracked, and ground Argentine corn were applied to the data. In only three cases was a significant difference noted between the digestibilities for the corn in the different states of subdivision. The organic matter of cracked corn was more completely digested than was the organic matter of whole corn. The odds were 49:1 that this difference was not due to chance. However, the digestibility of the organic matter of the ground corn fell between the digestibilities noted for the whole corn and cracked corn. The effect of grinding on the digestibility of organic matter was ascribed to the effect of grinding on the digestibility of the ether
SEPTEMBER,
1935.
VOL. XIV,
Comparison with Indian Corn Because the writer was unable to find any reports in the literature about digestion trials on Argentine corn, he has compared the values herein presented with a number of digestion coefficients found for Indian corn. These are summarized in Table 4, and the average digestibilities found by the writer on Argentine corn are included. Evidently there is no great difference between the digestibilities of Argentine corn and Indian corn. The data reported for the digestibility of dry matter and organic matter of corn are quite consistent. There is a wide variation
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271
between the digestibility coefficients of protein. However, if the very low values reported by Fields and Ford (1900) are eliminated, the range of the digestibility of protein is from 68.30 to 92.51 percent, with an average of 78.72 percent. The writer has found the average digestibility of the crude protein of Argentine corn to be slightly greater than this average for Indian corn. The apparent digestibility of fat may not approximate the true digestibility very closely. Much of the fat in the feces is of metabolic origin (Krakower (1934)), and this makes the apparent digestibility lower than the true value. The apparent digestibility coefficients reported for fat from corn are very uniform. In all cases where digestibility coefficients were determined for whole corn and cracked corn or ground corn, the values obtained for the digestibility of fat were lower in the case of the whole corn. This agrees with the writer's observations on Argentine corn. Probably the finer division of the grain enables enzymes to attack the fat more quickly after the feed enters the digestive tract. This, in view of the relatively short time required for the passage of food through the bird's digestive tract, may account for the better digestibility of fat in the case of cracked and ground corn. The reported digestibility of the crude fiber of corn is extremely variable. Average coefficients of apparent digestibility range from negative values to 31.20, with even greater variations for individual trials. The writer's values for Argentine corn fall within the range covered by the reported values for dent corn. There is unusually close agreement among the various reports on the digestibility of the nitrogen-free extract of corn fed to chickens. The values herein presented for the digestibility of the nitrogenfree extract of Argentine corn agree very closely with those previously reported for dent corn.
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extract portion. The digestibility of organic matter without the ether extract was not significantly influenced by grinding. The digestibility coefficients for ash were nearly twice as great in the case of the ground corn as in the cases of whole corn and cracked corn. In spite of the relatively large standard errors of the average digestibilities of the ash, the odds were more than 99:1 that this difference was not due to chance. In the case of cracked corn there was a much larger percentage of ether extract digested than there was in the case of whole corn. The odds were more than 99:1 that this difference was not due to chance. The digestibility of either extract was slightly better in the case of ground corn than in the case of cracked corn, but the odds that this difference was not due to chance were only 14:1, and therefore the difference was not statistically significant. None of the differences in digestibility between individual birds were statistically significant. The rather unusually close agreement between individual birds, as shown in Table 3, may be due to the fact that the data from any bird which showed any irregularities during the course of the digestion trial were discarded.
No.
272
POULTRY SUMMARY
REFERENCES
Association of Official Agricultural Chemists, 1930. Ed. 3, 593 pp., Illus. Washington, B.C.
