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Evaluation of Activated Sludge as Feedstuff in Broiler Diets1
Evaluation of Activated Sludge as Feedstuff in Broiler Diets1 BIANKA LIPSTEIN Department of Poultry Science, Agricultural Research Organization, The Volcani Center, Bet Dagan 50250, Israel S. KARY Tahal, Water Planning for Israel, Tel Aviv, Israel (Received for publication June 22, 1983) ABSTRACT The nutritional values of two activated sludge samples from water treatment plants were assessed in young chicks and in broilers in two separate trials. The diets containing 0, 6, 12, and 18% activated sludge were formulated by computer in a linear programming system. Up to 12% activated sludge in well-balanced chick and broiler diets seems to be a suitable protein supplement with no adverse effect on growth performance. Increased feed intake along with increased levels of sludge in the diet resulted in poorer feed utilization in the young chicks. In the finisher period, however, the increase in feed intake resulted in increased body weight without any reduction in feed utilization. No abnormalities were observed in size or appearance of the examined internal organs except for enlarged livers at the end of the finisher period. (Key words: activated water-treatment sludge, broiler diet, protein supplement, broiler growth) 1984 Poultry Science 63:1213-1217 INTRODUCTION
Activated sludge from water treatment plants is rich in protein and may contribute significant amounts of phosphorus and calcium to the diet. It has been suggested that activated sludge could be used as a feed supplement for poultry (Pillai et al., 1967; Wong and Leung, 1979; Johnson and Damron, 1980; Beszedits, 1981; Damron et al, 1982; Lipstein et al, 1982) and in this way may help to provide important solutions for a cheap replacement for conventional feeds. The aim of the present study was to assess the nutritional value of activated sludge for broiler chicks of different ages and to determine its effect on performance and on some carcass quality traits. MATERIALS AND METHODS
Previous studies (Lipstein and Hurwitz, 1981, 1983) describe the experimental procedure methods used for chemical analyses, metabolizable energy (ME), and nitrogen retention, determinations.
1 Contribution from the Agricultural Research Organization, The Volcani Center, Bet Dagan, Israel. No. 782-E, 1983 Scries.
In the two experiments, three groups of 10 broilers each were assigned to each of the dietary treatments. The diets were fed ad libitum in mash form, the chicks were weighed individually each week, and feed consumption was determined on a group basis. The effects of activated sludge on degree of carcass fatness and size of liver and spleen in Trial 1 and on the size of kidneys and pancreas in Trial 2 were evaluated at the end of the experimental periods at 28 and 54 days of age in Trials 1 and 2, respectively, on 8 birds per treatment at each age. Materials. The two activated sludge samples used in this study originated from the Herzliya wastewater treatment plant (Sample A) and the Dan region wastewater project—demonstration plant (Sample B) and were referred to in our previous study as Samples E and D, respectively (Lipstein et al, 1982). The two samples were dried in drying beds to about 86 to 88% solids content and sterilized by gamma radiation at an intensity of 1.50 Mrad of 6 0 Co. Preparation of Experimental Diets. The chemical composition, ME content, and absorption coefficient of activated sludge were included in an LP-1 program of a Cyber computer (Control Data). The program was constrained to include activated sludge in diets at increasing concentrations.
1213
4
3
2
1
21.4 2955 .77 1.16 1.03 .68
.60
37.0 55.5 3.8 1.8 1.1 .16
21.1 2935 .78 1.11 1.02 .69
6.0 32.0 55.0 4.5 1.5 .5 .18 .03 .60
21.1 2917 .78 1.09 1.07 .67
12.0 28.0 53.0 5.5 1.0 .2 .18 .06 .60 .18 .09 .60
18.0 24.0 51.0 6.5 .5
21.1 2899 .78 1.07 1.16 .65
T4
Experiment 1
.60
6.0 33.0 54.0 4.0 1.6 .8 .17
21.4 2918 .78 1.12 1.11 .72
T5
12.0 29.0 52.0 4.6 1.2, .4 .16 .03 .60
21.4 2902 .78 1.11 1.09 .72
T6
Sludge B
.16 .06 .60
18.0 25.0 50.0 5.4 .8
(Ex
21.1 2902 .78 1.11 1.08 .72
T7
1) and finisher
SAA = Sulphur a m i n o acids.
