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Growth Response of Chicks to Antibiotics from 1950 to 1961
Growth Response of Chicks to Antibiotics from 1950 to 1961 D. A. HETH AND H. R. BIRD Department of Poultry Husbandry, University of Wisconsin, Madison (Received for publication August 28, 1961)
I
Weight % of Basal =
adequate. Some were of a semipurified type, some were simplified corn-soy diets and the remaining ones were practical broiler diets. In all trials feed and water were supplied ad libitum. For the most part, the experiments were conducted in wire floor, electrically heated batteries. In two instances in 1959 and one in 1960, however, the results were from groups reared in floor pens. During this ten year period the site of experimentation was changed as a new building was constructed in 1957. However, the same batteries and other equipment were used in the new location, so it is felt that the microorganism population should have remained similar. Although the length of the total experiments varied considerably, all data presented here apply to three week old chicks except for one instance in 1952 and another in 1959 when two week results are reported as three week data were unavailable. The results are presented as "Weight Percent of Basal" which was calculated by this formula:
Average weight of treated group Average weight of basal group
METHODS AND MATERIALS
The diets were of varying composition, but all were considered to be nutritionally Published with the approval of the Director of the Agricultural Experiment Station, College of Agriculture, Madison, Wisconsin. Supported in part by a grant from Commercial Solvents Corporation, Terre Haute, Indiana.
X 100
No attempt was made to determine if there was a general increase in the weights of the basal groups. The breed of chicks varied between experiments, but in most cases the chicks were either progeny from New Hampshire males and Single Comb White Leghorn females or a commercial broiler cross. The size of the groups also varied,
755
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T HAS BEEN REPORTED that continuous feeding of antibiotics to chicks for several years in the same environment resulted in a decrease in the growth response obtained from the antibiotics (Waibel et al., 1954; Libby and Schaible, 1955). Some laboratories, however, indicated that the feeding of a new antibiotic gave an improved response where one had no longer been attainable with an "old" antibiotic (McGinnis et al., 1959; Wiese and Peterson, 1959). The work reported here summarizes the results of antibiotic feeding at this station for the past ten years. Procaine penicillin was fed throughout the 10 year period, therefore the results obtained with it are summarized separately. The responses from chlortetracycline were summarized with those from oxytetracycline as there were insufficient trials for either to warrant recording the results separately. Henceforth, these will be referred to only as tetracyclines. Fewer data are presented for zinc bacitracin because it was fed with an adequate diet for only three years.
756
D. A. HETH AND H. R. BIRD
but those in the battery were usually between ten and twenty birds per group, while those in the floor pens were in groups of fifty. There were 1706 birds involved in the penicillin experiments, 2097 in the tetracycline ones, and 1147 in the zinc bacitracin trials. RESULTS AND DISCUSSION
TABLE 1.—Effect
of procaine penicillin and tetra-
cyclines on the growth of chicks fed an adequate diet Date experiment started
3rd week average weight Penicillin
Tetracycline
gm. 9-50* 173 9-50» 173 9-50* 173 10-50 214 10-50 214 10-50 214 11-50 181 11-50 181 5-51* 251 5-51* 240 5-51* 264 5-51* 255 6-51* 185 6-51* 221 6-51* 181 11-51* 153 U-51* 132 11-51* 139 11-51* 196 11-51* 173 11-51* 217 12-51* 232 12-51* 230 12-51* 228 12-51* 222 12-51* 208 2-52* 219 2-52* 228 2-52* 187 2-52* 184 2-52* 170 3-52* 164 3-52* 212 3-52* 206 3-52* 222 3-52 251 3-52 204 3-52 198 3-52 214 3-52* 241 4-52* 225 4-52* 136 4-52* 266 4-52* 201 5-52* 147 (2 wk. trial) 6-52* 202 9-52* 285 9-52* 248 9-52* 269 9-52* 215 9-52* 196 9-52* 196 12-52* 204 1-53* 189 5-53* 198 5-53* 206 7-53* 196 11-55 273 3-56 125 4-56 144 7-56 163 8-56 212 11-56 160 11-56 128 11-56 128 1-57 141 1-57 141 2-57 134 10-57 182 11-57 177 2-58 262 3-58 233
gm. 226 (10) 226 (20) 219 (30) 230 (5) 204 (10) 222 (20) 196 (10) 215 (10)
gm.