Bartlett, J. M., 1910. Maine Exp. Sta. Bui. 184. Brown, E. W., 1904. U. S. Dept. Agr., Bur. An Ind. Bui. 56. BrUggemann, H., 1931. Archiv. Landw. Abt. B. (Archiv. f. Tierernahrung u. Tierzucht) 5:89126. Fields, J., and Ford, A. G., 1900. Okla. Agr. Exp. Sta. Bui. 46. Fisher, R. A., 1932. Statistical Methods for Research Workers, Ed. 4, Oliver and Boyd, London. Fraps, G. S., 1928. Texas Exp. Sta. Bui. 372. Hainan, E. T., 1928. Jour. Agr. Sci. 18:426-431. Henning, H. I., 1929. Die Landw. Versuchs-Stationen 108:253-286. Kaupp, B. F., and Ivey, J. E., 1923. N.C. Exp. Sta. Tech. Bui. 22. Katayama, T., 1924. Bull, of the Imp. Agr. Expt. Sta. in Japan. 3 : No. 1. (Original not seen. A translation of the original by H. W. Titus was read.) Krakower, A., 1934. Am. Jour. Physiol. 107:146156. Kriiger, K., 1925. Landw. Jahrb. 61:909-936. Lehmann, F., ( ? ) . (Original not seen. These data are quoted from the article by H. Peters). Mangold, E., 1928. Archiv. f. Gefliigelkunde 2: 312-324. Nitzescu, J. J., 1918. Pfliiger's Archiv. f. die Gesamte Physiologie 172:275-317. Paraschtschuk, S., 1902. Jour. f. Landw. 50:15-32. Peters, H., 1933. Wissen. Archiv. Landw. Abt. B. (Archiv. f. Tierernahrung u. Tierzucht) 9:438469. Radeff, T., 1928. Biochem. Z. 193:192-196. Stotz, H., 1933. Wissen. Archiv. Landw. Abt. B. (Archiv. f. Tierernahrung u. Tierzucht) 9:426437. Szalagyi, K., and Kriwuscha, A., 1918. Biochem. Z. 88: 286-291. Titus, H. W., 1928. Poul. Sci. 8:80-84.
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The digestibility of whole, cracked, and finely ground Argentine flint corn was studied with Rhode Island Red cocks which were surgically altered so that the urine and the feces were voided separately. Coefficients of apparent digestibility were determined for the total dry matter, organic matter, crude protein, true protein, ash, ether extract, crude fiber, and nitrogen-free extract. Grinding, did not change the apparent digestibility of Argentine corn except in the cases of organic matter, ash, and ether extract. The difference in the digestibility of organic matter was caused by the ether extract portion. The digestibility of organic matter without the ether extract was not significantly influenced by grinding. Coarse cracking increased the digestibility of ether extract to near its maximum digestibility, while fine grinding was required to improve the utilization of ash. In general, grinding the Argentine corn improved its digestibility, but the improvement was small and it probably was not significant. The digestibility of Argentine flint corn was found to be essentially the same as that previously reported on dent (Indian) corn.
SCIENCE
FRITZ
Bettsvitte Research Center of U. S. Department of Agriculture, Beltsville, Maryland (Received for Publication July 23, 1934)
O
MATERIAL
One hundred pounds of Argentine corn (purchased September, 1932) was set aside for the experiment. This was divided into three equal portions. One of these portions was kept without further treatment, to be fed as the whole grain. A second portion was coarsely cracked. The third portion was finely ground by repeated grinding in a cereal mill. The chemical composition of the three corn samples is given in Table 1. Five Rhode Island Red cocks were used in this study, which was conducted from February 1
Four of these birds were operated upon by W. H. Burrows of this Bureau.
11 to November 17, 1933. Paraschtschuk (1902) and Nitzescu (1918) have shown that there is no marked difference between the digestibilities obtained by hens and by cocks on the same diet. These five cocks were altered by surgical means1 so that the urine and the feces were voided separately. This was done by bringing the colon to the exterior about two inches below the cloaca. The operation has been described in detail by Paraschtschuk (1902), Katayama (1924), and others who have used this technic successfully. Katayama (1924) has shown that this operation does not change the bird's ability to digest its food. All of the birds were operated upon at least seven weeks before they were placed on experiment, and all from which data are here reported were in excellent health at all times while on experiment. Any apparent irregularity was considered sufficient cause temporarily to remove a bird from experiment. The most common cause for the removal of birds from experiment was an impacted crop. No grit was fed to these birds for at least two months prior to the beginning of the experiments, and no grit was fed during the course of the experiments. This does not, however, mean that there was no grit in the birds' gizzards. Kaupp and Ivey (1923) have shown that grit may remain in the bird's gizzard for a period longer than two months. PROCEDURE
Each bird was placed in an individual .wire cage 26 inches high, 21 inches long, and 17 inches wide. The Argentine corn
[267]
Downloaded from http://ps.oxfordjournals.org/ at New York University on December 15, 2014
NE of the problems which have confronted poultrymen is the question of the relative feeding values of whole and ground grains. Fields and Ford (1900), Kriiger (1925), Mangold (1928), Bartlett (1910), and others have found no significant differences in digestibility due to the state of subdivision of a grain when fed. Kaupp and Ivey (1923) found slightly better digestibility for corn meal than for whole corn. The object of this investigation was to study the effect of grinding on digestibility. Argentine flint corn was selected because it is the hardest grain that is used to any extent in animal feeding. A second reason for studying this grain was that there was no information on the digestibility of Argentine flint corn in the literature. Since this grain is being used to an increasing extent in poultry feeding, more information on its feeding value was desired.
