Total replacement of fish meal with animal protein

Aquaculture Research, 1998, 29, 275–280

Total replacement of fish meal with animal protein sources in Nile tilapia, Oreochromis niloticus (L.), feeds A-F M El-Sayed Oceanography Department, Faculty of Science, University of Alexandria, Alexandria, Egypt

Correspondence: Dr A-F M El-Sayed, Oceanography Department, Faculty of Science, University of Alexandria, Alexandria, Egypt

Abstract

The effects of total replacement of dietary fish meal (FM) with animal protein sources on the growth, feed efficiency and profit indices of Nile tilapia, Oreochromis niloticus (L.), were investigated. Shrimp meal (SM), blood meal (BM), meat and bone meal (MBM), BM 1 MBM mix and poultry by-product meal (PBM) replaced FM in six isonitrogenous (30% crude protein), isocaloric (400 kcal GE 100 g–1) diets. The diets were fed to O. niloticus fingerlings (12.5 g) to satiation twice a day for 150 days. The growth of fish fed SM, PBM and MBM was not significantly different from those fed the FM-based diet, while feed conversion and protein efficiency ratios were significantly retarded. Further reduction in fish performance was noticed when BM or BM 1 MBM replaced FM in the control diet. Cost–benefit analyses of the test diets indicated that these sources were economically superior to FM. The PBM-based diet produced higher carcass lipid than other diets. Fish fed SM, MBM and PBM diets had significantly higher ash contents (P , 0.05).

Introduction Tilapia have gained a great culture potential in many tropical and subtropical regions of the world. As a result, world production of cultured tilapia was tripled between 1984 and 1994 (FAO 1996). Since feed represents more than 50% of the operating costs of intensive culture, special attention has been given to tilapia nutrition with emphasis on protein requirements.

© 1998 Blackwell Science Ltd.

Despite the fact that fish meal (FM) is the single most expensive major ingredient in aquaculture feeds (Tacon 1993), it is widely used as the main source of dietary protein for most commercially farmed fish species. In the mean time, the shortage in world production of fish meal, coupled with increased demand and competition with terrestrial domestic animals, has further increased FM prices (FAO 1983). In the long-run, many developing countries may not be able to depend on FM as a protein source for aquafeeds. Therefore, it is necessary that other FM replacements are found. In this regard, many attempts have been made to partially or totally replace fish meal with lessexpensive protein sources in fish feeds. Most of terrestrial animal by-product meals, including poultry by-product meal (PBM), hydrolysed feather meal (HFM), blood meal (BM), and meat and bone meal (MBM) have high protein contents and favourable essential amino acid (EAA) profiles (NRC 1983). However, these feeds may be deficient in one or more of the EAAs, especially lysine, isoleucine and methionine (Tacon & Jackson 1985). Therefore, if the proper ratio of these byproducts is maintained in the diet, the quality of this diet is likely to improve (Davies, Williamson, Robinson & Bateson 1989). Animal by-product sources have been extensively studied as partial or total fish meal replacements in tilapia feeds (Falaye 1982; Tacon, Jauncey, Falaye, Pantah, MacGowen & Stafford 1983; Otubusin 1987; Davies et al. 1989; Bishop, Angus & Watts 1995; Rodriguez-Serna, Olvera-Novoa & CarmonaOsalde 1996). However, most of these studies were short-term, indoor and conducted in closed systems.

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Animal protein sources for Nile tilapia A-F M El-Sayed


Thus, it is not surprising that varying results have been reported. Therefore, the present study was conducted to evaluate a long-term biological and economical potential of shrimp meal (SM), BM, MBM, and PBM as total FM replacements in practical diets fed to Nile tilapia, Oreochromis niloticus (L.).

Materials and methods Nile tilapia fingerlings (mixed sexes) were obtained from Maryut Fish Farming Company, Alexandria, Egypt. Thirty fish (12.5 g initial weight) were stocked in 1.9 m3 outdoor concrete tanks (2 3 1.2 3 0.80 m) filled with 1.50 m3 brackish water (6 p.p.t.) obtained from West Nubaria Drain, near Alexandria. The tanks were provided with continuous aeration through an air compressor. The water lost as a result of evaporation and faeces siphoning was replaced twice a week. The walls and bottoms of the tanks were scraped and cleaned weekly to minimize algal growth. Six isonitrogenous (30% crude protein), isocaloric (400 kcal GE 100 g–1) cold pelleted diets were prepared; SM, BM, MBM and PBM were used as total fish meal replacements in the control diet. The characteristics and composition of these sources are given in Table 1, while the composition and essential amino acid (EAA) contents of the test diets are given in Tables 2 and 3. The diets were prepared as described by El-Sayed (1990). Each diet was fed to duplicate groups of fish to satiation, twice a day at 0900 and 1600 h, 6 days a week, for 150 days (from 16 May to 13 October 1996). The fish were collectively weighed monthly and their growth rates were calculated. Water quality parameters including dissolved oxygen (mg

