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Effect of Antibiotics on the Protein Requirement of Broilers
POULTRY S C I E N C E September, 1952, Vol. 3 1 , N o . 5
S. J. SLINGER, J. E. BERGEY, W. F. PEPPER, E. S. SNYDER AND D. ARTHUR Departments of Poultry Husbandry and Nutrition, Ontario Agricultural College, Guelph, Canada (Received for publication July 19,1951)
M
OORE el al. (1946) found that streptomycin caused growth stimulation in chicks while Stokstad and Jukes (1950) and Whitehill et al. (1950) showed that chick growth was stimulated by aureomycin. Scott and Glista (1950), using a corn-soybean oil meal ration fortified with known vitamins, found that aureomycin did not stimulate growth except for a slight response during the first few weeks with ab libitum feeding and not at all when feed intake was equated. Matterson el al. (1951) found that of the antibiotics— streptomycin, aureomycin, penicillin, terramycin and bacitracin—the first named was the least effective in promoting growth response in chicks. These latter workers point out that their data as a whole suggest that the better the quality of the ration with respect to protein and vitamins, the less the growth response obtained by supplementing the ration with antibiotics. I t may be significant that the diet used by Scott and Glista was particularly well fortified in these respects. Several workers have noted a lower protein requirement in the presence of antibiotics. Thayer (1950) reported that the
incorporation of antibiotics will allow the use of lower protein feeds provided that vitamin Bj 2 and other B vitamins are increased. In addition, Machlin et al. (1951) stated, as a result of their work, that "the protein requirement for early growth of chicks appeared to be decreased slightly by addition of aureomycin to the diet. Aureomycin stimulated growth most effectively when added to a diet containing 19 percent protein. It was less effective with lower levels. Aureomycin increased efficiency of feed utilization when added to a corn-soybean diet containing vitamin B12. The effect of aureomycin was more pronounced with increasing protein levels." Slinger et al. (1951) presented evidence to suggest that penicillin and aureomycin increase the lysine requirement of the poult for normal feather pigmentation. A higher lysine requirement in the presence of antibiotic may possibly be explained on the basis of increased availability of ingested protein under such conditions, since the findings of Kratzer el al. (1950) indicate that the level of lysine required to prevent pigmentation failure increased as the protein level was raised.
757
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Effect of Antibiotics on the Protein Requirement of Broilers
758
S. SLINGER, J. BERGEY, W. P E P P E R , E. SNYDER, D. ARTHUR TABLE 1.—Composition of basal diets
17 17
EXPERIMENT 1
Procedure.—This experiment was made to determine the effect of penicillin on the protein requirement of Barred Plymouth Rock male chicks. The birds were reared on litter in similar pens of the same brooder house. Brooding heat was supplied by electric hovers. Each group comprised 76 chicks. The birds were distributed into the experimental groups on the basis of weight and. in a random manner. The chicks were weighed individually at 10 weeks of age and feed consumption was recorded. TABLE 2.—Percentage composition of diets Protein content of diet (%) Ingredient
Basal No. 1 Wheat shorts Soybean oil meal (44%)
17
20
23
26
70 30
70 20 10
70 10 20
70 — 30
1,129 1,182
4.69
3.64 3.52
3.30
7.66 7.85
20 20
+
1,309 1,356
— 3.59
3.42 3.33
2.63
7.39 7.51
23 23
—' +
1,411 1,446
— 2.48
3.09 3.04
1.62
6.99 7.08
3.24 3.00
7.41
6.62 6.44
26 26
1,363 1,445
mixed 8 times and protein (NX6.25) analyses were made on one occasion, with the following results: 17.4, 20.2, 23.5 and 26.3 percent. Each diet was fed in the absence of antibiotic and in the presence of 10 p.p.m. of penicillin G potassium. According to the data of Fraps (1946) wheat shorts and solvent process soybean oil meal have approximately the same productive energy content. Therefore, the energy value was maintained at approximately the same level for all diets, namely, 885 Calories per pound. Feed and water were supplied ad libitum and insoluble grit was sprinkled on the feed once
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The composition of the basal diet is shown in Table 1 (Basal No. 1). While Ingredient Basal No. 1 Basal No. 2 this diet contained 15 percent of animal Ground yellow corn 49.0 pounds 51.0 pounds Ground wheat 4.3 pounds protein ingredients, it was considered ad— Fish meal (65%) 5.0 pounds 13.0 pounds Meat meal (50%) 5.0 pounds visable to include additional vitamin Bi2 — Dried buttermilk 5.0 pounds 3.0 pounds Limestone 0.75 pounds 1.0 pounds to ensure against any possible deficiency Steamed bone meal 1.25 pounds — Iodized salt 0.25 pounds 0.2 pounds of this vitamin with the higher levels of Fish oil (400D-2.400A) 0.5 pounds 0.5 pounds Dehydrated alfalfa 1.25 pounds 1.0 pounds protein. The diet contained Megasul, a Manganese sulfate (tech.) 9 gm. 11.4 gm. Riboflavin 200 mg. 150 mg. product designated as containing 25 perNiacin 1 gm. 1 gm. Ca pantothenate 300 mg. cent nitrophenide, as a coccidiosis pre— mg. Vitamin Bu .0.1 — Megasul 22.7 gm. ventative. The percentage composition of — 72 pounds Totals 70 pounds the individual diets is shown in Table 2. Wheat shorts was replaced step-wise by soybean oil meal in order to achieve levels Slinger el al. (1951) obtained a greater reof protein calculated to be 17, 20, 23 and sponse to antibiotics using a 28 than a 20 26 percent. The experimental diets were percent protein' diet for turkey poults. This suggested an increase in the growth TABLE 3.-—Effect of penicillin on growth, feed potential maximum and a possible inefficiency and feed consumption at 10 weeks of age crease in the protein requirement under the influence of antibiotics. However, it Treatment In In may be that a 20 percent level of protein " " Feed A Penicillin „„„ ™' crease V~~At „ " e crease ^. „ A , crease crease G no*£ , . is so far below the requirement of this Protein tasauin T ^ 1 nenicillin S a m nenicillin „ <„£ c "k , (gm ) (10 species as to be limiting. p.p.m.)
