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Studies on Feed Efficiency
Studies on Feed Efficiency I.
T H E RELATIVE E F F I C I E N C Y OF CORN AND W H E A T PRODUCTS IN* CHICK RATIONS* C. W. CARRICK AND ROY E. ROBERTS Department of Poultry Husbandry, Purdue University, Agricultural Experiment Station, Lafayelie, Indiana (Received for publication September 6, 1946)
* Journal Paper No. 266 of the Purdue University Agricultural Experiment Station. 111
EXPERIMENTAL
Three experiments were conducted using Barred Plymouth Rock chicks in the first two trials and White Plymouth Rock chicks in the third. Male chicks were used in all trials, and only a negligible error resulted in the sexing. Five-deck starting batteries (Oakes) were used for the first four weeks and finishing batteries thereafter. Strips of five-eighths inch mesh hardware cloth were placed on the feed in the troughs to keep wastage at a minimum. The chicks were banded and individual weights were obtained. The control ration was similar to that used by Mishler et al. (1946) and was as follows: Ground yellow corn Soybean oil meal (44%) Dried whey , Dehydrated alfalfa leaf meal Distillers' dried solubles Liver meal Steamed bone meal Ground limestone Salt mixture Total
Percent 55. 25. 3. 5. 5. 4. 1 •5 1. 0.5 100.0
The salt mixture consisted of 90 percent iodizecl salt and 10 percent manganese sulphate. D-activated animal sterol was included to provide 100 vitamin D units per 100 grams of ration. In Trial III, 3 percent of soybean oil meal was replaced by meat and bone scraps, and the bone meal was reduced to 0.5 percent. The experimental ration was the same,
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HEAT bran and wheat middlings have been shown to have relatively low digestibility according to Bartlett (1910), Kaupp and Ivey (1923), and Fraps (1928). Roberts and Carrick (1943) reported experiments which indicated that a higher percentage of bran and middlings in a ration, fed to chicks from 6 to 12 weeks of age, resulted in a greater amount of feed per unit of gain than when corn replaced the wheat products. Heuser et al. (1945) have also reported decreased efficiency and a slower growth rate with high fiber rations, involving bran and middlings. Mishler et al. (1946) found that the replacement of ground corn with 10 percent each of bran and middlings resulted in decreased growth and a greater amount of feed per unit of gain. Their results were obtained when the wheat products replaced ground yellow corn in either a simple corn and soybean oil meal ration supplemented with minerals and synthetic vitamins or a laboratory control ration which has repeatedly given rapid growth and efficient gains. Since bran and middlings are relatively expensive feeds, considering their nutritive values, and since these products have recently been difficult to obtain, it seemed desirable to conduct experiments to measure their value in a more definite way.
112
C. W. CARRICK AND ROY E. ROBERTS
except that 20 percent of ground yellow corn was replaced by 10 percent each of wheat bran and wheat standard middlings. Both rations were fed as mash. The terms "corn ration" and "wheat products ration" will be used hereafter to designate the two treatments. RESULTS
Trial I. In this trial, which began September 20, 1944, 240 day-old male
were made to compare each battery of five lots on the corn ration with each battery on the wheat products ration for each biweekly period. After the first period all of these comparisons showed differences either highly significant or approaching high significance, thus indicating that fewer lots than the 10 actually used, suffice to measure differences of 8 percent or more in feed-gain ratios. It will be noted in Table 1 that during
Biweekly Periods Ration 1
2
4
5
3.05 3.09
4.07 4.09
4.73 3.74*
2.68 2.58
3.33 3.28
3.96 4.56*
3.08 2.63
4.08 3.30
4.65 3.85
3 Feed-gain ratios
Wheat products
2.16 2.02
2.36 2.39
Corn
1.94 1.94
2.19 2.14
Averages Wheat products Corn
2.09 1.94
2.37 2.17
**Percent increase
7.7
9.2
'
17.1
23.6
20.8
Grams of feed per chick Wheat products Corn
145 143
353 344
698 688
1,065 1,024
1,287 1,286
""
* The rations were reversed during this period for one battery in each treatment. ** Average percentage increase in feed-gain ratios for wheat products over corn, with corn as 100 percent. After the first biweekly period the differences in feed-gain ratios were all highly significant.
