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Anticoccidial Activity of Monensin in Floor-Pen Experiments1
DDT
139
AND EGG SHELL THICKNESS
Wiemeyer, S. N., and R. D. Porter, 1970. DDE thins eggshells of captive American kestrels. Nature, 227: 737-739.
Wurster, C. F., Jr. and D. B. Wingate, 1968. D D T residues and declining reproduction in the Bermuda petrel. Science, 1S9: 979-981.
Anticoccidial Activity of Monensin in Floor-Pen Experiments1 W. MALCOLM REID, LARRY KOWALSKI AND JOHN RICE Department of Poultry Science, University of Georgia, A thens, Georgia 30601 (Received for publication May 4, 1971) ABSTRACT The anticoccidial agent monensin has been tested in 5 floor-pen experiments and compared with unmedicated and with positive control treatments (amprolium + ethopabate in 4, clopidol in 2 and zoalene in 1 experiment). Severity of coccidiosis exposure was increased by an oocyst-seeding technique, increasing litter moisture content to 30% or higher, and various attempts to prevent early development of immunity. Coccidiosis-associated mortality occurred in only 0.06% of 1SS2 birds on monensin (with or without roxarsone), 1.41% of 1556 birds on amprolium + ethopabate (with or without roxarsone), 0.05% of 200 birds on zoalene (with roxarsone), 0% of 401 birds on clopidol (with roxarsone) and 6.0% of 1750 birds on unmedicated feed. Coccidiosis-associated mortality occurred in 1/31 pens on monensin (when fed at the recommended level), 15/31 pens on amprolium plus ethopabate, 1/4 on zoalene, 0/8 on clopidol and 33/45 pens on unmedicated feed. Weight gains of monensin-medicated treatments (with or without roxarsone) were significantly greater (P < 0.05) in 16/17 possible treatment comparisons with unmedicated birds. Feed conversion was improved in 11/17 comparisons. Monensin and other anticoccidial agents partially or completely suppressed development of lesions and lesion scores in all parts of the digestive system. Species included Eimeria acervulina, E. brunetti, E. maxima, E. mivati, E. necatrix and E. tenella. The latter species sometimes produced mild lesions early in the life of the bird with monensin as well as amprolium plus ethopabate and zoalene. Evidence of coccidial immunity was demonstrated to five of six species (all except E. necatrix) by immunity challenge and by comparing lesions found in birds of different agents from the same floor pens. POULTRY SCIENCE 5 1 : 139-146,
ONENSIN has recently been described as an anticoccidial agent which may prove useful to the poultry industry (Shumard et al., 1970). This compound, which is a fermentation product produced by Streptomyces cinnamonensis (Haney and Hoehn, 1968), is entirely different in chemical structure from other agents now marketed as anticoccidials. Improved poultry production must be demonstrated before the potential benefits of an anticoccidial can be determined. Three types of experimentation—laboratory testing (Waletzky, 1970), floor-pen experiments (Brewer and Kowalski; and Reid,
M
1 University of Georgia College of Agriculture Experiment Station Journal Series Paper 1055, College Station, Athens, Georgia 30601.
1972
1971) and field experiments (Edgar, 1970; Vezey, 1970; and Kilgore, 1970) have been accepted in evaluation of anticoccidial agents (Reid et al., 1969). Laboratory experiments provide only limited data on production efficiency in commercial poultry production. Floor-pen experiments provide an experimental method which permits simultaneous comparisons of flocks on an experimental anticoccidial (e.g. monensin), positive controls (other reference anticoccidials) and negative controls (on unmedicated feed). Similar data on production efficiency may be obtained from large field experiments but may require much greater expense for medication and chickens. Insufficient exposure to coccidiosis in floor-pen
140
W. M. REID, L. KOWALSKI AND J. RICE T A B L E 1.—Anticoccidial activity of monensin in floor pens {Experiment 1) C
Treatment
A—unmedicated controls 2 B—"susceptible controls" C—monensin (0.0121%) D—amprolium (0.0125%) +ethopabate (0.0004%)
Wt. kg.
1.49C1 1.65ab 1.72ab 1.61
Feed conversion
2.54°b 2.31 2.21 a 2.38 b c
Si-sho™ng
10S1S asso- morciated tality mor- from tality coccidiosis
2/150 2/150 0/150 0/150
2/3 1/3 0/3 0/3
1 Means with the same superscripts were not significantly different (P> 0.05). 2 Birds were kept partially susceptible by feeding a mixture of buquinolate 0.00825%, clopidol 0.0125%, and nicarbazin 0.02% for 6 weeks after which all medication was withdrawn.
experiments, due to rapid development of immunity, has frequently resulted in no test of the anticoccidial activity. The experimental design may require some degree of artificiality to duplicate conditions in field flocks where susceptible birds may be exposed to an overwhelming build-up of oocysts. In five floor-pen experiments the anticoccidial agent monensin has been compared with unmedicated control treatments and several other anticoccidial agents. Various techniques were employed to insure the presence of sufficient coccidiosis exposure to test anticoccidial activity. MATERIALS AND METHODS Five experiments were conducted in an open-type commercial house containing 20 pens on each side of a central hallway. Each pen contained approximately 4.8 square meters of floor space. In each experiment 50 broiler-strain chicks (Cobb's White Rocks or Cobb 100 Crossbreed) from the same hatch were placed in a pen. Before the trial concrete floors were cleaned and covered with approximately 10 cm. of new pine-shavings litter. A commercial-type feed formula (Kirkland and Fuller, 1970) was fed ad libitum. The starter ration was fed for approximately 4 weeks followed by a finisher ration which contained additional fat and corn gluten
meal. Each treatment group included 4 pen replications except in Experiment 1 and treatments B and F in Experiment 2 (see Table 2) where there were 3 pens. All experiments were terminated at 8 weeks. Monensin and the reference anticoccidials amprolium + ethopabate (Experiments 1, 3, 4 and 5), zoalene (Experiment 2) and clopidol (Experiments 3 and 5) were added to the feed at levels indicated in Tables 1-5. Designs of the S experiments included some treatments to test other experimental anticoccidials and methods of increasing severity of coccidiosis exposure. Most of these have been omitted from this report. Some data on roxarsone, a widely used "growth promotion" arsenical, have been included to assist in interpretation of activity of monensin and other anticoccidials. Oocyst-seeding was used in some pens (Reid et ah, 1969; and Mitchell and Scoggins, 1970). Five battery-reared susceptible birds of the same or an older age were inoculated with S X or 10 X the recommended dosage of Coccivac D 2 and were placed in cages suspended over the litter of the floor pens. The age of floor-pen birds when these seeder-birds were placed in cages was 38 days in Experiment 1, 14 days in Experiments 2, 3 and 4 and 1 day in Experiment 5. Measured quantities of water were added to the litter to increase moisture levels. Litter samples collected in a cup-sized scoop from S different areas of the pen were thoroughly mixed in a gallon jar for moisture determinations. A weighed sample was dried in a hot air oven and then reweighed to determine the moisture content of the litter. Various levels of moisture content (20%—"moderate," 40%—"high" and 2 Coccivac D , Sterwin Laboratories, Inc., is certified to contain live oocysts of Eimeria acervulina, E. brunetti, E. hagani, E. maxima, E. mivati, E. necatrix, E. praecox and E. tenella.