Peni- Tetracillin cycline 131 131 127 107 95 104 108 119
The month and year of each experiment with procaine penicillin and the tetra287 (25-c) 114 269 (25-c) 112 cyclines, the level of antibiotic supple273 (25-c) 103 278 (25-c) 109 mentation, three-week average weights for 233 (25-c) 126 245 (25-c) 111 both the control and treated groups, and 212 (25-c) 117 201 (15-c) 168 (15) 131 110 weight percent of basal are given in Table 160 (15) 172 (15-c) 130 121 165 (15-c) 178(15) 119 128 1. The figures for weight percent of basal 224 (15-c) 198 (15) 114 101 190 (15-c) 219 (15) 110 127 for the decade are plotted in Figures 1, 229 (15-c) 228 (15) 106 105 271 (15-c) 264 (15) 117 114 2, and 3. Sixty-one trials were con257 (15-c) 252 (15) 112 110 249 (15) 252 (15-c) 111 109 ducted with procaine penicillin. Of the 226 (15) 228 (15-c) 103 102 236 (15) 234 (15-c) 112 113 sixty-one trials, thirty-one were conducted 226(15) 258 (15-c) 118 103 217 (15-c) 205 (15) 95 90 at a level of supplementation of fifteen 200 (15-c) 192 (15) 107 103 198 (15-c) 218 (15) 108 118 mg./kg., ten at two to five mg./kg., eight 221 (15-c) 210(15) 130 124 190 (10) 116 at thirty or thirty-five mg./kg. and the re251 (15) 118 216(15) 105 mainder at various intermediate levels. Tet240 (15) 108 270(15) 108 racyclines were fed in sixty different trials 217 (15-c) 106 237 (15-c) 120 at levels of supplementation ranging from 239 (15-c) 112 250 (15-c) 104 ten to thirty-five mg./kg. 224 (15-c) 237(15) 100 105 164 (15-c) 164 (15) 121 121 The results may be subdivided into two 270 (15-c) 283 (15) 101 106 214 (10) 106 definite time periods: with the tetracy152 (15-c) 122 (15) 103 83 clines, the first period extended from 1951 208 (10) 103 277(15) 97 to 1952 and the second period from late 245 (15) 99 264 (15) 98 1955 to late 1960. During the intervening 225 (15) 105 210 (2) 107 time no antibiotic growth stimulation ex198 (4) 101 208 (4) 102 » periments were conducted with an ade189 (4) 100 197 (4) 99 quate diet. However, during this period an223 (15) 108 190 (15) 97 tibiotics were routinely fed in experiments 284 (15) 286 (35-c) 105 104 154 (30) 123 being conducted for other purposes. The 166 (30) 115 188 (30) 115 same situation exists with procaine peni221 (30) 104 154 (30) 96 cillin, but with slightly different time pe157 (35-c) 150 (5) 123 117 181 (10-c) 141 riods. Table 2 gives the results of experi156 (10-c) 123 (5) 111 87 167 (35-c) 118 ments with zinc bacitracin. No subdivision 152 (35-c) 113 232 (35-c) 227 (35) 127 125 of the decade is possible with this anti169 (35-c) 160 (35) 95 90 250 (10) 257 (35-c) 98 95 biotic, because it was fed with an adequate 262 (10) 112 diet only during the years 1956 to 1959. Numbers in parentheses refer to milligrams per kilogram of During this period, a total of twenty-five antibiotic used. Letter following tetracycline level denotes kind tetracycline fed—c-chlortetracycline, o-oxytetracycline. trials involving zinc bacitracin were con* Date previously reported by Waibel et al.
