Evaluation of Activated Sludge as a Feedstuff in Layer Diets1

Evaluation of Activated Sludge as a Feedstuff in Layer Diets1

Evaluation of Activated Sludge as a Feedstuff in Layer Diets1 BIANKA LIPSTEIN,2 EDNA NACHTOMI,3 S. KARY,4 and EUGENIA ALUMOT3 Departments of Poultry S...

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Evaluation of Activated Sludge as a Feedstuff in Layer Diets1 BIANKA LIPSTEIN,2 EDNA NACHTOMI,3 S. KARY,4 and EUGENIA ALUMOT3 Departments of Poultry Science and Animal Nutrition, Agricultural Research Organization, The Volcani Center, Bet Dagan 50250, Israel and Tahal, Water Planning for Israel, Tel Aviv, Israel (Received for publication March 4, 1985)

INTRODUCTION

showed that activated sludge, at a level up to 12% in chick and broiler diets, seems to be a suitable protein supplement with no adverse effect on growth performance (Lipstein and Kary, 1984). The aim of the present study was to evaluate the nutritional value of activated sludge for laying hens and to assess its influence on performance and mineral content of eggs.

The possibility of using activated sludge from sewage water treatment plants as a feed supplement in place of the conventional feedstuffs used in poultry feeding appears to be potentially of great importance (Pillai et al, 1967; Wong and Leung, 1979; Johnson and Damron, 1980; Beszedits, 1981; Damron et al, 1982; Lipstein et al, 1982; Lipstein and Kary, 1984). The activated sludge is rich in protein and would contribute significant amounts of phosphorus and calcium to the diet (Pillai et al, 1967; Damron et al, 1982; Lipstein et al, 1982; Lipstein and Kary, 1984). It has been found that the mineral composition of local activated sludge does not prevent its use as a feed ingredient for young birds (Nachtomi et al, 1984). Although the amounts of iron and zinc consumed by chicks fed a diet containing 20% sludge were larger than those consumed by control chicks, the minerals were found to be excreted. Our previous studies

MATERIALS AND METHODS Materials. The two activated sludge samples used in this study originated from the Dan region wastewater project-demonstration plant (Experiment 1) and the Herzliya wastewater treatment plant (Experiment 2) and were referred to in our previous study as Samples B and E, respectively (Lipstein et al, 1982). The two samples were dried in drying beds to ca. 86 to 88% solids content and sterilized by gamma radiation at an intensity of 1.50 Mrad of 60 Co. Feeding Experiments. The experiments were carried out with Leghorn Rhode Island Red cross-bred hens housed in individual cages. When egg production was at its peak, the hens were chosen on the basis of their individual daily egg records, egg weight, and body weight. The selected birds were divided into 12 groups of 12 hens each, and four groups were allotted

1 Contribution from the Agricultural Research Organization, The Volcani Center, Bet Dagan, Israel; No. 1360-E, 1985 series. 2 Department of Poultry Science. 3 Department of Animal Nutrition. "Tahal, Water Planning for Israel.

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ABSTRACT The nutritional value of two different local activated sludge samples was assessed in two experiments with laying hens. Diets formulated by computer in a linear programming system contained 10 and 20% sludge in Experiment 1, and 7.5% and 15% sludge in Experiment 2. The inclusion of up to 20% sludge in diets in the first trial, and up to 7.5% sludge in the second, had no adverse effect on production rate, egg weight, feed intake, feed conversion, or shell egg density. However, in Experiment 2, 15% sludge in the diet reduced production rate and egg weight, which resulted in decreased feed conversion. There were no differences in the mineral content of eggs, the degree of fatness, or the size of the liver between control hens and those fed the 20% sludge-containing diet. The results demonstrate the potential nutritional value of activated sludge in laying hen diets. (Key words: sludge, performance of laying hens, minerals in eggs) 1986 Poultry Science 6 5 : 9 2 - 9 7

SLUDGE IN LAYER DIETS

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TABLE 1. Composition of layer diets (%) Experiment 2

Experiment 1 Treatment no.

