2004 Poultry Science Association, Inc.
Nutrient Value of Tilapia Meal N. M. Dale,*,1 M. Zumbado,† A. G. Gernat,‡ and G. Romo§ *Poultry Science Department, University of Georgia, Athens, Georgia 30602; †University of Costa Rica, San Jose, Costa Rica; ‡Poultry Science Department, North Carolina State University, Raleigh, North Carolina 27695; and §Pronaca, Quito, Ecuador
Primary Audience: Nutritionists, Quality Control Personnel, Purchasing Agents SUMMARY By-products of the processing of tilapia are beginning to appear as feed ingredients. Eight samples were obtained and evaluated for nutrient content so as to provide the nutritionist with a baseline of information with which to consider possible use of this ingredient. At the present time, there is considerable variation in the composition of tilapia meals from different sources. Nutrient composition ranged from: CP, 52.5 to 57.8%; TMEn, 2,374 to 3,269 kcal/kg; and Ca, 5.2 to 10.6%. As significant variation was noted in levels of most nutrients, confirmatory analysis on specific samples is recommended prior to general use in formulation. Key words: tilapia meal, fish meal, protein, metabolizable energy, fatty acid 2004 J. Appl. Poult. Res. 13:370–372
DESCRIPTION OF PROBLEM Fish meals can generally be divided into 2 overall classes: those produced from whole fish and those derived from offal in which fillets have been removed for human consumption. Tables of nutrient composition, such as the NRC Nutrient Requirements of Poultry [1] and the Feedstuffs Ingredient Analysis Table [2], list nutritional parameters for a number of whole fishmeals. Previous studies from this laboratory have documented the composition of several offal-type meals, including tuna meal [3] and catfish meal [4]. As might be expected, the protein level of the offal meals is somewhat lower than that of anchovy or menhaden meals [1] as the major protein tissue (fillets) have been removed for human markets. Tilapia (Oreochromus niloticus), a fresh-water fish originally from Africa but now grown in many areas, is becoming popular in many 1
markets. As a result, increasing amounts of processing offal are available for rendering into high-protein fish meal. Romo [5] observed, based on commercial processing in Ecuador, that 69.5% of tilapia’s live BW is waste tissue and 30.5% is edible fillets. Ponce and Gernat [6], reporting from Honduras, estimate that approximately 36% of the BW of tilapia consists of edible fillets, leaving 64% available for processing into fish meal. The same authors [6] investigated the use of several levels of tilapia meal in broiler diets and found it to be a highly satisfactory feed ingredient. A detailed nutrient description of the sample of tilapia meal used in that study was provided. However, a more general survey of the nutrient composition of tilapia meal has yet to be reported. The objective of this study is to begin to establish a database for those interested in the use of tilapia meal as a feed ingredient.
To whom correspondence should be addressed:
[email protected].
DALE ET AL.: TILAPIA MEAL
371
TABLE 1. Composition of tilapia meal: proximate composition and TMEn (as-is basis) Sample Component Crude protein (%) Ether extract (%) Ash (%) Dry matter (%) TMEn (kcal/kg)
Average ± SD
1
2
3
4
5
6
7
8
55.6 12.7 23.1 91.0 3,051
57.8 13.8 25.9 93.2 3,133
54.0 15.6 25.5 92.6 3,269
56.0 10.0 24.6 92.5 2,860
52.5 7.9 30.1 94.4 2,374
53.8 8.4 29.5 92.4 2,440
54.6 12.1 25.8 92.5 3,088
54.1 13.0 25.5 92.5 3,060
54.8 11.7 26.3 92.6 2,909
± ± ± ± ±
1.6 2.7 2.4 0.9 330
TABLE 2. Composition of tilapia meal: amino acids (as-is basis) and pepsin digestibility, samples 1 to 8 Amino acid Lysine Methionine Cystine Threonine Tryptophan Arginine Valine Isoleucine Leucine Histidine Pepsin digestibility (samples 1 and 2, respectively) 0.2% 0.002%
MATERIALS AND METHODS A total of 8 samples of tilapia meal were obtained from Costa Rica, Honduras, and Ecuador. Proximate composition and mineral content [7], amino acids [8], and TMEn [9, 10] were determined for each sample. Pepsin digestibility (0.2 and 0.002% pepsin) was evaluated on 2 samples [11]. Fatty acid composition was determined on a composite of several samples [12].
