Replacement value of some household wastes as energy substitutes in low-cost diets for rearing catfish in South-Western Nigeria

Bioresource Technology 37 ( 1991 ) 197-203

Replacement Value of Some Household Wastes as Energy Substitutes in Low-Cost Diets for Rearing Catfish in South-Western Nigeria Oyedapo A. Fagbenro & Ifeoluwa A. Arowosoge Department of Fisheries and Wildlife, Federal University of Technology, PMB 704, Akure, Nigeria (Received 6 April 1990; revised version received 3 October 1990; accepted 15 October 1990)

Abstract

Trials on growth performance, nutrient utilization and digestibility, as well as carcass composition, were conducted on the clariid ca~sh, Clarias isheriensis (Sydenham, 1980) to evaluate the replacement value of peels of cassava, yam and plantain, and maize chaff, as substitutes for maize in low-cost fish diets. Triplicate groups of C. isheriensi fingerlings (mean weight, 34.72g) were fed for 84 days with 37% crude-protein diets containing each of the energy substitutes at 25% inclusion level The maize chaff diet produced the greatest body weight increases and best growth performance as well as the best feed utilization. This was followed by yam peel, plantain peel and cassava peel diets in decreasing order. Apparent nutrient digestibility coefficients of the experimental diets followed a similar trend. Only the maize chaff diet compared favourably with the control (yellow maize) diet with regard to nutrient utilization and digestibility, which indicated that maize chaff had the greatest potential and desirability as a replacement for yellow maize as the energy source in low-cost diets for C. isheriensis. Key words: Household wastes, dietary energy, substitutes, low-cost diet, growth, feed efficiency, digestibility, catfish. INTRODUCTION Recently, the cost of animal (fish and livestock) feeds has followed an upward trend, due largely to a steep rise in the purchase price of feed ingre-

dients, particularly cereals, legumes and protein concentrates, which are conventionally used for animal-feed preparation in Nigeria and other developing countries. The prohibitive cost of these ingredients is attributed to their alternative uses, especially as human food. The competition thus created between man and other animals is further compounded by inadequate local production of these feedstuffs. One approach that has been developed to reduce the cost of animal feeds is the use of farm wastes, agro-industrial by-products or household wastes, either as direct feeds or incorporated as components of feeds along with other ingredients rich in carbohydrates, proteins, fats and minerals (Aletor, 1986; Fagbenro & Arowosoge, 1988). Dietary energy needs of fish are supplied by fats, proteins and carbohydrates, of which carbohydrates are the cheapest and most abundant source. Energy needs required for body maintenance and voluntary activity must be satisfied before growth can occur. Fish preferentially use protein and fat for energy, and carbohydrates sparingly; however carbohydrates are used more efficiently by warm water fish than by cold water fish species (Watanabe & Takashim, 1977; NRC, 1983). The ability of fish to utilize carbohydrates as an energy source gives rise to the 'protein sparing effect' whereby the fish is allowed to conserve and use the protein component of diets to meet amino-acid requirements for growth. This results in better nitrogen (protein) retention which potentially reduces costs. The important effects of protein sparing nutrients (carbohydrates and fats) to fish growth have been well studied and the protein-to-energy ratios in production diets for