2

1

Composition, calculated Crude protein, % ME,2 kcal/kg SAA,3 % Lysine, % Calcium, % Phosphorus, %

10.0 17.4 63.2 1.70

15.8 72.7 1.36 1.69 7.74

20.0 19.1 53.8 1.99

7.5

6.01

4.28

16.0 72.8 1.25 1.69 7.50

.14

.14

.14

.16

.65

.65

.65

.65

13.85 2850 .535 .635 3.43

.84

13.82 2850 .532 .664 3.43

.58

.58

13.77 2850 .529 .695 3.43 .58

3

13.83 2853 .539 .603 3.44

11.2 69.5 3.00 1.20 6.80 .15 .04 .65

13.84 2854 .533 .590 3.42

.58

.58

15.0 6.2

66.5 4.70 .72

6.02 .15 .08 .65

13.89 2859 .538 .588 3.44 .58

'As percentage of diet: sodium chloride, .30; vitamin mix, .25; mineral mix, .10. The composition of the latter two are given by Bartov et al. (1971). 2

ME = Metabolizable energy.

3

SAA = Sulphur amino acids.

to each of the three treatments. Table 1 shows the composition of diets formulated by linear programming based on amino acid requirements as calculated by Model B (Hurwitz and Bornstein, 197 3, 1977) for hens weighing 1,900 g, gaining weight at .5 g/day, and having an egg

production of 83% of eggs averaging 59 g. The experimental diets were fed for 78 and 61 days in Experiments 1 and 2, respectively. Individual body weights were measured at the beginning of the experiment and at monthly intervals. Individual egg production

TABLE 2. Performance of laying hens fed graded levels of activated sludge during a 78-day period (Experiment 1)\ Sludge in diet, %

0

10

20

Treatment no.

1

2

3

Production rate, % Initial egg weight, g Average egg weight, g Egg weight change, g3 Egg mass, g/day Initial body weight, g Weight gain, g Feed intake, g/day Feed conversion, g/egg Feed efficiency, g/g egg mass Shell density, mg/cm 2 4

82.1 59.7 62.7

81.9 59.0 62.3

79.9 59.5 64.1

5.5

5.7

6.3

51.5 1706

51.1 1731

51.2 1712

143 110 134

125 112 136

73 114 143

2.13 77.8

2.19 75.9

1

Average of four replicates of 12 hens.

2

SE = Standard error calculated from error mean square of analysis of variance.

3

Difference between pre-experimental egg weight and that after a 78-day period.

4

Shell weight per surface area.

2.24 74.8

SE2

1.84 .51 .54 .39

1.36 14.05 11.33 1.32 2.27 .04

1.02

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Activated sludge Soybean meal Sorghum grain Soybean oil soapstock Dicalcium phosphate Limestone DL-Methionine L-Lysine Constant ingredients1

2

1

3

94

LIPSTEINETAL.

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records were kept daily throughout the experiment. Individual egg weights were recorded for 3 consecutive days every month and feed consumption was determined on a group basis for 1-month periods. Egg mass for any experimental period was obtained from the average of egg weights at the beginning and end of the period and multiplied by the egg production rate. Feed conversion expressed as g feed/g egg was then calculated from feed consumption and egg mass data and was also expressed as grams feed/egg. These calculations, as well as analyses on a monthly basis and for the entire experiment, were performed by an especially written computer program, which affects standard analysis of variance and the Multiple Range Test (S. Hurwitz, unpublished). The influence of sludge on mineral content in the egg was studied by analyzing 16 eggs from each control and 20%-sludge treatment at the end of Experiment 1. The effect of sludge on degree of carcass fatness and on liver size in Experiment 1 was evaluated at the end of the experimental period. Eight hens per treatment were killed in order to determine the quantity of abdominal fat and liver size expressed as percentage of body weight. Chemical Analyses. Trace elements were determined by atomic absorption spectrometry (Perkin-Elmer, model 2380). Lead was determined by flameless AAS (Perkin-Elmer, model 5000, with HGA 500 graphite furnace and deuterium background corrector), according to Banin et al. (1981). Calcium was determined by automatic titration (Precision Scientific) and phosphorus according to Gomori (1942). Determination of minerals in eggs was done on lyophilized pooled samples of two eggs without shells. Eight samples were examined of each of the control eggs and the eggs from hens fed 20% sludge in the diet. Digestion was by dry ashing at 500 C or wet digestion with H N 0 3 and HCIO4 (5:1) on fat-free samples. The purpose of the first experiment was to determine the effect of activated sludge Sample A at 10 and 20% as a source of protein, phosphorus, and calcium for laying hens and to assess the influence of the activated sludge on performance, mineral content of eggs, and some of the carcass quality traits of laying hens. The second experiment, in which another sludge, Sample B, had been used, was conducted in the same way as the first, except that dietary levels were 7.5 and 15%.