l–1), pH, temperature, and ammonia-N (mg l–1) were monitored weekly. At the end of the trial, five fish from each tank were removed and frozen for determination of body composition. Initial body analyses were performed on a pooled sample of five fish which were weighed and frozen prior to the study. Body water, lipid, protein and ash contents were determined using the standard AOAC (1980) methods. Fish performance, including average daily gain (ADG), specific growth rate (SGR), feed conversion ratio (FCR) and protein efficiency ratio (PER), were determined as described by Castell & Tiews (1980). Cost–benefit analyses of the diets, including incidence cost (IC) and profit index (PI), were performed according to Miller (1976). A one-way analysis of variance (ANOVA) was used to test the effects of fish meal replacements in the diets on fish performance. Orthogonal polynomial procedures were used to compare means at the P 5 0.05 significance level, as described by Gill (1981). Least significant difference (LSD) was used to test for the differences among means when F-values from the ANOVA were significant.

Results The effects of protein sources on fish performance and cost-benefit analyses are given in Table 4. All diets produced excellent growth rates throughout the study (Fig. 1). The growth rates of fish fed SM, PBM and MBM were not significantly different (P . 0.05) from those fed the FM-based diet, while the FCR and PER were significantly retarded (P , 0.05). Moreover, BM or BM 1 MBM produced

Table 1 Processing and chemical composition (as-fed) of protein sources used in the study Composition

Source

Initial number

Processing

CP

EE

Ash

Shrimp meal Fish meal Blood meal1 Meat and bone meal1 Poultry by-product2

5–04–226 5–02–025 5–00–381 5–00–388 5–03–798

local, sun-dried commercial herring, defatted, imported sun-dried, commercial local, commercial local, fullfat, commercial

51.66 70.39 81.20 61.80 53.85

5.53 6.21 1.07 4.00 23.00

26.80 11.60 3.32 20.76 18.20

1Alexandria 2The

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Abbatoirs, Al-Amirya, Alexandria, Egypt. United Company for Poultry Production, Abees, Alexandria, Egypt.

© 1998 Blackwell Science Ltd, Aquaculture Research, 29, 275–280



Table 2 Composition and proximate analyses (on as-fed basis) of the test diets Diet

Ingredient (%)

1

Fish meal Shrimp meal Blood meal Meat and bone meal Poultry by-product Wheat bran Corn starch Sardine oil Soybean oil Vitamin mix1 Mineral mix2 Monocalcium phosphate Alpha cellulose Crude protein Ether extract Ash Crude fibre Nitrogen-free extract3 GE (kcal 100 g–1)4 Cost kg–1 5

35.0 – – – –

2

3

4

5

6

–

– –

– – –

– – – –

– –

50.0 – – – 45.0 10.0 1.0 2.0 1.0 1.0

30.0 – – 30.0 10.0 2.0 2.0 1.0 1.0

–

–

5.0 31.57 5.90 7.78 11.61 43.14 415.0 2.60

4.0 30.85 7.77 13.33 8.84 39.21 413.0 1.72

46.0 10.0 1.5 1.5 1.0 1.0 2.0 7.0 30.81 7.03 6.93 10.89 44.34 416.0 1.59

40.0 –

15.0 20.0 47.0 29.0 10.0 1.0 1.0 1.0 1.0

36.0 10.0 2.5 2.5 1.0 1.0 –

–

7.0 30.05 8.00 10.83 11.14 39.98 415.0 1.75

10.0 29.57 11.00 10.78 12.91 35.74 421.0 1.63

– 30.0 10.0 3.0 3.0 1.0 1.0 2.0 15.0 30.40 7.04 9.89 9.67 43.00 419.0 1.65

1Each

kilogram contains: vitamin A, 1 000 000 IU; vitamin D3, 500 000 IU; vitamin E, 750 000 IU; vitamin K, 300 mg; ascorbic acid, 2000 mg; thiamine, 550 mg; riboflavin, 100 mg; pantothenic acid, 2500 mg; nicotinic acid, 2000 mg; pyridoxine, 1000 mg; niacin, 7 mg; cyanocobalamine, 2 mg. 2Each kilogram contains (mg): Fe, 80; Mg, 167; Mn, 12; Cu, 11; I, 15; Se, 12; Co, 1. 3Determined by difference. 4Gross energy, based on 5.65, 4.2 and 9.5 kcal g–1 protein, carbohydrate and lipid, respectively. 5Prices in Egyptian pounds; £1.00 5 US$0.29, based on 1996 exchange prices. Labour and processing costs were included by adding 25% of the ingredients costs.

