Influences of Previous Calcium and Phosphorus Intake and Plant Phosphorus on the Requirement of Developing Turkeys for Calcium and Phosphorus1

Influences of Previous Calcium and Phosphorus Intake and Plant Phosphorus on the Requirement of Developing Turkeys for Calcium and Phosphorus1 FRANCIS E. NELSON, LEO S. JENSEN AND JAMES MCGINNIS Washington State University, Pullman (Received for publication June 11, 1962)

Tf STABLISHED calcium and phos-*—' phorus requirements for turkey poults from 0-8 weeks vary considerably among investigators (Wilcox et al., 1953). After reviewing the literature on phosphorus requirement, Almquist (1954) concluded that 0.6% readily available phosphorus was needed by the poult. Blaylock et al. (1961) reported that 0.8% calcium and 0.8% total phosphorus were adequate for maximum growth from 0-8 weeks, while Formica et al. (1961) reported that 0.65% total phosphorus and 0.8% calcium produced normal growth. These results suggest that the calcium and phosphorus requirements of turkey poults from 0-8 weeks are lower than those recommended by the National Research Council (1960). Nelson et al. (1961) suggested that requirements for calcium and phosphorus for developing turkeys were lower than those recommended by the National Research Council (1960). A level of 0.6% for both calcium and total phosphorus was found to be adequate for optimum growth of turkeys from 8-20 weeks. Even lower levels were adequate when a 1:1 ratio of calcium to phosphorus was maintained. Sullivan (1962) has essentially confirmed these results. Wilcox et al. (1961) reported that Broad Breasted Bronze male turkeys require at least 0.8% total phosphorus 1 Scientific Paper No. 2231. Washington Agricultural Experiment Stations, Pullman.

from 6-20 weeks of age and at least 0.6% total phosphorus after 20 weeks of age, but females require only 0.6% total phosphorus. Experiment 1 of the present report was designed to study the effect of the calcium and phosphorus intake during the early growing period on the performance of turkeys from 8-20 weeks of age fed a diet containing 0.6% calcium and 0.6% total phosphorus. Experiment 2 was designed to study the availability of plant phosphorus for growing turkeys and to study further the minimum calcium and phosphorus requirements for growing turkeys. Experiment 1. Six hundred day-old unsexed Broad Breasted Bronze (BBB) turkeys were distributed into 60 groups of 10 poults each. Four groups were randomly assigned to each of 15 diets. They were reared the first 4 weeks in wire-floored, electrically-heated batteries in an airconditioned room. At 4 weeks of age the 4 groups on each diet were consolidated into 2 groups and transferred to concrete floored pens, having wood shavings as litter. At 8 weeks of age, the turkeys were placed together on a sparse alfalfa range where they were maintained for 12 weeks. The poults were supplied feed and water ad libitum. Composition of basal diets is given in Table 1. The basal diet from 0-8 weeks was calculated to contain .23% inorganic

579

580

F. E. NELSON, L. S. JENSEN AND J. MCGINNIS

TABLE 1.—Percentage composition of basal diets 0-8 weeks

Ingredients

48.59 Ground yellow corn Soybean oil meal (50% protein) 40.00 Dehydrated alfalfa meal (17% protein) 2.50 Dried whole whey 2.00 Fish meal, herring (72% protein) 5.00 Salt .50 Calcium carbonate .53 Dicalcium phosphate .38 Premix .501

8-14 weeks

14-20 weeks

66.64

76.64

28.00

18.00

2.50

2.50

—

—

—

—

.50 .48 1.38 .502

.50 .48 1.38 .502

1 Supplies the following per pound of diet: bacitracin, 5 mg.; vitamin A, 2,400 I.U.; vitamin D3, 1,000 I.C.U.; riboflavin, 1.7 mg.; pantothenic acid, 5 mg.; choline, 300 mg.; niacin, 10 mg.; manganese, 50 mg.; zinc, 23 mg.; and sulfaquinoxaline, 200 mg. 2 Supplies the following per pound of diet: bacitracin, 5 mg.; vitamin A, 2,000 I.U.; vitamin D 3 , 800 I.C.U.; riboflavin, 1 mg.; zinc, 23 mg.; manganese, 50 mg.; and 4-nitrophenylarsonic acid, 58 mg.

