The Effect of Antibiotic Supplementation on Growth and Energy Utilization of Chicks

The Effect of Antibiotic Supplementation on Growth and Energy Utilization of Chicks J. J. BEGIN Department of Animal Sciences, University of Kentucky,

Lexington, Kentucky 40506

(Received for publication March 19, 1971)

tabolism showed no agreement as to the influence antibiotics have on the metabolizable energy derived from the diet. Nelson et al. (1963) reported that some, but not all, of the antibiotics they investigated increased the metabolizable energy content of a practical chick diet and that this increase in metabolizable energy content was correlated with growth stimulation and a decrease in intestinal weight. Gorril et al. (1960) concluded that an increased energy digestibility coefficient in swine was related to increased growth due to antibiotic supplementation. Sibbald et al. (1961), in studies with both chicks and poults, found no significant effects on dietary metabolizable energy content attributable to antibiotic additions to the diet. Slinger et al. (1962) reported that the addition of antibiotics to turkey starting diets had no influence on their metabolizable energy values. The experiments reported here were part of a series conducted at intervals over a period of 3 years, starting in 1967 and terminating in 1970, to determine whether antibiotics retained their growth-promoting ability after approximately 17 years of continuous use in the same laboratory. During the course of these experiments the metabolizable energy values of the diets were determined, and the efficiency of energy utilization was calculated. The investigation reported in this paper (No. 71-5-17) is in connection with a project of the Kentucky Agricultural Experiment Station and is published with approval of the Director.

EXPERIMENTAL PROCEDURE Inbred-hybrid male chicks were used in experiment 1 and males of a New Hampshire X Columbian cross were used in experiments 2 and 3. In all experiments 10 chicks were assigned at random at 1 day of age to each experimental group. All chicks were wing-banded, weighed individually and placed in wire-floored pens in electrically heated battery brooders in a room with controlled temperature. Three groups of birds were fed each diet in all experiments. Feed and water were available ad libitum. Composition of the basal diet used in all 3 experiments is shown in Table 1, and the supplementary levels of chlortetracycline are shown in Tables 2, 3 and 4. A mixture of chromic oxide, water and wheat flour, baked and ground, was added to all diets to supply 0.3 percent chromic oxide as an index material. Each experiment was of 4 weeks' duration, with body weight and feed consumption data being recorded at weekly intervals. Excreta samples were collected from each pen on 2 consecutive days during the fourth week of each experiment. A sample of feed and the composited excreta samples from each pen were analyzed for moisture, gross energy, chromic oxide and nitrogen by methods described previously (Begin, 1969). From the analytical results, the metabolizable energy of the experimental diets, corrected for nitrogen equilibrium, was calculated. The determination of carcass energy gains in experiment 3 were accomplished by sacrificing 10-day-old chicks at the beginning of the experiment. These were fro-

1496

Downloaded from http://ps.oxfordjournals.org/ at West Virginia University, Health Science Libraryy on April 12, 2015

studies on the effect of antiSEVERAL biotic supplementation on energy me-

1497

ANTIBIOTIC SUPPLEMENTATION

TABLE 3.—The effect oj chlortetracycline supplementation on growth and utilization oj feed and energy by heavy breed chicks} Experiment 2

TABLE 1.—Composition of the basal diet Ingredients

Percent

CTC 2 level mg./kg. 0 100 200

100.00 1 Supplied the following per kilogram of diet: vitamin A, 6,600 I.U.; vitamin D 3 , 660 I.C.U.; vitamin E, 35 mg.; menadione sodium bisulfite, 11 mg.; riboflavin, 3 mg.; d-pantothenic acid, 9.25 mg.; niacin, 27 mg.; choline chloride, 1.35 gm.; vitamin B12, 10 meg.; butylated hydroxy toluene, 125 mg.; manganese, 60 mg.; zinc, 60 mg.; plus cerelose as carrier. 2 Chromic oxide premix contained 30 percent chromic oxide and 70 percent wheat flour.

zen for future analysis to obtain the initial gross energy content of the birds. When the experiment was terminated at 4 weeks, the chicks were fasted for approximately 16 hours and individually weighed. Five birds nearest the group average were selected from each experimental group and sacrificed, frozen and stored for final gross energy determinations. The procedures for processing the carcasses and determining gross energy have been described previously (Begin, 1969). Energy utilization values were calculated from the determined metabolizable energy values, carcass energy gains, weight gains and feed consumption data. The mean data TABLE 2.—Effect of chlortetracycline supplementation on growth and the utilization of feed and energy by light breed chicks} Experiment 1 CTC 2 level mg./kg. 0 50 100 200 1 2