197 Bioresource Technology 0960-8524/91/S03.50 © 1991 Elsevier Science Publishers Ltd, England. Printed in Great Britain

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various cultured fish species have been established within a range of 7.3-11.6 kcal/g protein (Lee & Putman, 1973; Mazid et al., 1979; Takeuchi et al., 1979; Winfree & Stickney, 1981; Mgbenka, 1983; Machiels & Henken, 1985; Reis et al., 1988). Carbohydrates (energy sources) being cheaper and more readily available than protein sources, would be economical if incorporated into animal feeds without compromising growth and feed conversion efficiency. Dietary energy requirements are the most neglected area of fish nutrition (Lovell, 1989) despite its relevance to fish growth. Cassava peel (CP), yam peel (YP), plantain peel (PP) and maize chaff (MC) are produced in large quantities as wastes by most households, hotels and restaurants in Nigeria. Interest in the utilization of these household wastes in fish diets is recent and results of preliminary evaluation studies are limited (Faturoti & Akinbote, 1986; Mgbenka & Agua, 1989). This study was therefore designed to investigate the effects of replacing yellow maize (the traditional energy source in animal diets) with cassava peels, yam peels, plantain peels and maize chaff compounded into practical diets, on the growth, nutrient utilization and digestibility, as well as carcass composition, of the dwarf African mud catfish, Clarias isheriensis (Family Clariidae). It is hoped that a successful replacement with these energy substitutes will not only create an avenue for the utilization of these hitherto waste by-products of the human food industry, but also reduce environmental pollution which is currently engaging the attention of public health workers and ecologists in Nigeria. C. isheriensis was selected as the experimental fish because of its ominivorous dietary habits, ability to survive under adverse water-quality conditions, and its capability of efficiently converting low-quality inexpensive food materials into highquality fish protein (Fagbenro & Syndenham, 1988; Fagbenro, 1990a).

METHODS

Peels of cassava, yam, plantain and maize chaff were obtained from waste dumps of the Main Cafeteria, Federal University of Technology, Akure, washed and oven-dried at 60°C for 48 h. The peels were each milled into powder using a split-disc grinder. A control diet was then prepared with yellow maize and other ingredients to compound a 37% crude protein diet (deter-

mined dietary protein requirement of C. bsheriensis (Fagbenro, 1990b). Four experimental diets (37% crude protein component) were also prepared incorporating the energy substitutes at 25% inclusion level (dry weight), thus having 5% of the yellow maize (Table 1). Proximate analyses of all diets (Table 2) were conducted in triplicate using the AOAC (1980) methods. C. isheriensis fingerlings with a mean weight of 28.48 g were obtained from a private fish farm and transported for 2.5 h to the Akure Fish Farm in an aerated and insulated fish-holding box. The fingerlings were later transferred into aerated concrete tanks (5 × 4.5 × 1.5 m) and acclimated for two weeks after a prophylactic treatment with 3 ppm of potassium permanganate. They were fed with a complete diet (37% crude protein level) during this period. At the commencement of this study, the fingerlings were randomly sorted into groups of 20 (mean weight, 34.72 g). Triplicate random groups of 20 fingerlings per dietary treatment were then fed ad libitum each of the prepared diets at 3% of their wet body weight, inside fifteen 120-1itre capacity (75 x 40 × 40 cm) glass aquaria. Feeding was done twice daily for 84 days (12 weeks). Control weighings of experimental fish were made in weekly batches and diet rations were adjusted accordingly with weight gains. Fresh spring water was supplied to the aquaria every 48 h after stale water had been drained out and feed residues filtered off. Continuous aeration was provided in all aquaria. Both pH and dissolved oxygen concentration (DO2) of water in all

T a b l e 1. G r o s s c o m p o s i t i o n of e x p e r i m e n t a l diets ( g / 1 0 0 g diet)

Ingredients

Diets Cassava Yam Plantain Maize Yellow peel peel peel chaff maize (CP) (YP) (PP) (Me) (YM)"

Yellow m a i z e C a s s a v a peel Yam peel P l a n t a i n peel M a i z e chaff B l o o d meal Shrimp heads Palm oil B o n e meal O y s t e r shell NaCI Cellulose (binder) C h r o m i c oxide " C o n t r o l diet.

5 25 ---25 30 8'50 3 2 0-50 0-50 0"50

5 5 . . . 25 --25 --25 25 30 30 8"50 8'50 3 3 2 2 0.50 0"50 0.50 0.50 0.50 0.50

5

30

. --25 25 30 8-50 3 2 0"50 0"50 0.50

---25 30 8.50 3 2 0'50 0.50 0.50

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Household wastes as food for catfish

Table 2. Proximatecompositionof experimentaldiets (% weight)(mean of triplicateanalysis) Nutrients

Moisture Crude protein Crude fat Crude fibre Ash" Nitrogen-free extracts i,

Control diet (YM) 11-95 _+0.03 37-17 _+0.04 8.44 + 0"05 4-11 _+0"04 3"94 + 0'02 34.39

Experimental diets (7 ~ 11.77 + 0"06 36.64 + 0.01 6-08 _+0-02 9-08 + 0"06 1.97 _+0.01 34-56