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TABLE 1.—Chemical composition of the Argentine corn Average composition on an air-dry basis Condition of Argentine corn
Whole
Moisture
Crude protein (total Nx 6.25)
True protein (albuminoid Nx 6.25)
Ash
Ether extract
Crude fiber
Percent 9.50
Percent 11.17
Percent 10.71
Percent 1.57
Percent 5.06
Percent 1.87
Cracked
11.61
10.90
10.62
1.56
5.77
1.78
Ground
11.65
10.82
10.63
1.68
5.83
1.73
Daily weight of feed = 0.462 X (live weight)% The feed given each bird per day was force-fed, with the aid of a German silver funnel and plunger, in two equal portions, at 9:30 a.m. and at 3:30 p.m. Enemas were given twice daily, at 9:00 a.m. and at 4:00 p.m. At all other times a glass plug was kept in the artificial anus. The samples collected by means of the enemas at 4:00 p.m. one day and at 9:00 a.m., on the following day were combined. This combined sample was mixed with 10 ex. of glacial acetic acid and then dried on a boiling water bath. Records of the daily weight of the feces were kept. After the daily excretion became constant—• usually after three or four days on the experiment diet—the feces samples for eight days were collected and combined.
Downloaded from http://ps.oxfordjournals.org/ at New York University on December 15, 2014
was the only feed allowed the birds while on experiment, and the amount fed each bird per day was calculated from the live weight of the bird at the beginning of the digestion trial. The birds were fed at least sufficient feed for maintenance. Since the maintenance requirement is approximately proportional to the two-thirds power of the live weight, the following formula was used to calculate the daily weight of the feed, based on the report by Titus (1928) that a bird weighing 1,632 grams required approximately 64.00 grams of a normal allmash diet per day for maintenance:
The eight-day feces samples were ground, and analyzed by official methods, Association of Official Agricultural Chemists (1930), for moisture, crude protein, true protein, ash, ether extract, and crude fiber. Organic matter was calculated by subtracting the amount of ash from the total amount of dry matter. Nitrogen-free extract was calculated by subtracting from the organic matter the combined weights of crude protein, ether extract, and crude fiber. Similar determinations were made on the corn samples. From the weight and composition of the feed and feces the digestibility coefficients were calculated for each of these constituents. Data were obtained from nine digestion trials with whole Argentine corn, seven trials with cracked Argentine corn, and six trials with ground Argentine corn. Two-week intervals elapsed after a bird completed one digestion trial and before the bird was again placed on experiment. During these intervals the birds were held in the metabolism cages and fed a normal, all-mash diet, supplemented with fresh lettuce. Variance analyses of the data were made. Fisher's (1932) "z" test was used to indicate whether grinding had had a significant effect upon digestibility. The "t" test was used to test the significance of the differences between the average digestibilities of the grain in the different states of subdivision. The standard errors were calcu-
87.71 + 0.44 0.88 + 0.31
88.13 + 0.41 0.95 + 0.29
86.68 + 0.36 1.24+0.25
Organic matter
86.22±1.08 2.82 + 0.76 85.07+1.17 2.48 + 0.83
82.81 + 1.39 3.08±0.98
85.62 + 0.95 3.17 + 0.67