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Basal
Weight—% of basal
GROWTH RESPONSE TO ANTIBIOTICS TABLE 1.—Continued Date experiment
3rd week average weight
started
Basal
Penicillin
10-58 11-58 12-58 1-59 (floor pen) 1-59 2-59 2-59 4-59 5-59 6-59 12-59
172 215 177 235
226 (4) 225 (4) 200 (4)
Tetracycline 236 224 199 237
(lO-o) (lO-o) (lO-o) (lO-o)
Weight—% of basal Peni- Tetracillin cyclic 131 105 113
127 104 112 101
256 (lO-o) 229 (lO-o) 209 (lO-o) 188 (lO-o) 222 (lO-o) 207 (lO-o) 141 (lO-o)
111 109 101 96 116 112 95
257 257 257 272 272 272 302
284 313 246 302 288 283 316
(10-c) (20-c) (lO-o) (10-c) (20-c) (lO-o) (10-c)
110 122 96 111 106 104 105
302
322 (20-c)
107
302
331 (lO-o)
110
(2 wk. trial
floor pen) 2-60 2-60 2-60 5-60 5-60 5-60 12-60 (floor pen) 12-60 (floor pen) 12-60 (floor pen)
ducted. Of these, thirteen were at the 10 or 20 mg./kg. supplementation level, nine at one hundred mg./kg. and three at 35 mg./kg. A negative weight response occurred in six of the twenty-five diets. These six were dispersed throughout the three year period and the low, intermediate and higher levels of supplementation were each represented. In the years 1950 to mid 1953 a total of 46 trials was conducted with procaine penicillin. In only eight of these (17.5 percent) did the antibiotic-fed group grow at a lower rate than the basal. During the last year of this period, no response was obtained that exceeded 110% of basal. This period of poor response has previously been reported by Waibel et al., in 1954. It was concluded at that time that the apparent lack of response was due in part to improved growth of basal groups and the possibility of an alteration in the microorganism population. When trials were resumed in 1956 to 1959, a total of 15 trials was conducted and in four of these the antibiotic-fed groups grew at a lower rate than the basal.
During the first period (1951 to 1953) thirty-one trials involved a tetracycline (chlortetracycline exclusively). In only one did the antibiotic-fed group reach a lower weight than the basal. Of the twenty-nine trials with tetracyclines in the later period, there were five in which the antibiotic-fed groups attained lower weights than the basals. The average responses for the two periods were calculated and found to be very similar—being 108.5% of basal for the period 1950-1954 and 108.8% of basal for the second period with procaine penicillin. The comparable figures were 112.3 and 110.2 for the corresponding periods with the tetracyclines. Low levels of zinc bacitracin (comparable with those of procaine penicillin and tetracyclines) gave an average response of 105.9 percent of the basal TABLE 2.—Effect of zinc bacitracin on the growth of chicks fed an adequate diet Date experiment started
3rd week average weight Weight— %of Treated basal Control
gm. gm. w Level Supplementation (comparable ine penicillini and tetracyclines) 155 (35) 11-30-56 128 193 (35) 1-11-57 141 154 (35) 11-22-57 177 228 (10) 2-14-58 262 218 (10) 10-2-58 172 186 (10) 10-30-58 215 11-27-58 177 206 (10) 245 (10) 12-30-58 235 262 (10) 12-30-58 230 228 (10) 2-25-59 210 2-25-59 208 225 (10) 209 (10) 4-2-59 196 196 (10) 5-7-59 192 6-12-59 185 171 (10) 10-9-59 181 175 (20) 12-1-59 149 162 (20) gh Level Supplementation 10-2-58 172 236 (100) 11-27-58 177 210 (100) 12-30-58 230 278 (100) 12-30-58 235 287 (100) 229 (100) 2-25-59 208 4-2-59 196 186 (100) 5-7-59 192 235 (100) 190 (100) 6-12-59 185 12-1-59 149 161 (100)
to pro121 137 87 79 127 86 116 104 114 109 108 107 102 92 97 109 137 119 121 122 110 95 122 103 108
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230 210 208 196 192 185 149
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51
52
53
54
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56
57
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59
60
61
YEARS FIG. 1. Changes in response of chicks fed procaine penicillin from 1950 to 1959. Each dot represents one trial.
150
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o
no 10 0 X ©
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52
53
54
55
56
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59
YEARS FIG. 2. Changes in response of chicks fed tetracyclines from 1951 to 1961. Each dot represents one trial.
