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Poisoning of Turkey Poults from Whorled Milkweed (Asclepias galioides)
Poisoning of Turkey Poults from Whorled Milkweed [Asclepias galioides) GEO. W.
STILES
(Presented at annual meeting August, 1941; received for publication September 15, 1941)
A
INTRODUCTION REVIEW of the literature on milk-
state that chickens may be poisoned by milkweeds but no specific instances are
weed poisoning shows that various cited, species of this plant are known to be toxic HISTORY OF POISONING IN TURKEY for horses, cattle, sheep, goats (Durrell POULTS FROM MILKWEED and Newsom, 1939; Fleming and Peterson, i n southern Colorado, between Florence 1920; Gates, 1930; Marsh, Clawson, and and Canon City, during the spring of 1941, Couch, 1920; and Muenscher, 1939), and a turkey raiser turned a few early henin a few instances for chickens. However, hatched poults, three weeks old, into a no references to the poisoning of turkeys small yard where young milkweed plants by milkweed have come to the writer's w e re growing. The tender milkweed shoots attention. grew inside the pen along the fence adjoinThe earliest record of suspected poison- frig a larger patch just outside, and the ing in chickens is given by Pammel (1917), poults were seen eating them. Soon afterwho reported the loss of about 500 chicks, ward several poults had a series of fits and during one season, which fed on young died within a few hours. The yard was sprouts of Asclepiadacae in the state of supposedly freed from the noxious weed, New Hampshire. In this instance the with a hoe, and the incident was forgotten, owner suspected the milkweed of killing ' A short time later a commercial lot of her chicks and they stopped dying when 500 poults, also about three weeks old, in removed from the plant-infested yard, which mortality prior to that time had Laboratory investigations were not made to been only 2 percent, was turned into the prove the contention that milkweed caused same yard about 9:00 o'clock in the mornthe death loss. ing. This flock of poults had not received In California, observations by Campbell any green food for several days, and con(1931) show that Asclepias mexicana ap- sequently when turned into the yard, they peared to be the definite cause of losses were hungry for any tempting greens in among chickens which had eaten the sight. Within about one and a half hours young shoots of the plant. Feeding experi- approximately 10 percent of the flock were ments on mature fowls proved the toxic having spasms, and nearly all the 50 poults nature of this weed. which sickened on milkweed died within a In their bulletin on poisonous plants in few hours. When this second lot of poults Colorado, Durrell and Newsom (1939) began to show symptoms identical with the [263]
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Bacteriologist in Charge, Branch Pathological Laboratory, Bureau of Animal Industry, U. S. Department of Agriculture, Denver, Colorado
264
GEO. W. STILES
A. M.
Temperature Curve of Turkey No. 6, Table No. 1. P. M.
Fed milkweed Plant No. 2. One gram per 100 grams body weight. Died after 9 hours, 14» minutes.
first lot, the owner discovered that a second crop of young milkweed plants had grown in the yard since he had first attempted their eradication. On removal of the remainder of the turkeys from the milkweed infested yard, the losses again stopped. Attention is called to the fact that older turkey poults running at large on the premises where abundant green food, other than the milkweed, was available showed no desire to eat the poisonous plant. It was probably because no other greens were available that the poisoned poults ate the milkweed plant and died. In the same neighborhood, it was reported that another turkey raiser lost about 75 of her flock of ISO poults, which was attributed to milkweed poisoning, during the 1940 season. Also within recent years, 52 head of cattle were said to have died from eating this plant on a ranch in that vicinity. Investigations by the writer into turkey losses in the vicinity of La Junta, Colorado, in the Arkansas Valley, suggest that whorled milkweed is responsible for a con-
siderable mortality. Two specific instances are cited: (1) A flock of 200 young poults was turned out each morning and in less than an hour several began to stagger and have convulsions, resulting in the death of 10 to 15 birds daily. An experienced turkey raiser was called who watched these poults one morning after they were released from the brooder. They were seen to eat the young tender shoots of milkweed growing nearby, and shortly afterward they developed the symptoms as experienced on previous days. A loss of about 20 percent had occurred in three days. The brooder was immediately moved and further loss of this character did not occur. (2) The camp of another flock of 950 half-grown turkeys was moved to an area on the river bottom where the vegetation consisted of cottonwood trees, willows, tough salt grass, large sunflowers and cockleburs, and scattered patches of milkweed. The latter was the only succulent green plant growing there. The following morning 39 turkeys were found dead and
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D ed p : U P.M.
POISONING OF TURKEY POULTS FROM WHORLED MILKWEED
(3) Running movements of the legs and tremors of the wings and eyelids were sometimes seen. The heart action appeared unusually rapid, and when the bird was aroused during quiet periods, a new series of spasms was provoked. (4) Before death occurred, the spasms became less in number and intensity, until
SYMPTOMS OF MILKWEED POISONING
In acutely fatal cases of milkweed poisoning of turkey poults, the first symptoms usually occurred within approximately one hour after the birds ate the plant, and death came a few hours later. The type of symptoms noted may be grouped in four stages as follows: (1) The prodromal stage was ushered in by drowsiness and listlessness, slightly irregular movements, and a lack of coordination. (2) When convulsions began, the fowl lost muscular control of its legs and wings, fell backward like a pouter pigeon, lay on its side or even on its back, with wings flapping and legs trembling. These symptoms were of the clonic or intermittent type. The head was twisted and neck arched. Breathing became difficult and the bird was unable to stand. The pupils of the eyes were moderately dilated when compared with normal specimens.