ME = Metabolizable energy.
C o n s t a n t ingredients: sodium chloride, . 2 5 % ; vitamin mix, . 2 5 % ; mineral mix, .10%. Detailed c o m p o s i t i o n describe
T = T r e a t m e n t number.
Crude protein, % ME, 3 kcal/kg SAA, 4 % Lysine, % Calcium, % Phosphorus, %
Composition (calculated)
Sludge S o y b e a n meal Sorghum grain Soybean oil soapstock Dicalcium p h o s p h a t e Limestone DL-Methionine L-Lysine C o n s t a n t ingredients 2
Ingredients, %
T3
Tl1
T2
Sludge A
of diets fed during the starter (Experiment
Control
T A B L E 1. Composition
SLUDGE AS FEEDSTUFF FOR BROILERS
1215
All diets were designed according to the recommendations of the National Research Council (1977) for starter and finisher periods. The composition of diets in two experiments are presented in Table 1. RESULTS The results of chemical analyses and composition of amino acids and fatty acids, ME, and protein absorption were described in our previous study (Lipstein et al, 1982). Experiment 1. The purpose of this experiment was to determine the effects of two activated sludge samples on the performance and some carcass quality traits of chicks between the ages of 1 and 4 weeks. A summary of the performance of the chicks is given in Table 2. The weight gain in sludgecontaining diets was equal to or higher than (5%) that of the control diet. The inclusion of sludge in the diets increased feed consumption. The only significant differences were those between diets containing 12 and 18% from Sample A and only 18% from Sample B and the control diet. A gradual increase in feed intake resulted in poorer feed utilization, particularly in response to diets containing 18% activated sludge. The determined ME values of the diets were slightly higher than the calculated ones (Table 1), and furthermore, they decreased with increasing sludge levels. Protein retention (Table 2) was similar in all diets except that containing 18% of Sludge A. Degree of fatness (Table 2) of the birds was not affected by the sludge supplements nor were the sizes of livers and spleen, expressed as a percentage of body weight. Experiment 2. The purpose of this trial was to evaluate the nutritional value of activated sludge in diets fed to broilers from 5 to 8 weeks of age, a period when the greatest quantity of feed is being consumed. The sludge-containing diets (Table 3) caused an increase in feed consumption up to 11% in diets containing 18% sludge. The weight gains were slightly but consistently greater (P<.01) than the control diet. The difference was 7 to 8%. Due to the higher weight gain, the increase in feed consumption did not reduce feed utilization except for the diet containing 18% sludge. The ME levels (Table 3) show that in all treatments the determined ME values were 3 to 7% lower than the calculated ones (Table 1),
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LIPSTEIN AND KARY TABLE 3. Performance,1 carcass fatness,1 and internal organs2 of broilers fed diets containing sludge from 5 to 7.5 weeks (Experiment 2)
Weight gain, g Feed consumption, g Feed/gain ratio Metabolizable energy of diets, kcal/kg Nitrogen retention, % Abdominal fat,1 % Liver, % of body weight Spleen, % of body weight Kidney, % of body weight Pancreas, % of body weight
Control diet
6%
^ E 12%
18%
996& 2530 A 2.54AB 2864 48.4 1.83* 2.14 a .147 .209 .70
1070A 2659AB 2.49 A 2940 47.9 2.14 a b 2.26 a .123 .221 .73
1069 A 2678AB 2.51AB 2897 47.8 2.22 a b 2.28 a .140 .223 .70
1077 A 2823 B 2.62 B 2709 46.4 2.54 b 2.55 b .133 .220 .68
' ' ' Any two mean values not followed by a common letter differ significantly (capital letters, P<.01; lower case letters, P<.05). 1
Average of three replicates of 10 birds each.