chicks were sorted according to weight and distributed into 20 lots of 12 chicks each. Two batteries of 5 lots each were assigned to each ration. The average feedgain ratio (grams of feed per gram of gain) was calculated for each lot and the averages were tested for statistical significance. Table 1 gives average feed-gain ratios by batteries for each biweekly period. After the initial biweekly period the differences in the feed-gain ratios between the lots fed the corn and the wheat products rations were all highly significant (1 percent level). Further statistical analyses
the fifth biweekly period, one battery of chicks on the wheat products ration was changed to the corn ration and one battery on the corn ration was changed to the wheat products ration. This reversal of treatments showed a reversal in the feedgain ratios, as might be expected, since there should be no cumulative effect in treatments of this kind. These differences between the two rations were highly significant when all lots were involved. When any battery of five lots on one ration was compared with either battery on the other ration, the differences in the feed-gain
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TABLE 1.—Averagefeed-gain ratios and feed consumption for each battery in Trial I
113
STUDIES ON FEED EFFICIENCY
were not as great as in Trial I, but after the first period, all were highly significant. The feed required per chick, after the first two weeks was greater for the chicks fed the wheat products and the differences between the two treatments were greater than those found in Trial I. Unlike the results obtained in Trial I, there was little difference for any period between the treatments for either body weights or gains. The. average body weights at 6 weeks and 8 weeks of age
TABLE 2.—Average weights and gains in weight per chick in Trial I
Biweekly periods 1
2
3
4
5
Average weights in grams at end of period Ration Corn Wheat products Difference
110 106
269 254
4
15
532 484 48**
844 749 95**
1,134 1,076 58**
Average gains in grams for period Ration Corn Wheat products Difference
74 70
159 149
4
262 228
10* -
34**
311 262 49**
333 280 53**
' Significant. ! * Highly significant.
the wheat products ration. Gains were also in favor of the corn ration lots. The differences in weights at 6 weeks of age and thereafter were highly significant. Differences between the gains were significant in the second biweekly period and were highly significant thereafter. Trial II. Ten lots of 15 male day-old chicks each were involved in this trial, which was a repetition of Trial I, except that there was no reversal in treatments and the trial was discontinued at 8 weeks. The chicks were started February 27, 1945. Table 3 gives the average feed-gain ratios by batteries for each biweekly period. The differences for the two rations
were 512 and 792 grams for those fed wheat products and 515 and 807 grams for those fed the corn ration. The differences between treatments were not significant. The chicks on the wheat products ration grew better than those in Trial I, while those on the corn ration did not grow quite as well. In Trial II the wheat bran used was of a very light color and came from a northwestern mill, while that used in Trial I was brown and came from a nearby mill. Possibly different varieties of wheat, growing conditions or other factors may influence the feeding value of the bran. Unfortunately we had no history on
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ratio were highly significant, except where the original corn lots were compared with the wheat products lots which were fed corn during the previous 8 weeks. In this case, however, the difference was well above significance (5 percent level). Table I shows that the chicks fed the wheat products ration required slightly more feed per chick during each period. Table 2 shows that the chicks fed on the corn ration had greater average weights at the end of each period than those given
114
C. W. CARRICK AND R O Y E. ROBERTS
either sample used. Trial III. After considerable statistical analysis of the data obtained from Trials I and II, involving numerous correlations between weights and gains at different ages it seemed desirable to use pairing in Trial III. The best basis for TABLE 3.—Average feed-gain ratios and feed consumption for each battery in Trial II Biweekly periods 1 2
3
4
Feed-gain ratios Wheat products
2.13 2.09
2.22 2.87 2.38 2.71
3.40 3.36
Corn
2.10 2.16 2.59 2.13 2.10 2.55
3.00 2.95
Average Wheat products Corn
2.11 2.30 2.79 2.11 2.13 2.57
3.38 2.98
*Percent increase
0.0
8.0
8.6
13.4
Grams of feed per chick Wheat products Corn
151 152
389 355
653 615
944 870
* Average percentage increase in feed-gain ratios for wheat products over corn, with corn as 100 percent. After the first biweekly period the differences in feed-gain ratios were all highly significant.