milkweed, showing typical convulsions.
finally exhaustion and coma followed. Increased embarrassment of respiration, accompanied by gasping, was noted. Victims of milkweed poisoning die from respiratory paralysis. The symptoms as above noted may be less severe in cases of a milder degree of poisoning, extending over longer periods of time. The temperature chart curve is generally downward, from the normal beginning to a drop of several degrees at the expiration of the fowl. The matter of differential diagnosis by milkweed poisoning in turkeys should be considered in relation to the history of the case, lesions observed, and laboratory findings. AUTOPSY FINDINGS
The gross examination of poults which died within a few hours after being fed the
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IS were sick. The writer saw one of these sick birds a few days later and it was still staggering and lacked coordination of its legs and wings. Nearly all the sick turkeys died within a few days. The local veterinarian, owner, and other interested persons described the symptoms of the sick birds as similar to those peculiar to milkweed poisoning. Specimens of the milkweed secured from this area proved to be toxic and identical with the species of the plant known to have killed turkeys in the vicinity of Canon City, Colorado. After careful consideration of these two cases from the Arkansas Valley, and weighing of the available evidence, the circumstances suggest that in all probability these turkeys died from milkweed poisoning. With increasing attention called to the toxic nature of this milkweed, it is more than likely other cases of poisoning of turkeys will be ascribed to this weed.
265
266
GEO.
W.
milkweed showed only slight lesions. Their crops were generally distended with a small amount of gas and usually contained a considerable quantity of the poisonous plant mixed with mucus. The heart and mesenteric arterioles appeared congested. The lungs were slightly edematous. Histopathological sections of the brain, heart, liver, and kidneys did not reveal significant changes.
Immature plants were examined by members of the Denver Forest Service, United States Department of Agriculture, who tentatively classified the weed as Asclepias galioides. More mature specimens of the milkweed were submitted to W. T. Huffman, Veterinarian in Charge, Stock Poisoning Plants, Bureau of Animal Industry, who reports the plant appears to be Asclepias galioides. Specimens of the milkweed from both the Canon "City and La Junta, Colorado, areas were sent to the Bureau of Plant Industry for identification. Assistant Botanist F. R. Fosberg of that bureau makes the following report: I have looked at the specimens of Asclepias which you brought over today, collected by G. W. Stiles in Colorado, and I have compared them with considerable series of Asclepias verticillata and A. galioides. I should tentatively call them A. galioides, but must confess that the more I look at the plants of these two species the less convinced I am that they are more than weak varieties of one species. The so-called distinguishing characteristics in the hoods in the flower do not hold at all. The differences in habit are fairly conspicuous in extreme plants, but unfortunately the material from Colorado is more or less intermediate between the two in habit. There is a man out in Missouri who is working on a monograph of this genus. When this comes out, I will doubtless be in a better position to give positive identifications of these plants. For the time, all I can say is that these Colorado specimens would go into Asclepias galioides in the commonly accepted sense, but whether this species
will hold up or have to be reidentified or even reduced to variety of A. verticillata I am not at present in a position to say. I regret not being able to give a positive answer, even though the specimens are perfectly satisfactory; but, unfortunately, the state of the taxonomy of this large genus prohibits an honestly positive determination in the case of certain species.
In view of the reports from three authorities, the writer is calling this milkweed Asclepias galioides. CHEMICAL ANALYSIS OF THE MILKWEED Sample 2 of the milkweed in question was examined for selenium1 and the results indicated the presence of only a trace of this element, an insufficient amount to cause illness or death. An analysis made by the Bureau of Animal Industry in Washington, D.C., for HCN was negative. DISTRIBUTION OF MILKWEED Various species of milkweed are reported in many sections of the United States. Some are known to be highly toxic for livestock, although other species are relatively free from poisonous principles. The milkweed in question, Asclepias galioides, has a limited geographical range, being reported in western and southern Colorado, western Kansas (Gates, 1930), northern New Mexico, western and eastern Arizona, and in southern Utah. Hoffman states this plant may also be found in eastern Nevada adjacent to the Utah area. It is possible that this plant may also be found in northwest Oklahoma and the Panhandle region of Texas. This weed is reported spreading into new areas along irrigation ditches, streams, and by other mechanical means. 1
Examination made by the chemists of the U. S. Food and Drug Administration, Federal Security Agency, Denver, Colorado, and Dr. H. G. Byers of the Bureau of Plant Industry, U. S. Department of Agriculture, Washington, D.C.
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IDENTIFICATION OF THE SPECIES
STILES
POISONING OF TURKEY POULTS FROM WHORLED MILKWEED ECONOMIC IMPORTANCE OF THE MILKWEED MENACE TO THE TURKEY INDUSTRY
The poisonous plant's work is becoming more complicated as the supply of desirable feed is reduced and the poisonous species given an opportunity to spread. Most of the species of poisonous plants that have been reported for the first time during recent years have always been with us, yet were not eaten by livestock.