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100
I-
759
GROWTH RESPONSE TO ANTIBIOTICS
weight. Higher levels of zinc bacitracin (100 mg./kg.) gave a response of 115.2 percent. Thus the average responses to the three types of antibiotics were similar and the results obtained in the later period were as good as those obtained earlier. Since these experiments covered a ten year duration, they offer a better perspective of variations in antibiotic response than does any report published previously. The earlier report by Waibel et al. (1954) covered only a three year period and it was indicated at that time that a lack of antibiotic response had occurred in the third year (mid 1952 to mid 1953). However, when this period of decreased response is reevaluated in the light of a longer time and greater number of trials, it becomes clear that the results in 1952-1953 were not the beginning of a long-term trend.
SUMMARY The growth responses obtained from low levels of procaine penicillin, chlortetracycline and oxytetracycline for the period 1950 to 1960 have been presented. The results were subdivided into two periods— 1950 to 1953 and 1956 to 1960. Zinc bacitracin results are also given, but only for the period 1956 to 1959. The following conclusions can be drawn from the data—
140 X
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X
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_
57
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58 EARS
.
59
J
60
FIG. 3. Changes in response of chicks fed zinc bacitracin from 1956 to 1960. Each symbol represents one trial (dots represent 10 to 35 mg./kg. supplementation level; X represent 100 mg./kg.)
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1) No long term changes occurred in the weight responses obtained with procaine penicillin or tetracyclines. Variations among trials were found in each period for both procaine penicillin and the tetracyclines. 2) Zinc bacitracin compared favorably with both procaine penicillin and the
760
D. A. HETH AND H. R. BIRD
cin (100 mg. per kilogram) gave an average response of 115.2 percent. REFERENCES Libby, D. A., and P. J. Schaible, 1955. Observations on growth responses to antibiotics and arsonic acids. Science, 121: 733-734. McGinnis, J., L. H. Merrill, R. E. Fry and L. S. Jensen, 1958. Use-history of antibiotics as related to their efficacy in promoting growth of turkeys. Poultry Sci. 37: 810-813. Waibel, P. E., O. J. Abbott, C. A. Baumann and H. R. Bird, 1954. Disappearance of the growth response of chicks to dietary antibiotics in an "old" environment. Poultry Sci. 33: 1141-1146. Wiese, A. C , and C. F. Petersen, 1959. Comparison of several antibiotics for chick growth. Poultry Sci. 38: 1259.
Capacity of the Adult Chicken for Exercise on the Treadmill* Physiology
HAROLD S. WEISS With the technical assistance of KURT TEXTOR Laboratories, Dept. of Poultry Science, Rutgers, The State University New Brunswick, New Jersey
of New
Jersey,
(Received for publication August 28, 1961)
ALTHOUGH various exercise tolerance -**• tests are widely used in clinical practice and medical research to estimate physical and physiological functions (see, for example, Bard, Chapter 47, 1956; and Astrand, 1956), they seem to have found limited application in the animal sciences. In poultry, forced physical activity has been used in connection with such studies as: stress and adrenal hormone interaction (Garren and Shaffner, 1954; Connor and Shaffner, 1954); lipid metabolism and atherogenesis (Warnock et al., 1957; Wong et al., 1959); hematological changes * Paper of the Journal Series, New Jersey Agricultural Experiment Station, Rutgers, the State University of New Jersey, New Brunswick, New Jersey. Supported in part by U. S. PHS research grant H-5719.
(Anderson et al., 1959); blood uric-acid levels (Hudson and Taylor, 1960); feather removal (Knapp and Newell, 1961); and the mortality differences between genetically selected hyper- and hypotensive strains (Sturkie and Textor, 1961). However, apart from the data supplied by Garren and Shaffner (1954) for the growing chick exercised in a revolving drum, little appears to be known of the characteristics involved in the bird's resistance to muscular fatigue. This report surveys a variety of natural and experimental factors which might relate to the capacity of the adult chicken for exercise on a treadmill. PROCEDURE
All exercise tests were made on a horizontal, multiplace, variable speed treadmill
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tetracyclines in terms of growth response obtained. 3) The average weights of groups fed procaine penicillin at levels of 4 to 30 mg./kg. were 108.S and 108.8 percent of weight of basal groups in the two periods studied. Average weights of groups fed tetracyclines at levels of 10 to 35 mg./kg. were 112.3 percent of basal for the earlier of the two periods studied and 110.2 percent of basal for the later one. Zinc bacitracin at levels of 10 to 35 mg./ kg. gave an average weight of 105.9 percent of basal for the period 1956 to 1959. A high level of zinc bacitra-
I
Weight % of Basal =
adequate. Some were of a semipurified type, some were simplified corn-soy diets and the remaining ones were practical broiler diets. In all trials feed and water were supplied ad libitum. For the most part, the experiments were conducted in wire floor, electrically heated batteries. In two instances in 1959 and one in 1960, however, the results were from groups reared in floor pens. During this ten year period the site of experimentation was changed as a new building was constructed in 1957. However, the same batteries and other equipment were used in the new location, so it is felt that the microorganism population should have remained similar. Although the length of the total experiments varied considerably, all data presented here apply to three week old chicks except for one instance in 1952 and another in 1959 when two week results are reported as three week data were unavailable. The results are presented as "Weight Percent of Basal" which was calculated by this formula:
Average weight of treated group Average weight of basal group
METHODS AND MATERIALS
The diets were of varying composition, but all were considered to be nutritionally Published with the approval of the Director of the Agricultural Experiment Station, College of Agriculture, Madison, Wisconsin. Supported in part by a grant from Commercial Solvents Corporation, Terre Haute, Indiana.