phosphorus and .37% plant phosphorus. A commercial grade of dicalcium phosphate and ground limestone was used to

adjust the level of calcium and phosphorus in the diets for the first 8 weeks. These supplements were added at the expense of corn. From 8 to 20 weeks, all the turkey were fed a diet calculated to contain 0.6% calcium and 0.6% total phosphorus. Levels of calcium and phosphorus used during the first 8 weeks are given in Table 2. Body weight gain was measured at 13 days, 4, 8, and 20 weeks of age. Feed efficiency was calculated at 4 and 8 weeks of age. The third, fourth, and distal phalanges of the fourth digit of the left foot, of the fourth digit of the right foot, and of the second digit of the left foot were removed from all turkeys at 4, 8 and 20 weeks, respectively. Toe ash content was determined by the method of Evans and Carver (1944). The data were analyzed using multiple F tests as described by Duncan (1955). Results on gain and feed efficiency from

TABLE 2.—Effect of different levels of calcium and phosphorus on gain and feed efficiency of poults from 0-8 weeks of age Diet

0-4 week

Ca Calc.

%

.60 .70 .80 .90 1.00 .90 1.05 1.20 1.35 1.50 1.20 1.40 1.60 1.80 2.00

P Det.

%

2

.64 .72 .84 .86 1.00 .94 1.05 1.27 1.39 1.53 1.32 1.44 1.60 1.74 2.00

Calc.

%

.6 .7 .8 .9 1.0 .6 .7 .8 .9 1.0 .6 .7 .8 .9 1.0

Det.

%

2

.60 .70 .75 .83 .87 .52 .73 .80 .83 .88 .53 .67 .76 .80 1.02

13 day gain

1

4-8 week Feed

Gain

Feed Gain

Gain gm. 179 abc 177 abc 190 c 177 abc 182 be 172 ab 186 be 185 be 181 be 185 be 166 a 189 c 181 be 179 abc 190 c

gm. 510 ab 547 cd 575 cd 541 be 566 cd 504 a 576 cd 566 cd 552 cd 577 cd 480 a 568 cd 562 cd 549 cd 582 d

% 1.75 ab 1.67 be 1.64c 1.65 be 1.68 be 1.75 ab 1.67 be 1.65 be 1.66 be 1.65 be 1.83 a 1.71 be 1.67 be 1.65 be 1.71 be

gam gm. 1213 ab 1288 abc 1353 bed 1301 abc 1345 abed 1296 abc 1501 d 1330 abc 1366 bed 1404 cd 1190 a 1406 cd 1430 cd 1307 abc 1410 cd

% 2.08 2.01 1.97 2.03 2.00 1.97 2.OS 1.97 2.01 2.00 2.02 2.00 2.11 2.02 1.99

1 Letters to the right of the data indicate significance at the 5% level of probability (Duncan, 1955). Values with the same letter are not significantly different from each other at the level of probability indicated. 2 Determined by A.O.A.C. method (1955).

CALCIUM AND PHOSPHORUS REQUIREMENTS

0-8 weeks are present in Table 2. There were no significant differences in weight at 13 days of age, but at 4 weeks the bird fed the lowest level of phosphorus (0.6%) with the two higher levels of calcium were significantly lower in body weight (P<.05) than for poults fed all other phosphorus levels. Reducing the calcium level at 0.6% phosphorus level increased weight gains at 4 weeks of age. Turkeys fed the 0.6 and 1.2% calcium in combination with 0.6% phosphorus showed a reduced gain for the 4-8 week period. Birds fed 0.6% phosphorus diets required more feed to produce a pound of gain during the first 4 weeks, but there were no significant differences in feed utilization during the 4-8 week period. Evidence of rickets was first observed at 15 days of age in poults fed the 1.2% calcium and 0.6% phosphorus diet, at 17 days in poults fed the 0.9% calcium and 0.6% phosphorus diet, and at 19 days in poults fed the 0.6% calcium and 0.6% phosphorus diet. Rickets did not develop in poults fed the other diets, and after four weeks of age the symptoms of rickets became less severe in the affected poults. Sticking of excreta to some of the screens in the batteries was noticed on the 10th day. Each screen was scored for degree of adherence of droppings at 19 and 28 days of age (Table 3). Screens were scored on the basis of 0 to 5 with the higher number indicating a greater severity of the condition. Results show that the condition was correlated with calcium: phosphorus ratio and that the condition was much less severe as the ratio was widened. Weight gain for the 8-20 week period is shown in Table 4. Even though statistically significant differences were not obtained, the lowest gains were made by male turkeys fed the 0.6% and 0.7% phosphorus diets from 0-8 weeks of age.