Dr. Huffman later reported: We made a feeding on August 4, to a sheep, of the leaves you sent us and got very definite results. The dosage was figured as 0.05 percent dry of the body weight of the sheep, which, if figured on the basis of 75 percent moisture, would be equivalent to 0.2 percent green plant. This 'would correspond very closely with the minimum lethal dose for sheep as given in Department Bulletin No. 800. This feeding was so near the lethal dose that for a time we expected the animal to die, but today it has started eating again. The symptoms corresponded with milkweed poisoning so that there appears to be very little question that this is Asdepias galioides. This milkweed, like our A. labrijormis, appears to be much more toxic during the early growth 2 Personal communication from Dr. W. T. Huffman, Veterinarian in Charge of Investigations of Stock Poisoning by Plants, Bureau of Animal Industry, Salt Lake City, Utah.
period so that the collection you made was probably at about its most toxic stage. The milkweeds all appear to lose toxicity upon drying or at maturity but the more toxic ones retain sufficient toxicity to be poisonous when cut with hay or after maturity on the range. With the A. labrijormis, we have considerable loss on the range during the winter from sheep eating the dry mature leaves.
During the marketing season of 1940, it is reported that 150,000 turkeys were sold from the Arkansas Valley of Colorado, in which region the whorled milkweed is extensively found. In a locality where the turkey industry is so important to the farm income as it is in this area, losses from milkweed poisoning contribute one more hazard, in addition to the already known ailments common to turkeys. FEEDING EXPERIMENTS IN THE LABORATORY
Feeding experiments were conducted on 13 turkey poults and 4 chickens. Some of the birds were weighed and hand-fed definite amounts of finely chopped milkweed; others were allowed to eat the plants at liberty. Three samples of the plant were used for the feeding experiment. The sample designated as Number 1 was collected June 9, soon after the occurrence of a heavy poult loss, and the stems were quite small and tender. This plant was about six inches tall at that time. Sample 2'was collected June 25 and was from 12 to 15 inches in height and beginning to bloom. The stems were of considerable size and tough. Sample 3, a more mature plant than numbers 1 and 2, was collected July 21, near La Junta, Colorado. Both the leaves and stems were finely chopped in each sample of the weed used, except in the experiment with the turkey which was fed only the dried leaves of the plant, and one pullet, which received leaves
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In regions where Asdepias galioides abounds, poisoning of turkeys may be of considerable economic importance. A practicing veterinarian in southeastern Colorado states he has observed losses in turkeys on the range during the past several years which he has attributed to whorled milkweed poisoning, and his description of the symptoms correspond to the observations of the writer in cases described in this paper. Adequate care should be exercised to prevent livestock poisoning in areas known to be infested by this plant. Sufficient wholesome green food should be provided for fowls and an effort made to eradicate toxic milkweed completely from the premises. Huffman2 says:
267
268
GEO. W. STILES
DISCUSSION Whorled milkweed, Asclepias galioides, appears to be toxic for turkeys. This state-
weed, especially the leaves of the immature plant. By studying Table 1, it will be seen that the feeding of 1 gram of the young plant to 100 grams of turkey weight, or 1 percent of the body weight, resulted in death in less than five hours. The onset of convulsions usually developed within about one hour. Smaller amounts of the milkweed caused death after a longer period. Comparing turkeys 1, 2, and 3 which were fed the young plant 1, with turkeys 6 and 7 which received the more mature weed 2, it will be observed that the younger plant appeared more toxic than the older maturing milkweed. It is known (Gates, 1930) in relation to cocklebur poisoning in swine that the two-leaf stage of the
TABLE 1.—Experimental feeding of turkeys Grams Grams No. weight weed
Time of feeding
First symptoms
Died 1:07 p.m. Died 10:32 a.m. l h r . , 4 m i n . 12:53 p.m. Died 10:43 a.m. 53 min. 2:34 p.m. Died 12:28 p.m. 2 hrs., 5 min. Several hrs. Died later Died 9:56 a.m. 56 min. 6:14 p.m. Died 1:15 p.m. 1 hr., 30 min. Several hrs. Died later Several hrs. Died later None Lived None Lived
113
1.13
9:40 a.m.
2
64
0.64
9:28 a.m.
3
735
7.35
9:50 a.m.
4 5
110 84
0.89 ?
10:23 a.m. 1:45 p.m.
6
605
6.05
9:00 a.m.
7 8
300 164
3.00 ?
11:45 a.m. 10:00 a.m.
9
261
?
10:00 a.m.
? ?
10:00 a.m. 10:00 a.m.
20?
1:50 p.m.
2:50 p.m.
lhr.
?
1:30 p.m.
4:30 p.m.
3 hrs.
12 1,000 13
Estimate 4 lbs.
Results
45 min.
1
10 11
10:25 a.m.
Time
ment results from field observations and experimental feeding. The turkeys eat the young tender shoots of the plant more readily than they eat the tougher mature weed. In the absence of other greens, turkeys may consume toxic amounts of milk-
Died 5:12 p.m. Died
Length of time
Remarks
3 hrs., 27 min. Fed plant 1 3 hrs., 25 min. Fed plant 1 4 hrs., 44 min. Fed plant 1 During night Fed plant 1 Next day Fed plant 1 9:45 a.m. 9 hrs., 14 min. Fed plant 2 During night During night
Fed plant 2 These four poults were fed a small quantity During night of plant 2 in feed. Seen to eat fragments occasionally 3 hrs., 22 min. Fed dried leaves only, plant 2 Fed plant 3 Next day
young plant is highly toxic, while the mature weed seems to be harmless. Turkeys 8 to 11, inclusive, were fed a small amount of plant 2 along with their regular feed one morning. Occasionally a bird was seen picking fragments of the
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from plant 3. The weighed milkweed was placed on a sheet of white paper or in a dish, in cases where the hand-feeding method was used, and the bird was held firmly by an attendant. A small pinch or forceps full of the weed was placed well back into the throat, followed by a few drops of water from a medicine dropper to facilitate swallowing. This was repeated until all fragments had been fed, taking care not to lose any portion of the sample. Records dated from the time of the completed feeding until the death of the victim in fatal cases.