141
ANTICOCCIDIAL ACTIVITY OF MONENSIN TABLE 2.—Anticoccidial activity of monensin in floor pens (Experiment 2)
Wt. gain kg. Treatment
A- -unmedicated controls B - -"susceptible controls" 3 C- -monensin (0.0121% 0-4 wks. .0006% 4-8 wks.)4 D - -monensin (0.0121% 40-4 wks. .0006% 4-8 wks.) E - -zoalene F - -(roxarsone)
0.005%
Feed conversion Coccidiosis associated 4 wks. 8 wks. mortality
Pens showing mortality from coccidiosis
4 wks.
8 wks.
_ — —
0.44" 0.39° 0.51 b 0.54*b
1.49" 1.53" 1.65s 1.70"
2.28 c 2.08b° 2.01»b 1.90ab
2.41»b 2.33" 2.35"
11/200 1/150 0/200 1/2004
3/4 1/3 0/4 0/4
+ +
0.55" 0.54»b
1.70" 1.63"
1.8r> 1.92<*
2.38" 2.37*
1/200 0/150
1/4 0/3
+
2.49W2
1
Means with the same superscript were not significantly different (P>0.05) between treatment means. Differences were not significant (P>0.05). Birds were kept susceptible by feeding a mixture of anticoccidial A for 2 weeks after which all medication was withdrawn. 4 Due to a mixing error the monensin level was inadvertently reduced to l/20th the recommended level. One bird died of coccidiosis (E. tenella) 7 days after this inadvertent reduction in level. This death has been excluded from mortality counts. Four-week weights and feed conversions were taken before this mixing error occurred. 2
3
60%—"very high") were included in the design of Experiment 4. These proposed levels were somewhat exceeded in the S determinations made on each pen (Table 4). In Experiment 5 a constant level of 30% moisture was maintained throughout the experiment in all pens. In an attempt to prevent the immunity which has often prevented natural outbreaks of coccidiosis in floor-pen experiments, one treatment group (Experiments
1, 2 and 3) known as the "susceptible control" chickens was maintained temporarily on one or more anticoccidial agents. After withdrawal of the anticoccidial, severe outbreaks of coccidiosis were expected. These birds sometimes proved to be immune, but these "susceptible control" treatments are summarized and regarded as a class of unmedicated controls. Parameters used here in evaluating anticoccidial activity include: 1) average bird
TABLE 3.—Anticoccidial activity of monensin in floor pens (Experiment 3)
Treatment A—-unmedicated B—"susceptible controls" 2 C—monensin (0.0121%) D—monensin (0.0121%) E—amprolium (0.0125%) +ethopabate (0.004%) "high E " F—amprolium (0.0125%) -f-ethopabate (0.004%) "high E " G—clopidol (0.0125%) H—(roxarsone) 1
Coccidiosis associated mortality
Pens showing mortality from coccidiosis
2.52" 2.21» 2.20* 2.23*
15/200 22/200 0/200 1/200 2/200
4/4 4/4 0/4 1/4 2/4
1.65"1
2.36 b
4/200
3/4
1.80*b 1.62*=
2.21* 2.37 b
0/200 5/200
0/4 3/4
Roxarsone 0.005%
Wt. kg.
Feed conversion
+
1.S5'1 1.58d= 1.74b° 1.85* 1.72b=
+ +
2 .44bc
Means with the same superscript were not significantly different (P>0.05). 2 Birds were kept partially susceptible by feeding-clopidol+roxarsone for 2 weeks then withdrawing medication.
142
W. M. REID, L. KOWALSKI AND J. RICE TABLE 4.—A nticoccidial activity of monensin in floor-pen experiments {Experiment 4)
Treatment
A—unmedicated controls1 high moisture B—unmedicated controls moderate moisture C—unmedicated controls moderate moisture D—unmedicated controls very high moisture E—monensin (0.01%)+roxarsone (0.005%) high moisture F—amprolium (0.0125%)-f ethopabate (0.0004%) moderate moisture G—amprolium (0.0125%)+ethopabate (0.0004%) moderate moisture H—amprolium (0.0125%)+ethopabate (0.0004%) high moisture
Ooc st j^l seeding
+ — +
Pens R ° x a r " Av. Utter Feed Coccidiosis showing sone moisture Wt. kg. conver- associated mortality mortality from 0 0 0 5 % day 25 sion coccidiosis
-
1.26rf2
46%
-
1
32%
-
1.30 "*
30%
1.24
4.32
20/200
4/4
b
4.07<=
26/200
4/4
3.06"
0/200
0/4
+
+ + + +
44%
1.44"
+
h
1.33 <= 1.32'"= 1.36
46%
3.69'"=
4/4
1.34
30%
4/4
10/200
69%
+
19/200
J
-
35%
4.03<=
d
+
—
1
b
b
3.53" <=
4/200
3/4
b
6/200
3/4
3.41">>
5/200
3/4
3.30»
1
Eight grams of vitamin K and 15,000,000 International Units of vitamin A were added to the ration in all treatments. 2 Means with the same superscript were not significantly different (P>0.05).
weight at 8 weeks when the trial was terminated, 2) feed conversion at 8 weeks (weight of feed consumed -~ live weight of birds), 3) coccidiosis-associated mortality (other factors may also have contributed to death), and 4) average lesion scores. Lesions on samples of 4 birds per pen were scored (Johnson and Reid, 1970) in the upper, middle and lower intestine and cecum at 3 weeks of age in Experiment 5, at
4 weeks of age in Experiments 2, 3 and 4, 6 weeks in Experiment 3 and 8 weeks in Experiments 1, 2 and 3. Data were analyzed by analysis of variance and Duncan's (19SS) multiple range test. The experimental design of some experiments permitted several different comparisons between medicated and nonmedicated treatment groups. Immunity development. Seventy birds
TABLE 5.—Anticoccidial activity of monensin in floor pens {Experiment 5)
Treatment
A—unmedicated (oocyst seeding) B—unmedicated (no oocyst seeding) C—monensin (0.0121%) D—monensin (0.0121%) E—amprolium (0.0125%)+ethopabate (0.004%) "high E " F—amprolium (0.0125%)+ethopabate (0.004%) "high E " G—roxarsone (0.005%) H—clopidol (0.0125%) 1 2
Oocyst seeding
+ — + +
Roxarsone 0.005%
+
+ + + +
+ + +
Wt
Pens P . Coccidiosis showing ' S- conversion associated mortality mortality from coccidiosis k
1.55bl 1.58b 1.70" 1.69"
28 13 10
1/200 1/200 0/201 0/201
1/4 1/4 0/4 0/4
1.65"
2.28
1/200
1/4
1.70" 1.65" 1.70"
.13 .25 ,14
0/206 5/200 0/201
0/4 3/4 0/4
262
Means with the same superscript were not significantly different (P>0.05) between treatment means. Differences were not significantly different (P>0.05).