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TABLE 3.—Effect of calcium and phosphorus levels on adherence of excreta to the screens1 <-y

Ca (%)

P(%)

0.6 0.7 0.8 0.9 1.0 0.9 1.05 1.20 1.35 1.50 1.2 1.4 1.6 1.8 2.0

0.6 0.7 0.8 0.9 1.0 0.6 0.7 0.8 0.9 1.0 0.6 0.7 0.8 0.9 1.0

19 day av. score

28 day av. score

4.8 3.5 4.3 2.8 4.3 4.0 1.8 3.5 0.8 1.0 2.3 1.8 0.8 0.8 0.5

5.0 4.2 4.0 2.8 4.0 3.5 1.8 1.0 0.2 0.0 0.8 0.8 0.0 0.0 0.0

1 Screens were scored on the basis of 0 to 5, with 0 denoting no adhering of excreta and 5 maximum adherenace of excreta.

The calcium and phosphorus levels fed from 0-8 weeks of age had no apparent effect on gains of female turkeys. Percentage toe ash of the poults at 4 and 8 weeks increased as the level of both calcium and phosphorus was increased in the diet (Table 5). At the lower levels of TABLE 4.—Weight gain of developing turkeys fed different levels of calcium and phosphorus during the first 8 weeks1 Diet—0-8 weeks

Gain—8-20 weeks

Ca

P

Female

%

%

.6 .7 .8 .9 1.0 .9 1.05 1.20 1.35 1.50 1.20 1.40 1.60 1.80 2.0

.6 .7 .8 .9 1.0 .6 .7 .8 .9 1.0 .6 .7 .8 .9 1.0

gm. 3,709 3,545 3,772 3,891 3,403 3,313 3,664 3,784 3,615 3,525 3,528 3,651 3,772 3,891 3,877

Male gm. 4,734 4,982 5,631 5,506 5,319 5,062 5,050 5,461 5,347 5,280 4,794 5,245 5,460 5,533 5,212

Sex av. gm. 4,222 4,263 4,702 4,699 4,291 4,181 4,357 4,622 4,481 4,402 4,162 4,448 4,616 4,712 4,545

1 All birds were fed the same diet containing 0.6% calcium and 0.6% phosphorus after 8 weeks.

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F. E. N E L S O N , L. S. J E N S E N AND J.

TABLE 5.—Percent toe ash oj birds Jed different calcium and phosphorus levels, Experiment 1 Diet to 8 weeks P

%

%

%

%

.6 .7 .8 .9 1.0 .6 .7 .8 .9 1.0 .6 .7 .8 .9 1.0

11.56 11.66 12.41 13.04 12.59 9.65 12.19 12.91 13.04 13.31 9.00 11.42 13.05 13.44 13.97

12.36 12.52 13.73 14.10 14.25 12.24 13.96 14.52 14.76 14.81 11.67 13.36 14.74 14.81 15.32

.6 .7 .8 .9 1.0 .9 1.05 1.20 1.35 1.50 1.2 1.4 1.6 1.8 2.0

Experiment 2. Three hundred thirty-six male turkeys, 8 weeks of age, were distributed into 24 pens of 14 each. These groups were placed in a pole house on dirt floors with wheat straw and wood shavings as litter. For the first 8 weeks the birds were fed a diet calculated to contain 2 % calcium, 1 % phosphorus, 2 8 % protein and 785 Calories of productive energy per pound. Each of six experimental diets was fed to four pens of 14 male turkeys.

Toe ash

Ca

4 weeks

20 weeks1

8 weeks

MCGINNIS

% 19.26 19.68 19.49 19.56 19.63 19.28 19.48 19.90 19.75 19.45 19.32 19.37 19.84 19.62 19.94

Composition of the diets fed from 8 to 14 and 14 to 20 weeks is presented in Table 6. The diets were calculated to be approximately isocaloric and isonitrogenous. Protein level was adjusted to approximately 16% for the 15-20 week period. A commercial grade of dicalcium phosphate and ground limestone was used to adjust the levels of calcium and phosphorus in the diets. Measurements of gain in body weight and feed efficiency were made at 12, 16 and 20 weeks. Toe ash was determined at 12, 16 and 20 weeks, as described in experiment 1.