759
ANTIBIOTICS AND PROTEIN REQUIREMENTS
TABLE 4.—Analysis of variance of mean weights Source of variation
D. F.
Protein level Penicillin PenicillinXprotein level Error
3 1 3 579
29,604.31** 5,570.41** 213.42 441.79
** Significant at P < 0.01.
clarify this situation, the volume of the diets was measured and feed consumption was calculated in liters. These values are presented in Table 3, and indicate that the groups fed diets containing 17 percent protein consumed a considerably greater volume of feed than those fed diets with 20 percent protein. It is therefore apparent that the greater weights of the groups fed the 23 percent protein diet, as compared to those fed the 20 percent protein diet, is not attributable to the difference in the volume of these feeds. Quality of the dressed carcasses was assessed by measuring the breast-angle as an index of fleshing and by objective examination to indicate the extent of external fat deposition or finish. The angle of the breast was measured, after dressing, using a modification of the type of instrument recently used by several workers. The apparatus has a moveable arm and records the angle formed by the breast when held in position. In this case the measurement was taken 0.5 inches from the anterior end of the keel bone. The average breast-width measurement for each group is presented in Table 5. Each bird was assigned a grade for finish according to Canadian Government standards (1939) for this criterion. These data are also presented in Table 5. It may be noted that penicillin caused a significant increase in mean breast angle with diets containing 17 and 26 percent protein but did not do so with intermediate levels. The mean breast
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weekly. At the conclusion of the experiment 25 average birds from each group were slaughtered and the carcasses examined for market quality. Results and Discussion.—Sexing the newly hatched chicks was not absolutely accurate, but positive sex identification was made at a later date. The weight data, presented in Table 3, are representative of males only. The greatest number of females in any group was 5 and the minimum total number of birds remaining in any group at 10 weeks of age was 74. The values for feed efficiency, also set forth in Table 3, are basedxon total birds. The weights were examined statistically according to the method of unweighted means (Yates, 1934). The results of this analysis are presented in Table 4. It may be noted that the effects of protein level and penicillin were highly significant. Interactions between the level of protein and penicillin were not found to be significant. However, an examination of the individual mean weights and feed efficiencies indicates that there was a greater response from penicillin with the 26 percent protein-diet than at lower levels. The data suggest that, in the absence of antibiotic, the highest level of protein tended to depress growth and feed efficiency as compared to the diet containing 23 percent protein. The depressing effect of the high level of protein appeared to be considerably relieved by the presence of penicillin in the diet. Substituting soybean oil meal for wheat shorts in order to raise the level of protein caused the volume to decrease with increasing protein content. In view of this, it may be considered that the increased weight using the 23 percent protein-diet as compared to that containing 20 percent protein, was due to the fact that the higher volume of the latter diet limited feed consumption. To
760
S. SLINGER, J. BERGEY, W. PEPPER, E. SNYDER, D. ARTHUR TABLE 5.—Effect Treatment
Protein
Finish (percent in grade)
Mean breast angle augic
Penicillin .-, . . _
of penicillin and protein on market quality
Mean diff.
/'value
2
P
64.4
17
1.6 17
4.26
67.0
20
0.5 20
1.38
23
69.6
+
0.2
0.55
0.9
2.12
26
69.7
+
80
20
72
28
60
40
56
44
28
72
36
64
44
56
>0.05
68.8
26
4
<0.05
Where x\ and x% are the means, (s.d.)i and (s.d.)2 are the standard deviations and Ni and Ni are the numbers of birds per group.
X\ — *2
'(s.d.y (s.d.)22 — • + iVi N2 ^ 2 P = Probability obtained from a table of "t" values. P < 0 . 0 5 is usually considered as indicating significance.
angles of groups fed the 23 percent protein-diets proved significantly greater (P<0.01) than those of birds which had received the 20 percent protein-diets. These results indicate that while penicillin improved protein utilization under certain conditions, the protein requirement for maximum fleshing was 23 percent in the presence or absence of antibiotic. In general, increasing the level of protein or including penicillin in the diets, decreased the degree of finish. The similar effect of both protein and penicillin in this regard is further evidence that penicillin enhanced protein utilization. TABLE 6.—Percentage composition of diets Protein content of diet (%)
Basal No. 2 Yellow corn Soybean oil meal (50%) Corn oil
17
20
23
26 26+oil
72 28
72 21
72 14
72 7
72 4.25
•— —
14
21
—
—
—
21 2.75
7 •
EXPERIMENT 2
Procedure.—This experiment was made to determine the influence of aureomycin on the protein requirement of male chicks resulting from a cross of Light Sussex d" X New Hampshire 9 and was an attempt to extend and verify the findings in the former trial. Each group comprised 20 chicks which were reared in electrically heated battery brooders, with raised wire floors, for the 10 weeks' duration of the experiment. The chicks were weighed individually at 10 weeks of age and feed consumption was recorded. The composition of the basal diet is shown in Table 1 (Basal No. 2) while the percentage composition of the experimental diets is presented in Table 6. The calculated protein content of the diets employed was 17, 20, 23 and 26 percent. The diets were mixed twice and protein (NX6.25) analyses made on one series of the mixed diets gave values of 17.2, 20.3, 23.5 and 26.6 percent. All diets were fed
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69.8
23
96
>0.05
67.5
+
B
<0.01
66.0
+
A and better
ANTIBIOTICS AND PROTEIN REQUIREMENTS
Since corn is higher in energy than 50 percent-soybean oil meal, the energy level decreased as protein was increased. The productive energy content of all diets was calculated using the data of Fraps (1946). Since no figure is given for 50 percent protein-soybean oil meal production coefficients were used to arrive at a value for this product. On this basis the energy content of the 17 percent protein-diet was 1,077 Calories per pound and the energy level decreased by 37 Calories per pound with each increase of 3 percent in protein, so that the energy content of the 26 percent protein-diet was 966 Calories per pound. Considering the possibility that 966 Calories per pound might be insufficient energy for the proper utilization of the 26 percent protein diet, additional groups were fed diets containing essentially this same level of protein but with enough corn oil added to