ANTICOCCIDIAL ACTIVITY OF MONENSIN
from Experiment 3 fed on monensin-medicated ration for 8 weeks were moved to individual cages and given unmedicated feed for 10 days. Ten birds were individually weighed and inoculated with each of the six species E. acervulina, E. brunetti, E. maxima, E. mivati, E. necatrix and E. tenella using techniques described by Reid et al. (1968). Ten additional birds were weighed but were not inoculated. Seven days postinoculation all birds were reweighed and gain or loss determined. Presence or absence of immunity was judged by comparison of group means of inoculated versus uninoculated controls. If mean weight differences between inoculated and uninoculated birds were statistically significant (P < 0.0S), the flock (treatment group) was classed as "susceptible"; but if nonsignificant, they were classed "immune." Observations on immunity were made while monitoring lesion scores of flocks of various ages in different experiments.
143
of 17 possible comparisons (Experiments 1, 3 and 4). Similar improvement was shown in 6 out of 16 comparisons with amprolium plus ethopabate (Experiments 1 and 3). Mortality. Coccidiosis-associated mortality from all 5 experiments for different treatments compared to total birds in all experiments (disregarding presence or absence of roxarsone) was: unmedicated controls 105/1750 (6.0%), susceptible controls 25/500 (5.00%), monensin 1/1552 (0.06%), amprolium plus ethopabate 22/ 1556 (1.41%), roxarsone alone ,10/550 (1.82%), zoalene 1/200 (0.05%) and clopidol 0/401 (0%). Since each individual pen represents a separate biological system involving interaction between birds, parasites, anticoccidials and other ecological factors, pen mortality was also recorded (Tables 1-5). Deaths occurred in 2 of 31 pens in the 5 experiments where birds were provided feed medicated with monensin. One of these deaths (Experiment 2) occurred 7 days following accidental reducRESULTS Weights. Monensin-medicated treatment tion of the monensin level from 0.0121% to groups of birds (with or without roxarsone, 0.0006%. Mortality occurred in 33 out of Tables 1-5) were heavier than unmedi- 45 of the pens on unmedicated feed (incated (including "susceptible") controls at cluding "susceptible controls"). Losses 8 weeks of age in all 5 floor-pen experi- were as high as 20% in one pen ("susceptiments. These differences were significant ble control") in Experiment 3 and 16% in (P < 0.05) in 16 out of 17 possible treat- Experiment 4. Mortality also occurred in ment comparisons. Birds fed on amprolium 15 out of 31 pens on amprolium plus ethoplus ethopabate showed significant in- pabate, 6 out of 11 on roxarsone alone, 1 creases in weights in 11 out of 16 compari- out of 4 on zoalene and 0 out of 8 on clopisons. Monensin-medicated birds were sig- dol. Lesion scores. Severity of lesions varied nificantly heavier in 5 out of 8 possible with the time of sampling and the time at comparisons over amprolium plus ethopawhich oocyst-seeder birds were introduced bate. No significant differences were found into the suspended cages in the floor-pens. in the single experiments where zoalene + Lesion score totals from the 4 areas of the roxarsone and clopidol + roxarsone were gut are recorded by treatment and expericompared with monensin + roxarsone. ment (Fig. 1) at the time when most leFeed conversions. Monensin-medicated sions were present. These scores were debirds (with or without roxarsone) had termined at 8 weeks in Experiment 1 and 4 lower feed conversion compared to unmediweeks in Experiments 2, 3 and 4 and 3 cated and "susceptible controls." Improveweeks in Experiment 5. ment was significant (P < 0.05) in 11 out
144
W.
M.
R E I D , L.
KOWALSKI AND J. B
Upper
M
Mid
RICE
Intestine Inteitine
• Po"""" ' "
1A IB 2A 28 3A 3B 4A 4B 4C 4D 5A 5B unmedicored
W^ v i ^ t i B ID 3E 3F
IC 2C 2D 3C 3D 4E 5C 5D
controls
monenjin
4F 4G 4H 5E 5F
amprolium + ethopabate
2F 3H 5G roxarione
2E 100lene
3G 5H dopidol
FIG. 1. Total lesion scores from different treatment groups from five floor-pen experiments. Scores represent 3 or 4 pen averages with each treatment group. Letters indicate treatments identified in Tables 1-5.
Immunity development. Immunity to E. acervulina, E. brunetti, E. maxima, E. mivati and E. tenella was demonstrated following 8 weeks on monensin-medicated feed in Experiment 3. However, these birds remained susceptible to E. necatrix. Since birds from pens on unmedicated feed showed no weight loss after challenge with all species, they were immune. Additional observations on development of immunity came from lesion scoring sample birds of different ages. The monensinmedicated birds usually had some lesions from the 2nd to the Sth week. By the 6th week there were fewer lesions and usually none by the 8th week. Absence of lesions at this time is directly attributed to immunity developed earlier in the life of the birds. DISCUSSION AND CONCLUSION'S
Live weights are one of the first measures of profits to the poultry producer. Monensin-medicated birds weighed more than unmedicated controls in all experiments. These differences were statistically significant (P < 0.0S) in all S of the ex-
periments. Monensin alone (Experiment 1) or combined with roxarsone (Experiments 1, 3 and 4) weighed significantly more (P < 0.0S) than amprolium plus ethopabate in 5 out of 8 treatment comparisons. No significant differences were demonstrated with zoalene or clopidol. These results demonstrate the ability of monensin to protect birds under conditions where coccidiosis was fully demonstrated. Feed conversion combines both profits (weights) and expenses (feed—which is the item of greatest expense) in a combination useful to the producer. The modern poultryman must keep his feed conversion figure at 2.1 or lower to be competitive. Such a low level was achieved only in one treatment (monensin plus roxarsone in Experiment 5) in the 5 experiments. The higher feed conversion figures reflect the stresses used to induce coccidiosis. In all experiments the feed conversion for monensin was better (lower) than in unmedicated (or susceptible) controls. Differences were significant in Experiments 1, 2, 3 and 4. Monensin had a feed conversion equally as
ANTICOCCIDIAL ACTIVITY OF MONENSIN
good and in a few instances significantly better than amprolium plus ethopabate. No significant differences occurred between monensin and other reference anticoccidials (Tables 1-5). Monensin at the level of 0.0121% or 0.01% prevented coccidiosis mortality in all treatments and experiments except for one death (Experiment 3, D). This protection was demonstrated in spite of adverse conditions which produced moderate to severe mortality in unmedicated controls. These conditions were produced by high moisture levels, susceptible flocks and a sudden build-up of oocysts through the use of the oocyst-seeding technique. Mortality up to 20% per pen is among the highest ever reported for natural outbreaks in floor-pen experiments. The 50 to 100% mortality sometimes used in experimental trials has not been demonstrated in floorpen experiments. In reducing coccidiosis mortality monensin out-performed amprolium plus ethopabate which permitted some mortality when moisture levels exceeded 26% in some pens in these experiments. There are insufficient data to compare monensin with other anticoccidials. Both monensin and amprolium plus ethopabate reduced the severity of lesions as demonstrated in Figure 1. This suppression is most noticed in the upper intestine (E. acervulina and E. mivati), middle intestine (E. maxima and E. necatrix) and lower intestine (E. brunetti). Both anticoccidials did permit some lesions due to E. tenella under conditions favorable to coccidiosis. There were insufficient observations to make comparisons with clopidol and zoalene. The severity or percentage of a flock demonstrating lesions gives some indication of performance of an anticoccidial agent. Judgment on economic importance of this parameter in drug efficacy studies is more difficult than with other criteria. Lesion scores of + 1 of E. acervulina and of E.