POISONING O F T U R K E Y POULTS FROM WHORLED
269
MILKWEED
TABLE 2.—Experimental feeding of chickens Grams Grams No. weight weed
Time of feeding
First symptoms
1
63
0.63
9:25 a.m.
11:30 a.m.
2
90
0.90
9:30 a.m.
Mild
3
818
8.18
10:15 a.m.
Listless
4 1,500
15.00
9:50 a.m.
Dumpy
Time
Results
2hrs., 5min. Died next day Some hours Lived later Lived
Remarks
24hrs.,9min. Fed plant 1
6 days later
Fed plant 1, no marked spasms Fed plant 2, no marked spasms Fed plant 3
same plant developed mild symptoms, but lived. One pullet which received 1 percent of its body weight of the milkweed, number 2, failed to produce active symptoms of poisoning. Aside from listlessness and refusal to eat for a few days, no ill effects resulted, although turkey 6, Table 1, which weighed 605 grams, fed that day of the same sample and same amount per body weight, died after 9 hours and 14 minutes. It showed typical symptoms of milkweed poisoning. Another pullet fed 1 percent of plant 3 developed mild symptoms and died six days later. SUMMARY
1. Field observations in southern Colorado (supplemented by feeding experiments, indicate whorled milkweed (Asclepias galioides) is toxic for turkeys. 2. Young turkeys fed 1 gram of milkweed per 100 grams of turkey weight produced spasms within about one hour and, usually, death in less than five hours after feeding. Immature, tender plants appeared more toxic than more mature weeds. 3. Whorled milkweed is found in southern Colorado, southwestern Kansas, northern New Mexico and Arizona, southern Utah, and possibly in southeastern Nevada, in northwestern Oklahoma, and the Panhandle of Texas. 4. The economic importance pertaining to losses in turkeys from eating poisonous milkweed may be a serious factor in localities where this plant thrives abundantly.
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plant out of the mash and eating it. Two of the four three-week-old poults showed convulsions during the afternoon of the day they received this mixture and died that night. The other two poults survived. There was no definite evidence that all four poults actually ate the plant. In the case of turkey 12, special attention is noted that this fowl was fed only the dried leaves of plant 2. Although the intention had been to give this turkey 2 percent of its weight, or 20 grams of the milkweed, a small quantity of the dried leaves was lost duing the process of feeding. The feeding was completed at 1:50 P.M. and the first convulsions developed one hour later. The usual symptoms of milkweed poisoning followed. (Observe the photograph showing spasms.) This bird died 3 hours and 22 minutes after feeding. From the crop of the dead turkey was recovered 5.5 grams of the substance fed; from the gizzard 13.2 grams, or a total of 18.7 grams from a possible 20 grams of the dried plant intended for feeding. The experiment would indicate the dried weed retained a large percent of its toxic principle. In comparing the toxicity of milkweed for turkeys and chickens, the limited number of experiments show that chickens are less susceptible to the poisonous principle of the plant than are turkeys. One of the chickens, number 1, Table 2, fed experimentally, died 24 hours after it had been fed 1 percent of the plant per body weight. A second chick fed a similar amount of the
Died
Length of time
270
GEO. W. STILES
5. E v e r y effort s h o u l d b e m a d e to p r o -
and
the
broad-leaved
or
showy
milkweed
(Asclepias spedosa); plants poisonous to Nevada N e v a d a A " s™^"™1 Experiment Station -Bulletin No. 99. _ . , , , - . „ , „ „ . . , . , t
REFERENCES Campbell, Harvey W., 1931. The whorled milkweed as a poisonous plant for poultry. The Monthly Bulletin, California Department of Agriculture August Durrell, L. W., and I. E. Newsom, 1939. Colorado's poisonous and injurious plants. Colorado Agricultural Experiment Station Bulletin No. 455. Fleming, C. E., and N. F. Peterson, 1920. The narrow-leaved milkweed (Asclepias mcxicana)
Gates, Frank C , 1930. Principal poisonous plants m Kansas. Kansas Agricultural Experiment Station Technical Bulletin No. 25. Marsh > c - Dwight, A. B. Clawson, and J. F. Couch > 1 9 2 ° - The whorled milkweed (Asdepias galioides) as a poisonous plant. U.S.D.A. Bulletin No - 80°Muenscher, Walter Conrad, 1939. Poisonous plants of the United States. Macmillan Company. Pammel, L. H., 1917. Milkweed poisonous to chickens. Journal of the American Veterinary Medical Association 12:235.
Errata THE PANTOTHENIC ACID REQUIREMENT OF CHICKS J. C. BAUEENFEIND, L. C. NOERIS AND G. F. HEUSEE POULTRY SCIENCE, March, 1942, Pages 142-146
PAGE 143 in Table 1, describing the O Nbasal diet, the decimal point for the vitamin percentages should be placed two places to the left. The table should read as follows:
Percent Riboflavin .'..' Nicotinic acid Thiamin
.0.000325 0.000300 0.000150
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vide wholesome green feed for turkeys and to eradicate the deadly milkweed from , . J. , premises known to be infested.