Weight Feed gain intake gm. 256a 3 272b 287b 277b

gm. 545 525 549 553

Gain feed gm. 0.470a 0.519b 0.522b 0.500b

M.E. per gram diet kcal. 2.93 2.95 2.96 2.93

Gain M.E. intake kcal. 1,599 1,546 1,629 1,620

Inbred-hybrid males. Chlortetracycline as Aurofac '50/' American Cyanamid Co., , Inc. inc. 3 Means having the same superscript are not significantly different.

gm. 300a» 331b 337b

gm. 605 602 630

feed

M.E. per gram diet

M.E. intake

gm. 0.495a 0.551b 0.535b

kcal. 2.95 2.94 2.93

kcal. 1,783a 1,768a l,8S0b

Gain

Gain kcal. M.E. gm. 0.168a 0.188b 0.182b

1 New Hampshire XColumbian Males. 2 Chlortetracycline as Aurofac " 5 0 , " American Cyanamide Co., Inc. 3 Means having the same superscript are not significantly different.

obtained in all 3 experiments were subjected to the analysis of variance, Snedecor (19S6), with significant means determined by the multiple range test of Duncan (1955). RESULTS AND DISCUSSION

In experiment 1, four levels of chlortetracycline were added to the basal diet at the expense of the total diet and fed to light breed male chicks. The levels of antibiotic fed and the experimental results are shown in Table 2. The weight gain data indicate that the addition of all three levels of chlortetracycline to the diet improved growth, with the greatest growth response being obtained on the diets containing the 2 highest levels of the antibiotic. Statistical examination of the data shows that the difference in growth rate of the chicks fed the TABLE 4.—Effect of chlortetracycline supplementation on weight gains, carcass energy gains and efficiency of energy utilization by heavy breed chicks} Experiment 3 CTC 2 level

kcal. M.E. gm. 0.160a 0.176b 0.176b 0.171b

Weight Feed gain intake

mg./kg. 0 50 100 200

Wt. Weight gain gain feed gm. 298a« 327b 327b 323b

gm. 0.529a O.S48b 0.568b 0.553b

M.E. per gram diet

M . E . Carcass intake e " ^ f

M.E. 3 em

kcal. 2.95 2.94 2.93 2.95

kcal. 1,666 1,757 1,688 1,724

31.26a 33.65b 33.97b 34.04b

galn

kcal. 521a 591b 561b 587b

Clency

%

1 New Hampshire X Columbian Males. 2 Chlortetracycline as Aurofac " 5 0 , " American Cyanamide Co., Inc. 3 (kcal. gained/kcal. of M . E . consumed) X100. 4 Means having the same superscript are not significantly different.

Downloaded from http://ps.oxfordjournals.org/ at West Virginia University, Health Science Libraryy on April 12, 2015

53.75 35.00 1.00 2.00 0.25 5.00 1.00 2.00

Ground yellow corn Dehul'.ed soybean meal Ground limestone Defluorinated phosphate Salt Vitamin and mineral premix1 Chromic oxide premix2 Corn oil

1498

J. J. BEGIN

the metabolizable energy values determined on each of the experimental diets were not affected by the presence or absence of antibiotics in the diet. In this experiment a difference in energy consumption was noted when the 200 mg./kg. level of chlortetracycline was fed. This difference in energy consumption was found to be significant (P < 0.05). The weight gain per kilocalorie of metabolizable energy consumed was greater for both of the antibiotic-fed groups than for the chicks fed the unsupplemented basal diet. Statistically, these differences were highly significant (P < 0.01). Experiment 3 was conducted using heavy breed male chicks which were fed the same levels of chlortetracycline as employed in experiment 1. In addition to data on growth, feed utilization and dietary metabolizable energy, the storage of carcass energy was determined and the caloric efficiency of the experimental diets was calculated as the calories gained per kilocalorie of metabolizable energy consumed. The dietary treatments and experimental results are shown in Table 4. The weight gain data show that the supplementation of the basal diet with 50, 100 or 200 mg. of chlortetracycline per kilogram of diet had a stimulatory effect on growth. The differences in the weight gain data of the birds fed the unsupplemented basal diet and those fed the various levels of antibiotic were highly significant (P < 0.01). In this experiment, as in the previous two trials, supplementation of the diets with chlortetracycline improved feed utilization. Statistical analysis of the feed conversion data shows that these differences were highly significant (P < 0.01). Neither the amount of energy derived from the experimental diets measured as metabolizable energy nor the calorie intake of the various groups was found to vary significantly. All three levels of chlortetracycline enhanced the storage of tissue energy.