145
mivati were considered coccidiasis (nonpathogenic) and not coccidiosis (Reid and Johnson, 1970; and Johnson and Reid, 1971) in unmedicated laboratory experiments. Final decisions on selection of an anticoccidial agent will be made following field and laboratory observations as well as on production performance. Concern over appearance of lesions should be weighed against the profits at marketing time. The present experiments indicate no problems with coccidiosis mortality on monensin. If frequent monitoring of flocks for lesions is practiced, some low score lesions may cause the poultryman concern early in the life of the flock. These may be severe enough under stress conditions to permit occasional blood-stained droppings. The mild nature of these lesions in these experimental trials was indicated by the satisfactory production records at market age. Development of immunity to 5 of 6 species occurred while birds were on monensin in Experiment 3. Lack of immunity to E. necatrix merely indicates that the anticoccidial agent interrupted cycling of oocysts in this particular trial. When oocyst output is reduced by anticoccidials under field conditions, they usually interfere with development of immunity. For this reason some manufacturers recommend reducing levels or discontinuing use of anticoccidial in the period between 6 and 12 weeks of age in replacement flocks. Further experiments may be desirable to determine the optimum time at which monensin could be withdrawn under different field conditions. The oocyst-seeding procedure used in the present experiments provided more opportunity for development of immunity than would occur in many field operations. ACKNOWLEDGMENTS
The Coccivac used in these experiments was furnished by Sterwin Laboratories,
146
W. M. REID, L. KOWALSKI AND J. RICE
Inc. The following contributed technical assistance in conducting one or more of these experiments: Mrs. Joyce Johnson, L. R. McDougald, K. S. Hegde, E. M. Taylor, M. Z. Charney and J. L. Mabon. REFERENCES Brewer, R. N., and L. M. Kowalski, 1970. Coccidiosis: Evaluation of anticoccidial drugs in floorpen trials. Exp. Parasitol. 28: 64-71. Duncan, D. B., 1955. Multiple range and multiple F tests. Biometrics, 11: 1-42. Edgar, S. A., 1970. Coccidiosis: Evaluations of coccidiostats under field conditions; statement of problems. Exp. Parasitol. 28: 90-94. Haney, M. E., Jr., and M. M. Hoehn, 1968. Monensin, a new biologically active compound. I. Discovery and isolation. Antimicrob. Agents Chemother.—1967: 349-352. Johnson, J., and W. M. Reid, 1970. Anticoccidial drugs: Lesion scoring techniques in battery and floor-pen experiments with chickens. Exp. Parasitol. 28:30-36. Johnson, J., and W. M. Reid, 1971. Pathogenicity of Eimeria mivati in light and heavy coccidial infections. Poultry Sci. SO: 1202-1205. Kilgore, R. L., 1970. Coccidiosis: Problems involved in obtaining reliable field data. Exp. Parasitol. 28: 118-121. Kirkland, W. M., and H. L. Fuller, 1970. Effect of
ethoxyquin on the nutritional value of animal by-products. Proc. Georgia Nutr. Conf.: 67 _ 76. Mitchell, G. A., and R. W. Scoggins, 1970. Avian Eimeria infection technique: suspended seeder cage. Exp. Parasitol. 28: 87-89. Reid, W. M., 1971. Anticoccidials—methods of testing and evaluation. X I X World Veterinary Congress, Mexico City. (In press.) Reid, W. M., and J. Johnson, 1970. Pathogenicity of Eimeria acervulina in light and heavy coccidial infections. Avian Diseases, 14: 166-171. Reid, W. M., H. E. Womack and J. Johnson, 1968. Coccidiosis susceptibility in layer flock replacement programs. Poultry Sci. 47: 892-899. Reid, W. M., R. N. Brewer, J. Johnson, E. M. Taylor, K. S. Hegde and L. M. Kowalski, 1969. Evaluation of techniques used in studies on efficacy of anticoccidial drugs in chickens. Am. J. Vet. Res. 30:447-459. Shumard, R. F., M. E. Callender and W. M. Reid, 1970. Monensin, a new anticoccidial agent. 14th World Poultry Congress, Madrid, Spain. (In press.) Vezey, S. A., 1970. Coccidiosis: problems in recognition in field operations. Exp. Parasitol. 28: 95-98. Waletzky, E., 1970. Laboratory anticoccidial evaluation trials: Review of designs, variables, criteria, and predictive value for field use. Exp. Parasitol. 28: 42-62.
NEWS AND NOTES (Continued from page 129) HUBBARD NOTES John C. Huttar, Jr. has been named Sales Manager of Hubbard Farms. For nearly 20 years he has been associated with primary breeding organizations, with a broad range of assignments in both sales and production. He is a native of Trumansburg, New York, and a graduate of Cornell University. MICHIGAN NOTES Gilbert A. Leveille, formerly Professor of Nutritional Biochemistry at the University of Illinois, became Chairman of the Department of Food Science and Human Nutrition at Michigan State University, effective July 1. He succeeds Dr. Jacob A. Hoefer, who was appointed temporary Acting Chairman when the De-
partment was formed as part of the College of Agriculture and Natural Resources and College of Human Ecology last October. Dr. Hoefer will continue to serve as Professor of Animal Husbandry and Associate Director of the Agricultural Experiment Station. Prior to joining the faculty at the University of Illinois in 1965, Dr. Leveille was with the U.S. Army Medical Research and Nutrition Laboratory in Denver, Colorado, first as a Research Chemist, 1960 to 1962, then as Chief of the Lipid and Protein Nutrition Branch, 1962 to 1966. He received a bachelor's degree at the University of Massachusetts and a master's and a Ph.D. degree at Rutgers University. Dr. Leveille has served as a team member in nutrition surveys of Malaya and Nigeria and a
(Continued on page 161)
139
AND EGG SHELL THICKNESS
Wiemeyer, S. N., and R. D. Porter, 1970. DDE thins eggshells of captive American kestrels. Nature, 227: 737-739.
