Arsenicals in Animal Feeds and Wastes

5 Arsenicals in Animal Feeds and Wastes

Downloaded by UNIV OF CALIFORNIA SAN DIEGO on June 5, 2015 | http://pubs.acs.org Publication Date: June 1, 1975 | doi: 10.1021/bk-1975-0007.ch005

C. C. CALVERT Biological Waste Management Laboratory, Agricultural Environmental Quality Institute, Agricultural Research Service, Department of Agriculture, Beltsville, Md. 20705 Since arsenic trioxide was first obtained from copper smelting over 4000 years ago, this element has been used for a variety of medicinal purposes (1). The modern era of arsenic use in medicine began with the characterization of arsanilic acid by Erlich and Bertheim in 1907 (2) and was extended more recently by the discovery in 1945 by Morehouse and Mayfield (3) that an organic arsenical, 3-nitro-4-hydroxyphenylarsonic acid commonly called (3-nitro), could be used to control coccidiosis and promote growth in chicks. Since that time, other organic arsenicals such as arsenosobenzene, arsanilic acid, 4-nitrophenylarsonic acid and p-ureidobenzenearsonic acid have been shown to have both therapeutic and growth-promotant properties as feed additives for poultry and swine. At the present time, a l l of these compounds, with the exception of arsenosobenzene, are approved by the U.S. Food and Drug Administration for use in poultry and swine feeds but only at levels low enough to preclude residues in edible animal tissue which would be a hazard to human health. The objective of this discussion will be to review briefly the efficacy of these arsenic compounds with respect to animal production, the absorption and excretion of these arsenicals when fed to animals and, finally, the fate of arsenic in animal excreta. Arsenicals in Swine and Poultry Feeds Table 1 shows the chemical structure of 4 arsenicals currently approved for use as growth promotants or therapeutic agents, or both, in poultry and swine feeds. The arsenic in a l l these compounds is pentavalent. Changing the substituents on the ring changes the growth-promoting and anti-parasite effects of the compound. Note that arsanilic acid and 3-nitro are approved for both poultry and swine, whereas 4-nitrophenylarsonic acid and p-ureidobenzenearsonic acid are approved only for turkeys. The use of these compounds in turkeys is limited to feeding for therapeutic purposes and may not be used as growth promotants (4). 70

In Arsenical Pesticides; Woolson, E.; ACS Symposium Series; American Chemical Society: Washington, DC, 1975.

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Animal Feeds and Wastes

Table 1.

Chemical s t r u c t u r e of a r s e n i c a l s used i n animal feeding As 0 (OH), As 0 (OH),


0

N0 NH.

OH 3-nitro-4-hydroxyphenylarsonic A c i d (Poultry & Swine)

A r s a n i l i c Acid (Poultry & Swine) As 0 ( 0 H )

o

n

As 0 ( 0 H )

o

NO,

4-nitrophenylarsonic (Turkeys)

o

NH CO NH_ Acid

p-ureidobenzenearsonic A c i d (Turkeys)

The FDA has e s t a b l i s h e d l e v e l s a t which these compounds may be used i n animal feeds, and i t has a l s o determined the maximum l e v e l s of a r s e n i c that may be present i n marketed p o u l t r y and swine. These maximum use l e v e l s and maximum t i s s u e l e v e l s are shown i n Table 2. In order that these t i s s u e l e v e l s may be met, the user of a r s e n i c a l - c o n t a i n i n g feed i s r e q u i r e d by FDA regul a t i o n s to withdraw the a r s e n i c - c o n t a i n i n g feed f o r a t l e a s t 5 days before slaughter. Growth Response from the Use o f A r s e n i c a l s Many experiments have expanded on the o r i g i n a l demonstration of the e f f i c a c y of 3 - n i t r o and other a r s e n i c a l s i n both p o u l t r y and swine r a t i o n s . No attempt w i l l be made i n t h i s d i s c u s s i o n to cover a l l of the research that has been conducted with the a r s e n i c a l s i n feed, but a few examples of the types o f responses obtained w i l l be presented. A number of reviews on t h i s subject are i n the l i t e r a t u r e and should be consulted f o r more d e t a i l e d information (5-9.). Baron (9), a t a symposium i n London i n 1969, presented examples of the type of responses that may be obtained by feeding a r s e n i c a l s to growing chickens. Results of a study i n which 3- n i t r o was f e d i n 15 t r i a l s to a t o t a l of 1148 b i r d s f o r a 4-week p e r i o d are shown i n Table 3. As can be seen i n t h i s t a b l e , the average response i n weight increase due to a r s e n i c i n these s t u d i e s was 4.1%. The response i n feed to gain r a t i o was 1.6%. The r e s u l t s shown i n Table 4 show the average responses from 5 t r i a l s i n v o l v i n g more than 2500 chickens f o r an 8-week feeding p e r i o d . This p e r i o d represents the time needed to b r i n g a