T A B L E 7.—Effect of aureomycin ion growth and feed efficiency at 10 weeks of age Treatment
Average Increase due to Aureoweight Pro- mycin (gm.) aureomycin tein HC1 (%) (%) (20p.p.ra.) 17 17 20 20 23 23 26 26 26+oil 26+oil
Feed/ gam
Increase due to aureomycin
2.52 2.48
1.59
(%)
+
1,304 1,394
+
1,523 1,598
4.92
+
1,577 1,635
3.68
2.46 2.45 2.42 2.37
+
1,622 1,674
3.21
2.52 2.47
1.98
+
1,697 1,719
1.30
2.41 2.38
1.24
6.90
0.41 2.07
raise the energy content to about the same level as present in the 23 percent protein-diet. Feed and water were supplied ad libitum and insoluble grit was sprinkled on the feed twice weekly. Results and Discussion.—The weight and feed efficiency data are presented in Table 7. Upon final sexing of the birds some pullets were encountered in certain pens—the maximum number in any group being 2. The weight data do not include values for females but such weights were included for purposes of calculating feed efficiency. Very little mortality occurred in the experiment but there was some incidence of perosis. When birds were affected with perosis to the extent that it interfered with feed consumption, their weights were not used for average weight calculations but were included in computing feed efficiency. The weight data for groups other than those fed the 26 percent protein-diets plus corn oil were examined statistically by the method indicated previously. The latter groups were not included in the analysis since this portion of the experiment involved a different experimental design. The results of this analysis are presented in Table 8. I t may be noted that the effects of protein level and
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with and without 20 p.p.m. of aureomycin HC1. I t was considered possible that in the former experiment a deficiency of energy was responsible for the failure of the highest protein level in the absence of antibiotic. For the present experiment, in an attempt to maintain energy levels as high as practicable, corn was used almost solely as the cereal grain component while fish meal and 50 percent proteinsoybean oil meal were employed as protein supplements. In order to increase the protein content, ground corn was replaced by 50 percent protein-soybean oil meal, in a step-wise manner. The corn was ground in such a way that the volume of this material was the same as the volume of the soybean oil meal used. In this way the volume of all diets remained relatively constant. Volume was measured on the 10 diets used and the average was found to be 711 ml. per pound with a range of 700-720 ml. per pound.
761
762
S. SLINGER, J. BERGEY, W. PEPPER, E. SNYDER, D. ARTHUR
TABLE 8.—Analysis of variance of mean weights Source of variation Protein level Aureomycin AureomycinXprotein level Error
D.F. 3 1 3 167
m e a n
square 35,347.01** 9,405.06** 154.16 1,305.20
** Significant at P < 0 . 0 1 .
Groups fed either 17 or 20 percent protein-diets were well finished and superior in this respect to groups fed higher levels of protein. Diets containing in excess of 20 percent protein were found to have produced an unsatisfactory degree of finish for market purposes. This is of interest when it is considered that the 23 percent protein-diet contained about 1,000 Calories per pound and indicates that the energy requirement to obtain a satisfactory degree of finish using such a level of protein is beyond what could be achieved in practice. Upon examination of the dressed carcasses it was also observed that aureomycin had improved external fat deposition in the case of birds fed the 17 and 20 percent protein-diets but not for groups fed higher levels of this nutrient. Since the 23 percent protein-diet contained about 1,000 Calories per pound it would appear that the energy level at which aureomycin is effective in improving finish
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aureomycin were highly significant while interactions between aureomycin and protein level were not significant. Increasing the protein content of broiler diets in practice, would probably be accomplished by replacing a high energycereal grain, such as corn or wheat, by soybean oil meal. This would be comparable to the procedure followed in the first portion of the present experiment and would involve a lowering of the energy level with increasing protein. It was of interest to determine the result of increasing the level of protein from 23 to 26 percent both with a reduction in energy and with the energy level maintained constant. Comparing the mean square, with the error mean square for the experiment as a whole gave a measure of the significance of the differences between means. Raising the protein content from 23 to 26 percent either with a reduction in energy or when the energy level was maintained resulted in a highly significant increase in weight P<0.01. The weights of the birds fed diets containing 26 percent protein plus corn oil did not prove significantly superior to those of the groups fed the same level of protein without corn oil. However, when both weight and feed efficiency are considered the data indicate that the higher energy diets were somewhat superior as compared to those without added corn oil. These results suggest that the energy requirement for maximum weight and feed efficiency, using a diet containing 26 per-
cent protein, was in excess of 966 Calories per pound. At the conclusion of the experiment all birds were slaughtered, dressed and examined for market quality. In this experiment the birds were not graded individually but notes were made on the fleshing and finish of the groups as a whole. Raising the level of protein from 17 to 20 percent was found to improve fleshing but further increases were without effect. Aureomycin did not appear to influence fleshing except when added to the 26 percent protein-diet without corn oil and the 17 percent protein-diet. Added to the former diet aureomycin improved fleshing while included in the latter diet the antibiotic decreased fleshing. The difference in fleshing response to antibiotic may possibly be explained on the basis of differences in the levels of protein and energy in the various diets.