2
Average of 8 birds, expressed as percent of body weight.
and in the diet containing 18% sludge the difference was even greater (11%). Protein retention (Table 3) was identical irrespective of treatment. Abdominal fat increased as sludge in diets increased (Table 3). Similarly, the size of the liver shows a very slight but gradual increase as level of sludge increased in the diet. However, the sizes of the spleen, kidneys, and pancreas were unaffected by feeding dietary sludge. DISCUSSION Performance Data. The performance obtained in the two experiments indicates that activated sludge may be used in starter and finisher diets at levels up to 12% with no adverse effect. It is important to point out that the inclusion of increasing levels of sludge, up to 18% of the diet, did not depress appetite. Conversely, there was an increase in feed consumption that caused better weight gain but lower feed utilization in the young chicks (Table 2). Feed utilization in the finisher period (Table 3) was not reduced, as increased feed intake caused an equivalent increase in weight gain. This increased feed consumption is in agreement with that obtained by Kienholz et al. (1981) and Damron et al. (1982) with chicks. Working with rats, Smith and Staples (1976) obtained a feed intake about 10% greater than the control with diets containing up to 25% sludge.
The increase in body weight gain on sludgecontaining diets observed in the present study is in agreement with the results obtained by Firth and Johnson (1955), who reported a growth response in excess of 8% due to dry activated sludge at 2 and 10%. Damron et al. (1982) found that the inclusion of 6% Chicago sludge had no adverse effect on growth performance and that hen production criteria were not influenced by the addition of up to 7% sludge to the diet. Pillai et al. (1967) indicated that sludge has a beneficial effect on growth of chicks. Although in the two trials the diets were suggested to be isocaloric, in both of them increased levels of sludge caused a graded decrease in the determined ME values (Tables 2 and 3), except diets containing 6 and 12% sludge in Trial 2, which indicated that the assumed ME content of the sludge samples was an overestimate. Similar degrees of nitrogen retention in all diets in both experiments (except for the diet containing 18% sludge in Experiment 1), together with the protein absorption of sludge samples (Lipstein et al, 1982), confirm that sludge protein was almost as digestible as conventional protein sources. She of Internal Organs and Fatness. It is assumed that activated sludge may contain potentially toxic materials such as heavy metals, pesticides, and other undesirable
SLUDGE AS FEEDSTUFF FOR BROILERS
1217
chicks. Poultry Sci. 62:2247-2254. Beszedits, S., 1981. Utilizing waste activated sludge for animal feeding. Feedstuffs, April 6:25—26. Damron, B. L., H. R. Wilson, M. F. Hall, W. L. Johnson, O. Osuna, R. L. Suber, and G. T. Edds, 1982. Effects of feeding dried municipal sludge to broiler-type chicks and laying hens. Poultry Sci. 61:1073-1081. Firth, J. A., and B. C. Johnson, 1955. Sewage sludge as a feed ingredient for swine and poultry. J. Agric. FoodChem. 3:795-796. Johnson, Z. J., and B. L. Damron, 1980. Performance of White Leghorn hens fed various levels of municipal sludge or selected minerals. Poultry Sci. 59:1565. (Abstr.) Kienholz, E. W., G. M. Ward, D. E. Johnson, J. Baxter, G. Braude, and G. Stern. 1979. Metropolitan Denver sewage sludge fed to feedlot steers. J. Anim. Sci. 4 8 : 7 3 5 - 7 4 1 . Kienholz, E. W„ N.S.K. Young, J. L. Smith, and C. A. Whiteman, 1981. Reduced vitamin A levels of chicks fed anaerobically digested sewage sludge. Poultry Sci. 60:884-886. Lipstein, B., and S. Hurwitz, 1981. The nutritional value of sewage-grown, alum-flocculated Micractinium algae in broiler and layer diets. Poultry Sci. 60:2628-2638. Lipstein, B., and S. Hurwitz, 1983. The nutritional value of sewage-grown samples of Chlorella and Micractinium in broiler diets. Poultry Sci. 62: 1254-1260. Lipstein, B., S. Kary, and S. Hurwitz, 1982. The nutritional value of activated sludge for poultry. Nutr. Rep. Int. 25:829-836. National Research Council, 1977. Nutrient Requirements of Poultry. 1. Nutrient Requirements of Domestic Animals. 