TABLE 4.—Average feed-gain ratios and feed consumption for each battery in Trial III Weekly periods Ration 1 2
3
4
Feed-gain ratios
pairing appeared to be the gain during the 2 to 4 week period. The corn ration was fed for the first four weeks. The experimental rations were started April 17, 1946. Twenty sets of 20 chicks each were sorted so that in each set the gain from two to four weeks differed by only a few grams. About 30 of the largest chicks out of the original 500 started as day-old chicks were eliminated because of their great differences in gains, and over 60 of the smaller ones were also eliminated. This procedure resulted in somewhat higher average gains and body weights per lot than would be expected from an
Wheat products
2.46 2.75 2.93 2.41 2.65 2.78
3.12 3.22
Corn
2.34 2.50 2,64 2.29 2.50 2.71
2.95 2.89
Average Wheat products Corn
2.43 2.32
2.70 2.86 2.50 2.68
3.17 2.92
*Percent increase
4.7
8.0
8.6
6.7
Grams of feed per chick Wheat products Corn
320 315
410 392
466 444
517 489
* Average percentage increase in feed-gain ratios for wheat products over corn, with corn as 100 percent. In each period the differences in feed-gain ratios were highly significant.
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Ration
unselected group. The data for each chick were recorded on an individual card, the cards arrayed according to gain, and each chick within a set of 20 was assigned to a battery deck by using a table of random numbers. In this way each chick was paired with a similar chick in each of the other decks, also each deck and each battery tended to be equalized. White Plymouth Rock males were used in this trial. Two batteries of 5 decks each were assigned to each ration. Body weights and feed consumption were recorded weekly. Table 4 gives the average feed-gain ratios by batteries for each weekly period. The differences between rations for each period were all highly significant. The feed required per chick was again greater for the chicks fed the wheat products. Table 5 shows that the average weights at the end of each period and the average gains during each period were slightly in favor of the chicks fed the corn ration.
115
STUDIES ON FEED EFFICIENCY
eights The difference between average weights hough at the end of the fourth period, although ignifionly 14 grams, was well above significance. The differences in average gains for none of the weekly periods were :e significant, but when the gains for periods iods 1 and 2 were combined (4-6 weeks), ), the difference, though small, approachedI high significance. When the gains for periods iods 3 and 4 or for periods 1 to 4 were combined, bined, the differences were highly significant. it.
There was some evidence that results might be influenced by location in the batteries. In Trial I the difference between top and bottom decks was almost significant for both the 8-week body weights and was significant for feed-gain ratios. In Trial I I the difference between top and bottom decks was almost significant for feed efficiency during the 6 to 8-week period, but body weights were about the same. In Trial III the plan of the experi-
weight per chick in Trial III
1
3
2
fWeekly periods 4 1-2
3-4
1-4
Average weights in grams at end of period Ration Corn Wheat products Difference
445 444
602 596
768 759
1
6
9
937 923 14*
—
— — —
—
—
Average gains in grams for period Ration Corn Wheat products Difference
136 132
157 152
166 163
168 163
4
5
3
5
293 284 9*
334 326 8**
627 611 16**
t The chicks were 4 weeks old at the start of period 1. * Significant. ** Highly significant.
When the half of the pairs which gained most during the 2 to 4-week periodi were involved, the difference in the 4 to 8-week 5-week gain was highly significant, but when sn the data for the lower half were used, the difhe difference was not significant. The mean difference in 4 to 8-week gain. between :tween the rations was 27 grams for the upper half and 7 grams for the lower half.:. The unadjusted gains for all chickss from 4 to 8 weeks showed a difference of 16 grams between the two rations. When these gains were adjusted for feed intake, ntake, the difference was found to be 40 grams. ;rams. Co variance was used in arriving at these adjusted values.
ment was.quite different and deck had no effect on either gain or feed efficiency. There was no evidence that any battery deck other than the bottom deck had any effect in the results in any of the trials. Possibly the light or the temperature may have been factors unfavorable for the bottom decks in the first two trials, but with the design used in Trial I I I these factors were apparently eliminated. In this trial chemical analyses were obtained for the protein and fiber content of each ration and for the wheat products as shown in Table 6. As would be expected the wheat products ration was higher in both protein and fiber.
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TABLE 5.—Average weighs at end of each period and gains in
116
C. W. CARRICK AND ROY E. ROBERTS DISCUSSION
In all of these experiments, the chicks fed on the wheat products ration consumed more feed per chicken, required more feed per unit of gain, and made less gain than those fed on the corn ration. Since the chickens fed on the wheat products ration consumed more feed per chicken, intake of feed would be ruled out as a factor in the results obtained. Obvi-
Wheat bran Wheat middlings Wheat products ration Corn ration
Protein
Fiber
15.9 15.4 23.8 22.5
8.9 7.8 5.8 4.3
ously trie replacement of corn by wheat products would increase the fiber content of the ration, but it would also reduce the caloric value of the ration. Both digestion trials and feeding trials have shown that feeds and rations high in fiber are not well utilized. Possibly the laxative properties of a ration may also enter into its utilization. The results of these experiments might support several viewpoints as to the cause of the results, but the evidence is only indirect at best: They do present very definite evidence that the replacement of corn with bran and middlings in a supposedly adequate ration did reduce the efficiency of the ration. Similar results might not be obtained on rations lower in protein or other growth factors. From a practical viewpoint it is important to know the relative efficiency of feeds and rations. The procedure employed in Trial III indicates that small differences in the efficiency of two rations may be measured within a week. This procedure would make it possible to determine the relative efficiency of several ra-
SUMMARY
1. When 10 percent each wheat bran and wheat middlings replaced 20 percent ground yellow corn in a ration known to give rapid growth, more feed was required per unit of gain than when the wheat products were not included.