ANTIBIOTICS AND PROTEIN REQUIREMENTS
SUMMARY AND CONCLUSIONS
Two experiments were made to determine the influence of antibiotics on the protein requirement of heavy-breed male broilers. Protein levels of 17, 20, 23 and26 percent were employed in each experiment. The effects of protein level and antibiotic (penicillin or aureomycin) were highly significant. Interactions between the level of protein and antibiotic did not prove to be significant in either experiment. Evidence is presented to indicate that
antibiotics enhanced the utilization of both protein and energy compounds. This may well explain why the antibiotics failed to reduce the requirement for either protein or energy. Under the conditions of these experiments the protein requirement for maximum growth and feed efficiency to 10 weeks of age was in excess of 20 percent. On the other hand, levels of protein which resulted in maximum growth and feed efficiency were too high for the production of broilers of optimum market quality. It is suggested that heavy-breed male broilers be fed diets containing in excess of 20 percent protein during the growing period and that the level be reduced to 20 percent or less for a finishing period of a few weeks. ACKNOWLEDGEMENT We are indebted to Lederle Laboratories for the Megasul and aureomycin HC1; to Merck and Company for the niacin, calcium pantothenate and vitamin B12; and to Chas. Pfizer and Company for the penicillin G potassium used in this work. REFERENCES Fraps, C. S. 1946. Composition and productive energy, of poultry feeds and rations. Texas Agr. Exp. Sta. Bui. 678. Machlin, L. J., C. A. Denton, W. L. Kellogg and H. R. Bird, 1951. Effect of dietary antibiotic upon feed efficiency and protein requirement of growing chickens. Private communication. Matterson, L. D., E. P. Singsen, L. Decker and A. Kozeff, 1951. A comparison of several antibiotics as growth stimulants in practical chickstarting rations. Storrs Agr. Exp. Sta. Bui. 275. Moore, P. R., A. Evenson, T. D. Luckey, E. Mccoy, C. A. Elvehjem and E. B. Hart, 1946. Use of sulfasuxidine, streptothricin and streptomycin in nutritional studies with the chick. J. Biol. Chem. 165:437-441. Regulations under the provisions of the live stock and live stock products act of the Statutes of Canada, 1939. Chapter 47. Respecting the grading and marketing of dressed and eviscerated poultry.
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increases as the protein content of the diet is raised. These results suggest that while aureomycin enhances energy utilization, improved finish is obtained only when the energy level is sufficiently high. The results of the present experiments do not support the conclusion that the requirement for either protein or energy is reduced in the presence of antibiotic. This is probabiy due to the fact that the utilization of both protein and energy was enhanced by incuding antibiotic in the diet. I t may well be that all nutrients are utilized better in the presence of antibiotic. This being the case, one would not expect antibiotic to influence nutritive requirements when fed with properly balanced diets. The protein requirement for maximum weight and feed efficiency in these experiments was in excess of 20 percent in both the absence and presence of antibiotic. However, the protein requirement for the production of broilers with suitable market quality was less than for maximum weight and feed efficiency. From a practical standpoint it would therefore seem advisable, if feeding broilers such as these, to employ a level of protein in excess of 20 percent for the growing period only, and to reduce this to 20 percent or less for a finishing period of a few weeks.
763
764
J. B. O ' N E I L
Scott, H. M., and W. A. Glista, 1950. The effect of aureomycin and arsonic acid on chick growth. Poultry Sci. 29:921-923. Slinger, S. J., K. M. Gartley, W. F. Pepper and D. C. Hill, 1951. The inuflence of animal protein factor supplements and antibiotics on the incidence and severity of white feathers in turkeys. J. Nutrition 43:345-355. Stokstad, E. L. R., and T. H. Jukes, 1950. Further observations on the "animal protein factor." Proc. Soc. Exp. Biol. Med. 73: 523. Thayer, R. S., 1950. Talk before the Oklahoma Feed
Conference, as reported in the reprint of an address "Vitamin B12 and antibiotic developments in nutrition—a review" by G. P. Whitlock before the Nutrition Committee of the Feed Institute, Inc., Des Moines, Iowa, 1951. Whitehill, A. R., J. J. Oleson and B. L. Hutchings, 1950. Stimulatory effect of aureomycin on the growth of chicks. Proc. Soc. Exp. Biol. Med. 74: 11. < Yates, F., 1934. The analysis of multiple classifications with unequal numbers in the different classes. Jour. Am. Stat. Assoc. 29: 51.
J. B. O ' N E I L Poultry Department, University of Saskatchewan, Saskatoon, Canada (Received for publication October 27, 1951)
A
SURVEY of the literature indicates that it is not necessary to hatch chicks from breeders deficient of vitamin B12 in order to produce deficiencies of this vitamin in the chicks used for experimental purposes. Hill and Branion (1950) studied the replacement value of an APF supplement for varying amounts of fish meal using chicks from hens fed well balanced diets and maintained on floor litter. Sherwood and Couch (1950) used chicks from hens also kept in floor pens and fed a mixture of animal proteins. Results published by Briggs et al. (1950) support these findings and the authors state that a vitamin B12 deficiency may be produced in chicks without the use of "stress factors." Miller and Groschke (1950) describe a short chick assay method for measuring APF activity when the chicks are hatched from eggs produced by hens fed a mixture of animal protein feeds.