YP

PP

11.83 + 0.07 37.28 + 0.04 6' 12 _+0'01 7.18 _+0"04 2"22 + 0'02 35.37

11.59 _+0.08 36'92 + 0-01 6.15 + 0"02 4.94 _+0-02 1-16 _+0"01 39.24

MC 11'64 _+0.05 37"05 _+0"04 6"14 + 0"03 6"32 _+0"03 1-21 _+0'01 37.64

"Contains the silica component. hObtained by difference. Table 3. Fish survival and water quality" monitored in all dietary treatments during the 84-day experiment Dietary treatments YM Initial number of fish Final number of fish Survival (%) Mean water temperature (°C) Mean pH

CP

YP

PP

MC

60 60 100 27.5 _+0"0

60 56 93.33 27.5 + 0.0

60 60 100 27.5 + 0.0

60 58 100 28.0 _+0.1

60 60 100 27.5 + 0"1

8-0 + 0.2

7-7 _+(I.3

8.0 + 0.2

8-3 _+0.4

8-4 _+0.3

"Mean of 12 readings.

aquaria were routinely monitored as well as mortality in all treatments (Table 3). Based on earlier observations that C. isheriensis started defecating at about 8 h after feeding (Fagbenro, 1990b), experimental fish were removed, anaesthetized with 2% quinaldine and stripped for faeces accordingly. Faecal samples collected for each treatment were pooled and oven-dried at 60°C for 24h. Fish were reintroduced after recovery to the appropriate aquarium. Faecal samples thus collected were analysed for the 0-50% chromic oxide ( C r 2 0 3 ) content using the method of Furukawa and Tsukahara (1966), and the apparent nutrient digestibility coefficient of each dietary treatment was determined by the formula: Apparent digestibility coefficient (ADC)(%)-100 -

% C r 2 0 3 in feed 100 x %Cr203 in faeces

x % nutrient_ in faeces/ % nutrient in feed ] Six fingerlings were taken at the start of the feeding trial and six fish were also randomly selected from each treatment at the end of the feeding trial for proximate analysis following

AOAC (1980) methods. The indices used to evaluate growth performance and nutrient utilization include the following: Average daily growth (ADG)(g/fish/day)=

-

Final mean body weight Initial mean body weight (g) Culture period (days)

Specific growth rate (SGR)(% per day) -In W2- In W1 × 100 T~ - T1 where W, = weight of fish at time TI, and W2 = weight of fish at time T2. Protein efficiency ratio (PER)= Weight gain by fish (g) Protein intake (g) Feed conversion ratio (FCR)= Dry weight of food fed (g) Live weight gain by fish (g)

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Data collected on growth performance and nutrient utilization were subjected to analysis of variance (ANOVA) followed by the least significant difference (LSD) test for comparisons among treatment means.

Growth performance There was no significant difference (P>0.05) among the initial mean body weights of experimental fish in all dietary treatments. The final mean body weights were however significantly different (P<0"05) (Table 3). The best growth performance (represented by average daily growth (ADG) and specific growth rate (SGR) values) was obtained from the MC diet, while the poorest was obtained with the CP diet (Table 4). However, in all the energy substituted diets (CP, YP, PP and MC), growth performance was significantly (P<0"05) lower than in the control (YM) dietary treatment.

RESULTS

Proximate composition of diets The proportion of nutrients (Table 2) showed that the crude protein content of the control (YM) diet was 37.17% while that of the experimental diets ranged between 36.64 and 37.28%. Crude fat content was highest in the YM diet at 8.44%; others being similar at between 6.08 and 6.15%. Nitrogen-free extracts (obtained by difference) were also similar for all diets, except for the plantain peel (PP) diet with 39.24%. Crude fibre content was highest in the cassava peel (CP) diet at 9.08%, while the ash content was highest in the YM diet.

Nutrient utilization and digestibility Feed conversion ratio (FCR) values were good in all dietary treatments, the best value being obtained with the MC diet. The protein efficiency ratio (PER) very much followed the same pattern as weight gain values (Table 4) and revealed that fish fed on the experimental diets performed significantly (P < 0"05) poorer than those on the control diet. Apparent digestibility coefficients (Table 5) showed that nitrogen-free extractives were well digested on all diets, although the coefficient was highest for the control diet and least for the cassava peel diet. Differences were not significantly different (P > 0"05).