X 100
No attempt was made to determine if there was a general increase in the weights of the basal groups. The breed of chicks varied between experiments, but in most cases the chicks were either progeny from New Hampshire males and Single Comb White Leghorn females or a commercial broiler cross. The size of the groups also varied,
755
Downloaded from http://ps.oxfordjournals.org/ at Zentralbibliothek on May 6, 2015
T HAS BEEN REPORTED that continuous feeding of antibiotics to chicks for several years in the same environment resulted in a decrease in the growth response obtained from the antibiotics (Waibel et al., 1954; Libby and Schaible, 1955). Some laboratories, however, indicated that the feeding of a new antibiotic gave an improved response where one had no longer been attainable with an "old" antibiotic (McGinnis et al., 1959; Wiese and Peterson, 1959). The work reported here summarizes the results of antibiotic feeding at this station for the past ten years. Procaine penicillin was fed throughout the 10 year period, therefore the results obtained with it are summarized separately. The responses from chlortetracycline were summarized with those from oxytetracycline as there were insufficient trials for either to warrant recording the results separately. Henceforth, these will be referred to only as tetracyclines. Fewer data are presented for zinc bacitracin because it was fed with an adequate diet for only three years.
756
D. A. HETH AND H. R. BIRD
but those in the battery were usually between ten and twenty birds per group, while those in the floor pens were in groups of fifty. There were 1706 birds involved in the penicillin experiments, 2097 in the tetracycline ones, and 1147 in the zinc bacitracin trials. RESULTS AND DISCUSSION
TABLE 1.—Effect
of procaine penicillin and tetra-
cyclines on the growth of chicks fed an adequate diet Date experiment started
3rd week average weight Penicillin
Tetracycline
gm. 9-50* 173 9-50» 173 9-50* 173 10-50 214 10-50 214 10-50 214 11-50 181 11-50 181 5-51* 251 5-51* 240 5-51* 264 5-51* 255 6-51* 185 6-51* 221 6-51* 181 11-51* 153 U-51* 132 11-51* 139 11-51* 196 11-51* 173 11-51* 217 12-51* 232 12-51* 230 12-51* 228 12-51* 222 12-51* 208 2-52* 219 2-52* 228 2-52* 187 2-52* 184 2-52* 170 3-52* 164 3-52* 212 3-52* 206 3-52* 222 3-52 251 3-52 204 3-52 198 3-52 214 3-52* 241 4-52* 225 4-52* 136 4-52* 266 4-52* 201 5-52* 147 (2 wk. trial) 6-52* 202 9-52* 285 9-52* 248 9-52* 269 9-52* 215 9-52* 196 9-52* 196 12-52* 204 1-53* 189 5-53* 198 5-53* 206 7-53* 196 11-55 273 3-56 125 4-56 144 7-56 163 8-56 212 11-56 160 11-56 128 11-56 128 1-57 141 1-57 141 2-57 134 10-57 182 11-57 177 2-58 262 3-58 233
gm. 226 (10) 226 (20) 219 (30) 230 (5) 204 (10) 222 (20) 196 (10) 215 (10)
gm.