Downloaded from http://ps.oxfordjournals.org/ at West Virginia University, Health Science Libraryy on April 12, 2015

diets containing either 100 or 200 mg./kg. levels of chlortetracycline and the chicks fed the basal diet was highly significant (P < 0.01), while the differences observed on the lowest level of antibiotic supplementation were significant (P < O.OS). There was a reduction in feed intake by the group receiving the 50 mg./kg. level of antibiotic, but their intake was not found to differ significantly from that of the other groups. All levels of chlortetracycline fed produced a marked improvement in feed utilization. When compared with the data of the groups fed the control diet, these differences were found to be highly significant (P < 0.01). Neither the metabolizable energy value of the diets nor the consumption of energy was influenced by the feeding of antibiotics. The data on caloric efficiency, measured as the weight gain per kilocalorie of metabolizable energy consumed show that the chicks fed diets supplemented with chlortetracycline utilize dietary calories for weight gains more efficiently than do chicks fed the unsupplemented basal diet. These differences were found to be highly significant (P < 0.01). Summarized in Table 3 are the data from experiment 2. In this trial heavy breed male chicks were fed either the basal diet or the basal diet supplemented with 100 or 200 mg. of chlortetracycline per kilogram of diet. The results indicate that both of the supplemental levels of the antibiotic improved the growth rate of the birds. Statistical analysis of the growth data shows that the differences observed were significant (P < 0.05). The addition of chlortetracycline to the diet had no effect on feed consumption, but antibiotic supplementation did improve feed utilization. The data show that less feed was required per unit of gain when chlortetracycline was added at either level to the diet. These differences were found to be highly significant (P < 0.01). As in experiment 1,

1499

ANTIBIOTIC SUPPLEMENTATION

with those of Sibbald et al. (1961) and Slinger et al. (1962). The results of these three experiments show that the feeding of chlortetracycline to chicks had little or no stimulatory effect on either feed or energy consumption, thus the beneficial effects observed in growth rate and feed and energy utilization were not the result of greater intake. The improvements noted in both feed and caloric efficiency indicate that perhaps antibiotics improve the utilization of nutrients through their ability to increase the digestibility and assimilability of the entire diet. How antibiotics mediate this effect of change in the rate or pattern of the metabolic processes, which cause the chick to make better use of the nutrients available to it, is still unanswered. SUMMARY

Various levels of chlortetracycline were fed in 3 experiments to either light or heavy breed male chicks. In all three experiments the chlortetracycline supplementation increased growth rate and feed and energy utilization without any effect on the amount of metabolizable energy derived from the diet or on the total intake of feedor energy. This series of experiments also demonstrated that an antibiotic such as chlortetracycline still retains its effectiveness after many years of continuous use in the same laboratory and that the amount needed for maximum response is no more than 50 mg of antibiotic per kilogram of diet. REFERENCES Begin, J. J., 1969. The effect of diet and breed of chicken on metabolic efficiency of nitrogen and energy utilization.. Poultry Sci. 48: 48-54. Begin, J. J., D. W. MacLaury, R. Risner and W. M. Insko, Jr., 1953. Breed, sex and age variation among chicks in response to antibiotic supplementation. Kentucky Agr. Exp. Sta. Bui. 597. Bird, H. R., 1968. Effectiveness of antibiotics in

Downloaded from http://ps.oxfordjournals.org/ at West Virginia University, Health Science Libraryy on April 12, 2015

Analysis of the energy gain data reveals that the differences in energy gain of the chicks fed diets supplemented with the antibiotic as compared with the amount of carcass energy stored by the chicks receiving the control diet were highly significant (P < 0.01). The efficiency of energy utilization, measured as energy gain per kilocalorie consumed, of the chicks fed chlortetracycline was significantly greater (P < 0.01) than the efficiency of the non-antibiotic fed birds. It is interesting to note that these experiments demonstrate that antibiotics retain their growth-promoting ability over a great many years in surroundings in which antibiotics have been in more or less continuous use. In experiments conducted in 1953 in this same laboratory, chlortetracycline produced a growth response of 107 percent of the controls when fed to White Plymouth Rock chicks for 4 weeks (Begin et al., 1953). In experiments 2 and 3 reported here, in which comparable breeds were used, chlortetracycline produced a response of 110 percent of the controls. This continued response to antibiotic supplementation is in agreement with the reports of Heth and Bird (1962) and Bird (1968). Except for experiment 1 there was no indication that more than 50 mg. of chlortetracycline per kilogram of diet was necessary for maximum growth response or feed and energy utilization. There was no evidence in any of the experiments that the addition of chlortetracycline to the diet had any influence on the amount of metabolizable energy derived from the diet. This is not in agreement with the results of Nelson et al. (1963). This difference in results may be accounted for by the fact that they did not feed chlortetracycline and, also, their results indicated that not all antibiotics produce a greater dietary metabolizable energy value. The results presented here are in agreement