~2T

21

Turkeys

PoultrySwine

Swine

Poultry-

170g/ton(187 mg/kg)

45g/ton(50 mg/kg) 68g/ton(75 mg/kg)

90g/ton(100 mg/kg)

90g/ton(100 mg/kg)

p-ureidobenzenearsonic acid Turkeys 340g/ton(375 mg/kg) 1/ Source: (4) . 2] B r o i l e r s , l a y i n g hens and turkeys.

4-n i tropheny1arsonic acid

3- n i t r o - 4 hydroxyphenylarsonic acid

Arsanilic acid

Table 2.

Same as a r s a n i l i c a c i d

Same as a r s a n i l i c a c i d

Same as a r s a n i l i c a c i d Same as a r s a n i l i c a c i d

0.5 mg/kg f r e s h , uncooked muscle 2.0 mg/kg f r e s h , uncooked by-products 0.5 mg/kg f r e s h muscle and by-products other than kidney & l i v e r 2.0 mg/kg f r e s h , uncooked kidney & l i v e r

^, Maximum p e r m i s s i b l e l e v e l s of a r s e n i c a l s i n animal feeds and maximum D e r m i s s i b l e l e v e l s o f a r s e n i c i n animal t i s s u e . — Maximum Maximum Species feed l e v e l tissue arsenic l e v e l Compound


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Wastes

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chicken to market s i z e . In t h i s t e s t , the i n c r e a s e i n weight was not s i g n i f i c a n t , but feed conversion w i t h a r s e n i c supplement was s i g n i f i c a n t l y improved - 1.99 g of feed to produce 1 g of l i v e weight gain with the a r s e n i c a l compared w i t h 2.04 g of feed f o r each gram of g a i n with the c o n t r o l s .


Table 3.

Treatment

Summary of t e s t s to show the e f f e c t of feeding 3-nitro-4-hydroxyphenylarsonic a c i d (0.005%) on the weight g a i n and feed e f f i c i e n c y of b r o i l e r c h i c k s during the f i r s t 4 weeks of l i f e . — Average Average feed Average feed conversion Average weight T r i a l s B i r d s weight response conversion response (No.) (No.) (g feed/g (%) (%) (g) weight)

3-Nitro 15 Nonmedicated controls 15 1/ Source: (9). Table 4.

1148

530

1148

510

4.1

1.70

1.6

1.73

Summary of t e s t s to show the e f f e c t of feeding 3 - n i t r o (0.005%) on the growth and feed e f f i c i e n c y , of b r o i l e r s during the f i r s t 8 weeks of l i f e . Average feed Average Trials conversion weight Birds (No..) (No.) (g feed/g weight) (g) 7

Treatment

3-Nitro 5 Nonmedicated controls 5 11 Source: ( 9 ) .

2568

1448

1.99

2568

1430

2.04

Results of an i n v e s t i g a t i o n by Hansen (10) on the response of growing swine to 3-nitro are shown i n Table 5. The a r s e n i c a l was f e d i n t h i s study f o r the f u l l growing p e r i o d and r e s u l t e d i n a s i g n i f i c a n t improvement i n both average d a i l y g a i n and feed conversion.


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74


Table 5.

E f f e c t of 3 - n i t r o on growth r a t e and feed conversion of growing sheep.— Average d a i l y g a i n from weaning Feed conversion to 90.9 kg (kg feed/kg weight) (kg)

3-nitro (40 mg/kg of feed) Nonmedicated c o n t r o l s 1/ Source: (10).