STILES
(Presented at annual meeting August, 1941; received for publication September 15, 1941)
A
INTRODUCTION REVIEW of the literature on milk-
state that chickens may be poisoned by milkweeds but no specific instances are
weed poisoning shows that various cited, species of this plant are known to be toxic HISTORY OF POISONING IN TURKEY for horses, cattle, sheep, goats (Durrell POULTS FROM MILKWEED and Newsom, 1939; Fleming and Peterson, i n southern Colorado, between Florence 1920; Gates, 1930; Marsh, Clawson, and and Canon City, during the spring of 1941, Couch, 1920; and Muenscher, 1939), and a turkey raiser turned a few early henin a few instances for chickens. However, hatched poults, three weeks old, into a no references to the poisoning of turkeys small yard where young milkweed plants by milkweed have come to the writer's w e re growing. The tender milkweed shoots attention. grew inside the pen along the fence adjoinThe earliest record of suspected poison- frig a larger patch just outside, and the ing in chickens is given by Pammel (1917), poults were seen eating them. Soon afterwho reported the loss of about 500 chicks, ward several poults had a series of fits and during one season, which fed on young died within a few hours. The yard was sprouts of Asclepiadacae in the state of supposedly freed from the noxious weed, New Hampshire. In this instance the with a hoe, and the incident was forgotten, owner suspected the milkweed of killing ' A short time later a commercial lot of her chicks and they stopped dying when 500 poults, also about three weeks old, in removed from the plant-infested yard, which mortality prior to that time had Laboratory investigations were not made to been only 2 percent, was turned into the prove the contention that milkweed caused same yard about 9:00 o'clock in the mornthe death loss. ing. This flock of poults had not received In California, observations by Campbell any green food for several days, and con(1931) show that Asclepias mexicana ap- sequently when turned into the yard, they peared to be the definite cause of losses were hungry for any tempting greens in among chickens which had eaten the sight. Within about one and a half hours young shoots of the plant. Feeding experi- approximately 10 percent of the flock were ments on mature fowls proved the toxic having spasms, and nearly all the 50 poults nature of this weed. which sickened on milkweed died within a In their bulletin on poisonous plants in few hours. When this second lot of poults Colorado, Durrell and Newsom (1939) began to show symptoms identical with the [263]
Downloaded from http://ps.oxfordjournals.org/ at East Tennessee State University on May 26, 2015
Bacteriologist in Charge, Branch Pathological Laboratory, Bureau of Animal Industry, U. S. Department of Agriculture, Denver, Colorado
264
GEO. W. STILES
A. M.
Temperature Curve of Turkey No. 6, Table No. 1. P. M.
Fed milkweed Plant No. 2. One gram per 100 grams body weight. Died after 9 hours, 14» minutes.
first lot, the owner discovered that a second crop of young milkweed plants had grown in the yard since he had first attempted their eradication. On removal of the remainder of the turkeys from the milkweed infested yard, the losses again stopped. Attention is called to the fact that older turkey poults running at large on the premises where abundant green food, other than the milkweed, was available showed no desire to eat the poisonous plant. It was probably because no other greens were available that the poisoned poults ate the milkweed plant and died. In the same neighborhood, it was reported that another turkey raiser lost about 75 of her flock of ISO poults, which was attributed to milkweed poisoning, during the 1940 season. Also within recent years, 52 head of cattle were said to have died from eating this plant on a ranch in that vicinity. Investigations by the writer into turkey losses in the vicinity of La Junta, Colorado, in the Arkansas Valley, suggest that whorled milkweed is responsible for a con-
siderable mortality. Two specific instances are cited: (1) A flock of 200 young poults was turned out each morning and in less than an hour several began to stagger and have convulsions, resulting in the death of 10 to 15 birds daily. An experienced turkey raiser was called who watched these poults one morning after they were released from the brooder. They were seen to eat the young tender shoots of milkweed growing nearby, and shortly afterward they developed the symptoms as experienced on previous days. A loss of about 20 percent had occurred in three days. The brooder was immediately moved and further loss of this character did not occur. (2) The camp of another flock of 950 half-grown turkeys was moved to an area on the river bottom where the vegetation consisted of cottonwood trees, willows, tough salt grass, large sunflowers and cockleburs, and scattered patches of milkweed. The latter was the only succulent green plant growing there. The following morning 39 turkeys were found dead and
Downloaded from http://ps.oxfordjournals.org/ at East Tennessee State University on May 26, 2015
D ed p : U P.M.
POISONING OF TURKEY POULTS FROM WHORLED MILKWEED
(3) Running movements of the legs and tremors of the wings and eyelids were sometimes seen. The heart action appeared unusually rapid, and when the bird was aroused during quiet periods, a new series of spasms was provoked. (4) Before death occurred, the spasms became less in number and intensity, until
SYMPTOMS OF MILKWEED POISONING
In acutely fatal cases of milkweed poisoning of turkey poults, the first symptoms usually occurred within approximately one hour after the birds ate the plant, and death came a few hours later. The type of symptoms noted may be grouped in four stages as follows: (1) The prodromal stage was ushered in by drowsiness and listlessness, slightly irregular movements, and a lack of coordination. (2) When convulsions began, the fowl lost muscular control of its legs and wings, fell backward like a pouter pigeon, lay on its side or even on its back, with wings flapping and legs trembling. These symptoms were of the clonic or intermittent type. The head was twisted and neck arched. Breathing became difficult and the bird was unable to stand. The pupils of the eyes were moderately dilated when compared with normal specimens.