Evidence of the carryover of unknown factor or factors has been presented by several workers. Bird et al. (1946) reported a high mortality rate in chicks from hens fed a soybean oil meal diet and that the supplementing of the breeders' diet with either cow manure or sardine meal resulted in a much lower mortality. However, the supplementation of the chick's diet did not improve livability. On the other hand, if the hens' diet contained either fish meal or cow manure, this growth factor was transferred in sufficient quantities to insure normal growth of the chicks to six weeks of age (Rubin and Bird, 1946). In their report, Bethke et al. (1947) found that chicks produced from hens receiving soybean oil meal did not grow as well as those from soybean oil meal and fish meal. McGinnis and Carver (1947) using diets with either soybean oil meal or Alaska pea meal as sources of protein, report poor growth and high
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Further Evidence of the Carryover of Vitamin B12 in Chicks
S. J. SLINGER, J. E. BERGEY, W. F. PEPPER, E. S. SNYDER AND D. ARTHUR Departments of Poultry Husbandry and Nutrition, Ontario Agricultural College, Guelph, Canada (Received for publication July 19,1951)
M
OORE el al. (1946) found that streptomycin caused growth stimulation in chicks while Stokstad and Jukes (1950) and Whitehill et al. (1950) showed that chick growth was stimulated by aureomycin. Scott and Glista (1950), using a corn-soybean oil meal ration fortified with known vitamins, found that aureomycin did not stimulate growth except for a slight response during the first few weeks with ab libitum feeding and not at all when feed intake was equated. Matterson el al. (1951) found that of the antibiotics— streptomycin, aureomycin, penicillin, terramycin and bacitracin—the first named was the least effective in promoting growth response in chicks. These latter workers point out that their data as a whole suggest that the better the quality of the ration with respect to protein and vitamins, the less the growth response obtained by supplementing the ration with antibiotics. I t may be significant that the diet used by Scott and Glista was particularly well fortified in these respects. Several workers have noted a lower protein requirement in the presence of antibiotics. Thayer (1950) reported that the
incorporation of antibiotics will allow the use of lower protein feeds provided that vitamin Bj 2 and other B vitamins are increased. In addition, Machlin et al. (1951) stated, as a result of their work, that "the protein requirement for early growth of chicks appeared to be decreased slightly by addition of aureomycin to the diet. Aureomycin stimulated growth most effectively when added to a diet containing 19 percent protein. It was less effective with lower levels. Aureomycin increased efficiency of feed utilization when added to a corn-soybean diet containing vitamin B12. The effect of aureomycin was more pronounced with increasing protein levels." Slinger et al. (1951) presented evidence to suggest that penicillin and aureomycin increase the lysine requirement of the poult for normal feather pigmentation. A higher lysine requirement in the presence of antibiotic may possibly be explained on the basis of increased availability of ingested protein under such conditions, since the findings of Kratzer el al. (1950) indicate that the level of lysine required to prevent pigmentation failure increased as the protein level was raised.
757
Downloaded from http://ps.oxfordjournals.org/ at Mount Allison University on June 22, 2015
Effect of Antibiotics on the Protein Requirement of Broilers
758
S. SLINGER, J. BERGEY, W. P E P P E R , E. SNYDER, D. ARTHUR TABLE 1.—Composition of basal diets
17 17
EXPERIMENT 1
Procedure.—This experiment was made to determine the effect of penicillin on the protein requirement of Barred Plymouth Rock male chicks. The birds were reared on litter in similar pens of the same brooder house. Brooding heat was supplied by electric hovers. Each group comprised 76 chicks. The birds were distributed into the experimental groups on the basis of weight and. in a random manner. The chicks were weighed individually at 10 weeks of age and feed consumption was recorded. TABLE 2.—Percentage composition of diets Protein content of diet (%) Ingredient
Basal No. 1 Wheat shorts Soybean oil meal (44%)
17
20
23
26
70 30
70 20 10
70 10 20
70 — 30
1,129 1,182
4.69
3.64 3.52
3.30
7.66 7.85
20 20
+
1,309 1,356
— 3.59
3.42 3.33
2.63
7.39 7.51
23 23
—' +
1,411 1,446
— 2.48
3.09 3.04
1.62
6.99 7.08
3.24 3.00
7.41
6.62 6.44
26 26
1,363 1,445
mixed 8 times and protein (NX6.25) analyses were made on one occasion, with the following results: 17.4, 20.2, 23.5 and 26.3 percent. Each diet was fed in the absence of antibiotic and in the presence of 10 p.p.m. of penicillin G potassium. According to the data of Fraps (1946) wheat shorts and solvent process soybean oil meal have approximately the same productive energy content. Therefore, the energy value was maintained at approximately the same level for all diets, namely, 885 Calories per pound. Feed and water were supplied ad libitum and insoluble grit was sprinkled on the feed once
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The composition of the basal diet is shown in Table 1 (Basal No. 1). While Ingredient Basal No. 1 Basal No. 2 this diet contained 15 percent of animal Ground yellow corn 49.0 pounds 51.0 pounds Ground wheat 4.3 pounds protein ingredients, it was considered ad— Fish meal (65%) 5.0 pounds 13.0 pounds Meat meal (50%) 5.0 pounds visable to include additional vitamin Bi2 — Dried buttermilk 5.0 pounds 3.0 pounds Limestone 0.75 pounds 1.0 pounds to ensure against any possible deficiency Steamed bone meal 1.25 pounds — Iodized salt 0.25 pounds 0.2 pounds of this vitamin with the higher levels of Fish oil (400D-2.400A) 0.5 pounds 0.5 pounds Dehydrated alfalfa 1.25 pounds 1.0 pounds protein. The diet contained Megasul, a Manganese sulfate (tech.) 9 gm. 11.4 gm. Riboflavin 200 mg. 150 mg. product designated as containing 25 perNiacin 1 gm. 1 gm. Ca pantothenate 300 mg. cent nitrophenide, as a coccidiosis pre— mg. Vitamin Bu .0.1 — Megasul 22.7 gm. ventative. The percentage composition of — 72 pounds Totals 70 pounds the individual diets is shown in Table 2. Wheat shorts was replaced step-wise by soybean oil meal in order to achieve levels Slinger el al. (1951) obtained a greater reof protein calculated to be 17, 20, 23 and sponse to antibiotics using a 28 than a 20 26 percent. The experimental diets were percent protein' diet for turkey poults. This suggested an increase in the growth TABLE 3.-—Effect of penicillin on growth, feed potential maximum and a possible inefficiency and feed consumption at 10 weeks of age crease in the protein requirement under the influence of antibiotics. However, it Treatment In In may be that a 20 percent level of protein " " Feed A Penicillin „„„ ™' crease V~~At „ " e crease ^. „ A , crease crease G no*£ , . is so far below the requirement of this Protein tasauin T ^ 1 nenicillin S a m nenicillin „ <„£ c "k , (gm ) (10 species as to be limiting. p.p.m.)