1 All birds birds were fed the same diet containing 0.6% phosphorus and 0.6% calcium from 8-20 weeks.

phosphorus, the toe ash was lower when the ratio of phosphorus to calcium was wider, and poults fed diets containing 0 . 6 % phosphorus in combination with either 0.9 or 1.2% calcium showed the greatest increase in toe ash between 4 and 8 weeks of age. This observation is in agreement with the decreased severity of rickets in these birds during this time.

Results of gain, feed efficiency and toe ash are shown in Table 7. The lowest level of phosphorus (0.35%) was inadequate for growth, feed utilization and toe ash of

TABLE 6.—Percent composition oj diets used in experiment 2 8-15 weeks

15-20 weeks

Ingredients Dehydrated alfalfa meal (17% protein) Ground yellow corn Soybean oil meal (50% protein) Salt Wheat bran Tallow Limestone Dicalcium phosphate Premix 1 Analysis Calcium (calculated) % Calcium (determined) 2 Phosphorus (calculated) % Phosphorus (determined) % Protein (calculated) % Calories Productive Energy (calc.) 1

1

2

3

4

5

6

1

2

3

4

5

6

2.50 67.90

2.50 67.50

2.50 48.80

2.50 67.23

2.50 48.01

2.50 65.95

2.50 71.90

2.50 77.50

2.50 58.51

2.50 77.15

2.50 58.00

2.50 75.95

28.00 0.50

28.00 0.50

28.00 0.50

18.00 0.50

18.00 0.50

0.50

—

.75 0.50

1.90 0.50

— — .60 — 0.50

— — — 0.50

0.50

—

.75 0.50

16.75 0.50 15.00 5.25 .88 .61 0.50

18.25 0.50

— — .40

16.75 0.50 15.00 5.00 .94

18.00 0.50

— — — 0.50

26.75 0.50 15.00 5.25 .88 .61 0.50

28.25 0.50

— — .60 — 0.50

26.75 0.50 15.00 5.00 .95

1.00

— — .52

1.00

— — .52

— — .40 1.90 0.50

.35 .30 .35 .38 20.19

.50 .52 .35 .41 20.16

.49 .50 .49 .45 20.21

.49 .50 .49 .49 20.14

.60 .61 .60 .60 20.14

.70 .69 .70 .77 20.20

.35 .31 .35 .35 16.09

.50 .47 .35 .35 16.06

.49 .47 .49 .46 16.11

.49 .50 .49 .50 16.04

.60 .62 .60 .55 16.04

.70 .70 .70 .71 16.10

968

965

959

961

957

956

1,018

1,015

1,009

1,011

1,007

1,006

Supplies the following per pound of diet: bacitracin, 5 mg.; riboflavin, 1 mg.; vitamin A, 2,000 I.U.; vitamin D3, 800 I.C.U.; zinc, 23 mg.; and manganese, 50 mg. 2 Determined by A.O.A.C. method (1955).

CALCIUM AND P H O S P H O R U S R E Q U I R E M E N T S

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TABLE 7.—Effect of different levels of calcium and phosphorus on gain, feed efficiency and toe ash of male turkeys from 8 to 20 weeks {Experiment 2)1 Diets 1

2

3

4

5

6

.35 .35 .35

.50 .35 .35

-

—

.49 .49 .49 —

.49 .49 .35 .14

.60 .60 .49 .11

.70 .70 .35 .35

A v. period or age (weeks) 8-12 12-16 16-20 8-20

1,911 2,094ab 2,063b 6,068b

1,867 1,954a 1,800a 5,621a

2,014 2,243bcd 2,386c 6,643c

1,917 2,360d 2,228b 6,505c

8-12 12-16 16-20 8-20

2.53 3.16ab 4.37ab 3.38ab

2.54 3.27a 4.67a 3.48a

2.48 3.08bc 4.07c 3.25b

2.59 2.94c 4.20c 3.29b

12.39ab 12.97ab M5.22

12.09a 11.69a al3.51

13.13bc 13.85bc cl6.50

13.96c 14.49c cl6.87

Calcium — % Total phosphorus, % Plant phosphorus, % Inorganic phosphorus, %

12 16 20

Average gain (gm.) 1,982 1,885 2,271cd 2,184bc 2,278bc 2,159b 6,531c 6,253b Feed/gain 2.55 2.54 3.00abc 3.11abc 4.23bc 4.24bc 3.28b 3.32b Toe Ash (%) 13.51c 13.53c 14.49bc 14.63c cl6.47 cl6.35