Wurster, C. F., Jr. and D. B. Wingate, 1968. D D T residues and declining reproduction in the Bermuda petrel. Science, 1S9: 979-981.
Anticoccidial Activity of Monensin in Floor-Pen Experiments1 W. MALCOLM REID, LARRY KOWALSKI AND JOHN RICE Department of Poultry Science, University of Georgia, A thens, Georgia 30601 (Received for publication May 4, 1971) ABSTRACT The anticoccidial agent monensin has been tested in 5 floor-pen experiments and compared with unmedicated and with positive control treatments (amprolium + ethopabate in 4, clopidol in 2 and zoalene in 1 experiment). Severity of coccidiosis exposure was increased by an oocyst-seeding technique, increasing litter moisture content to 30% or higher, and various attempts to prevent early development of immunity. Coccidiosis-associated mortality occurred in only 0.06% of 1SS2 birds on monensin (with or without roxarsone), 1.41% of 1556 birds on amprolium + ethopabate (with or without roxarsone), 0.05% of 200 birds on zoalene (with roxarsone), 0% of 401 birds on clopidol (with roxarsone) and 6.0% of 1750 birds on unmedicated feed. Coccidiosis-associated mortality occurred in 1/31 pens on monensin (when fed at the recommended level), 15/31 pens on amprolium plus ethopabate, 1/4 on zoalene, 0/8 on clopidol and 33/45 pens on unmedicated feed. Weight gains of monensin-medicated treatments (with or without roxarsone) were significantly greater (P < 0.05) in 16/17 possible treatment comparisons with unmedicated birds. Feed conversion was improved in 11/17 comparisons. Monensin and other anticoccidial agents partially or completely suppressed development of lesions and lesion scores in all parts of the digestive system. Species included Eimeria acervulina, E. brunetti, E. maxima, E. mivati, E. necatrix and E. tenella. The latter species sometimes produced mild lesions early in the life of the bird with monensin as well as amprolium plus ethopabate and zoalene. Evidence of coccidial immunity was demonstrated to five of six species (all except E. necatrix) by immunity challenge and by comparing lesions found in birds of different agents from the same floor pens. POULTRY SCIENCE 5 1 : 139-146,
ONENSIN has recently been described as an anticoccidial agent which may prove useful to the poultry industry (Shumard et al., 1970). This compound, which is a fermentation product produced by Streptomyces cinnamonensis (Haney and Hoehn, 1968), is entirely different in chemical structure from other agents now marketed as anticoccidials. Improved poultry production must be demonstrated before the potential benefits of an anticoccidial can be determined. Three types of experimentation—laboratory testing (Waletzky, 1970), floor-pen experiments (Brewer and Kowalski; and Reid,
M
1 University of Georgia College of Agriculture Experiment Station Journal Series Paper 1055, College Station, Athens, Georgia 30601.
1972
1971) and field experiments (Edgar, 1970; Vezey, 1970; and Kilgore, 1970) have been accepted in evaluation of anticoccidial agents (Reid et al., 1969). Laboratory experiments provide only limited data on production efficiency in commercial poultry production. Floor-pen experiments provide an experimental method which permits simultaneous comparisons of flocks on an experimental anticoccidial (e.g. monensin), positive controls (other reference anticoccidials) and negative controls (on unmedicated feed). Similar data on production efficiency may be obtained from large field experiments but may require much greater expense for medication and chickens. Insufficient exposure to coccidiosis in floor-pen
140
W. M. REID, L. KOWALSKI AND J. RICE T A B L E 1.—Anticoccidial activity of monensin in floor pens {Experiment 1) C
Treatment
A—unmedicated controls 2 B—"susceptible controls" C—monensin (0.0121%) D—amprolium (0.0125%) +ethopabate (0.0004%)
Wt. kg.
1.49C1 1.65ab 1.72ab 1.61
Feed conversion
2.54°b 2.31 2.21 a 2.38 b c
Si-sho™ng
10S1S asso- morciated tality mor- from tality coccidiosis
2/150 2/150 0/150 0/150
2/3 1/3 0/3 0/3
1 Means with the same superscripts were not significantly different (P> 0.05). 2 Birds were kept partially susceptible by feeding a mixture of buquinolate 0.00825%, clopidol 0.0125%, and nicarbazin 0.02% for 6 weeks after which all medication was withdrawn.
experiments, due to rapid development of immunity, has frequently resulted in no test of the anticoccidial activity. The experimental design may require some degree of artificiality to duplicate conditions in field flocks where susceptible birds may be exposed to an overwhelming build-up of oocysts. In five floor-pen experiments the anticoccidial agent monensin has been compared with unmedicated control treatments and several other anticoccidial agents. Various techniques were employed to insure the presence of sufficient coccidiosis exposure to test anticoccidial activity. MATERIALS AND METHODS Five experiments were conducted in an open-type commercial house containing 20 pens on each side of a central hallway. Each pen contained approximately 4.8 square meters of floor space. In each experiment 50 broiler-strain chicks (Cobb's White Rocks or Cobb 100 Crossbreed) from the same hatch were placed in a pen. Before the trial concrete floors were cleaned and covered with approximately 10 cm. of new pine-shavings litter. A commercial-type feed formula (Kirkland and Fuller, 1970) was fed ad libitum. The starter ration was fed for approximately 4 weeks followed by a finisher ration which contained additional fat and corn gluten
meal. Each treatment group included 4 pen replications except in Experiment 1 and treatments B and F in Experiment 2 (see Table 2) where there were 3 pens. All experiments were terminated at 8 weeks. Monensin and the reference anticoccidials amprolium + ethopabate (Experiments 1, 3, 4 and 5), zoalene (Experiment 2) and clopidol (Experiments 3 and 5) were added to the feed at levels indicated in Tables 1-5. Designs of the S experiments included some treatments to test other experimental anticoccidials and methods of increasing severity of coccidiosis exposure. Most of these have been omitted from this report. Some data on roxarsone, a widely used "growth promotion" arsenical, have been included to assist in interpretation of activity of monensin and other anticoccidials. Oocyst-seeding was used in some pens (Reid et ah, 1969; and Mitchell and Scoggins, 1970). Five battery-reared susceptible birds of the same or an older age were inoculated with S X or 10 X the recommended dosage of Coccivac D 2 and were placed in cages suspended over the litter of the floor pens. The age of floor-pen birds when these seeder-birds were placed in cages was 38 days in Experiment 1, 14 days in Experiments 2, 3 and 4 and 1 day in Experiment 5. Measured quantities of water were added to the litter to increase moisture levels. Litter samples collected in a cup-sized scoop from S different areas of the pen were thoroughly mixed in a gallon jar for moisture determinations. A weighed sample was dried in a hot air oven and then reweighed to determine the moisture content of the litter. Various levels of moisture content (20%—"moderate," 40%—"high" and 2 Coccivac D , Sterwin Laboratories, Inc., is certified to contain live oocysts of Eimeria acervulina, E. brunetti, E. hagani, E. maxima, E. mivati, E. necatrix, E. praecox and E. tenella.