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TABLE 6.—Protein and fiber analyses of wheal products and rations used in Trial III
tions, within a few weeks time and with the same chicks, since rather definite differences were obtained in a week's time after the chicks were 4 weeks old. Different rations could be compared each week in many cases. The results in Trial III indicate that chicks with the greatest ability to gain may be better measurement material for experiments of this kind, so far as determining differences in gains are concerned. We have planned another experiment to throw light upon the ability to gain and its effect on feed efficiency. The procedure in Trial III had several advantages over that used in the previous trials. By starting the chicks on the experimental rations at 4 weeks of age, the mortality factor thereafter is likely to be negligible, sex identification is quite accurate in most varieties, any runts or abnormal chicks can be eliminated, and greater precision can be obtained by pairing according to the ability of the chicks to gain during the 2 to 4-week period. Also, the influence of variation in temperature can be reduced because after four weeks no brooder heat is necessary under ordinary laboratory conditions. The growth and feed consumption during the first four weeks are not sufficient to show much difference, so that the extra work is hardly justified during this period. It is believed that experiments of this kind will give much more satisfactory information concerning feeds and rations for practical application than can be obtained from digestion trials.
117
STUDIES ON FEED EFFICIENCY
2. The use of the wheat products reduced the rate of growth obtained from the type of ration used. 3. The feed consumption per chick was greater for the lots fed on the wheat products ration than for those fed on the corn ration. 4. Suggestions are made concerning technics for comparing the relative feed efficiency of rations for young chickens. We are greatly indebted to S. R. Miles, Research Statistician of the Purdue University Agricultural Experiment Station, for valuable suggestions on the design of these experiments and for assistance in the statistical analysis of the data, and to the Department of Agricultural Chemistry for the chemical analyses of the feeds.
Bartlett, J. M., 1910. Digestion experiments with poultry. Maine Agr. ,Exp. Sta. Bui. 184. Fraps, G. S., 1928. Digestibility and production coefficients of poultry feeds. Texas Agr. Exp. Sta. Bui. 372. Heuser, G. F., L. C. Norris, H. T. Peeler, and M. L. Scott, 1945. Further studies on the apparent effect of digestibility upon growth, weight maintenance and egg production. Poultry Sci. 24:142-145. Kaupp, B. F., and J. E. Ivey, 1923. Digestive coefficients of poultry feeds and rapidity of digestion and fate of grit in the fowl. N. C. Agr. Exp. Sta. Tech. Bui. 22. Mishler, D. H., C. W. Carrick, Roy E. Roberts, and S. M. Hauge, 1946. Synthetic and natural vitamin supplements for corn and soybean oil meal chick rations. Poultry Sci. 25:479-485. Roberts, Roy E., and C. W. Carrick, 1943. Influence of starting rations upon subsequent growth. Poultry Sci. 22:425-432.
News and Notes A. Wade Brant has returned from service in the armed forces to his position of Assistant Poultryman, The State College of Washington, Pullman. Mr. Brant served two and one-half years in the Army as Counter-intelligence Corps Investigative Agent in the Philippines and
Japan. J. D. Sykes has been promoted to Vice President in charge of Public Relations of the Ralston Purina Company, St. Louis, Missouri.
Dr. Horace J. Davis, after serving in the European Theatre with the armed forces, has returned to Louisiana State University, Baton Rouge, as Associate Professor of Animal Industry. The First International Congress of Physio-Pathology of Animal Reproduction and Artificial Insemination will be held in Milan, Italy, on April 9 to 15, 1948. The General Secretary of the Congress is Professor Telesforo Bonadonna. "Istituto-L. Spallangani," Via Bronzetti 17, Milano, Italy.