milkweed, showing typical convulsions.
finally exhaustion and coma followed. Increased embarrassment of respiration, accompanied by gasping, was noted. Victims of milkweed poisoning die from respiratory paralysis. The symptoms as above noted may be less severe in cases of a milder degree of poisoning, extending over longer periods of time. The temperature chart curve is generally downward, from the normal beginning to a drop of several degrees at the expiration of the fowl. The matter of differential diagnosis by milkweed poisoning in turkeys should be considered in relation to the history of the case, lesions observed, and laboratory findings. AUTOPSY FINDINGS
The gross examination of poults which died within a few hours after being fed the
Downloaded from http://ps.oxfordjournals.org/ at East Tennessee State University on May 26, 2015
IS were sick. The writer saw one of these sick birds a few days later and it was still staggering and lacked coordination of its legs and wings. Nearly all the sick turkeys died within a few days. The local veterinarian, owner, and other interested persons described the symptoms of the sick birds as similar to those peculiar to milkweed poisoning. Specimens of the milkweed secured from this area proved to be toxic and identical with the species of the plant known to have killed turkeys in the vicinity of Canon City, Colorado. After careful consideration of these two cases from the Arkansas Valley, and weighing of the available evidence, the circumstances suggest that in all probability these turkeys died from milkweed poisoning. With increasing attention called to the toxic nature of this milkweed, it is more than likely other cases of poisoning of turkeys will be ascribed to this weed.
265
266
GEO.
W.
milkweed showed only slight lesions. Their crops were generally distended with a small amount of gas and usually contained a considerable quantity of the poisonous plant mixed with mucus. The heart and mesenteric arterioles appeared congested. The lungs were slightly edematous. Histopathological sections of the brain, heart, liver, and kidneys did not reveal significant changes.
Immature plants were examined by members of the Denver Forest Service, United States Department of Agriculture, who tentatively classified the weed as Asclepias galioides. More mature specimens of the milkweed were submitted to W. T. Huffman, Veterinarian in Charge, Stock Poisoning Plants, Bureau of Animal Industry, who reports the plant appears to be Asclepias galioides. Specimens of the milkweed from both the Canon "City and La Junta, Colorado, areas were sent to the Bureau of Plant Industry for identification. Assistant Botanist F. R. Fosberg of that bureau makes the following report: I have looked at the specimens of Asclepias which you brought over today, collected by G. W. Stiles in Colorado, and I have compared them with considerable series of Asclepias verticillata and A. galioides. I should tentatively call them A. galioides, but must confess that the more I look at the plants of these two species the less convinced I am that they are more than weak varieties of one species. The so-called distinguishing characteristics in the hoods in the flower do not hold at all. The differences in habit are fairly conspicuous in extreme plants, but unfortunately the material from Colorado is more or less intermediate between the two in habit. There is a man out in Missouri who is working on a monograph of this genus. When this comes out, I will doubtless be in a better position to give positive identifications of these plants. For the time, all I can say is that these Colorado specimens would go into Asclepias galioides in the commonly accepted sense, but whether this species
will hold up or have to be reidentified or even reduced to variety of A. verticillata I am not at present in a position to say. I regret not being able to give a positive answer, even though the specimens are perfectly satisfactory; but, unfortunately, the state of the taxonomy of this large genus prohibits an honestly positive determination in the case of certain species.
In view of the reports from three authorities, the writer is calling this milkweed Asclepias galioides. CHEMICAL ANALYSIS OF THE MILKWEED Sample 2 of the milkweed in question was examined for selenium1 and the results indicated the presence of only a trace of this element, an insufficient amount to cause illness or death. An analysis made by the Bureau of Animal Industry in Washington, D.C., for HCN was negative. DISTRIBUTION OF MILKWEED Various species of milkweed are reported in many sections of the United States. Some are known to be highly toxic for livestock, although other species are relatively free from poisonous principles. The milkweed in question, Asclepias galioides, has a limited geographical range, being reported in western and southern Colorado, western Kansas (Gates, 1930), northern New Mexico, western and eastern Arizona, and in southern Utah. Hoffman states this plant may also be found in eastern Nevada adjacent to the Utah area. It is possible that this plant may also be found in northwest Oklahoma and the Panhandle region of Texas. This weed is reported spreading into new areas along irrigation ditches, streams, and by other mechanical means. 1
Examination made by the chemists of the U. S. Food and Drug Administration, Federal Security Agency, Denver, Colorado, and Dr. H. G. Byers of the Bureau of Plant Industry, U. S. Department of Agriculture, Washington, D.C.
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IDENTIFICATION OF THE SPECIES
STILES
POISONING OF TURKEY POULTS FROM WHORLED MILKWEED ECONOMIC IMPORTANCE OF THE MILKWEED MENACE TO THE TURKEY INDUSTRY
The poisonous plant's work is becoming more complicated as the supply of desirable feed is reduced and the poisonous species given an opportunity to spread. Most of the species of poisonous plants that have been reported for the first time during recent years have always been with us, yet were not eaten by livestock.