0.79 0.75

3.50 3.56

Reporting these r e s u l t s i s not intended as an endorsement f o r 3 - n i t r o as the a r s e n i c a l of choice i n animal feeding. S i m i l a r responses have been shown w i t h other a r s e n i c a l s such as a r s a n i l i c a c i d f o r chickens, turkeys and growing swine. In the experiments reviewed f o r t h i s r e p o r t , no negative responses to a r s e n i c a l a d d i t i v e s were obtained i f supplementation d i d not exceed recommended l e v e l s . There were a few instances reported i n which no improvements i n growth and feed e f f i c e n c y were obtained from the a d d i t i o n of a r s e n i c a l s to swine and p o u l t r y d i e t s , but the high frequency of p o s i t i v e e f f e c t s from a r s e n i c a l s gives the producer that small edge that may w e l l be the d i f f e r e n c e between a p r o f i t and l o s s i n a modern swine and p o u l t r y feeding enterprise. A r s e n i c a l s are a l s o approved f o r feeding i n combination with other feed a d d i t i v e s such as c o c c i d i o s t a t s and a n t i b i o t i c s . There have been many experiments reported i n the l i t e r a t u r e t e s t i n g combinations of the a r s e n i c a l s with the wide v a r i e t y of a n t i b i o t i c s and c o c c i d i o s t a t s used i n p o u l t r y and swine d i e t s . Two reviews of these experiments (5,9) should be consulted f o r more detailed information. In many i n s t a n c e s , a combination of a r s e n i c a l and a n t i b i o t i c has improved growth that i s greater than that obtained w i t h e i t h e r of the a d d i t i v e s fed alone. There i s a t present no explanation as to why one a n t i b i o t i c w i l l respond one way when combined w i t h an a r s e n i c a l and another w i l l respond another way. Mechanism of. A c t i o n A number of t h e o r i e s have been proposed f o r the mechanism of a c t i o n of a r s e n i c a l s i n i n c r e a s i n g growth i n swine and p o u l t r y . Peoples (8) has suggested that the a r s e n i c a l may i n h i b i t those organisms that cause t h i c k e n i n g of the gut w a l l and therefore r e s u l t i n more e f f i c i e n t absorption of n u t r i e n t s . Another theory i s that these compounds a c t l i k e a n t i b i o t i c s and i n h i b i t harmful b a c t e r i a . However, s t u d i e s of the b a c t e r i o s t a t i c value of a r s e n i c a l s by F r o s t and Spruth (6) i n d i c a t e that with c e r t a i n b a c t e r i a , E s c h e r i c h i a c o l i and C l o s t r i d i u m p e r f r i n g e n s , f o r example, the a r s e n i c a l s are much l e s s e f f e c t i v e than conventional a n t i b i o t i c s . Another theory, proposed by Pope and Schaible (11),



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suggests that a r s e n i c a l s may exert a sparing e f f e c t on p r o t e i n . In t h i s study, egg production i n hens f e d a 13% p r o t e i n d i e t was increased by the a d d i t i o n of a r s a n i l i c a c i d to the d i e t to a l e v e l comparable with the egg production i n hens f e d a 16.5% p r o t e i n r a t i o n . Russo e t a l . (12) a l s o found that a r s a n i l i c a c i d reduced u r i n a r y n i t r o g e n e x c r e t i o n i n swine, and they suggested that a r s e n i c a l s exert a sparing e f f e c t on p r o t e i n by reducing p r o t e i n catabolism. Thus, no one mechanism can l i k e l y e x p l a i n the a c t i o n of an a r s e n i c a l , and probably a combination of f a c t o r s produces the observed responses. Uptake and D e p l e t i o n of A r s e n i c from Tissue A r s e n i c a l s i n an animal's feed w i l l r e s u l t i n a r s e n i c residues i n t i s s u e s . Data i n Table 6 show that the feeding o f a r s a n i l i c a c i d a t 0.01% o f a chick d i e t and 3-nitro-4-hydroxyphenylarsonic a c i d a t 0.005% r e s u l t s i n low l e v e l s of a r s e n i c i n l i v e r t i s s u e . Feeding 10 times the approved l e v e l s of e i t h e r of these a r s e n i c a l s d i d not r e s u l t i n 10 times the l e v e l of a r s e n i c i n the t i s s u e s . The data suggest that i n chicken l i v e r t i s s u e , there i s an upper l i m i t f o r a r s e n i c . These same authors a l s o presented evidence that a r s e n i c i n l i v e r and muscle of c h i c k s q u i c k l y reached a p l a t e a u l e v e l and d i d not i n c r e a s e f u r t h e r when a r s a n i l i c a c i d was f e d continuously a t 0.005% o f the r a t i o n f o r a 9-week p e r i o d . Table 6. Compound and