Fish survival and weight gain All fish fed actively and appeared healthy in all dietary treatments. Mortality occurred only in the CP diet and was low (Table 3). Mean weight gain by fish and % weight gain over the 84-day feeding period on maize chaff (MC) diet was the highest among the experimental diets (Table 4).

Table 4. G r o w t h p e r f o r m a n c e and f e e d utilization o f Clarias isheriensis fed the e x p e r i m e n t a l diets for 84 days Parameters

CP

Initial m e a n b o d y weight (g) Final m e a n b o d y weight (g) Total m e a n weight gain (g) % weight gain Average daily weight gain ( A D G ) (g/fish/day) Specific g r o w t h rate (SGR, % p e r day) F e e d c o n v e r s i o n ratio (FCR) P r o t e i n efficiency ratio (PER)

34.30 57.34 23.04 67"17 0.27

YB a d d d a

34.70 ~ 65"42 ' 30'72 ' 88'53 ' 0"37 '

PP 35"00 ~ 61"88 ' 26"88 ' 76"80" 0.32 "

MC 34"60 71"72 37"12 107"28 0.44

YM a h b h b

35"00 ~ 77"24 ~ 42"24 a 120"69" 0"50 ~

0"266 e

0.328 '

0"295 d

0"377 b

0"409 a

1.61 ~ 1.69 b

1.38 b 1"94 b

1"57 a 1"73 b

1"17 b,, 2"31 a

1"06 ~ 2"54 ~

MC

YM

,,b.,.,d, e M e a n s without c o m m o n s u p e r s c r i p t s in h o r i z o n t a l rows are significantly different ( P < 0.05).

Table 5. A p p a r e n t digestibility coefficient o f the e x p e r i m e n t a l diets fed to Clarias isheriensis CP Dry matter Protein Fat Fibre N i t r o g e n - f r e e extracts

70.12' 70.47 " 80.24 b 38"96 b 60.57 d

YP 68"53 72.05 70.32 30"45 66"43

PP c,d c '~ '~ '~

65"74 68.67 80.41 27"52 62"75

d c b ' ,,d

a, b,c,d M e a n s w i t h o u t c o m m o n s u p e r s c r i p t s in h o r i z o n t a l r o w s are significantly different ( P < 0.05).

83"89 88.01 84"58 65"17 76 41

d b b ~ b

88"25 91"56 90"27 68"35 85"29

a a ~ a

°

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Household wastes as food for ca(fish

Table 6. Effect of dietary treatments on the body (whole fish) composition of Clarias isheriensis fingerlings" Dietary treatment

% Wet weight Moisture

CP YP PP MC YM Initial flesh

72.49 + 0.79 b 70.41 + 0"55 b 71"37 + 0"76b 70"38+0"40 b'' 68"67 + 0"60 ' 74.38 + 0"03 e

Crude protein

Crude fat

Ash

20.05 +0-69' 21"37 + 0"57 b 20"22 + 0"39 '~ 21"31 +0"65 h 23"23 + 0"61 e 18.40 + 0.05 d

3.12 +0.76 b.e 2"97 + 0'54 h 3'32 + 0'60 ~'e 2'93+0"71 h 2"18 + 0"76 ' 3"91 + 0"08 ~

4.31 +0.57 b 5"01 + 0'75 e 4"28 + 0'53 h 5.06+0.72 e 5"46 + 0"64e 3-34 + 0"11 '~

"Six fish/dietary treatment were analysed. h,, a,eMeans without a common superscript in vertical rows are significantlydifferent (P = 0"05).

Carcass composition T h e results of carcass analysis of catfish (Table 6) showed that all groups of fish showed increases (though not significantly so) in protein content over the initial protein content (prior to comm e n c e m e n t of the experiment).