Peni- Tetracillin cycline 131 131 127 107 95 104 108 119
The month and year of each experiment with procaine penicillin and the tetra287 (25-c) 114 269 (25-c) 112 cyclines, the level of antibiotic supple273 (25-c) 103 278 (25-c) 109 mentation, three-week average weights for 233 (25-c) 126 245 (25-c) 111 both the control and treated groups, and 212 (25-c) 117 201 (15-c) 168 (15) 131 110 weight percent of basal are given in Table 160 (15) 172 (15-c) 130 121 165 (15-c) 178(15) 119 128 1. The figures for weight percent of basal 224 (15-c) 198 (15) 114 101 190 (15-c) 219 (15) 110 127 for the decade are plotted in Figures 1, 229 (15-c) 228 (15) 106 105 271 (15-c) 264 (15) 117 114 2, and 3. Sixty-one trials were con257 (15-c) 252 (15) 112 110 249 (15) 252 (15-c) 111 109 ducted with procaine penicillin. Of the 226 (15) 228 (15-c) 103 102 236 (15) 234 (15-c) 112 113 sixty-one trials, thirty-one were conducted 226(15) 258 (15-c) 118 103 217 (15-c) 205 (15) 95 90 at a level of supplementation of fifteen 200 (15-c) 192 (15) 107 103 198 (15-c) 218 (15) 108 118 mg./kg., ten at two to five mg./kg., eight 221 (15-c) 210(15) 130 124 190 (10) 116 at thirty or thirty-five mg./kg. and the re251 (15) 118 216(15) 105 mainder at various intermediate levels. Tet240 (15) 108 270(15) 108 racyclines were fed in sixty different trials 217 (15-c) 106 237 (15-c) 120 at levels of supplementation ranging from 239 (15-c) 112 250 (15-c) 104 ten to thirty-five mg./kg. 224 (15-c) 237(15) 100 105 164 (15-c) 164 (15) 121 121 The results may be subdivided into two 270 (15-c) 283 (15) 101 106 214 (10) 106 definite time periods: with the tetracy152 (15-c) 122 (15) 103 83 clines, the first period extended from 1951 208 (10) 103 277(15) 97 to 1952 and the second period from late 245 (15) 99 264 (15) 98 1955 to late 1960. During the intervening 225 (15) 105 210 (2) 107 time no antibiotic growth stimulation ex198 (4) 101 208 (4) 102 » periments were conducted with an ade189 (4) 100 197 (4) 99 quate diet. However, during this period an223 (15) 108 190 (15) 97 tibiotics were routinely fed in experiments 284 (15) 286 (35-c) 105 104 154 (30) 123 being conducted for other purposes. The 166 (30) 115 188 (30) 115 same situation exists with procaine peni221 (30) 104 154 (30) 96 cillin, but with slightly different time pe157 (35-c) 150 (5) 123 117 181 (10-c) 141 riods. Table 2 gives the results of experi156 (10-c) 123 (5) 111 87 167 (35-c) 118 ments with zinc bacitracin. No subdivision 152 (35-c) 113 232 (35-c) 227 (35) 127 125 of the decade is possible with this anti169 (35-c) 160 (35) 95 90 250 (10) 257 (35-c) 98 95 biotic, because it was fed with an adequate 262 (10) 112 diet only during the years 1956 to 1959. Numbers in parentheses refer to milligrams per kilogram of During this period, a total of twenty-five antibiotic used. Letter following tetracycline level denotes kind tetracycline fed—c-chlortetracycline, o-oxytetracycline. trials involving zinc bacitracin were con* Date previously reported by Waibel et al.