7th ed. Natl. Acad. Sci., Washington, DC. Pillai, S. C, E. G. Srinath, M. L. Mathur, P.M.N. ACKNOWLEDGMENTS Naidu, and P. G. Muthanna, 1967. Activated This study was supported in part by the sludge as a feed supplement for poultry. Water Environmental Protection Service, Ministry of Waste Treat. April:316-322. the Interior, Israel, and in part by the Egg and Smith, G. S., and H. E. Kiesling, 1977. Sewage solids as a feed supplement for ruminants: Nutritive Poultry Marketing Board. value, concerns for toxicants, and energy aspects. The authors gratefully acknowledge the 4th Annu. New Mexico State Univ. Conf. on helpful cooperation of T. Roth of the WasteEnergy, Las Cruces, NM, February 7—8. Smith, G. S., and C. R. Staples, 1976. Heavy metals in water and Water Quality Division, Tahal, and of rats fed sewage solids. J. Anim. Sci. 43:233. M. Ben Mosheh and J. Nissenbaum for their Wong, W. H., and K. L. Leung, 1979. Sewage sludge able technical assistance. and seaweed (Ulva sp.) as supplementary feed for chicks. Environ. Pollut. 1 3 : 9 3 - 1 0 1 . Yanai, S., S. Mokady, and Z. Berk, 1977. Algae grown REFERENCES on waste water as a source of protein; toxicologBartov, T., N. Pasternak, and N. Lisker, 1982. The ical and nutritional aspects. Proc. 11th FEBS nutritional value of moldy grains for broiler Mtg., Copenhagen. constituents (Smith and Kiesling, 1977; Damron et al, 1982). It is known that these adverse factors usually depress appetite and often affect the size of internal organs (Yanai et al., 1977; Kienholz et al., 1979). As mentioned before, appetite was not affected; rather, the reverse situation prevailed. Moreover, in the two trials, the sizes of the kidney, spleen, and pancreas were not affected by sludge-containing diets, and no gross abnormalities were observed in the external appearance of the examined organs (Tables 2 and 3). With regard to liver size, no differences were observed during the starter period, the most critical age for dietary damage. However, in the finisher period a definite trend appeared for a graded increase in the liver with increasing levels of sludge in the diet. This is in agreement with the results of Smith and Staples (1976), who reported that the sizes of the organs of rats were not affected by sludge-containing diets, and found no symptoms of toxicity except for the livers, which were enlarged by 10 and 25% sludge-containing diets. Unaffected appetite and a lack of difference in the sizes of examined organs appear to indicate that the toxic elements in activated sludge may be of lower quantity or lesser activity than usually presumed.
Activated sludge from water treatment plants is rich in protein and may contribute significant amounts of phosphorus and calcium to the diet. It has been suggested that activated sludge could be used as a feed supplement for poultry (Pillai et al., 1967; Wong and Leung, 1979; Johnson and Damron, 1980; Beszedits, 1981; Damron et al, 1982; Lipstein et al, 1982) and in this way may help to provide important solutions for a cheap replacement for conventional feeds. The aim of the present study was to assess the nutritional value of activated sludge for broiler chicks of different ages and to determine its effect on performance and on some carcass quality traits. MATERIALS AND METHODS
Previous studies (Lipstein and Hurwitz, 1981, 1983) describe the experimental procedure methods used for chemical analyses, metabolizable energy (ME), and nitrogen retention, determinations.
1 Contribution from the Agricultural Research Organization, The Volcani Center, Bet Dagan, Israel. No. 782-E, 1983 Scries.
In the two experiments, three groups of 10 broilers each were assigned to each of the dietary treatments. The diets were fed ad libitum in mash form, the chicks were weighed individually each week, and feed consumption was determined on a group basis. The effects of activated sludge on degree of carcass fatness and size of liver and spleen in Trial 1 and on the size of kidneys and pancreas in Trial 2 were evaluated at the end of the experimental periods at 28 and 54 days of age in Trials 1 and 2, respectively, on 8 birds per treatment at each age. Materials. The two activated sludge samples used in this study originated from the Herzliya wastewater treatment plant (Sample A) and the Dan region wastewater project—demonstration plant (Sample B) and were referred to in our previous study as Samples E and D, respectively (Lipstein et al, 1982). The two samples were dried in drying beds to about 86 to 88% solids content and sterilized by gamma radiation at an intensity of 1.50 Mrad of 6 0 Co. Preparation of Experimental Diets. The chemical composition, ME content, and absorption coefficient of activated sludge were included in an LP-1 program of a Cyber computer (Control Data). The program was constrained to include activated sludge in diets at increasing concentrations.