141
ANTICOCCIDIAL ACTIVITY OF MONENSIN TABLE 2.—Anticoccidial activity of monensin in floor pens (Experiment 2)
Wt. gain kg. Treatment
A- -unmedicated controls B - -"susceptible controls" 3 C- -monensin (0.0121% 0-4 wks. .0006% 4-8 wks.)4 D - -monensin (0.0121% 40-4 wks. .0006% 4-8 wks.) E - -zoalene F - -(roxarsone)
0.005%
Feed conversion Coccidiosis associated 4 wks. 8 wks. mortality
Pens showing mortality from coccidiosis
4 wks.
8 wks.
_ — —
0.44" 0.39° 0.51 b 0.54*b
1.49" 1.53" 1.65s 1.70"
2.28 c 2.08b° 2.01»b 1.90ab
2.41»b 2.33" 2.35"
11/200 1/150 0/200 1/2004
3/4 1/3 0/4 0/4
+ +
0.55" 0.54»b
1.70" 1.63"
1.8r> 1.92<*
2.38" 2.37*
1/200 0/150
1/4 0/3
+
2.49W2
1
Means with the same superscript were not significantly different (P>0.05) between treatment means. Differences were not significant (P>0.05). Birds were kept susceptible by feeding a mixture of anticoccidial A for 2 weeks after which all medication was withdrawn. 4 Due to a mixing error the monensin level was inadvertently reduced to l/20th the recommended level. One bird died of coccidiosis (E. tenella) 7 days after this inadvertent reduction in level. This death has been excluded from mortality counts. Four-week weights and feed conversions were taken before this mixing error occurred. 2
3
60%—"very high") were included in the design of Experiment 4. These proposed levels were somewhat exceeded in the S determinations made on each pen (Table 4). In Experiment 5 a constant level of 30% moisture was maintained throughout the experiment in all pens. In an attempt to prevent the immunity which has often prevented natural outbreaks of coccidiosis in floor-pen experiments, one treatment group (Experiments
1, 2 and 3) known as the "susceptible control" chickens was maintained temporarily on one or more anticoccidial agents. After withdrawal of the anticoccidial, severe outbreaks of coccidiosis were expected. These birds sometimes proved to be immune, but these "susceptible control" treatments are summarized and regarded as a class of unmedicated controls. Parameters used here in evaluating anticoccidial activity include: 1) average bird
TABLE 3.—Anticoccidial activity of monensin in floor pens (Experiment 3)
Treatment A—-unmedicated B—"susceptible controls" 2 C—monensin (0.0121%) D—monensin (0.0121%) E—amprolium (0.0125%) +ethopabate (0.004%) "high E " F—amprolium (0.0125%) -f-ethopabate (0.004%) "high E " G—clopidol (0.0125%) H—(roxarsone) 1
Coccidiosis associated mortality
Pens showing mortality from coccidiosis
2.52" 2.21» 2.20* 2.23*
15/200 22/200 0/200 1/200 2/200
4/4 4/4 0/4 1/4 2/4
1.65"1
2.36 b
4/200
3/4
1.80*b 1.62*=
2.21* 2.37 b
0/200 5/200
0/4 3/4
Roxarsone 0.005%
Wt. kg.
Feed conversion
+
1.S5'1 1.58d= 1.74b° 1.85* 1.72b=
+ +
2 .44bc
Means with the same superscript were not significantly different (P>0.05). 2 Birds were kept partially susceptible by feeding-clopidol+roxarsone for 2 weeks then withdrawing medication.
142
W. M. REID, L. KOWALSKI AND J. RICE TABLE 4.—A nticoccidial activity of monensin in floor-pen experiments {Experiment 4)
Treatment
A—unmedicated controls1 high moisture B—unmedicated controls moderate moisture C—unmedicated controls moderate moisture D—unmedicated controls very high moisture E—monensin (0.01%)+roxarsone (0.005%) high moisture F—amprolium (0.0125%)-f ethopabate (0.0004%) moderate moisture G—amprolium (0.0125%)+ethopabate (0.0004%) moderate moisture H—amprolium (0.0125%)+ethopabate (0.0004%) high moisture
Ooc st j^l seeding
+ — +
Pens R ° x a r " Av. Utter Feed Coccidiosis showing sone moisture Wt. kg. conver- associated mortality mortality from 0 0 0 5 % day 25 sion coccidiosis
-
1.26rf2
46%
-
1
32%
-
1.30 "*
30%
1.24
4.32
20/200
4/4
b
4.07<=
26/200
4/4
3.06"
0/200
0/4
+
+ + + +
44%
1.44"
+
h
1.33 <= 1.32'"= 1.36
46%
3.69'"=
4/4
1.34
30%
4/4
10/200
69%
+
19/200
J
-
35%
4.03<=
d
+
—
1
b
b
3.53" <=
4/200
3/4
b
6/200
3/4
3.41">>
5/200
3/4
3.30»
1
Eight grams of vitamin K and 15,000,000 International Units of vitamin A were added to the ration in all treatments. 2 Means with the same superscript were not significantly different (P>0.05).
weight at 8 weeks when the trial was terminated, 2) feed conversion at 8 weeks (weight of feed consumed -~ live weight of birds), 3) coccidiosis-associated mortality (other factors may also have contributed to death), and 4) average lesion scores. Lesions on samples of 4 birds per pen were scored (Johnson and Reid, 1970) in the upper, middle and lower intestine and cecum at 3 weeks of age in Experiment 5, at
4 weeks of age in Experiments 2, 3 and 4, 6 weeks in Experiment 3 and 8 weeks in Experiments 1, 2 and 3. Data were analyzed by analysis of variance and Duncan's (19SS) multiple range test. The experimental design of some experiments permitted several different comparisons between medicated and nonmedicated treatment groups. Immunity development. Seventy birds
TABLE 5.—Anticoccidial activity of monensin in floor pens {Experiment 5)
Treatment
A—unmedicated (oocyst seeding) B—unmedicated (no oocyst seeding) C—monensin (0.0121%) D—monensin (0.0121%) E—amprolium (0.0125%)+ethopabate (0.004%) "high E " F—amprolium (0.0125%)+ethopabate (0.004%) "high E " G—roxarsone (0.005%) H—clopidol (0.0125%) 1 2
Oocyst seeding
+ — + +
Roxarsone 0.005%
+
+ + + +
+ + +
Wt
Pens P . Coccidiosis showing ' S- conversion associated mortality mortality from coccidiosis k
1.55bl 1.58b 1.70" 1.69"
28 13 10
1/200 1/200 0/201 0/201
1/4 1/4 0/4 0/4
1.65"
2.28
1/200
1/4
1.70" 1.65" 1.70"
.13 .25 ,14
0/206 5/200 0/201
0/4 3/4 0/4
262
Means with the same superscript were not significantly different (P>0.05) between treatment means. Differences were not significantly different (P>0.05).