Downloaded from http://ps.oxfordjournals.org/ at Zentralbibliothek on May 6, 2015
Basal
Weight—% of basal
GROWTH RESPONSE TO ANTIBIOTICS TABLE 1.—Continued Date experiment
3rd week average weight
started
Basal
Penicillin
10-58 11-58 12-58 1-59 (floor pen) 1-59 2-59 2-59 4-59 5-59 6-59 12-59
172 215 177 235
226 (4) 225 (4) 200 (4)
Tetracycline 236 224 199 237
(lO-o) (lO-o) (lO-o) (lO-o)
Weight—% of basal Peni- Tetracillin cyclic 131 105 113
127 104 112 101
256 (lO-o) 229 (lO-o) 209 (lO-o) 188 (lO-o) 222 (lO-o) 207 (lO-o) 141 (lO-o)
111 109 101 96 116 112 95
257 257 257 272 272 272 302
284 313 246 302 288 283 316
(10-c) (20-c) (lO-o) (10-c) (20-c) (lO-o) (10-c)
110 122 96 111 106 104 105
302
322 (20-c)
107
302
331 (lO-o)
110
(2 wk. trial
floor pen) 2-60 2-60 2-60 5-60 5-60 5-60 12-60 (floor pen) 12-60 (floor pen) 12-60 (floor pen)
ducted. Of these, thirteen were at the 10 or 20 mg./kg. supplementation level, nine at one hundred mg./kg. and three at 35 mg./kg. A negative weight response occurred in six of the twenty-five diets. These six were dispersed throughout the three year period and the low, intermediate and higher levels of supplementation were each represented. In the years 1950 to mid 1953 a total of 46 trials was conducted with procaine penicillin. In only eight of these (17.5 percent) did the antibiotic-fed group grow at a lower rate than the basal. During the last year of this period, no response was obtained that exceeded 110% of basal. This period of poor response has previously been reported by Waibel et al., in 1954. It was concluded at that time that the apparent lack of response was due in part to improved growth of basal groups and the possibility of an alteration in the microorganism population. When trials were resumed in 1956 to 1959, a total of 15 trials was conducted and in four of these the antibiotic-fed groups grew at a lower rate than the basal.
During the first period (1951 to 1953) thirty-one trials involved a tetracycline (chlortetracycline exclusively). In only one did the antibiotic-fed group reach a lower weight than the basal. Of the twenty-nine trials with tetracyclines in the later period, there were five in which the antibiotic-fed groups attained lower weights than the basals. The average responses for the two periods were calculated and found to be very similar—being 108.5% of basal for the period 1950-1954 and 108.8% of basal for the second period with procaine penicillin. The comparable figures were 112.3 and 110.2 for the corresponding periods with the tetracyclines. Low levels of zinc bacitracin (comparable with those of procaine penicillin and tetracyclines) gave an average response of 105.9 percent of the basal TABLE 2.—Effect of zinc bacitracin on the growth of chicks fed an adequate diet Date experiment started
3rd week average weight Weight— %of Treated basal Control
gm. gm. w Level Supplementation (comparable ine penicillini and tetracyclines) 155 (35) 11-30-56 128 193 (35) 1-11-57 141 154 (35) 11-22-57 177 228 (10) 2-14-58 262 218 (10) 10-2-58 172 186 (10) 10-30-58 215 11-27-58 177 206 (10) 245 (10) 12-30-58 235 262 (10) 12-30-58 230 228 (10) 2-25-59 210 2-25-59 208 225 (10) 209 (10) 4-2-59 196 196 (10) 5-7-59 192 6-12-59 185 171 (10) 10-9-59 181 175 (20) 12-1-59 149 162 (20) gh Level Supplementation 10-2-58 172 236 (100) 11-27-58 177 210 (100) 12-30-58 230 278 (100) 12-30-58 235 287 (100) 229 (100) 2-25-59 208 4-2-59 196 186 (100) 5-7-59 192 235 (100) 190 (100) 6-12-59 185 12-1-59 149 161 (100)
to pro121 137 87 79 127 86 116 104 114 109 108 107 102 92 97 109 137 119 121 122 110 95 122 103 108
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230 210 208 196 192 185 149
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&0
51
52
53
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55
56
57
58
59
60
61
YEARS FIG. 1. Changes in response of chicks fed procaine penicillin from 1950 to 1959. Each dot represents one trial.
150
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no 10 0 X ©
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52
53
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57
58
59
YEARS FIG. 2. Changes in response of chicks fed tetracyclines from 1951 to 1961. Each dot represents one trial.
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100
I-
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GROWTH RESPONSE TO ANTIBIOTICS
weight. Higher levels of zinc bacitracin (100 mg./kg.) gave a response of 115.2 percent. Thus the average responses to the three types of antibiotics were similar and the results obtained in the later period were as good as those obtained earlier. Since these experiments covered a ten year duration, they offer a better perspective of variations in antibiotic response than does any report published previously. The earlier report by Waibel et al. (1954) covered only a three year period and it was indicated at that time that a lack of antibiotic response had occurred in the third year (mid 1952 to mid 1953). However, when this period of decreased response is reevaluated in the light of a longer time and greater number of trials, it becomes clear that the results in 1952-1953 were not the beginning of a long-term trend.