Table 3 Calculated essential amino acid (EAA) contents of the test diets (percentage of dietary protein) Diet

EAA

1

2

3

4

5

6

Arginine Histidine Isoleucine Leucine Lysine Methionine Phynylalanine Threonine Tryptophan Valine

4.06 2.95 3.05 3.89 4.44 1.98 2.66 2.31 0.95 2.49

2.86 1.48 3.14 4.81 3.55 1.36 2.20 1.92 0.77 2.83

2.26 3.29 1.04 4.84 4.28 0.78 3.26 3.41 1.33 2.92

2.43 1.39 2.38 4.79 3.14 0.73 2.33 2.21 0.59 2.21

4.32 1.09 2.97 3.57 2.17 1.65 2.51 2.69 0.73 3.26

2.58 2.34 1.63 4.76 4.05 0.71 2.80 2.74 1.00 2.58


the lowest fish performance. Fish survival for all treatments ranged between 93 and 100% (Table 4). All protein sources tested had significantly lower (P , 0.05) incidence costs (IC) and higher profit indices (PI) than the control diet. This indicated that those protein sources were economically superior (P , 0.05) to FM, even at 100% substitution levels. Body composition analyses of fish carcass fed the test diets are given in Table 5. With the exception of protein content, all body compositions were significantly affected (P , 0.05) by dietary protein source. Body water was inversely correlated with body lipids. The PBM-based diet produced higher carcass lipid than other diets, presumably because of the high fat content of PBM. In addition, fish fed SM, MBM and PBM diets had significantly higher (P , 0.05) ash contents, reflecting the ash contents of these sources.

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Table 4 Growth rates, feed efficiency and cost-benefit analyses of Oreochromis niloticus fed the test diets for 150 days. Values in the same column with different superscripts are significantly different at P 5 0.05* Protein source

Wi

Wf

ADG1

SGR2

FCR3

PER4

Survival (%)

IC5

PI6

FM SM BM MBM PBM BM 1 MBM

13 12 12 13 12 13

273a 258a 199b 240a,c 248a,c 220b,c

1.73a 1.62a 1.25b 1.51a,c 1.57a 1.38b

2.03a 2.03a 1.87b 1.94a 2.02a 1.89b

1.86a 2.00a 2.57b 2.31c 2.24c 2.48b

1.70a 1.61a 1.30b 1.59a 1.55a 1.34b

100 93 97 100 93 100

4.83a 3.44b 4.00c 3.60b 3.47b 4.09c

1.65a 2.32b 2.00c 2.22b 2.31b 1.95c

*Wi and Wf, initial and final fish weight (g fish–1); FM, fish meal; SM, shrimp meal; BM, blood meal; MBM, meat and bone meal; PBM, poultry by-product meal; and BM 1 MBM, blood meal and meat and bone meal mix. 1Average daily gain 5 weight gain (g)/time (days). 2Specific growth rate 5 100 (Ln W –Ln W )/time (days). f i 3Feed conversion ratio 5 dry feed consumed (g)/wet weight gain (g). 4Protein efficiency ratio 5 wet weight gain (g)/protein fed (g). 5Incidence cost 5 cost of kg feed consumed/kg fish produced. 6Profit index 5 value of fish crop/cost of feed consumed.

Figure 1 Growth of Oreochromis niloticus fed the test diets for 150 days: FM, fish meal; SM, shrimp meal; BM, blood meal; PBM, poultry byproduct meal; MBM, meat and bone meal; and BM 1 MBM, blood meal and meat and bone meal mix.