Dr. Huffman later reported: We made a feeding on August 4, to a sheep, of the leaves you sent us and got very definite results. The dosage was figured as 0.05 percent dry of the body weight of the sheep, which, if figured on the basis of 75 percent moisture, would be equivalent to 0.2 percent green plant. This 'would correspond very closely with the minimum lethal dose for sheep as given in Department Bulletin No. 800. This feeding was so near the lethal dose that for a time we expected the animal to die, but today it has started eating again. The symptoms corresponded with milkweed poisoning so that there appears to be very little question that this is Asdepias galioides. This milkweed, like our A. labrijormis, appears to be much more toxic during the early growth 2 Personal communication from Dr. W. T. Huffman, Veterinarian in Charge of Investigations of Stock Poisoning by Plants, Bureau of Animal Industry, Salt Lake City, Utah.
period so that the collection you made was probably at about its most toxic stage. The milkweeds all appear to lose toxicity upon drying or at maturity but the more toxic ones retain sufficient toxicity to be poisonous when cut with hay or after maturity on the range. With the A. labrijormis, we have considerable loss on the range during the winter from sheep eating the dry mature leaves.
During the marketing season of 1940, it is reported that 150,000 turkeys were sold from the Arkansas Valley of Colorado, in which region the whorled milkweed is extensively found. In a locality where the turkey industry is so important to the farm income as it is in this area, losses from milkweed poisoning contribute one more hazard, in addition to the already known ailments common to turkeys. FEEDING EXPERIMENTS IN THE LABORATORY
Feeding experiments were conducted on 13 turkey poults and 4 chickens. Some of the birds were weighed and hand-fed definite amounts of finely chopped milkweed; others were allowed to eat the plants at liberty. Three samples of the plant were used for the feeding experiment. The sample designated as Number 1 was collected June 9, soon after the occurrence of a heavy poult loss, and the stems were quite small and tender. This plant was about six inches tall at that time. Sample 2'was collected June 25 and was from 12 to 15 inches in height and beginning to bloom. The stems were of considerable size and tough. Sample 3, a more mature plant than numbers 1 and 2, was collected July 21, near La Junta, Colorado. Both the leaves and stems were finely chopped in each sample of the weed used, except in the experiment with the turkey which was fed only the dried leaves of the plant, and one pullet, which received leaves
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In regions where Asdepias galioides abounds, poisoning of turkeys may be of considerable economic importance. A practicing veterinarian in southeastern Colorado states he has observed losses in turkeys on the range during the past several years which he has attributed to whorled milkweed poisoning, and his description of the symptoms correspond to the observations of the writer in cases described in this paper. Adequate care should be exercised to prevent livestock poisoning in areas known to be infested by this plant. Sufficient wholesome green food should be provided for fowls and an effort made to eradicate toxic milkweed completely from the premises. Huffman2 says:
267
268
GEO. W. STILES
DISCUSSION Whorled milkweed, Asclepias galioides, appears to be toxic for turkeys. This state-
weed, especially the leaves of the immature plant. By studying Table 1, it will be seen that the feeding of 1 gram of the young plant to 100 grams of turkey weight, or 1 percent of the body weight, resulted in death in less than five hours. The onset of convulsions usually developed within about one hour. Smaller amounts of the milkweed caused death after a longer period. Comparing turkeys 1, 2, and 3 which were fed the young plant 1, with turkeys 6 and 7 which received the more mature weed 2, it will be observed that the younger plant appeared more toxic than the older maturing milkweed. It is known (Gates, 1930) in relation to cocklebur poisoning in swine that the two-leaf stage of the
TABLE 1.—Experimental feeding of turkeys Grams Grams No. weight weed
Time of feeding
First symptoms
Died 1:07 p.m. Died 10:32 a.m. l h r . , 4 m i n . 12:53 p.m. Died 10:43 a.m. 53 min. 2:34 p.m. Died 12:28 p.m. 2 hrs., 5 min. Several hrs. Died later Died 9:56 a.m. 56 min. 6:14 p.m. Died 1:15 p.m. 1 hr., 30 min. Several hrs. Died later Several hrs. Died later None Lived None Lived
113
1.13
9:40 a.m.
2
64
0.64
9:28 a.m.
3
735
7.35
9:50 a.m.
4 5
110 84
0.89 ?
10:23 a.m. 1:45 p.m.
6
605
6.05
9:00 a.m.
7 8
300 164
3.00 ?
11:45 a.m. 10:00 a.m.
9
261
?
10:00 a.m.
? ?
10:00 a.m. 10:00 a.m.
20?
1:50 p.m.
2:50 p.m.
lhr.
?
1:30 p.m.
4:30 p.m.
3 hrs.
12 1,000 13
Estimate 4 lbs.
Results
45 min.
1
10 11
10:25 a.m.
Time
ment results from field observations and experimental feeding. The turkeys eat the young tender shoots of the plant more readily than they eat the tougher mature weed. In the absence of other greens, turkeys may consume toxic amounts of milk-
Died 5:12 p.m. Died
Length of time
Remarks
3 hrs., 27 min. Fed plant 1 3 hrs., 25 min. Fed plant 1 4 hrs., 44 min. Fed plant 1 During night Fed plant 1 Next day Fed plant 1 9:45 a.m. 9 hrs., 14 min. Fed plant 2 During night During night
Fed plant 2 These four poults were fed a small quantity During night of plant 2 in feed. Seen to eat fragments occasionally 3 hrs., 22 min. Fed dried leaves only, plant 2 Fed plant 3 Next day
young plant is highly toxic, while the mature weed seems to be harmless. Turkeys 8 to 11, inclusive, were fed a small amount of plant 2 along with their regular feed one morning. Occasionally a bird was seen picking fragments of the
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from plant 3. The weighed milkweed was placed on a sheet of white paper or in a dish, in cases where the hand-feeding method was used, and the bird was held firmly by an attendant. A small pinch or forceps full of the weed was placed well back into the throat, followed by a few drops of water from a medicine dropper to facilitate swallowing. This was repeated until all fragments had been fed, taking care not to lose any portion of the sample. Records dated from the time of the completed feeding until the death of the victim in fatal cases.