True protein (albuminoid N X 6.25)
84.30+1.20 4.46+0.85
83.75+1.05 2.78 + 0.74
Crude protein (total N X (6.25)
91.25 + 1.61 2.04+1.14
87.05+1.52 2.83+1.07
26.83 + 4.17 9.61 + 2.95 45.73 + 4.50 11.51 + 3.18
75.02 + 1.34 5.48 + 0.95
Ether extract
26.81 + 4.17 17.66+2.95
Ash
Average coefficients of apparent digestibility
coefficients of apparent digestibility and their standard deviations
12.67 + 2.47 4.26+1.75
5
5
6
3
3
A
B
C
D
E
86.58 + 0.88
84.81+0.88
86.22 + 0.62
86.43 + 0.68
86.75 + 0.68
Dry matter
87.64 + 0.95
86.20 + 0.95
87.58 + 0.67
87.51 + 0.73
87.73 + 0.73
Organic" matter
83.06 + 2.89 76.64±4.08 75.11 + 4.08
27.00 + 6.24 21.42 + 9.89 32.39 + 8.05
83.68 + 0.96 83.61 + 1.35 88.20+1.35
81.77±1.53 86.23±1.53
18.49±3.53
13.52 + 3.53
17.85 + 2.49
12.68±2.73 86.10 + 3.16
35.75 + 6.24
81.38+1.08
89.58 + 3.16 ' l 3 . 1 5 ± 2 . 7 3
Crude fiber
39.22 + 6.24
Ether extract 8
86.50+1.05
86.85 + 1.05
85.40+1.19
Asha
84.37 + 1.19
True protein (Albuminoid N X 6.25)
Crude protein (total N X (6.25)
90.99 + 0.56
90.02 + 0.56
91.18±0.39
90.46 + 0.43
90.22 + 0.43
* The values given in the cases of organic matter, ash, and ether extract are complicated because differences in digestibility, due to grinding, were found; and the same bird was not used an equal number of times with each corn sample.
No. trials
Average coefficients of apparent digestibility Nitrogenfree extract
90.52 + 0.39 0.68 + 0.28
91.11 + 0.36 1.16 + 0.25
90.29 + 0.31 1.01 + 0.22
14.96 + 2.01 6.10+1.42 17.36 + 2.28 7.16+1.61
Nitrogenfree extract
Crude fiber
TABLE 3.—Average coefficients of apparent digestibility, and their standard errors, obtained with individual birds {without regard to the state of subdivision of the corn)
cr
Av.
Bird
Ground
<7
86.82 + 0.56 0.95±0.40
86.88 + 0.52 1.31 + 0.34
Av.
Cracked
85.38 + 0.46 1.53 + 0.33
0"
Av.
Whole
Dry matter
Av. or
Condition of Argentine corn
TABLE 2.—Average
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TABLE 4.—Summary of digestibility coefficients for corn, with chickens, reported in the literature Average coefficients of apparent digestibility Kind" and condition of corn
Investigator
Fraps (1928, compilation) Hainan (1928) Hallnan Henning (1929) Henning Kaupp & Ivey (1923) Kaupp & Ivey Kaupp & Ivey Lehmann (?) Mangold (1928) Mangold Paraschtschuk (1902) Peters (1933) Radeff (1928) Stotz (1933) Szalagyi & Kriwusche (1918) Fritz (this paper) Fritz (this paper) Fritz (this paper)
Whole Cracked Meal White Yellow Whole Meal
Organic matter
Crude protein (Total Nx 6.25)
Crude fat
Crude fiber
Nitrogenfree extract
86.6 83.3 83.1 86.65
68.3 72.2 74.6 83.95
87.0 87.1 87.6 85.32
— — —
91.6 88.1 86.0 89.25
49.8 48.3
91.7 92.8
14.53 27.35 7.277 0.0 0.0
92.5 91.5
74.9
85.1
14.8
90.1
71.8 79.5
91.6 78.0
15.2 5.0
91.9 87.5
93.8 83.75
90.2
81.5
95.1
83.91 84.67 83.21
68.71 74.04 73.50 76.70
75.26 86.26 84.50 85.00
82.58
89.21 84.08
92.51 87.09
83.43 83.09
80.03
82.92
87.12
76.02
Negative 19.72 19.76 5.86 6.66 6.80 11.00 19.72 19.76 31.20 2.68 17.01 21.46
85.38 86.88 86.82
86.68 88.13 87.71
84.4 83.75 84.30 82.81
75.02 87.05 91.25
14.96 17.36 12.67
81.9 78.6
Whole and cracked Meal Whole yellow "Flaked" steamed Whole Ground Whole Meal bolted Meal unbolted
84.6
Whole Ground Cracked
Whole Argentine Cracked Argentine Ground Argentine
" All of the values given in the above table are for dent (Indian) corn, unless otherwise stated. This value was designated "Digestibility coefficient of chemical energy."