ANTICOCCIDIAL ACTIVITY OF MONENSIN
from Experiment 3 fed on monensin-medicated ration for 8 weeks were moved to individual cages and given unmedicated feed for 10 days. Ten birds were individually weighed and inoculated with each of the six species E. acervulina, E. brunetti, E. maxima, E. mivati, E. necatrix and E. tenella using techniques described by Reid et al. (1968). Ten additional birds were weighed but were not inoculated. Seven days postinoculation all birds were reweighed and gain or loss determined. Presence or absence of immunity was judged by comparison of group means of inoculated versus uninoculated controls. If mean weight differences between inoculated and uninoculated birds were statistically significant (P < 0.0S), the flock (treatment group) was classed as "susceptible"; but if nonsignificant, they were classed "immune." Observations on immunity were made while monitoring lesion scores of flocks of various ages in different experiments.
143
of 17 possible comparisons (Experiments 1, 3 and 4). Similar improvement was shown in 6 out of 16 comparisons with amprolium plus ethopabate (Experiments 1 and 3). Mortality. Coccidiosis-associated mortality from all 5 experiments for different treatments compared to total birds in all experiments (disregarding presence or absence of roxarsone) was: unmedicated controls 105/1750 (6.0%), susceptible controls 25/500 (5.00%), monensin 1/1552 (0.06%), amprolium plus ethopabate 22/ 1556 (1.41%), roxarsone alone ,10/550 (1.82%), zoalene 1/200 (0.05%) and clopidol 0/401 (0%). Since each individual pen represents a separate biological system involving interaction between birds, parasites, anticoccidials and other ecological factors, pen mortality was also recorded (Tables 1-5). Deaths occurred in 2 of 31 pens in the 5 experiments where birds were provided feed medicated with monensin. One of these deaths (Experiment 2) occurred 7 days following accidental reducRESULTS Weights. Monensin-medicated treatment tion of the monensin level from 0.0121% to groups of birds (with or without roxarsone, 0.0006%. Mortality occurred in 33 out of Tables 1-5) were heavier than unmedi- 45 of the pens on unmedicated feed (incated (including "susceptible") controls at cluding "susceptible controls"). Losses 8 weeks of age in all 5 floor-pen experi- were as high as 20% in one pen ("susceptiments. These differences were significant ble control") in Experiment 3 and 16% in (P < 0.05) in 16 out of 17 possible treat- Experiment 4. Mortality also occurred in ment comparisons. Birds fed on amprolium 15 out of 31 pens on amprolium plus ethoplus ethopabate showed significant in- pabate, 6 out of 11 on roxarsone alone, 1 creases in weights in 11 out of 16 compari- out of 4 on zoalene and 0 out of 8 on clopisons. Monensin-medicated birds were sig- dol. Lesion scores. Severity of lesions varied nificantly heavier in 5 out of 8 possible with the time of sampling and the time at comparisons over amprolium plus ethopawhich oocyst-seeder birds were introduced bate. No significant differences were found into the suspended cages in the floor-pens. in the single experiments where zoalene + Lesion score totals from the 4 areas of the roxarsone and clopidol + roxarsone were gut are recorded by treatment and expericompared with monensin + roxarsone. ment (Fig. 1) at the time when most leFeed conversions. Monensin-medicated sions were present. These scores were debirds (with or without roxarsone) had termined at 8 weeks in Experiment 1 and 4 lower feed conversion compared to unmediweeks in Experiments 2, 3 and 4 and 3 cated and "susceptible controls." Improveweeks in Experiment 5. ment was significant (P < 0.05) in 11 out
144
W.
M.
R E I D , L.
KOWALSKI AND J. B
Upper
M
Mid
RICE
Intestine Inteitine
• Po"""" ' "
1A IB 2A 28 3A 3B 4A 4B 4C 4D 5A 5B unmedicored
W^ v i ^ t i B ID 3E 3F
IC 2C 2D 3C 3D 4E 5C 5D
controls
monenjin
4F 4G 4H 5E 5F
amprolium + ethopabate
2F 3H 5G roxarione
2E 100lene
3G 5H dopidol
FIG. 1. Total lesion scores from different treatment groups from five floor-pen experiments. Scores represent 3 or 4 pen averages with each treatment group. Letters indicate treatments identified in Tables 1-5.
Immunity development. Immunity to E. acervulina, E. brunetti, E. maxima, E. mivati and E. tenella was demonstrated following 8 weeks on monensin-medicated feed in Experiment 3. However, these birds remained susceptible to E. necatrix. Since birds from pens on unmedicated feed showed no weight loss after challenge with all species, they were immune. Additional observations on development of immunity came from lesion scoring sample birds of different ages. The monensinmedicated birds usually had some lesions from the 2nd to the Sth week. By the 6th week there were fewer lesions and usually none by the 8th week. Absence of lesions at this time is directly attributed to immunity developed earlier in the life of the birds. DISCUSSION AND CONCLUSION'S
Live weights are one of the first measures of profits to the poultry producer. Monensin-medicated birds weighed more than unmedicated controls in all experiments. These differences were statistically significant (P < 0.0S) in all S of the ex-
periments. Monensin alone (Experiment 1) or combined with roxarsone (Experiments 1, 3 and 4) weighed significantly more (P < 0.0S) than amprolium plus ethopabate in 5 out of 8 treatment comparisons. No significant differences were demonstrated with zoalene or clopidol. These results demonstrate the ability of monensin to protect birds under conditions where coccidiosis was fully demonstrated. Feed conversion combines both profits (weights) and expenses (feed—which is the item of greatest expense) in a combination useful to the producer. The modern poultryman must keep his feed conversion figure at 2.1 or lower to be competitive. Such a low level was achieved only in one treatment (monensin plus roxarsone in Experiment 5) in the 5 experiments. The higher feed conversion figures reflect the stresses used to induce coccidiosis. In all experiments the feed conversion for monensin was better (lower) than in unmedicated (or susceptible) controls. Differences were significant in Experiments 1, 2, 3 and 4. Monensin had a feed conversion equally as
ANTICOCCIDIAL ACTIVITY OF MONENSIN
good and in a few instances significantly better than amprolium plus ethopabate. No significant differences occurred between monensin and other reference anticoccidials (Tables 1-5). Monensin at the level of 0.0121% or 0.01% prevented coccidiosis mortality in all treatments and experiments except for one death (Experiment 3, D). This protection was demonstrated in spite of adverse conditions which produced moderate to severe mortality in unmedicated controls. These conditions were produced by high moisture levels, susceptible flocks and a sudden build-up of oocysts through the use of the oocyst-seeding technique. Mortality up to 20% per pen is among the highest ever reported for natural outbreaks in floor-pen experiments. The 50 to 100% mortality sometimes used in experimental trials has not been demonstrated in floorpen experiments. In reducing coccidiosis mortality monensin out-performed amprolium plus ethopabate which permitted some mortality when moisture levels exceeded 26% in some pens in these experiments. There are insufficient data to compare monensin with other anticoccidials. Both monensin and amprolium plus ethopabate reduced the severity of lesions as demonstrated in Figure 1. This suppression is most noticed in the upper intestine (E. acervulina and E. mivati), middle intestine (E. maxima and E. necatrix) and lower intestine (E. brunetti). Both anticoccidials did permit some lesions due to E. tenella under conditions favorable to coccidiosis. There were insufficient observations to make comparisons with clopidol and zoalene. The severity or percentage of a flock demonstrating lesions gives some indication of performance of an anticoccidial agent. Judgment on economic importance of this parameter in drug efficacy studies is more difficult than with other criteria. Lesion scores of + 1 of E. acervulina and of E.