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ACKNOWLEDGMENTS
REFERENCES
T H E RELATIVE E F F I C I E N C Y OF CORN AND W H E A T PRODUCTS IN* CHICK RATIONS* C. W. CARRICK AND ROY E. ROBERTS Department of Poultry Husbandry, Purdue University, Agricultural Experiment Station, Lafayelie, Indiana (Received for publication September 6, 1946)
* Journal Paper No. 266 of the Purdue University Agricultural Experiment Station. 111
EXPERIMENTAL
Three experiments were conducted using Barred Plymouth Rock chicks in the first two trials and White Plymouth Rock chicks in the third. Male chicks were used in all trials, and only a negligible error resulted in the sexing. Five-deck starting batteries (Oakes) were used for the first four weeks and finishing batteries thereafter. Strips of five-eighths inch mesh hardware cloth were placed on the feed in the troughs to keep wastage at a minimum. The chicks were banded and individual weights were obtained. The control ration was similar to that used by Mishler et al. (1946) and was as follows: Ground yellow corn Soybean oil meal (44%) Dried whey , Dehydrated alfalfa leaf meal Distillers' dried solubles Liver meal Steamed bone meal Ground limestone Salt mixture Total
Percent 55. 25. 3. 5. 5. 4. 1 •5 1. 0.5 100.0
The salt mixture consisted of 90 percent iodizecl salt and 10 percent manganese sulphate. D-activated animal sterol was included to provide 100 vitamin D units per 100 grams of ration. In Trial III, 3 percent of soybean oil meal was replaced by meat and bone scraps, and the bone meal was reduced to 0.5 percent. The experimental ration was the same,
Downloaded from http://ps.oxfordjournals.org/ at Mount Allison University on June 30, 2015
HEAT bran and wheat middlings have been shown to have relatively low digestibility according to Bartlett (1910), Kaupp and Ivey (1923), and Fraps (1928). Roberts and Carrick (1943) reported experiments which indicated that a higher percentage of bran and middlings in a ration, fed to chicks from 6 to 12 weeks of age, resulted in a greater amount of feed per unit of gain than when corn replaced the wheat products. Heuser et al. (1945) have also reported decreased efficiency and a slower growth rate with high fiber rations, involving bran and middlings. Mishler et al. (1946) found that the replacement of ground corn with 10 percent each of bran and middlings resulted in decreased growth and a greater amount of feed per unit of gain. Their results were obtained when the wheat products replaced ground yellow corn in either a simple corn and soybean oil meal ration supplemented with minerals and synthetic vitamins or a laboratory control ration which has repeatedly given rapid growth and efficient gains. Since bran and middlings are relatively expensive feeds, considering their nutritive values, and since these products have recently been difficult to obtain, it seemed desirable to conduct experiments to measure their value in a more definite way.
112
C. W. CARRICK AND ROY E. ROBERTS
except that 20 percent of ground yellow corn was replaced by 10 percent each of wheat bran and wheat standard middlings. Both rations were fed as mash. The terms "corn ration" and "wheat products ration" will be used hereafter to designate the two treatments. RESULTS
Trial I. In this trial, which began September 20, 1944, 240 day-old male
were made to compare each battery of five lots on the corn ration with each battery on the wheat products ration for each biweekly period. After the first period all of these comparisons showed differences either highly significant or approaching high significance, thus indicating that fewer lots than the 10 actually used, suffice to measure differences of 8 percent or more in feed-gain ratios. It will be noted in Table 1 that during
Biweekly Periods Ration 1
2
4
5
3.05 3.09
4.07 4.09
4.73 3.74*
2.68 2.58
3.33 3.28
3.96 4.56*
3.08 2.63
4.08 3.30
4.65 3.85
3 Feed-gain ratios
Wheat products
2.16 2.02
2.36 2.39
Corn
1.94 1.94
2.19 2.14
Averages Wheat products Corn
2.09 1.94
2.37 2.17
**Percent increase
7.7
9.2
'
17.1
23.6
20.8
Grams of feed per chick Wheat products Corn
145 143
353 344
698 688
1,065 1,024
1,287 1,286
""
* The rations were reversed during this period for one battery in each treatment. ** Average percentage increase in feed-gain ratios for wheat products over corn, with corn as 100 percent. After the first biweekly period the differences in feed-gain ratios were all highly significant.