b
lated from the error variances used in making the "z" tests. EXPERIMENTAL DATA The average coefficients of apparent digestibility found for the three Argentine corn samples are given in Table 2, together with their standard errors and their standard deviations. The average coefficients of apparent digestibility by individual birds are summarized in Table 3. DISCUSSION Appropriate tests of the significance of the differences between the digestibilities of
89.40 88.18 87.60 85.50 91.76 85.69 84.29 88.9 b 90.29 91.11 90.52
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Bartlett (1910) Bartlett Bartlett Brown (1909) Bruggemann (1931) Briiggemann Fields & Ford (1900) Fields & Ford Fraps (1928, compilation)
Dry matter
whole, cracked, and ground Argentine corn were applied to the data. In only three cases was a significant difference noted between the digestibilities for the corn in the different states of subdivision. The organic matter of cracked corn was more completely digested than was the organic matter of whole corn. The odds were 49:1 that this difference was not due to chance. However, the digestibility of the organic matter of the ground corn fell between the digestibilities noted for the whole corn and cracked corn. The effect of grinding on the digestibility of organic matter was ascribed to the effect of grinding on the digestibility of the ether
SEPTEMBER,
1935.
VOL. XIV,
Comparison with Indian Corn Because the writer was unable to find any reports in the literature about digestion trials on Argentine corn, he has compared the values herein presented with a number of digestion coefficients found for Indian corn. These are summarized in Table 4, and the average digestibilities found by the writer on Argentine corn are included. Evidently there is no great difference between the digestibilities of Argentine corn and Indian corn. The data reported for the digestibility of dry matter and organic matter of corn are quite consistent. There is a wide variation
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between the digestibility coefficients of protein. However, if the very low values reported by Fields and Ford (1900) are eliminated, the range of the digestibility of protein is from 68.30 to 92.51 percent, with an average of 78.72 percent. The writer has found the average digestibility of the crude protein of Argentine corn to be slightly greater than this average for Indian corn. The apparent digestibility of fat may not approximate the true digestibility very closely. Much of the fat in the feces is of metabolic origin (Krakower (1934)), and this makes the apparent digestibility lower than the true value. The apparent digestibility coefficients reported for fat from corn are very uniform. In all cases where digestibility coefficients were determined for whole corn and cracked corn or ground corn, the values obtained for the digestibility of fat were lower in the case of the whole corn. This agrees with the writer's observations on Argentine corn. Probably the finer division of the grain enables enzymes to attack the fat more quickly after the feed enters the digestive tract. This, in view of the relatively short time required for the passage of food through the bird's digestive tract, may account for the better digestibility of fat in the case of cracked and ground corn. The reported digestibility of the crude fiber of corn is extremely variable. Average coefficients of apparent digestibility range from negative values to 31.20, with even greater variations for individual trials. The writer's values for Argentine corn fall within the range covered by the reported values for dent corn. There is unusually close agreement among the various reports on the digestibility of the nitrogen-free extract of corn fed to chickens. The values herein presented for the digestibility of the nitrogenfree extract of Argentine corn agree very closely with those previously reported for dent corn.