1213
4
3
2
1
21.4 2955 .77 1.16 1.03 .68
.60
37.0 55.5 3.8 1.8 1.1 .16
21.1 2935 .78 1.11 1.02 .69
6.0 32.0 55.0 4.5 1.5 .5 .18 .03 .60
21.1 2917 .78 1.09 1.07 .67
12.0 28.0 53.0 5.5 1.0 .2 .18 .06 .60 .18 .09 .60
18.0 24.0 51.0 6.5 .5
21.1 2899 .78 1.07 1.16 .65
T4
Experiment 1
.60
6.0 33.0 54.0 4.0 1.6 .8 .17
21.4 2918 .78 1.12 1.11 .72
T5
12.0 29.0 52.0 4.6 1.2, .4 .16 .03 .60
21.4 2902 .78 1.11 1.09 .72
T6
Sludge B
.16 .06 .60
18.0 25.0 50.0 5.4 .8
(Ex
21.1 2902 .78 1.11 1.08 .72
T7
1) and finisher
SAA = Sulphur a m i n o acids.
ME = Metabolizable energy.
C o n s t a n t ingredients: sodium chloride, . 2 5 % ; vitamin mix, . 2 5 % ; mineral mix, .10%. Detailed c o m p o s i t i o n describe
T = T r e a t m e n t number.
Crude protein, % ME, 3 kcal/kg SAA, 4 % Lysine, % Calcium, % Phosphorus, %
Composition (calculated)
Sludge S o y b e a n meal Sorghum grain Soybean oil soapstock Dicalcium p h o s p h a t e Limestone DL-Methionine L-Lysine C o n s t a n t ingredients 2
Ingredients, %
T3
Tl1
T2
Sludge A
of diets fed during the starter (Experiment
Control
T A B L E 1. Composition
SLUDGE AS FEEDSTUFF FOR BROILERS
1215
All diets were designed according to the recommendations of the National Research Council (1977) for starter and finisher periods. The composition of diets in two experiments are presented in Table 1. RESULTS The results of chemical analyses and composition of amino acids and fatty acids, ME, and protein absorption were described in our previous study (Lipstein et al, 1982). Experiment 1. The purpose of this experiment was to determine the effects of two activated sludge samples on the performance and some carcass quality traits of chicks between the ages of 1 and 4 weeks. A summary of the performance of the chicks is given in Table 2. The weight gain in sludgecontaining diets was equal to or higher than (5%) that of the control diet. The inclusion of sludge in the diets increased feed consumption. The only significant differences were those between diets containing 12 and 18% from Sample A and only 18% from Sample B and the control diet. A gradual increase in feed intake resulted in poorer feed utilization, particularly in response to diets containing 18% activated sludge. The determined ME values of the diets were slightly higher than the calculated ones (Table 1), and furthermore, they decreased with increasing sludge levels. Protein retention (Table 2) was similar in all diets except that containing 18% of Sludge A. Degree of fatness (Table 2) of the birds was not affected by the sludge supplements nor were the sizes of livers and spleen, expressed as a percentage of body weight. Experiment 2. The purpose of this trial was to evaluate the nutritional value of activated sludge in diets fed to broilers from 5 to 8 weeks of age, a period when the greatest quantity of feed is being consumed. The sludge-containing diets (Table 3) caused an increase in feed consumption up to 11% in diets containing 18% sludge. The weight gains were slightly but consistently greater (P<.01) than the control diet. The difference was 7 to 8%. Due to the higher weight gain, the increase in feed consumption did not reduce feed utilization except for the diet containing 18% sludge. The ME levels (Table 3) show that in all treatments the determined ME values were 3 to 7% lower than the calculated ones (Table 1),
< < » CO
-H
Os r-
-H
:
o\ o H ^ f~ *o • rt X CO " *
CO s\j- sO Ox
^O h t ^ Wl tS rH N N \ 0 ^< '
X in
H
c
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v
III III: W
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H W
1216
LIPSTEIN AND KARY TABLE 3. Performance,1 carcass fatness,1 and internal organs2 of broilers fed diets containing sludge from 5 to 7.5 weeks (Experiment 2)