759
ANTIBIOTICS AND PROTEIN REQUIREMENTS
TABLE 4.—Analysis of variance of mean weights Source of variation
D. F.
Protein level Penicillin PenicillinXprotein level Error
3 1 3 579
29,604.31** 5,570.41** 213.42 441.79
** Significant at P < 0.01.
clarify this situation, the volume of the diets was measured and feed consumption was calculated in liters. These values are presented in Table 3, and indicate that the groups fed diets containing 17 percent protein consumed a considerably greater volume of feed than those fed diets with 20 percent protein. It is therefore apparent that the greater weights of the groups fed the 23 percent protein diet, as compared to those fed the 20 percent protein diet, is not attributable to the difference in the volume of these feeds. Quality of the dressed carcasses was assessed by measuring the breast-angle as an index of fleshing and by objective examination to indicate the extent of external fat deposition or finish. The angle of the breast was measured, after dressing, using a modification of the type of instrument recently used by several workers. The apparatus has a moveable arm and records the angle formed by the breast when held in position. In this case the measurement was taken 0.5 inches from the anterior end of the keel bone. The average breast-width measurement for each group is presented in Table 5. Each bird was assigned a grade for finish according to Canadian Government standards (1939) for this criterion. These data are also presented in Table 5. It may be noted that penicillin caused a significant increase in mean breast angle with diets containing 17 and 26 percent protein but did not do so with intermediate levels. The mean breast
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weekly. At the conclusion of the experiment 25 average birds from each group were slaughtered and the carcasses examined for market quality. Results and Discussion.—Sexing the newly hatched chicks was not absolutely accurate, but positive sex identification was made at a later date. The weight data, presented in Table 3, are representative of males only. The greatest number of females in any group was 5 and the minimum total number of birds remaining in any group at 10 weeks of age was 74. The values for feed efficiency, also set forth in Table 3, are basedxon total birds. The weights were examined statistically according to the method of unweighted means (Yates, 1934). The results of this analysis are presented in Table 4. It may be noted that the effects of protein level and penicillin were highly significant. Interactions between the level of protein and penicillin were not found to be significant. However, an examination of the individual mean weights and feed efficiencies indicates that there was a greater response from penicillin with the 26 percent protein-diet than at lower levels. The data suggest that, in the absence of antibiotic, the highest level of protein tended to depress growth and feed efficiency as compared to the diet containing 23 percent protein. The depressing effect of the high level of protein appeared to be considerably relieved by the presence of penicillin in the diet. Substituting soybean oil meal for wheat shorts in order to raise the level of protein caused the volume to decrease with increasing protein content. In view of this, it may be considered that the increased weight using the 23 percent protein-diet as compared to that containing 20 percent protein, was due to the fact that the higher volume of the latter diet limited feed consumption. To
760
S. SLINGER, J. BERGEY, W. PEPPER, E. SNYDER, D. ARTHUR TABLE 5.—Effect Treatment
Protein
Finish (percent in grade)
Mean breast angle augic
Penicillin .-, . . _
of penicillin and protein on market quality
Mean diff.
/'value
2
P
64.4
17
1.6 17
4.26
67.0
20
0.5 20
1.38
23
69.6
+
0.2
0.55
0.9
2.12
26
69.7
+
80
20
72
28
60
40
56
44
28
72
36
64
44
56
>0.05
68.8
26
4
<0.05
Where x\ and x% are the means, (s.d.)i and (s.d.)2 are the standard deviations and Ni and Ni are the numbers of birds per group.
X\ — *2
'(s.d.y (s.d.)22 — • + iVi N2 ^ 2 P = Probability obtained from a table of "t" values. P < 0 . 0 5 is usually considered as indicating significance.
angles of groups fed the 23 percent protein-diets proved significantly greater (P<0.01) than those of birds which had received the 20 percent protein-diets. These results indicate that while penicillin improved protein utilization under certain conditions, the protein requirement for maximum fleshing was 23 percent in the presence or absence of antibiotic. In general, increasing the level of protein or including penicillin in the diets, decreased the degree of finish. The similar effect of both protein and penicillin in this regard is further evidence that penicillin enhanced protein utilization. TABLE 6.—Percentage composition of diets Protein content of diet (%)
Basal No. 2 Yellow corn Soybean oil meal (50%) Corn oil
17
20
23
26 26+oil
72 28
72 21
72 14
72 7
72 4.25
•— —
14
21
—
—
—
21 2.75
7 •
EXPERIMENT 2
Procedure.—This experiment was made to determine the influence of aureomycin on the protein requirement of male chicks resulting from a cross of Light Sussex d" X New Hampshire 9 and was an attempt to extend and verify the findings in the former trial. Each group comprised 20 chicks which were reared in electrically heated battery brooders, with raised wire floors, for the 10 weeks' duration of the experiment. The chicks were weighed individually at 10 weeks of age and feed consumption was recorded. The composition of the basal diet is shown in Table 1 (Basal No. 2) while the percentage composition of the experimental diets is presented in Table 6. The calculated protein content of the diets employed was 17, 20, 23 and 26 percent. The diets were mixed twice and protein (NX6.25) analyses made on one series of the mixed diets gave values of 17.2, 20.3, 23.5 and 26.6 percent. All diets were fed
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69.8
23
96
>0.05
67.5
+
B
<0.01
66.0
+
A and better
ANTIBIOTICS AND PROTEIN REQUIREMENTS
Since corn is higher in energy than 50 percent-soybean oil meal, the energy level decreased as protein was increased. The productive energy content of all diets was calculated using the data of Fraps (1946). Since no figure is given for 50 percent protein-soybean oil meal production coefficients were used to arrive at a value for this product. On this basis the energy content of the 17 percent protein-diet was 1,077 Calories per pound and the energy level decreased by 37 Calories per pound with each increase of 3 percent in protein, so that the energy content of the 26 percent protein-diet was 966 Calories per pound. Considering the possibility that 966 Calories per pound might be insufficient energy for the proper utilization of the 26 percent protein diet, additional groups were fed diets containing essentially this same level of protein but with enough corn oil added to