DISCUSSION

Table 7. Proximate analysis of energy substitutes (% dry matter)a CP

Dry matter Crude protein Crude fibre Crude fat Total ash Nitrogen-freeextracts

YP

PP

27.9 17-7 18.4 5"6 11"2 9' 1 10.3 9"5 6.4 1-4 1.2 5'6 4-4 9-8 17.2 7 8 . 3 6 8 . 4 61'7

MC

YM

88.0 90.4 110-9 10"7 10.2 1.3 4.8 4-1 3.4 3.7 70.7 82.6

"Source: Oyenuga (1968). T h e incorporation of the different energy substitutes at the 25% level in the experimental diets had no effects on the protein content of the diets (Table 2) or on fish survival (Table 3), but weight gain and feed conversion indices (Table 4) showed remarkable differences between utilization of the different energy-substituted diets by C. isheriensis. This suggests that an o p t i m u m level of digestible energy is required for best conversion of feed into flesh. One of the factors that influences o p t i m u m protein levels in fish diets is the non-protein energy content of such diets that can spare protein energy for growth. For maximal growth of fish, protein synthesis and sufficient energy intake are needed. Values of growth performance and feed utilization indices (ADG, SGR, F C R and PER, Table 4) showed that the maize chaff (MC) diet gave the greatest body weight increases and also the best feed utilization, hence the best protein sparing, among the experimental diets. Lower values of fish growth and reduced feed utilization indices in the cassava peel (CP), yam peel (YP) and plantain peel (PP) diets must have been caused by their relatively lower nutrient digestibility coefficients (Table 5), particularly for the fibre component. As such, the trend of growth performance values (MC > Y P > P P > CP) recorded for C. isheriensis fed on the respective

energy substituted diets revealed the corresponding potentials of these energy sources in the diet. It seems therefore that the different energy sources are as acceptable to C. isheriensis as yellow maize. As the indirect m e t h o d of digestibility measurement used in this study assumed that faecal quality did not change over the period of collection (Furukawa, 1973), the digestibility coefficients of nutrients (Table 5) showed that only the M C diet c o m p a r e d favourably with the Y M (control) diet. This indicated that maize chaff might be the most preferred and highly desirable substitute energy source among the diets tested. Maize chaff (a by-product of the wet milling of maize) consists of the bran coating and maize germ, and approaches maize grain in nutritive value, except that it contains m o r e fibre (Table 7). With the equivalent high digestibility coefficients for fibre in Y M and M C diets (Table 5), it seems probable that soaking of the grain improved the digestibility of the fibre of the chaff, but according to Harris (1980), digestibilities of the fibre of dry maize grain and soaked grain were similarly high at 57 and 63% respectively. It has been established that 'digested' crude fibre of soaked maize yields as m u c h energy as digested starch (Popma, 1982; Mgbenka, 1983; Mangalik, 1986).

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Lovell (1980) reported that catfish eat to satisfy their metabolic energy requirement and, consequently, cease feeding when their calorie needs are met. The observation made that the body protein component of C. isheriensis was higher in all dietary treatments than that of the flesh prior to commencement of the feeding trial (Table 6) signified that protein retention was respectively higher in all dietary treatments, thus confirming a 37% dietary protein level as being adequate for optimum growth performance of C. isheriensis (Fagbenro, 1990b), its energy needs having been satisfied. As the African catfish does not accumulate a large amount of fat (Machiels, 1987), as the channel catfish does (Lovell, 1989), an optimum level of protein is required in its diet so that the fat content of the diet can be used mostly as an energy source, to spare protein. This proteinsparing action of fat was suspected to be responsible for the high body protein component of C. isheriensis (Table 6) compared with values reported for other fish species (Watanabe et al., 1977; Garling & Wilson, 1977; Murray et al., 1977; Winfree & Stickney, 1981; Mgbenka & Lovell, 1987; Reis etal., 1988). According to Henken et al. (1986), when the protein-to-energy ratio is lower than an optimum value, fish weight gain is less at a given protein level. On the other hand, excessively high proteinto-energy ratios increases fatness in fish and reduces dress-out percentage. The results of this study indicate that the dietary energy content in the 37% protein diets appears to be optimum for maximizing feed efficiency and minimizing body fat deposition only in the MC diet. Based on this, it is safe to conclude that maize chaff, rather than yam peel, cassava peel and plantain peel, could be a source of dietary energy as a substitute for yellow maize in low-cost diets for Clarias isheriensis. This study provides basic information on the utilization of household wastes as dietary energy substitutes for yellow maize in low-cost diets for tropical fishes, particularly C. isheriensis. The paucity of research on the use of these household wastes in fish nutrition provides few direct comparisons with other results. However, Faturoti and Akinbote (1986) reported that a 20% level of cassava peel incorporation (substituted for yellow maize) in low-cost diets resulted in optimal growth performance and nutrient utilization as well as satisfactory nutrient digestibility coefficients for the Nile tilapia, Oreochrornis niloticus (Trewavas, 1985). In a related study, Mgbenka