POISONING O F T U R K E Y POULTS FROM WHORLED
269
MILKWEED
TABLE 2.—Experimental feeding of chickens Grams Grams No. weight weed
Time of feeding
First symptoms
1
63
0.63
9:25 a.m.
11:30 a.m.
2
90
0.90
9:30 a.m.
Mild
3
818
8.18
10:15 a.m.
Listless
4 1,500
15.00
9:50 a.m.
Dumpy
Time
Results
2hrs., 5min. Died next day Some hours Lived later Lived
Remarks
24hrs.,9min. Fed plant 1
6 days later
Fed plant 1, no marked spasms Fed plant 2, no marked spasms Fed plant 3
same plant developed mild symptoms, but lived. One pullet which received 1 percent of its body weight of the milkweed, number 2, failed to produce active symptoms of poisoning. Aside from listlessness and refusal to eat for a few days, no ill effects resulted, although turkey 6, Table 1, which weighed 605 grams, fed that day of the same sample and same amount per body weight, died after 9 hours and 14 minutes. It showed typical symptoms of milkweed poisoning. Another pullet fed 1 percent of plant 3 developed mild symptoms and died six days later. SUMMARY
1. Field observations in southern Colorado (supplemented by feeding experiments, indicate whorled milkweed (Asclepias galioides) is toxic for turkeys. 2. Young turkeys fed 1 gram of milkweed per 100 grams of turkey weight produced spasms within about one hour and, usually, death in less than five hours after feeding. Immature, tender plants appeared more toxic than more mature weeds. 3. Whorled milkweed is found in southern Colorado, southwestern Kansas, northern New Mexico and Arizona, southern Utah, and possibly in southeastern Nevada, in northwestern Oklahoma, and the Panhandle of Texas. 4. The economic importance pertaining to losses in turkeys from eating poisonous milkweed may be a serious factor in localities where this plant thrives abundantly.
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plant out of the mash and eating it. Two of the four three-week-old poults showed convulsions during the afternoon of the day they received this mixture and died that night. The other two poults survived. There was no definite evidence that all four poults actually ate the plant. In the case of turkey 12, special attention is noted that this fowl was fed only the dried leaves of plant 2. Although the intention had been to give this turkey 2 percent of its weight, or 20 grams of the milkweed, a small quantity of the dried leaves was lost duing the process of feeding. The feeding was completed at 1:50 P.M. and the first convulsions developed one hour later. The usual symptoms of milkweed poisoning followed. (Observe the photograph showing spasms.) This bird died 3 hours and 22 minutes after feeding. From the crop of the dead turkey was recovered 5.5 grams of the substance fed; from the gizzard 13.2 grams, or a total of 18.7 grams from a possible 20 grams of the dried plant intended for feeding. The experiment would indicate the dried weed retained a large percent of its toxic principle. In comparing the toxicity of milkweed for turkeys and chickens, the limited number of experiments show that chickens are less susceptible to the poisonous principle of the plant than are turkeys. One of the chickens, number 1, Table 2, fed experimentally, died 24 hours after it had been fed 1 percent of the plant per body weight. A second chick fed a similar amount of the
Died
Length of time
270
GEO. W. STILES
5. E v e r y effort s h o u l d b e m a d e to p r o -
and
the
broad-leaved
or
showy
milkweed
(Asclepias spedosa); plants poisonous to Nevada N e v a d a A " s™^"™1 Experiment Station -Bulletin No. 99. _ . , , , - . „ , „ „ . . , . , t
REFERENCES Campbell, Harvey W., 1931. The whorled milkweed as a poisonous plant for poultry. The Monthly Bulletin, California Department of Agriculture August Durrell, L. W., and I. E. Newsom, 1939. Colorado's poisonous and injurious plants. Colorado Agricultural Experiment Station Bulletin No. 455. Fleming, C. E., and N. F. Peterson, 1920. The narrow-leaved milkweed (Asclepias mcxicana)
Gates, Frank C , 1930. Principal poisonous plants m Kansas. Kansas Agricultural Experiment Station Technical Bulletin No. 25. Marsh > c - Dwight, A. B. Clawson, and J. F. Couch > 1 9 2 ° - The whorled milkweed (Asdepias galioides) as a poisonous plant. U.S.D.A. Bulletin No - 80°Muenscher, Walter Conrad, 1939. Poisonous plants of the United States. Macmillan Company. Pammel, L. H., 1917. Milkweed poisonous to chickens. Journal of the American Veterinary Medical Association 12:235.
Errata THE PANTOTHENIC ACID REQUIREMENT OF CHICKS J. C. BAUEENFEIND, L. C. NOERIS AND G. F. HEUSEE POULTRY SCIENCE, March, 1942, Pages 142-146
PAGE 143 in Table 1, describing the O Nbasal diet, the decimal point for the vitamin percentages should be placed two places to the left. The table should read as follows:
Percent Riboflavin .'..' Nicotinic acid Thiamin
.0.000325 0.000300 0.000150
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vide wholesome green feed for turkeys and to eradicate the deadly milkweed from , . J. , premises known to be infested.