chicks were sorted according to weight and distributed into 20 lots of 12 chicks each. Two batteries of 5 lots each were assigned to each ration. The average feedgain ratio (grams of feed per gram of gain) was calculated for each lot and the averages were tested for statistical significance. Table 1 gives average feed-gain ratios by batteries for each biweekly period. After the initial biweekly period the differences in the feed-gain ratios between the lots fed the corn and the wheat products rations were all highly significant (1 percent level). Further statistical analyses
the fifth biweekly period, one battery of chicks on the wheat products ration was changed to the corn ration and one battery on the corn ration was changed to the wheat products ration. This reversal of treatments showed a reversal in the feedgain ratios, as might be expected, since there should be no cumulative effect in treatments of this kind. These differences between the two rations were highly significant when all lots were involved. When any battery of five lots on one ration was compared with either battery on the other ration, the differences in the feed-gain
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TABLE 1.—Averagefeed-gain ratios and feed consumption for each battery in Trial I
113
STUDIES ON FEED EFFICIENCY
were not as great as in Trial I, but after the first period, all were highly significant. The feed required per chick, after the first two weeks was greater for the chicks fed the wheat products and the differences between the two treatments were greater than those found in Trial I. Unlike the results obtained in Trial I, there was little difference for any period between the treatments for either body weights or gains. The. average body weights at 6 weeks and 8 weeks of age
TABLE 2.—Average weights and gains in weight per chick in Trial I
Biweekly periods 1
2
3
4
5
Average weights in grams at end of period Ration Corn Wheat products Difference
110 106
269 254
4
15
532 484 48**
844 749 95**
1,134 1,076 58**
Average gains in grams for period Ration Corn Wheat products Difference
74 70
159 149
4
262 228
10* -
34**
311 262 49**
333 280 53**
' Significant. ! * Highly significant.
the wheat products ration. Gains were also in favor of the corn ration lots. The differences in weights at 6 weeks of age and thereafter were highly significant. Differences between the gains were significant in the second biweekly period and were highly significant thereafter. Trial II. Ten lots of 15 male day-old chicks each were involved in this trial, which was a repetition of Trial I, except that there was no reversal in treatments and the trial was discontinued at 8 weeks. The chicks were started February 27, 1945. Table 3 gives the average feed-gain ratios by batteries for each biweekly period. The differences for the two rations
were 512 and 792 grams for those fed wheat products and 515 and 807 grams for those fed the corn ration. The differences between treatments were not significant. The chicks on the wheat products ration grew better than those in Trial I, while those on the corn ration did not grow quite as well. In Trial II the wheat bran used was of a very light color and came from a northwestern mill, while that used in Trial I was brown and came from a nearby mill. Possibly different varieties of wheat, growing conditions or other factors may influence the feeding value of the bran. Unfortunately we had no history on
Downloaded from http://ps.oxfordjournals.org/ at Mount Allison University on June 30, 2015
ratio were highly significant, except where the original corn lots were compared with the wheat products lots which were fed corn during the previous 8 weeks. In this case, however, the difference was well above significance (5 percent level). Table I shows that the chicks fed the wheat products ration required slightly more feed per chick during each period. Table 2 shows that the chicks fed on the corn ration had greater average weights at the end of each period than those given
114
C. W. CARRICK AND R O Y E. ROBERTS
either sample used. Trial III. After considerable statistical analysis of the data obtained from Trials I and II, involving numerous correlations between weights and gains at different ages it seemed desirable to use pairing in Trial III. The best basis for TABLE 3.—Average feed-gain ratios and feed consumption for each battery in Trial II Biweekly periods 1 2
3
4
Feed-gain ratios Wheat products
2.13 2.09
2.22 2.87 2.38 2.71
3.40 3.36
Corn
2.10 2.16 2.59 2.13 2.10 2.55
3.00 2.95
Average Wheat products Corn
2.11 2.30 2.79 2.11 2.13 2.57
3.38 2.98
*Percent increase
0.0
8.0
8.6
13.4
Grams of feed per chick Wheat products Corn
151 152
389 355
653 615
944 870
* Average percentage increase in feed-gain ratios for wheat products over corn, with corn as 100 percent. After the first biweekly period the differences in feed-gain ratios were all highly significant.