and Agua (1989) observed that the growth performance of the clariid catfish, Clarias gariepinus (Burchell, 1822), was lower on yam peel and plantain peel diets than on a wood fire-dried fish-waste diet, and attributed the poor growth to poor digestibility of both diets. REFERENCES Aletor, V. A. (1986). Agro-industrial by-products and wastes in livestock feeding; a review of prospects and problems. World Review of Animal Production, 22 (4), 35-41. AOAC (Association of Official Analytical Chemists) (1980). Official Methods of Analysis of the AOAC, 13th edn, ed. W. Hortwitz. AOC Washington, DC. Fagbenro, O. A. (1990a). Food composition and diegestive enzymes in the gut of pond-cultured Clarias isheriensis (Sydenham, 1980) (Siluriformes: Clariidae). Journal of Applied Ichthyology, 6, 91-8. Fagbenro, O. A. (1990b). Dietary protein requirements of Clarias isheriensis (Sydenham, 1980), (Osteichthyes: Siluriformes: Clariidae), fry and fingerlings. Journal of Applied Ichthyology, 6, 99-106. Fagbenro, O. A. & Arowosoge, A. I. (1988). Utilization of agricultural wastes and by-products in fish feeds production in Nigeria. Proceedings of the 6th Annual Conference of the Fisheries Society of Nigeria (FISCON), Fisheries Society of Nigeria, Lagos, pp. 121-30. Fagbenro, O. A. & Sydenham, D. H. J. (1988). Evaluation of Clarias isheriensis (Sydenham) under semi-intensive management in ponds. Aquaculture, 74, 287-91. Faturoti, E. O. & Akinbote, R. E. (1986). Growth responses and nutrient utilization in Oreochromis niloticus fed varying levels of dietary cassava peel. Nigerian Journal of Applied Fisheries and Hydrobiology, 1, 47-50. Furukawa, A. (1973). Diet in yellowtail culture. In Proceedings of the 1st International Conference on Aquaculture Nutrition, ed. K. S. Price Jr., W. S. Shaw & K. S. Danberg. University of Delaware, College of Marine Sciences, Newark, USA, pp. 85-104. Furukawa, A. & Tsukahara, H. (1966). On the acid digestion method for the determination of chromic oxide as index substance in the study of fish feeds. Bulletin of the Japanese Society of Science and Fisheries, 32, 502-6. Garling, D. L. & Wilson, R. P. (1977). Effects of dietary carbohydrates-to-lipid ratios on growth and body composition of fingerling channel catfish. Progressive Fish Culturist, 39 (1), 43-7. Harris, L. E. (1980). Feedstuffs. Fish Feed Technology. ADCP/REP/80/11, FAO, Rome, pp. 111-70. Henken, A. M., Machiels, M. A. M., Decker, W. & Hogendoorn, H. (1986). The effect of dietary protein and energy content on growth rate and feed utilization of the African catfish, Clarias gariepinus (Burchell, 1822). Aquaculture, 58, 55-74. Lee, D. J. & Putman, C. B. (1973). The response of rainbow trout to varying protein/energy ratios in test diets. Journal of Nutrition, 103,916-22. Lovell, R. T. (1980). Practical fish diets. In Fish Feed Technology. ADCP/REP/80/11, FAO, Rome, pp. 333-50. Lovell, R. T. (1989). Nutrition and Feeding Fish. Van Nostrand Reinhold Inc., USA. Machiels, M. A. M. (1987). A dynamic simulation model for growth of the African catfish, Clarias gariepinus (Burcheli, 1822). PhD Dissertation, Agricultural University, Wageningen, The Netherlands.

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