1 Letters to left and right of data indicate significance at the 1% and 5% level of probability, respectively (Duncan, 1955). Values with the same letter in the same row are not significantly different from each other at the level of probability indicated.

developing turkeys. However, the birds fed the diet containing 0.49% plant phosphorus had gains, feed utilization and toe ash equivalent to birds receiving the same or higher levels of phosphorus with part Of it being inorganic phosphorus. Leg weakness of the type often observed in male turkeys as they approached maturity did not develop in this experiment. DISCUSSION Results from experiment 1 showed t h a t 0.7% total phosphorus and 0.7% calcium were adequate for maximal growth of turkeys from 0-8 weeks of age. These results agree with Formica et al. (1961) who reported t h a t 0.65% phosphorus and 0.80% calcium were adequate for growth and normal bone ash. Although the toe ash in the present study continued to increase with higher levels of phosphorus,

rickets did not occur in poults which were fed as little as 0.7% phosphorus from 0-8 weeks and 0.6% phosphorus from 8-20 weeks. The improvement of the ricketic condition of the birds fed the 0 . 6 % phosphorus diet after 4 weeks may have been due to additional phosphorus intake from the litter. Singsen et al. (1962) showed t h a t phosphorus built up in litter of laying hens. The N R C (1960) recommendation of 2.0% calcium and 1.0% phosphorus (0.5% inorganic) for turkey poults from 0-8 weeks of age appears to be in excess of the minimum requirements when d a t a other than bone ash are considered. I t appears t h a t turkeys from 0-8 weeks of age require a minimum of 0 . 7 % total phosphorus (0.35% inorganic phosphorus) and 0.7% calcium for maximum weight gains. A level of 0 . 8 % of both minerals

584

F. E. N E L S O N , L. S. J E N S E N AND J.

would allow for slight excesses and greater bone deposition. Gains of female turkeys from 8-20 weeks were affected little by different levels of phosphorus and calcium fed during the first 8 weeks, but the gain of male turkeys fed 0.6% phosphorus was lowest. These lower gains may be related to the rachitic condition of these poults during the first 4 weeks of age. Toe ash of 20 week old turkeys was not influenced by the 0-8 week treatments. In this experiment the toe ash was 3 % higher than the values obtained in experiment 2 and in previous experiments (Nelson et al., 1961). This may be related to environment, as these birds were reared on range whereas the other birds with lower toe ash were reared in confinement. Results from experiment 2 suggest t h a t the phosphorus requirement for turkeys from 8-20 weeks can be supplied by phosphorus of plant origin. The diet containing 0.49% calcium and 0.49% phosphorus from plant sources gave equal or better growth, feed utilization and toe ash t h a n diets containing from 0.11 to 0.35% added inorganic phosphorus. These results suggest t h a t older turkeys can utilize plant phosphorus more efficiently t h a n young •poults. However, the apparent greater utilization of plant phosphorus may have been caused by re-ingestion of phosphorus from the excreta. Singsen et al. (1962) showed t h a t the phosphorus requirement of the laying hen on litter was less t h a n that in cages and suggested that the litter supplied part of the phosphorus requirement. SUMMARY

Experiments were conducted to s t u d y the effect of calcium and phosphorus intake during the early growing period on the performance of turkeys from 8-20 weeks of age and also to study the avail-