T A B L E 7.—Effect of aureomycin ion growth and feed efficiency at 10 weeks of age Treatment
Average Increase due to Aureoweight Pro- mycin (gm.) aureomycin tein HC1 (%) (%) (20p.p.ra.) 17 17 20 20 23 23 26 26 26+oil 26+oil
Feed/ gam
Increase due to aureomycin
2.52 2.48
1.59
(%)
+
1,304 1,394
+
1,523 1,598
4.92
+
1,577 1,635
3.68
2.46 2.45 2.42 2.37
+
1,622 1,674
3.21
2.52 2.47
1.98
+
1,697 1,719
1.30
2.41 2.38
1.24
6.90
0.41 2.07
raise the energy content to about the same level as present in the 23 percent protein-diet. Feed and water were supplied ad libitum and insoluble grit was sprinkled on the feed twice weekly. Results and Discussion.—The weight and feed efficiency data are presented in Table 7. Upon final sexing of the birds some pullets were encountered in certain pens—the maximum number in any group being 2. The weight data do not include values for females but such weights were included for purposes of calculating feed efficiency. Very little mortality occurred in the experiment but there was some incidence of perosis. When birds were affected with perosis to the extent that it interfered with feed consumption, their weights were not used for average weight calculations but were included in computing feed efficiency. The weight data for groups other than those fed the 26 percent protein-diets plus corn oil were examined statistically by the method indicated previously. The latter groups were not included in the analysis since this portion of the experiment involved a different experimental design. The results of this analysis are presented in Table 8. I t may be noted that the effects of protein level and
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with and without 20 p.p.m. of aureomycin HC1. I t was considered possible that in the former experiment a deficiency of energy was responsible for the failure of the highest protein level in the absence of antibiotic. For the present experiment, in an attempt to maintain energy levels as high as practicable, corn was used almost solely as the cereal grain component while fish meal and 50 percent proteinsoybean oil meal were employed as protein supplements. In order to increase the protein content, ground corn was replaced by 50 percent protein-soybean oil meal, in a step-wise manner. The corn was ground in such a way that the volume of this material was the same as the volume of the soybean oil meal used. In this way the volume of all diets remained relatively constant. Volume was measured on the 10 diets used and the average was found to be 711 ml. per pound with a range of 700-720 ml. per pound.
761
762
S. SLINGER, J. BERGEY, W. PEPPER, E. SNYDER, D. ARTHUR
TABLE 8.—Analysis of variance of mean weights Source of variation Protein level Aureomycin AureomycinXprotein level Error
D.F. 3 1 3 167
m e a n
square 35,347.01** 9,405.06** 154.16 1,305.20
** Significant at P < 0 . 0 1 .
Groups fed either 17 or 20 percent protein-diets were well finished and superior in this respect to groups fed higher levels of protein. Diets containing in excess of 20 percent protein were found to have produced an unsatisfactory degree of finish for market purposes. This is of interest when it is considered that the 23 percent protein-diet contained about 1,000 Calories per pound and indicates that the energy requirement to obtain a satisfactory degree of finish using such a level of protein is beyond what could be achieved in practice. Upon examination of the dressed carcasses it was also observed that aureomycin had improved external fat deposition in the case of birds fed the 17 and 20 percent protein-diets but not for groups fed higher levels of this nutrient. Since the 23 percent protein-diet contained about 1,000 Calories per pound it would appear that the energy level at which aureomycin is effective in improving finish
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aureomycin were highly significant while interactions between aureomycin and protein level were not significant. Increasing the protein content of broiler diets in practice, would probably be accomplished by replacing a high energycereal grain, such as corn or wheat, by soybean oil meal. This would be comparable to the procedure followed in the first portion of the present experiment and would involve a lowering of the energy level with increasing protein. It was of interest to determine the result of increasing the level of protein from 23 to 26 percent both with a reduction in energy and with the energy level maintained constant. Comparing the mean square, with the error mean square for the experiment as a whole gave a measure of the significance of the differences between means. Raising the protein content from 23 to 26 percent either with a reduction in energy or when the energy level was maintained resulted in a highly significant increase in weight P<0.01. The weights of the birds fed diets containing 26 percent protein plus corn oil did not prove significantly superior to those of the groups fed the same level of protein without corn oil. However, when both weight and feed efficiency are considered the data indicate that the higher energy diets were somewhat superior as compared to those without added corn oil. These results suggest that the energy requirement for maximum weight and feed efficiency, using a diet containing 26 per-
cent protein, was in excess of 966 Calories per pound. At the conclusion of the experiment all birds were slaughtered, dressed and examined for market quality. In this experiment the birds were not graded individually but notes were made on the fleshing and finish of the groups as a whole. Raising the level of protein from 17 to 20 percent was found to improve fleshing but further increases were without effect. Aureomycin did not appear to influence fleshing except when added to the 26 percent protein-diet without corn oil and the 17 percent protein-diet. Added to the former diet aureomycin improved fleshing while included in the latter diet the antibiotic decreased fleshing. The difference in fleshing response to antibiotic may possibly be explained on the basis of differences in the levels of protein and energy in the various diets.