RESULTS AND DISCUSSION From the proximate compositions of the 8 samples included in this study, substantial differences exist in the nutrient profile of tilapia meal (Table 1). Protein content was similar to that previously found for tuna meal [3]. However, although the protein of most samples was relatively consistent, samples 5 and 6 were below average. These had a correspondingly higher level of ash. This might suggest that a more complete removal of edible fillets had occurred with such samples, leaving a by-product with less meat residues and correspondingly more bone. Notable differences in ether extract were
Average (%) ± SD
Low (%)
High (%)
± ± ± ± ± ± ± ± ± ±
3.01 1.02 0.31 1.87 0.36 3.49 1.96 1.56 2.98 0.95
3.59 1.31 0.41 2.11 0.43 3.85 2.33 1.86 3.34 1.15
3.37 1.18 0.36 2.03 0.39 3.67 2.19 1.72 3.18 1.07
0.31 0.09 0.03 0.08 0.03 0.13 0.15 0.12 0.12 0.06
95.6, 94.3 95.0, 93.6
also apparent between samples, ranging from 7.9 to 15.6%. Dry matter for all samples was reasonably consistent in the low 90% range. Metabolizable energy varied widely but appeared to reflect differences in proximate composition. Eight samples are not considered an adequate database from which to generate a prediction equation for energy based on proximate composition. Nevertheless, it is apparent that samples with lowest TMEn (5 and 6) were also lowest in protein and ether extract and highest TABLE 3. Composition of tilapia meal: minerals (as-is basis), samples 1 to 8 Mineral Calcium Phosphorus Sodium Magnesium Potassium Iron Copper Zinc Manganese
Average (%) ± SD 8.4 4.1 0.38 0.15 0.38 ppm 187 9.0 67.5 13.9
± ± ± ± ± ± ± ± ± ±
1.9 0.9 0.04 0.04 0.10 105 105 2.8 13 10.4
Low (%) 5.2 2.6 0.31 0.10 0.26 99 8 50 6
High (5) 10.6 5.1 0.42 0.22 0.51 345 15 93 32
JAPR: Research Report
372 in ash. The amino acid composition of tilapia meal is shown in Table 2. Although levels of essential amino acids are consistently lower than in whole fish species, as a percentage of protein, they are very similar to values reported for catfish meal [4]. Although amino acid availability was not determined in this study, pepsin digestibility for samples 1 and 2 was consistently high (Table 2). Mineral content of tilapia meal is shown in Table 3. As will be noted, variation in these parameters was extreme, with high values occasionally being twice the magnitude of low, as is seen for calcium and the trace minerals. This is presumably due to different amounts of bone present in certain samples and possibly the rendering of mortality (whole fish). The fatty acid composition (Table 4) is generally similar to that of the meal from the other freshwater species studied at this laboratory (catfish meal). Major differences were that tilapia meal was higher in palmitic acid but lower in oleic acid than catfish meal [4]. As tilapia are farm reared in fresh water, without access to plankton, it is not sur-
TABLE 4. Composition of tilapia meal: fatty acid composition,A pooled samples Fatty acid Myristic (14:0) Palmitic (16:0) Palmitoleic (16:1) Stearic (18:0) Oleic (18:1) Linoleic (18:2) Arachidonic (20:1) Total omega-3 fatty acids
% 3.1 25.7 6.1 7.5 35.4 11.9 2.0 3.7
A
Only fatty acids present at least 2% included.
prising that levels of omega-3 fatty acids are extremely low. From the data presented above, it is evident that a great deal of variation exists in the nutritive composition of samples of tilapia meal. Although the causes of this variation are not clear, it can be postulated to be the result of 1) different sized tilapia at processing, 2) differing processing methods, 3) genetic stocks with different body compositions, or 4) variations in nutrient composition of the feed.
CONCLUSIONS AND APPLICATIONS 1. Due to the popularity of tilapia as a human foodstuff, increasing amounts of rendered tilapia meal are becoming available. 2. Proximate composition, ME, amino acid composition, pepsin digestiblity, mineral composition, and fatty acid analysis of tilapia meal are reported for those considering the use of this ingredient in formulated feeds.
REFERENCES AND NOTES 1. National Research Council. 1994. Nutrient Requirements of Poultry. 9th rev. ed. Natl. Acad. Press, Washington, DC. 2. Dale, N., and A. Batal. 2002. Feedstuffs Ingredient Analysis Table. Miller Publishing Co., Minnetonka, MN.
8. Experiment Station Chemical Laboratories, University of Missouri, Colombia, MO. Determination of amino acids was conducted using an HCLP procedure with a Beckman 6300 analyzer using an ion exchange column.
3. Zaviezo, D., and N. M. Dale. 1994. Nutrient content of tuna meal. Poult. Sci. 73:916–918.
9. Sibbald, I. R. 1976. A bioassay for true metabolizable energy of feedingstuffs. Poult. Sci. 55:303–308.
4. Dale, N. M. 2001. Nutrient value of catfish meal. J. Appl. Poult. Res. 10:252–254.
10. Dale, N. M., and H. L. Fuller. 1984. Correlation of protein content of feedstuffs with the magnitude of nitrogen correction in true metabolizable energy determinations. Poult. Sci. 63:1008–1012.
5. Romo, G. 2002. Unpublished data. Quito, Ecuador. 6. Ponce, L. E., and A. G. Gernat. 2002. The effect of using different levels of tilapia by-product meal in broiler diets. Poult. Sci. 81:1045–1049. 7. Agriservices Laboratory, University of Georgia, Athens, GA. Assoc. Off. Anal. Chem. 1980. Official Methods of Analysis. 13th ed. AOAC, Washington, DC.
11. Ampro Laboratories, Cumming, GA. Assoc. Off. Anal. Chem. 1980. Official Methods of Analysis. 13th ed. AOAC, Washington, DC. 12. POS Pilot Plant Corp., Saskatoon, SK, Canada.