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SLUDGE IN LAYER DIETS RESULTS Experiment 1. Results presented in Table 2 show no significant differences in p r o d u c t i o n rate, egg weight, b o d y weight, o r egg shell density between controls a n d laying hens receiving any of t h e diets containing activated sludge. T h e r e were very small differences in feed conversion a n d feed efficiency b e t w e e n controls and laying hens fed 20%-sludgecontaining diets.

show t h a t w i t h u p t o 20% sludge in diets t h e r e were no significant differences in any of t h e parameters examined between e x p e r i m e n t a l diets and c o n t r o l . In E x p e r i m e n t 2, 7.5% sludge in diets p r o d u c e d no significant differences from t h e control. T h e results of this experim e n t are in agreement with D a m r o n et al. ( 1 9 8 2 ) , w h o f o u n d t h a t h e n p r o d u c t i o n criteria were n o t influenced b y t h e addition of u p t o 7% sludge in t h e diet. T h e different effects of t h e high levels of t h e t w o sludge samples on hen p e r f o r m a n c e w e r e probably caused b y t h e different nutritional values of these samples. In spite of t h e relatively small difference in total p r o t e i n (28 and 32%, respectively), there were considerable variations in nitrogen absorption (Sample A, 4 9 % and Sample B, 79%) a n d m e t a b o l i z a b l e energy c o n t e n t (Sample A, 1 7 6 1 kcal/kg, almost two-fold higher t h a n t h a t of Sample B, 9 3 4 kcal/kg) as described in a previous s t u d y (Lipstein et al, 1 9 8 2 ) . Due t o these differences, t h e c o m p o s i t i o n of t h e diets containing t h e high level of sludge was different (Table 1). In t h e first experiment, t h e sludge sample was s u b s t i t u t e d for sorghum grain. In t h e second experiment, t h e other sludge sample replaced a b o u t two-thirds soybean m e a l a n d onethird sorghum grain, according t o c o m p u t e r i z e d linear programming. These figures indicate t h a t t h e chemical c o m p o s i t i o n of t h e sludge as well as its biological evaluation did not, in t h e m selves, provide a reliable estimate for t h e nutritional value.

DISCUSSION

It should b e n o t e d that, because of t h e low metabolizable energy c o n t e n t of t h e sludge sample used in Trial 2, t h e need for s o y b e a n oil soapstock in t h e diet increased w i t h t h e rise in sludge level. In b o t h trials, t h e need for dical-

T h e results of hen p e r f o r m a n c e (Tables 2 and 5) indicate t h a t t h e local activated sludge m a y be a d d e d u p t o a certain limit t o diets w i t h n o adverse effect. T h e results of E x p e r i m e n t 1

TABLE 4. Effect of sludge-containing diets on abdominal fat and size of the liver in hens (Experiment l)1 Sludge in diet

Abdominal fat2

Liver

3.4 ± .26 3.5 ± .42 3.4 ± .18

2.5 ± .12 2.1 ± .09 2.3 ± .17

(%)

Liver dry matter

(%)

0 10 20 1

Average of eight hens in each treatment.

2

Expressed as percent of body weight.

3

Standard error calculated from error mean square of analysis of variance.

32.6 ± 2.8 30.2 ± 1.9 29.3 ± 1.5

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T h e mineral c o n t e n t of t h e sludge sample used in this e x p e r i m e n t was: m a c r o e l e m e n t s (% dry m a t t e r ) P, 1.6; Ca, 8 . 5 ; microelements ( p p m / d r y w t ) Fe* 7 0 0 0 ; Z n 1 5 8 6 ; Cu, 2 1 0 ; Mn, 1 2 8 ; Cd, . 9 3 ; a n d Pb, . 4 7 . Mineral concentrat i o n of t h e eggs did n o t indicate any difference b e t w e e n control eggs a n d eggs from hens fed 20% sludge in their diet (Table 3). T h e degree of fatness and t h e size of t h e liver were n o t affected significantly b y t h e sludge s u p p l e m e n t (Table 4 ) . Experiment 2. T h e results from this trial (Table 5) d o n o t show any differences, except in t h e case of feed efficiency, b e t w e e n control a n d laying h e n s receiving u p t o 7.5% sludge in t h e diets. T h e inclusion of 15% sludge in a diet caused a decrease in t h e p r o d u c t i o n rate, egg weight, and weight gain. This resulted in a significant decrease in feed conversion and feed efficiency; however, feed intake was similar in all t r e a t m e n t s .