ANTIBIOTICS AND PROTEIN REQUIREMENTS
SUMMARY AND CONCLUSIONS
Two experiments were made to determine the influence of antibiotics on the protein requirement of heavy-breed male broilers. Protein levels of 17, 20, 23 and26 percent were employed in each experiment. The effects of protein level and antibiotic (penicillin or aureomycin) were highly significant. Interactions between the level of protein and antibiotic did not prove to be significant in either experiment. Evidence is presented to indicate that
antibiotics enhanced the utilization of both protein and energy compounds. This may well explain why the antibiotics failed to reduce the requirement for either protein or energy. Under the conditions of these experiments the protein requirement for maximum growth and feed efficiency to 10 weeks of age was in excess of 20 percent. On the other hand, levels of protein which resulted in maximum growth and feed efficiency were too high for the production of broilers of optimum market quality. It is suggested that heavy-breed male broilers be fed diets containing in excess of 20 percent protein during the growing period and that the level be reduced to 20 percent or less for a finishing period of a few weeks. ACKNOWLEDGEMENT We are indebted to Lederle Laboratories for the Megasul and aureomycin HC1; to Merck and Company for the niacin, calcium pantothenate and vitamin B12; and to Chas. Pfizer and Company for the penicillin G potassium used in this work. REFERENCES Fraps, C. S. 1946. Composition and productive energy, of poultry feeds and rations. Texas Agr. Exp. Sta. Bui. 678. Machlin, L. J., C. A. Denton, W. L. Kellogg and H. R. Bird, 1951. Effect of dietary antibiotic upon feed efficiency and protein requirement of growing chickens. Private communication. Matterson, L. D., E. P. Singsen, L. Decker and A. Kozeff, 1951. A comparison of several antibiotics as growth stimulants in practical chickstarting rations. Storrs Agr. Exp. Sta. Bui. 275. Moore, P. R., A. Evenson, T. D. Luckey, E. Mccoy, C. A. Elvehjem and E. B. Hart, 1946. Use of sulfasuxidine, streptothricin and streptomycin in nutritional studies with the chick. J. Biol. Chem. 165:437-441. Regulations under the provisions of the live stock and live stock products act of the Statutes of Canada, 1939. Chapter 47. Respecting the grading and marketing of dressed and eviscerated poultry.
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increases as the protein content of the diet is raised. These results suggest that while aureomycin enhances energy utilization, improved finish is obtained only when the energy level is sufficiently high. The results of the present experiments do not support the conclusion that the requirement for either protein or energy is reduced in the presence of antibiotic. This is probabiy due to the fact that the utilization of both protein and energy was enhanced by incuding antibiotic in the diet. I t may well be that all nutrients are utilized better in the presence of antibiotic. This being the case, one would not expect antibiotic to influence nutritive requirements when fed with properly balanced diets. The protein requirement for maximum weight and feed efficiency in these experiments was in excess of 20 percent in both the absence and presence of antibiotic. However, the protein requirement for the production of broilers with suitable market quality was less than for maximum weight and feed efficiency. From a practical standpoint it would therefore seem advisable, if feeding broilers such as these, to employ a level of protein in excess of 20 percent for the growing period only, and to reduce this to 20 percent or less for a finishing period of a few weeks.
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Scott, H. M., and W. A. Glista, 1950. The effect of aureomycin and arsonic acid on chick growth. Poultry Sci. 29:921-923. Slinger, S. J., K. M. Gartley, W. F. Pepper and D. C. Hill, 1951. The inuflence of animal protein factor supplements and antibiotics on the incidence and severity of white feathers in turkeys. J. Nutrition 43:345-355. Stokstad, E. L. R., and T. H. Jukes, 1950. Further observations on the "animal protein factor." Proc. Soc. Exp. Biol. Med. 73: 523. Thayer, R. S., 1950. Talk before the Oklahoma Feed
Conference, as reported in the reprint of an address "Vitamin B12 and antibiotic developments in nutrition—a review" by G. P. Whitlock before the Nutrition Committee of the Feed Institute, Inc., Des Moines, Iowa, 1951. Whitehill, A. R., J. J. Oleson and B. L. Hutchings, 1950. Stimulatory effect of aureomycin on the growth of chicks. Proc. Soc. Exp. Biol. Med. 74: 11. < Yates, F., 1934. The analysis of multiple classifications with unequal numbers in the different classes. Jour. Am. Stat. Assoc. 29: 51.
J. B. O ' N E I L Poultry Department, University of Saskatchewan, Saskatoon, Canada (Received for publication October 27, 1951)
A
SURVEY of the literature indicates that it is not necessary to hatch chicks from breeders deficient of vitamin B12 in order to produce deficiencies of this vitamin in the chicks used for experimental purposes. Hill and Branion (1950) studied the replacement value of an APF supplement for varying amounts of fish meal using chicks from hens fed well balanced diets and maintained on floor litter. Sherwood and Couch (1950) used chicks from hens also kept in floor pens and fed a mixture of animal proteins. Results published by Briggs et al. (1950) support these findings and the authors state that a vitamin B12 deficiency may be produced in chicks without the use of "stress factors." Miller and Groschke (1950) describe a short chick assay method for measuring APF activity when the chicks are hatched from eggs produced by hens fed a mixture of animal protein feeds.
Evidence of the carryover of unknown factor or factors has been presented by several workers. Bird et al. (1946) reported a high mortality rate in chicks from hens fed a soybean oil meal diet and that the supplementing of the breeders' diet with either cow manure or sardine meal resulted in a much lower mortality. However, the supplementation of the chick's diet did not improve livability. On the other hand, if the hens' diet contained either fish meal or cow manure, this growth factor was transferred in sufficient quantities to insure normal growth of the chicks to six weeks of age (Rubin and Bird, 1946). In their report, Bethke et al. (1947) found that chicks produced from hens receiving soybean oil meal did not grow as well as those from soybean oil meal and fish meal. McGinnis and Carver (1947) using diets with either soybean oil meal or Alaska pea meal as sources of protein, report poor growth and high
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Further Evidence of the Carryover of Vitamin B12 in Chicks