Table 5 Body composition analyses (on wet weight basis) of Oreochromis niloticus fed the test diets. Values in the same row with different superscripts are significantly different at P 5 0.05* Final

Component (%)

Initial

FM

SM

BM

MBM

PBM

BM 1 MBM

Water Protein Lipid Ash

70.38 16.67 5.78 5.22

70.32a 16.98 6.52a 5.49a

69.71a 16.73 6.84a 7.53b

71.67b 16.47 5.57b 5.68a

70.00a 17.20 6.67a 7.43b

67.12c 16.51 7.76c 6.91b

71.23b 16.69 5.75b 6.55b

*FM, fish meal; SM, shrimp meal; BM, blood meal; MBM, meat and bone meal; PBM, poultry by-product meal; and BM 1 MBM, blood meal and meat and bone meal mix.

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Discussion The present study clearly demonstrated that SM, MBM and PBM can totally replace FM in practical diets for Nile tilapia. On the other hand, BM, had produced significantly lower performance. Similar results have been reported by Davies et al. (1989) on tilapia, Oreochromis mossambicus Peters, fry. The authors found that diets containing MBM or high MBM:BM ratios (3:1 and 2:3) were superior to FM, even at a 100% substitution level. When BM was used as a total replacement of FM, fish growth was still comparable to the control diet. Recently, Rodriguez-Serna et al. (1996) found that commercial defatted animal by-product meal (a combination of BM, MBM, feather meal and FM) supplemented with soybean oil completely replaced FM in the diets fed to Nile tilapia for 7 weeks, with no adverse effects on fish performance. The present results also agreed well with those of Higgs, Markert, Macquarrie, McBride, Dosanjh, Cicholas & Hoaking (1979), who found that a mixture of PBM and HFM supplemented with essential amino acids (EAA) completely replaced FM in test diets fed to coho salmon, Oncorhynchus kisutch (Walbaum). On the other hand, many authors reported that between 30% and 75% of dietary FM could be replaced by animal by-products. Tacon et al. (1983) found that hexane extracted MBM or MBM 1 BM (4:1) both supplemented with methionine can replace up to 50% of FM protein in test diets fed to Nile tilapia fry for 6 weeks. This is in agreement with the results of Viola & Zohar (1984), who reported that up to 50% of FM could be replaced by poultry by-products in the diets of tilapia hybrids. In addition, Otubusin (1987) found that BM levels exceeding 50% of FM protein in diets fed to Nile tilapia fingerlings reared in cages for 120 days resulted in a significant reduction in fish growth, while 10% level was the most efficient. The differences among these results may have been related to protein source, quality and processing, fish species and size, experimental period and culture systems. The excellent growth of tilapia fed the test diets in the present study indicated that the EAA values of these diets were good, despite being lower than that reported by Santiago & Lovell (1988) for Nile tilapia fry. However, BM was deficient in methionine and isoleucine, and MBM was deficient in methionine and tryptophan. External supplementation of these EAA may have improved fish



performance, as has been reported by Higgs et al. (1979) and Tacon et al. (1983). However, the cost and unavailability of these EAA in Egypt may not encourage this approach. The effect of natural food present in the rearing tanks on fish performance was insignificant. The continuous scraping and cleaning of the walls and bottoms of the tanks significantly minimized algal growth. However, no trials were conducted to investigate the contribution of natural foods to fish growth. The increased fat content of PBM in the present study may have not adversely affected fish growth. This is in contradiction with the finding of El-Sayed (1994) on silver sea bream, Rhabdosargus sarba (Forsskål). This author found that the performance of fish fed PBM above 25% substitution level was significantly reduced, partly as a result of the high fat content of PBM. Most of the works reviewed have evaluated FM replacements in tilapia feeds from biological or nutritional viewpoints. Little attention has been paid to economic analyses of these protein sources. Only a few studies have been conducted into this subject and these have indicated that those unconventional protein sources were more economical than FM because of their local availability at low prices. The cost-benefit analyses of the present study clearly indicated that SM, BM, MBM and PBM are better protein sources for Nile tilapia than FM. Similar results were reported by other workers. The economic evaluation of cottonseed meal (El-Sayed 1990), corn gluten feed and meal (Wu, Rasati, Sessa & Brown 1995), and animal by-product meal (Rodriguez-Serna et al. 1996) as single protein sources for Nile tilapia, and brewery waste (OduroBoateng & Bart-Plange 1988) for Tilapia busumana indicated that these sources were economically superior to FM, even at total replacement levels. In conclusion, the present study revealed that SM, MBM, BM and PBM can totally replace FM in practical Nile tilapia diets under the experimental conditions employed. In addition, these protein sources are locally available at much lower prices than imported fish meal.

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