145
mivati were considered coccidiasis (nonpathogenic) and not coccidiosis (Reid and Johnson, 1970; and Johnson and Reid, 1971) in unmedicated laboratory experiments. Final decisions on selection of an anticoccidial agent will be made following field and laboratory observations as well as on production performance. Concern over appearance of lesions should be weighed against the profits at marketing time. The present experiments indicate no problems with coccidiosis mortality on monensin. If frequent monitoring of flocks for lesions is practiced, some low score lesions may cause the poultryman concern early in the life of the flock. These may be severe enough under stress conditions to permit occasional blood-stained droppings. The mild nature of these lesions in these experimental trials was indicated by the satisfactory production records at market age. Development of immunity to 5 of 6 species occurred while birds were on monensin in Experiment 3. Lack of immunity to E. necatrix merely indicates that the anticoccidial agent interrupted cycling of oocysts in this particular trial. When oocyst output is reduced by anticoccidials under field conditions, they usually interfere with development of immunity. For this reason some manufacturers recommend reducing levels or discontinuing use of anticoccidial in the period between 6 and 12 weeks of age in replacement flocks. Further experiments may be desirable to determine the optimum time at which monensin could be withdrawn under different field conditions. The oocyst-seeding procedure used in the present experiments provided more opportunity for development of immunity than would occur in many field operations. ACKNOWLEDGMENTS
The Coccivac used in these experiments was furnished by Sterwin Laboratories,
146
W. M. REID, L. KOWALSKI AND J. RICE
Inc. The following contributed technical assistance in conducting one or more of these experiments: Mrs. Joyce Johnson, L. R. McDougald, K. S. Hegde, E. M. Taylor, M. Z. Charney and J. L. Mabon. REFERENCES Brewer, R. N., and L. M. Kowalski, 1970. Coccidiosis: Evaluation of anticoccidial drugs in floorpen trials. Exp. Parasitol. 28: 64-71. Duncan, D. B., 1955. Multiple range and multiple F tests. Biometrics, 11: 1-42. Edgar, S. A., 1970. Coccidiosis: Evaluations of coccidiostats under field conditions; statement of problems. Exp. Parasitol. 28: 90-94. Haney, M. E., Jr., and M. M. Hoehn, 1968. Monensin, a new biologically active compound. I. Discovery and isolation. Antimicrob. Agents Chemother.—1967: 349-352. Johnson, J., and W. M. Reid, 1970. Anticoccidial drugs: Lesion scoring techniques in battery and floor-pen experiments with chickens. Exp. Parasitol. 28:30-36. Johnson, J., and W. M. Reid, 1971. Pathogenicity of Eimeria mivati in light and heavy coccidial infections. Poultry Sci. SO: 1202-1205. Kilgore, R. L., 1970. Coccidiosis: Problems involved in obtaining reliable field data. Exp. Parasitol. 28: 118-121. Kirkland, W. M., and H. L. Fuller, 1970. Effect of
ethoxyquin on the nutritional value of animal by-products. Proc. Georgia Nutr. Conf.: 67 _ 76. Mitchell, G. A., and R. W. Scoggins, 1970. Avian Eimeria infection technique: suspended seeder cage. Exp. Parasitol. 28: 87-89. Reid, W. M., 1971. Anticoccidials—methods of testing and evaluation. X I X World Veterinary Congress, Mexico City. (In press.) Reid, W. M., and J. Johnson, 1970. Pathogenicity of Eimeria acervulina in light and heavy coccidial infections. Avian Diseases, 14: 166-171. Reid, W. M., H. E. Womack and J. Johnson, 1968. Coccidiosis susceptibility in layer flock replacement programs. Poultry Sci. 47: 892-899. Reid, W. M., R. N. Brewer, J. Johnson, E. M. Taylor, K. S. Hegde and L. M. Kowalski, 1969. Evaluation of techniques used in studies on efficacy of anticoccidial drugs in chickens. Am. J. Vet. Res. 30:447-459. Shumard, R. F., M. E. Callender and W. M. Reid, 1970. Monensin, a new anticoccidial agent. 14th World Poultry Congress, Madrid, Spain. (In press.) Vezey, S. A., 1970. Coccidiosis: problems in recognition in field operations. Exp. Parasitol. 28: 95-98. Waletzky, E., 1970. Laboratory anticoccidial evaluation trials: Review of designs, variables, criteria, and predictive value for field use. Exp. Parasitol. 28: 42-62.
NEWS AND NOTES (Continued from page 129) HUBBARD NOTES John C. Huttar, Jr. has been named Sales Manager of Hubbard Farms. For nearly 20 years he has been associated with primary breeding organizations, with a broad range of assignments in both sales and production. He is a native of Trumansburg, New York, and a graduate of Cornell University. MICHIGAN NOTES Gilbert A. Leveille, formerly Professor of Nutritional Biochemistry at the University of Illinois, became Chairman of the Department of Food Science and Human Nutrition at Michigan State University, effective July 1. He succeeds Dr. Jacob A. Hoefer, who was appointed temporary Acting Chairman when the De-
partment was formed as part of the College of Agriculture and Natural Resources and College of Human Ecology last October. Dr. Hoefer will continue to serve as Professor of Animal Husbandry and Associate Director of the Agricultural Experiment Station. Prior to joining the faculty at the University of Illinois in 1965, Dr. Leveille was with the U.S. Army Medical Research and Nutrition Laboratory in Denver, Colorado, first as a Research Chemist, 1960 to 1962, then as Chief of the Lipid and Protein Nutrition Branch, 1962 to 1966. He received a bachelor's degree at the University of Massachusetts and a master's and a Ph.D. degree at Rutgers University. Dr. Leveille has served as a team member in nutrition surveys of Malaya and Nigeria and a
(Continued on page 161)