MCGINNIS

ability of plant phosphorus for growing turkeys. Levels of 0.7% calcium and 0.7% total phosphorus were adequate for maximal growth and feed utilization of turkey poults from 0-8 weeks, but not for maximal toe ash. Between 8 and 20 weeks of age a diet containing 0.6% calcium and 0.6% total phosphorus was adequate for growth and bone calcification, providing the calcium and phosphorus levels fed from 0-8 weeks were adequate for maximum growth. Results obtained in a second experiment showed t h a t the entire phosphorus requirement of turkeys (maintained on litter) between 8 and 20 weeks of age can be met with phosphorus contained in plant ingredients. No difference in body weight gains, feed efficiency or toe ash was found in turkeys at 20 weeks of age fed a diet containing 0.49% calcium and 0.49% phosphorus (all plant) and diets containing higher levels of these minerals. A diet containing 0.35% phosphorus (all plant) with 0.35% or 0.50% calcium did not support maximum growth or bone calcification between 8 and 20 weeks of age. REFERENCES Almquist, H. J., 1954. The phosphorus requirement of young chicks and poults. A review. Poultry Sci. 33:936-944. Association of Official Agricultural Chemists, 1955. Methods of Analysis. Eighth Edition. Blaylock, L. G., L. H. Neagle and C. F. LeFerre, 1961. Studies on the calcium and phosphorus requirements of growing turkeys. Poultry Sci. 40: 1381. Duncan, D. B., 1955. Multiple range and multiple F tests. Biom. 2: 1-42. Evans, R. S., and J. S. Carver, 1944. The toe ash as a measure of calcification in chicks. Poultry Sci. 23:351-352. Formica, S. O., M. S. Smidt, M. M. Bacharach, W. F. Davis and J. C. Fritz, 1961. Calcium and phosphorus requirements of growing turkeys and chickens. Poultry Sci. 40:1403. Nelson, F. E., L. S. Jensen and J. McGinnis, 1961.

CALCIUM AND P H O S P H O R U S R E Q U I R E M E N T S

Requirement of developing turkeys for calcium and phosphorus. Poultry Sci. 40: 407-111. National Research Council, 1960. Nutrient requirements of domestic animals. I. Nutrient requirements for poultry. Singsen, E. P., A. H. Spandorf, L. D. Matterson, J. A. Serafin and J. J. Tlustohowicz, 1962. Phosphorus in the nutrition of the adult hen. 1. Minimum phosphorus requirements. Poultry Sci. 41: 1401-1414. Sullivan, T. W., 1962. Studies on the calcium and

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phosphorus requirements of turkeys, 8 to 20 weeks of age. Poultry Sci. 41: 2S3-259. Wilcox, R. A., C. W. Carlson and W. Kohlmeyer, 1961. Effects of phosphorus supplementation on growing turkeys as measured by body weight and toe ash. Poultry Sci. 40: 1533-1536. Wilcox, R. W., C. W. Carlson, W. Kohlmeyer and G. F. Gostler, 1953. Calcium and phosphorus requirements of poults fed purified diets. Poultry Sci. 32: 1030-1035.

Studies on the Effect of l,2-Dimethyl-5-Nitroimidazole on Growth and Reproduction in Turkeys and Its Residual Concentration in Tissue4 H. B. C O N D R E N , 1 R. E. D A V I E S , 2 C. W. D E Y O E , 3 M. A. ZAVALA, C. R. C R E G E R AND J. R.

COUCH

Departments of Poultry Science and Biochemistry and Nutrition, A & M College of Texas, College Station, Texas (Received for publication June 15, 1962) f

I V HE infectious disease originating in •*• the ceca of poultry, and caused by the protozoal flagellate Histomonas meleagridis is known by various names: histomoniasis, infectious enterohepatitis, and blackhead. I t is described as being a subacute or chronic infectious disease with the principal lesions confined to the ceca and liver and is primarily a disease of turkeys. According to Barger et al. (1958) it is one of the most destructive infectious diseases to which turkeys are susceptible and is responsible for large losses in the turkey industry. Grumbles et al. (1952a) investigated the use of E n h e p t i n - P for the prevention Present addresses: John Sealy Hospital, Galveston, Texas. 2 The Skin and Cancer Hospital, Temple University School of Medicine, 804, Pine St, Philadelphia, Pa. 3 Dept. of Flour and Feed Milling, Kansas State University, Manhattan, Kansas. 4 This is a contribution of the Texas Agricultural Experiment Station. 1

and treatment of histomoniasis, and its effect on egg production, fertility and hatchability of turkey eggs. These workers found t h a t continuous feeding of this drug was effective in preventing mortality from blackhead, but it appeared to have little value when medication was started after the disease had appeared in the flock. The 0 . 1 % level of the drug showed some toxic effects of the birds and reduced egg production, fertility, and hatchability. Birds which received Enheptin-T, on the other hand, did not show toxic effects nor a reduction in egg production, fertility, or hatchability. Horton-Smith and Long (1956) investigated furazolidone [N-(5-nitro-2-furfurylidene) -3-amino-2-oxazolidone] for its prophylactic and therapeutic properties on blackhead. I t was found to be almost totally effective in preventing blackhead induced by feeding Heterakis ova when continuous medication was begun before the ova were administered. T h e y sug-