Weight gain, g Feed consumption, g Feed/gain ratio Metabolizable energy of diets, kcal/kg Nitrogen retention, % Abdominal fat,1 % Liver, % of body weight Spleen, % of body weight Kidney, % of body weight Pancreas, % of body weight
Control diet
6%
^ E 12%
18%
996& 2530 A 2.54AB 2864 48.4 1.83* 2.14 a .147 .209 .70
1070A 2659AB 2.49 A 2940 47.9 2.14 a b 2.26 a .123 .221 .73
1069 A 2678AB 2.51AB 2897 47.8 2.22 a b 2.28 a .140 .223 .70
1077 A 2823 B 2.62 B 2709 46.4 2.54 b 2.55 b .133 .220 .68
' ' ' Any two mean values not followed by a common letter differ significantly (capital letters, P<.01; lower case letters, P<.05). 1
Average of three replicates of 10 birds each.
2
Average of 8 birds, expressed as percent of body weight.
and in the diet containing 18% sludge the difference was even greater (11%). Protein retention (Table 3) was identical irrespective of treatment. Abdominal fat increased as sludge in diets increased (Table 3). Similarly, the size of the liver shows a very slight but gradual increase as level of sludge increased in the diet. However, the sizes of the spleen, kidneys, and pancreas were unaffected by feeding dietary sludge. DISCUSSION Performance Data. The performance obtained in the two experiments indicates that activated sludge may be used in starter and finisher diets at levels up to 12% with no adverse effect. It is important to point out that the inclusion of increasing levels of sludge, up to 18% of the diet, did not depress appetite. Conversely, there was an increase in feed consumption that caused better weight gain but lower feed utilization in the young chicks (Table 2). Feed utilization in the finisher period (Table 3) was not reduced, as increased feed intake caused an equivalent increase in weight gain. This increased feed consumption is in agreement with that obtained by Kienholz et al. (1981) and Damron et al. (1982) with chicks. Working with rats, Smith and Staples (1976) obtained a feed intake about 10% greater than the control with diets containing up to 25% sludge.
The increase in body weight gain on sludgecontaining diets observed in the present study is in agreement with the results obtained by Firth and Johnson (1955), who reported a growth response in excess of 8% due to dry activated sludge at 2 and 10%. Damron et al. (1982) found that the inclusion of 6% Chicago sludge had no adverse effect on growth performance and that hen production criteria were not influenced by the addition of up to 7% sludge to the diet. Pillai et al. (1967) indicated that sludge has a beneficial effect on growth of chicks. Although in the two trials the diets were suggested to be isocaloric, in both of them increased levels of sludge caused a graded decrease in the determined ME values (Tables 2 and 3), except diets containing 6 and 12% sludge in Trial 2, which indicated that the assumed ME content of the sludge samples was an overestimate. Similar degrees of nitrogen retention in all diets in both experiments (except for the diet containing 18% sludge in Experiment 1), together with the protein absorption of sludge samples (Lipstein et al, 1982), confirm that sludge protein was almost as digestible as conventional protein sources. She of Internal Organs and Fatness. It is assumed that activated sludge may contain potentially toxic materials such as heavy metals, pesticides, and other undesirable
SLUDGE AS FEEDSTUFF FOR BROILERS
1217