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extract portion. The digestibility of organic matter without the ether extract was not significantly influenced by grinding. The digestibility coefficients for ash were nearly twice as great in the case of the ground corn as in the cases of whole corn and cracked corn. In spite of the relatively large standard errors of the average digestibilities of the ash, the odds were more than 99:1 that this difference was not due to chance. In the case of cracked corn there was a much larger percentage of ether extract digested than there was in the case of whole corn. The odds were more than 99:1 that this difference was not due to chance. The digestibility of either extract was slightly better in the case of ground corn than in the case of cracked corn, but the odds that this difference was not due to chance were only 14:1, and therefore the difference was not statistically significant. None of the differences in digestibility between individual birds were statistically significant. The rather unusually close agreement between individual birds, as shown in Table 3, may be due to the fact that the data from any bird which showed any irregularities during the course of the digestion trial were discarded.
No.
272
POULTRY SUMMARY
REFERENCES
Association of Official Agricultural Chemists, 1930. Ed. 3, 593 pp., Illus. Washington, B.C.
Bartlett, J. M., 1910. Maine Exp. Sta. Bui. 184. Brown, E. W., 1904. U. S. Dept. Agr., Bur. An Ind. Bui. 56. BrUggemann, H., 1931. Archiv. Landw. Abt. B. (Archiv. f. Tierernahrung u. Tierzucht) 5:89126. Fields, J., and Ford, A. G., 1900. Okla. Agr. Exp. Sta. Bui. 46. Fisher, R. A., 1932. Statistical Methods for Research Workers, Ed. 4, Oliver and Boyd, London. Fraps, G. S., 1928. Texas Exp. Sta. Bui. 372. Hainan, E. T., 1928. Jour. Agr. Sci. 18:426-431. Henning, H. I., 1929. Die Landw. Versuchs-Stationen 108:253-286. Kaupp, B. F., and Ivey, J. E., 1923. N.C. Exp. Sta. Tech. Bui. 22. Katayama, T., 1924. Bull, of the Imp. Agr. Expt. Sta. in Japan. 3 : No. 1. (Original not seen. A translation of the original by H. W. Titus was read.) Krakower, A., 1934. Am. Jour. Physiol. 107:146156. Kriiger, K., 1925. Landw. Jahrb. 61:909-936. Lehmann, F., ( ? ) . (Original not seen. These data are quoted from the article by H. Peters). Mangold, E., 1928. Archiv. f. Gefliigelkunde 2: 312-324. Nitzescu, J. J., 1918. Pfliiger's Archiv. f. die Gesamte Physiologie 172:275-317. Paraschtschuk, S., 1902. Jour. f. Landw. 50:15-32. Peters, H., 1933. Wissen. Archiv. Landw. Abt. B. (Archiv. f. Tierernahrung u. Tierzucht) 9:438469. Radeff, T., 1928. Biochem. Z. 193:192-196. Stotz, H., 1933. Wissen. Archiv. Landw. Abt. B. (Archiv. f. Tierernahrung u. Tierzucht) 9:426437. Szalagyi, K., and Kriwuscha, A., 1918. Biochem. Z. 88: 286-291. Titus, H. W., 1928. Poul. Sci. 8:80-84.
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The digestibility of whole, cracked, and finely ground Argentine flint corn was studied with Rhode Island Red cocks which were surgically altered so that the urine and the feces were voided separately. Coefficients of apparent digestibility were determined for the total dry matter, organic matter, crude protein, true protein, ash, ether extract, crude fiber, and nitrogen-free extract. Grinding, did not change the apparent digestibility of Argentine corn except in the cases of organic matter, ash, and ether extract. The difference in the digestibility of organic matter was caused by the ether extract portion. The digestibility of organic matter without the ether extract was not significantly influenced by grinding. Coarse cracking increased the digestibility of ether extract to near its maximum digestibility, while fine grinding was required to improve the utilization of ash. In general, grinding the Argentine corn improved its digestibility, but the improvement was small and it probably was not significant. The digestibility of Argentine flint corn was found to be essentially the same as that previously reported on dent (Indian) corn.
SCIENCE