A r s e n i c found i n l i v e r s of chickens f e d v a r i o u s arsenicals.— A r s e n i c (As^O^) i n -

feed l e v e l

Arsanilic acid: 0.01% 0.1% 3-nitro-4-hydroxyphenylarsonic acid: 0.005% 0.05% Dodecylamine p-chlorphenylarsonate: 0.01% 1/ Source: ( 6 ) .

Feed —:

Fresh ppm

liver

45.4 455

1.2 6.4

18.7 187

2.4 7.5

23^3

2 ^

Evidence f o r the r a p i d i t y with which a r s e n i c i s taken up and e l i m i n a t e d from chicken t i s s u e s i s shown i n Table 7. These data by Baron (9) show that i n the kidney, l i v e r , muscle and s k i n of chicks f e d 0.005% 3 - n i t r o , there i s a l o w - l e v e l uptake of a r s e n i c that plateaus a f t e r 7 days of feeding and i s w e l l below tolerance l e v e l s a f t e r only 1 day of withdrawal o f the a r s e n i c a l .


ARSENICAL PESTICIDES

76 Table 7. Days On Test On Med. Off Med.

Summation of a r s e n i c l e v e l s (3-nJtro, of the d i e t ) i n chicken t i s s u e s . — 1 1

-

-

56 56

70 70

-

-

71

75

80

84

-1

-5

-10

-14

NonMed.

.22 .69 .03 .08

.10 .43 .01 .02

.09 .32 .02 .03

.08 .19 .02 .03

.05 .08 .02 .02

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Arsenic Kidney .93 Liver 1.31 Muscle .03 Skin .05 1/ Source: (9).

7 7

.005%

.76 2.43 .07 .11

.52 1.26 .05 .06

.64 1.26 .04 .05

Feeding a r s a n i l i c a c i d to swine a l s o r e s u l t s i n uptake of a r s e n i c i n l i v e r , kidney and spleen and, to a l e s s e r extent, i n muscle and blood. The method of feeding, and i n p a r t i c u l a r the water i n t a k e , may a l s o i n f l u e n c e the d e p o s i t i o n of t i s s u e a r s e n i c . Vorhies e t a l . (13) reported that a r s e n i c i n l i v e r increased from 1.8 ppm to 3.3 ppm when water intake i n swine was reduced. An e a r l i e r study by Bridges et a l . (14) a l s o showed t h i s e f f e c t . None of the a r s e n i c a l s have been approved by FDA f o r use i n feed f o r ruminant animals (beef c a t t l e , d a i r y cows or sheep). However, the c u r r e n t i n t e r e s t i n the use of animal wastes, p a r t i c u l a r l y d r i e d p o u l t r y excreta, as animal feed supplements has generated i n t e r e s t i n the a r s e n i c content of these wastes and i n the e f f e c t of a r s e n i c on the ruminant. Studies on the uptake of a r s e n i c from a r s e n i c a l s i n sheep have been conducted a t our l a b o r a t o r i e s at B e l t s v i l l e . In these i n v e s t i g a t i o n s , a r s e n i c , as a r s a n i l i c a c i d , has been fed to mature wethers at l e v e l s up to 273 mg/kg of d i e t f o r a p e r i o d of 28 days. The l e v e l s of a r s e n i c found i n various t i s s u e s i s shown i n Table 8. A l l t i s s u e s showed i n c r e a s i n g l e v e l s of a r s e n i c as the d i e t a r y a r s e n i c l e v e l s increased. Table 8. Arsenic fed (mg/kg of diet) 0.0 26.8 144.4 273.3

A r s e n i c l e v e l s i n t i s s u e s of wethers fed a r s a n i l i c a c i d f o r 28 days. Whole blood Liver Kidney Muscle mg/kg dry t i s s u e

Arsenicals in Animal Feeds and Wastes

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