chicks. Poultry Sci. 62:2247-2254. Beszedits, S., 1981. Utilizing waste activated sludge for animal feeding. Feedstuffs, April 6:25—26. Damron, B. L., H. R. Wilson, M. F. Hall, W. L. Johnson, O. Osuna, R. L. Suber, and G. T. Edds, 1982. Effects of feeding dried municipal sludge to broiler-type chicks and laying hens. Poultry Sci. 61:1073-1081. Firth, J. A., and B. C. Johnson, 1955. Sewage sludge as a feed ingredient for swine and poultry. J. Agric. FoodChem. 3:795-796. Johnson, Z. J., and B. L. Damron, 1980. Performance of White Leghorn hens fed various levels of municipal sludge or selected minerals. Poultry Sci. 59:1565. (Abstr.) Kienholz, E. W., G. M. Ward, D. E. Johnson, J. Baxter, G. Braude, and G. Stern. 1979. Metropolitan Denver sewage sludge fed to feedlot steers. J. Anim. Sci. 4 8 : 7 3 5 - 7 4 1 . Kienholz, E. W„ N.S.K. Young, J. L. Smith, and C. A. Whiteman, 1981. Reduced vitamin A levels of chicks fed anaerobically digested sewage sludge. Poultry Sci. 60:884-886. Lipstein, B., and S. Hurwitz, 1981. The nutritional value of sewage-grown, alum-flocculated Micractinium algae in broiler and layer diets. Poultry Sci. 60:2628-2638. Lipstein, B., and S. Hurwitz, 1983. The nutritional value of sewage-grown samples of Chlorella and Micractinium in broiler diets. Poultry Sci. 62: 1254-1260. Lipstein, B., S. Kary, and S. Hurwitz, 1982. The nutritional value of activated sludge for poultry. Nutr. Rep. Int. 25:829-836. National Research Council, 1977. Nutrient Requirements of Poultry. 1. Nutrient Requirements of Domestic Animals. 7th ed. Natl. Acad. Sci., Washington, DC. Pillai, S. C, E. G. Srinath, M. L. Mathur, P.M.N. ACKNOWLEDGMENTS Naidu, and P. G. Muthanna, 1967. Activated This study was supported in part by the sludge as a feed supplement for poultry. Water Environmental Protection Service, Ministry of Waste Treat. April:316-322. the Interior, Israel, and in part by the Egg and Smith, G. S., and H. E. Kiesling, 1977. Sewage solids as a feed supplement for ruminants: Nutritive Poultry Marketing Board. value, concerns for toxicants, and energy aspects. The authors gratefully acknowledge the 4th Annu. New Mexico State Univ. Conf. on helpful cooperation of T. Roth of the WasteEnergy, Las Cruces, NM, February 7—8. Smith, G. S., and C. R. Staples, 1976. Heavy metals in water and Water Quality Division, Tahal, and of rats fed sewage solids. J. Anim. Sci. 43:233. M. Ben Mosheh and J. Nissenbaum for their Wong, W. H., and K. L. Leung, 1979. Sewage sludge able technical assistance. and seaweed (Ulva sp.) as supplementary feed for chicks. Environ. Pollut. 1 3 : 9 3 - 1 0 1 . Yanai, S., S. Mokady, and Z. Berk, 1977. Algae grown REFERENCES on waste water as a source of protein; toxicologBartov, T., N. Pasternak, and N. Lisker, 1982. The ical and nutritional aspects. Proc. 11th FEBS nutritional value of moldy grains for broiler Mtg., Copenhagen. constituents (Smith and Kiesling, 1977; Damron et al, 1982). It is known that these adverse factors usually depress appetite and often affect the size of internal organs (Yanai et al., 1977; Kienholz et al., 1979). As mentioned before, appetite was not affected; rather, the reverse situation prevailed. Moreover, in the two trials, the sizes of the kidney, spleen, and pancreas were not affected by sludge-containing diets, and no gross abnormalities were observed in the external appearance of the examined organs (Tables 2 and 3). With regard to liver size, no differences were observed during the starter period, the most critical age for dietary damage. However, in the finisher period a definite trend appeared for a graded increase in the liver with increasing levels of sludge in the diet. This is in agreement with the results of Smith and Staples (1976), who reported that the sizes of the organs of rats were not affected by sludge-containing diets, and found no symptoms of toxicity except for the livers, which were enlarged by 10 and 25% sludge-containing diets. Unaffected appetite and a lack of difference in the sizes of examined organs appear to indicate that the toxic elements in activated sludge may be of lower quantity or lesser activity than usually presumed.