SUMMARY The growth responses obtained from low levels of procaine penicillin, chlortetracycline and oxytetracycline for the period 1950 to 1960 have been presented. The results were subdivided into two periods— 1950 to 1953 and 1956 to 1960. Zinc bacitracin results are also given, but only for the period 1956 to 1959. The following conclusions can be drawn from the data—
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o
X
X
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80
70 1 56
_
57
_
.
58 EARS
.
59
J
60
FIG. 3. Changes in response of chicks fed zinc bacitracin from 1956 to 1960. Each symbol represents one trial (dots represent 10 to 35 mg./kg. supplementation level; X represent 100 mg./kg.)
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1) No long term changes occurred in the weight responses obtained with procaine penicillin or tetracyclines. Variations among trials were found in each period for both procaine penicillin and the tetracyclines. 2) Zinc bacitracin compared favorably with both procaine penicillin and the
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D. A. HETH AND H. R. BIRD
cin (100 mg. per kilogram) gave an average response of 115.2 percent. REFERENCES Libby, D. A., and P. J. Schaible, 1955. Observations on growth responses to antibiotics and arsonic acids. Science, 121: 733-734. McGinnis, J., L. H. Merrill, R. E. Fry and L. S. Jensen, 1958. Use-history of antibiotics as related to their efficacy in promoting growth of turkeys. Poultry Sci. 37: 810-813. Waibel, P. E., O. J. Abbott, C. A. Baumann and H. R. Bird, 1954. Disappearance of the growth response of chicks to dietary antibiotics in an "old" environment. Poultry Sci. 33: 1141-1146. Wiese, A. C , and C. F. Petersen, 1959. Comparison of several antibiotics for chick growth. Poultry Sci. 38: 1259.
Capacity of the Adult Chicken for Exercise on the Treadmill* Physiology
HAROLD S. WEISS With the technical assistance of KURT TEXTOR Laboratories, Dept. of Poultry Science, Rutgers, The State University New Brunswick, New Jersey
of New
Jersey,
(Received for publication August 28, 1961)
ALTHOUGH various exercise tolerance -**• tests are widely used in clinical practice and medical research to estimate physical and physiological functions (see, for example, Bard, Chapter 47, 1956; and Astrand, 1956), they seem to have found limited application in the animal sciences. In poultry, forced physical activity has been used in connection with such studies as: stress and adrenal hormone interaction (Garren and Shaffner, 1954; Connor and Shaffner, 1954); lipid metabolism and atherogenesis (Warnock et al., 1957; Wong et al., 1959); hematological changes * Paper of the Journal Series, New Jersey Agricultural Experiment Station, Rutgers, the State University of New Jersey, New Brunswick, New Jersey. Supported in part by U. S. PHS research grant H-5719.
(Anderson et al., 1959); blood uric-acid levels (Hudson and Taylor, 1960); feather removal (Knapp and Newell, 1961); and the mortality differences between genetically selected hyper- and hypotensive strains (Sturkie and Textor, 1961). However, apart from the data supplied by Garren and Shaffner (1954) for the growing chick exercised in a revolving drum, little appears to be known of the characteristics involved in the bird's resistance to muscular fatigue. This report surveys a variety of natural and experimental factors which might relate to the capacity of the adult chicken for exercise on a treadmill. PROCEDURE
All exercise tests were made on a horizontal, multiplace, variable speed treadmill
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tetracyclines in terms of growth response obtained. 3) The average weights of groups fed procaine penicillin at levels of 4 to 30 mg./kg. were 108.S and 108.8 percent of weight of basal groups in the two periods studied. Average weights of groups fed tetracyclines at levels of 10 to 35 mg./kg. were 112.3 percent of basal for the earlier of the two periods studied and 110.2 percent of basal for the later one. Zinc bacitracin at levels of 10 to 35 mg./ kg. gave an average weight of 105.9 percent of basal for the period 1956 to 1959. A high level of zinc bacitra-