TABLE 4.—Average feed-gain ratios and feed consumption for each battery in Trial III Weekly periods Ration 1 2
3
4
Feed-gain ratios
pairing appeared to be the gain during the 2 to 4 week period. The corn ration was fed for the first four weeks. The experimental rations were started April 17, 1946. Twenty sets of 20 chicks each were sorted so that in each set the gain from two to four weeks differed by only a few grams. About 30 of the largest chicks out of the original 500 started as day-old chicks were eliminated because of their great differences in gains, and over 60 of the smaller ones were also eliminated. This procedure resulted in somewhat higher average gains and body weights per lot than would be expected from an
Wheat products
2.46 2.75 2.93 2.41 2.65 2.78
3.12 3.22
Corn
2.34 2.50 2,64 2.29 2.50 2.71
2.95 2.89
Average Wheat products Corn
2.43 2.32
2.70 2.86 2.50 2.68
3.17 2.92
*Percent increase
4.7
8.0
8.6
6.7
Grams of feed per chick Wheat products Corn
320 315
410 392
466 444
517 489
* Average percentage increase in feed-gain ratios for wheat products over corn, with corn as 100 percent. In each period the differences in feed-gain ratios were highly significant.
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Ration
unselected group. The data for each chick were recorded on an individual card, the cards arrayed according to gain, and each chick within a set of 20 was assigned to a battery deck by using a table of random numbers. In this way each chick was paired with a similar chick in each of the other decks, also each deck and each battery tended to be equalized. White Plymouth Rock males were used in this trial. Two batteries of 5 decks each were assigned to each ration. Body weights and feed consumption were recorded weekly. Table 4 gives the average feed-gain ratios by batteries for each weekly period. The differences between rations for each period were all highly significant. The feed required per chick was again greater for the chicks fed the wheat products. Table 5 shows that the average weights at the end of each period and the average gains during each period were slightly in favor of the chicks fed the corn ration.
115
STUDIES ON FEED EFFICIENCY
eights The difference between average weights hough at the end of the fourth period, although ignifionly 14 grams, was well above significance. The differences in average gains for none of the weekly periods were :e significant, but when the gains for periods iods 1 and 2 were combined (4-6 weeks), ), the difference, though small, approachedI high significance. When the gains for periods iods 3 and 4 or for periods 1 to 4 were combined, bined, the differences were highly significant. it.
There was some evidence that results might be influenced by location in the batteries. In Trial I the difference between top and bottom decks was almost significant for both the 8-week body weights and was significant for feed-gain ratios. In Trial I I the difference between top and bottom decks was almost significant for feed efficiency during the 6 to 8-week period, but body weights were about the same. In Trial III the plan of the experi-
weight per chick in Trial III
1
3
2
fWeekly periods 4 1-2
3-4
1-4
Average weights in grams at end of period Ration Corn Wheat products Difference
445 444
602 596
768 759
1
6
9
937 923 14*
—
— — —
—
—
Average gains in grams for period Ration Corn Wheat products Difference
136 132
157 152
166 163
168 163
4
5
3
5
293 284 9*
334 326 8**
627 611 16**
t The chicks were 4 weeks old at the start of period 1. * Significant. ** Highly significant.
When the half of the pairs which gained most during the 2 to 4-week periodi were involved, the difference in the 4 to 8-week 5-week gain was highly significant, but when sn the data for the lower half were used, the difhe difference was not significant. The mean difference in 4 to 8-week gain. between :tween the rations was 27 grams for the upper half and 7 grams for the lower half.:. The unadjusted gains for all chickss from 4 to 8 weeks showed a difference of 16 grams between the two rations. When these gains were adjusted for feed intake, ntake, the difference was found to be 40 grams. ;rams. Co variance was used in arriving at these adjusted values.
ment was.quite different and deck had no effect on either gain or feed efficiency. There was no evidence that any battery deck other than the bottom deck had any effect in the results in any of the trials. Possibly the light or the temperature may have been factors unfavorable for the bottom decks in the first two trials, but with the design used in Trial I I I these factors were apparently eliminated. In this trial chemical analyses were obtained for the protein and fiber content of each ration and for the wheat products as shown in Table 6. As would be expected the wheat products ration was higher in both protein and fiber.
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TABLE 5.—Average weighs at end of each period and gains in
116
C. W. CARRICK AND ROY E. ROBERTS DISCUSSION
In all of these experiments, the chicks fed on the wheat products ration consumed more feed per chicken, required more feed per unit of gain, and made less gain than those fed on the corn ration. Since the chickens fed on the wheat products ration consumed more feed per chicken, intake of feed would be ruled out as a factor in the results obtained. Obvi-
Wheat bran Wheat middlings Wheat products ration Corn ration
Protein
Fiber
15.9 15.4 23.8 22.5
8.9 7.8 5.8 4.3
ously trie replacement of corn by wheat products would increase the fiber content of the ration, but it would also reduce the caloric value of the ration. Both digestion trials and feeding trials have shown that feeds and rations high in fiber are not well utilized. Possibly the laxative properties of a ration may also enter into its utilization. The results of these experiments might support several viewpoints as to the cause of the results, but the evidence is only indirect at best: They do present very definite evidence that the replacement of corn with bran and middlings in a supposedly adequate ration did reduce the efficiency of the ration. Similar results might not be obtained on rations lower in protein or other growth factors. From a practical viewpoint it is important to know the relative efficiency of feeds and rations. The procedure employed in Trial III indicates that small differences in the efficiency of two rations may be measured within a week. This procedure would make it possible to determine the relative efficiency of several ra-
SUMMARY
1. When 10 percent each wheat bran and wheat middlings replaced 20 percent ground yellow corn in a ration known to give rapid growth, more feed was required per unit of gain than when the wheat products were not included.