1500

J. J. BEGIN able energy of the diet. Poultry Sci. 42: 909912. Sibbald, I. R., S. J. Slinger and G. C. Ashton, 1961. Factors affecting the metabolizable energy content of poultry feeds. 4. The influences of calcium, phosphorus, antibiotics and pantothenic acid. Poultry Sci. 40: 945-951. Slinger, S. J., W. F. Pepper, I. Motzok and I. R. Sibbald, 1962. Studies on the calcium requirement of turkeys. 3. Influence of chlortetracycline and reserpine during the starting and growing periods. Poultry Sci. 4 1 : 460-467. Snedecor, G. W., 1956. Statistical Methods, 5th Ed. The Iowa State College Press, Ames, Iowa.

NEWS AND NOTES (Continued from page 1455) 1955, has asked to be relieved of his administrative duties so he can devote full time to teaching and research.

Inc., Barron, Wisconsin, for l j years, and then served for two years in the Veterinary Corps of the U.S. Army.

C.D.A. POULTRY DIVISION

EDWARD W. BROWNING AWARD

M. S. Mitchell and W. K. Barr have been appointed to new posts in the Poultry Division of the Canada Department of Agriculture. Mitchell, formerly Chief of the Division's Production Section, becomes Chief of the Markets and Merchandising Section, succeeding Frank Payne, who is now Director of the Livestock Division. Barr, formerly Poultry Geneticist with the Production Section, takes over as Chief from Mr. Mitchell.

The Edward W. Browning Award has been established recently and it is expected to be one of the most coveted awards in agriculture. It will be presented annually to an individual who has made outstanding achievements in the improvement of food sources. Along with the honor of the award goes a cheque for $5000 and an engraved bronze medal. The award winner will be selected, and it will be presented by the American Society of Agronomy. This is a professional organization of more than 7,800 crop and soil scientists from over 80 countries. The Society strives to promote human welfare through advancing the acquisition and dissemination of scientific knowledge concerning the nature, use, improvement and interrelationships of plants, soils and environment. The Award is approved and administered by The New York Community Trust Foundation which administers philanthropic funds for the "well being of mankind" and which "seeks to carry out the aims of founders or donors in the light of contemporary conditions." Edward West Browning was a colorful and highly successful New York real estate operator who died in 1934. His altruistic character is best reflected by the terms of his will. Upon the death of his daughter in 1969, the court appointed the New York Community Trust to administer the Browning Award. The criteria for selection are: The award is for outstanding achievement in the improvement of

CONNECTICUT NOTES The College of Agricultural and Natural Resources at the University of Connecticut has established a new Department of Nutritional Sciences. Officially formed in July, 1970, from personnel in the Department of Poultry Science and Animal Industries in the College, and from Foods and Nutrition in Home Economics, the Cooperative Extension Service, the Health Center, and other parts of the Institution, it offers undergraduate programs as well as graduate programs at both the master's and doctoral levels. Dr. Lloyd Matterson is Acting Head. CUDDY NOTES Dr. Glenn E. Kolb has joined the staff of Cuddy Farms, Strathroy, Ontario. He received a D.V.M. degree at the University of Minnesota in 1967. After graduation he was on the staff of Jerome Foods,

(Continued on page 1519)

Downloaded from http://ps.oxfordjournals.org/ at West Virginia University, Health Science Libraryy on April 12, 2015

broiler feeds. Worlds' Poultry Sci. J. 24: 309312. Duncan, D. B., 1955. Multiple range and multiple F test. Biometrics, 11: 1-42. Gorril, A. O. L., J. M. Bell and C. M. Williams, 1960. Ingredient and processing interrelationships in swine feeds. Can. J. Animal Sci. 40: 100-106. Heth, D. A., and H. R. Bird, 1962. Growth response of chicks to antibiotics from 1950 to 1961. Poultry Sci. 4 1 : 755-760. Nelson, F. E., L. S. Jenson and J. McGinnis, 1963. Studies on the stimulation of growth by dietary antibiotics. 2. Effect of antibiotics on metaboliz-