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LIPSTEIN ET AL. TABLE 5. Performance of laying hens fed graded levels of sludge during a 61-day period (Experiment 2)1

Sludge in diet, %

7.5

Treatment no.

15.0 3

81.4a 58.1 61.2 4.1A 49.7A 1708 90A 105 129 A 2.10A 76.4

79.3 a 58.3 60.8

3.6 A 48.1A 1700 93A 108 136AB 2.24 B 77.8

72.8b 58.7 58.9 1.1B 42.8B 1710 39 B 108 149 B 2.53B 77.9

abAB ' ' ' Any two mean values not followed by a common letter differ significantly (capital letter, P<.01; lower case letter, P<.05). 1 Average of four replicates of 12 laying hens each. 2

Difference between pre-experimental egg weight and that after a 61-day period.

3

Shell weight per surface area.

cium phosphate in the diets decreased considerably with the rise in sludge level in the diets. Calculation of the mineral content of the diet containing 20% sludge showed that it did not exceed the tolerance level established by the National Research Council (1977) (except iron), which is in agreement with our previous study (Nachtomi et al, 1984). As to mineral content of the eggs (Table 3), there was no difference between eggs from hens receiving a sludge-containing diet and the control diet, which is in agreement with Johnson and Damron (1980) and Damron et al. (1982). This lack of higher levels of mineral content of eggs from experimental hens may be explained by a very low mineral retention in the body, as shown in our previous study (Nachtomi et al., 1984), in which higher levels of minerals consumed by chicks fed sludge-containing diets were almost entirely excreted and thus were not retained in the animal body. ACKNOWLEDGMENTS The authors gratefully acknowledge the helpful cooperation of Y. Navrot, Hebrew University of Jerusalem, Faculty of Agriculture, Rehovot, for the lead determinations; and Miriam Ben-Mosheh, S. Krasner, and Judith Nissenbaum for their able technical assistance.

REFERENCES Banin, A., I. Navrot, Y. Noi, and D. Ioles, 1981. Accumulation of heavy metals in arid-zone soils irrigated with treated sewage effluents and their uptake by Rhodes grass. J. Environ. Qual. 10: 536-540. Bartov, I., S. Bornstein, and P. Budowski, 1971. Variability of cholesterol concentration in plasma and egg yolks of hens and evaluation of the effect of some dietary oils. Poultry Sci. 50:1357-1364. Beszedits, S., 1981. Utilizing waste activated sludge for animal feeding. Feedstuffs 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. Gomori, G., 1942. A modification of the colorimetric phosphorus determination for use with photometric colorimeter. J. Lab. Clin. Med. 27:7584— 7592. Hurwitz, S., and S. Bornstein, 1973. The protein and amino acid requirements of laying hens: suggested models for calculation. Poultry Sci. 52: 1124-1134. Hurwitz, S., and S. Bornstein, 1977. The protein and amino acid requirements of laying hens: experimental evaluation of the models of calculation. 1. Application of two models under various conditions. Poultry Sci. 56:969-978. Johnson, W. L., and B. L. Damron, 1980. Performance of White Leghorn hens fed various levels of municipal sludge or selected minerals. Poultry Sci. 59:1565. (Abstr.) Lipstein, B., and S. Kary, 1984. Evaluation of acti-

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Production rate, % Initial egg weight, g Average egg weight, g Egg weight change, g2 Egg mass, g/day Initial body weight, g Weight gain, g Feed intake, g/day Feed conversion, g/egg Feed efficiency, g/g egg mass Shell density, rag/cm2 3

SLUDGE IN LAYER DIETS vated sludge as feedstuff in broiler diets. Poultry Sci. 63:1213-1217. Lipstein, B., S. Kary, and S. Hurwitz, 1982. The nutritional value of activated sludge for poultry. Nutr. Rep. Int. 25:829-836. Nachtomi, E., B. Lipstein, B. Iosif, and E. Alumot, 1984. Retention of minerals from activated sludge in growing chicks. Nutr. Rep. Int. 29: 511-517. National Research Council, 1977. Nutrient Require-

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ments 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. Naidu, and P. G. Muthanna, 1967. Activated sludge as a feed supplement for poultry. Water Waste Treat. April:316-322. Wong, W. H., and K. L. Leung, 1979. Sewage sludge and seaweed (Ulva sp.) as supplementary feed for chicks. Environ. Pollut. 1 3 : 9 3 - 1 0 1 .

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