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TABLE 6.—Protein and fiber analyses of wheal products and rations used in Trial III
tions, within a few weeks time and with the same chicks, since rather definite differences were obtained in a week's time after the chicks were 4 weeks old. Different rations could be compared each week in many cases. The results in Trial III indicate that chicks with the greatest ability to gain may be better measurement material for experiments of this kind, so far as determining differences in gains are concerned. We have planned another experiment to throw light upon the ability to gain and its effect on feed efficiency. The procedure in Trial III had several advantages over that used in the previous trials. By starting the chicks on the experimental rations at 4 weeks of age, the mortality factor thereafter is likely to be negligible, sex identification is quite accurate in most varieties, any runts or abnormal chicks can be eliminated, and greater precision can be obtained by pairing according to the ability of the chicks to gain during the 2 to 4-week period. Also, the influence of variation in temperature can be reduced because after four weeks no brooder heat is necessary under ordinary laboratory conditions. The growth and feed consumption during the first four weeks are not sufficient to show much difference, so that the extra work is hardly justified during this period. It is believed that experiments of this kind will give much more satisfactory information concerning feeds and rations for practical application than can be obtained from digestion trials.
117
STUDIES ON FEED EFFICIENCY
2. The use of the wheat products reduced the rate of growth obtained from the type of ration used. 3. The feed consumption per chick was greater for the lots fed on the wheat products ration than for those fed on the corn ration. 4. Suggestions are made concerning technics for comparing the relative feed efficiency of rations for young chickens. We are greatly indebted to S. R. Miles, Research Statistician of the Purdue University Agricultural Experiment Station, for valuable suggestions on the design of these experiments and for assistance in the statistical analysis of the data, and to the Department of Agricultural Chemistry for the chemical analyses of the feeds.
Bartlett, J. M., 1910. Digestion experiments with poultry. Maine Agr. ,Exp. Sta. Bui. 184. Fraps, G. S., 1928. Digestibility and production coefficients of poultry feeds. Texas Agr. Exp. Sta. Bui. 372. Heuser, G. F., L. C. Norris, H. T. Peeler, and M. L. Scott, 1945. Further studies on the apparent effect of digestibility upon growth, weight maintenance and egg production. Poultry Sci. 24:142-145. Kaupp, B. F., and J. E. Ivey, 1923. Digestive coefficients of poultry feeds and rapidity of digestion and fate of grit in the fowl. N. C. Agr. Exp. Sta. Tech. Bui. 22. Mishler, D. H., C. W. Carrick, Roy E. Roberts, and S. M. Hauge, 1946. Synthetic and natural vitamin supplements for corn and soybean oil meal chick rations. Poultry Sci. 25:479-485. Roberts, Roy E., and C. W. Carrick, 1943. Influence of starting rations upon subsequent growth. Poultry Sci. 22:425-432.
News and Notes A. Wade Brant has returned from service in the armed forces to his position of Assistant Poultryman, The State College of Washington, Pullman. Mr. Brant served two and one-half years in the Army as Counter-intelligence Corps Investigative Agent in the Philippines and
Japan. J. D. Sykes has been promoted to Vice President in charge of Public Relations of the Ralston Purina Company, St. Louis, Missouri.
Dr. Horace J. Davis, after serving in the European Theatre with the armed forces, has returned to Louisiana State University, Baton Rouge, as Associate Professor of Animal Industry. The First International Congress of Physio-Pathology of Animal Reproduction and Artificial Insemination will be held in Milan, Italy, on April 9 to 15, 1948. The General Secretary of the Congress is Professor Telesforo Bonadonna. "Istituto-L. Spallangani," Via Bronzetti 17, Milano, Italy.
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ACKNOWLEDGMENTS
REFERENCES