Chemical Composition, Digestibility, and Metabolizable Energy Content of Different Fat and Oil By-Products

01999Applied Poultry %mc+ Inc

CHEMICAL COMPOSITION, DIGESTIBILITY, AND METABOLIZABLE ENERGY CONTENT OF DIFFERENT FAT AND OILBY-PRODUCTS

Primary Audience: Nutritionists, Ingredient Buyers, Renderers, Oil Processors

DESCRIPTION OF PROBLEM In Costa R i a and other tropical countries the industry that produces oil for human consumption is based on processing palm oil as 1

To whom correspondence should be addressed

the predominant local source of oil products, d y margarine, shortenin& a d o&j specifically for food frying (oleine). Imported soybeans are also processed to supply oil to the market. During the process of oil extraction

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MARIO E. ZUMBADO' Centerf o r h i m a l Nutrition Research, School of Animal Science, Universityof Costa Rica, San Josk, Costa Rica Phone: (506)234-7220 F M : (506) 234-6I64 COR W. SCHEELE and CEES gWARERNAAK Institute f o r h i m a l Science and Health, Resemh Branch Rundenveg 2, Postbus 65, 82OOAB Le@@ The Netherlands

264

The present study sought first to describe the different fat products available for animal feedingin terms of their chemical composition and to determine the digestibility and metabolizable content of those products and blends. Through performing such analysis it also sought to compare some of the results obtained by two different laboratories using the same products but with some differences in procedures, equipment, and facilities.

MATERZALS AND METHODS Samples of different fat and oil products from Costa Rica were collected and stabilized with 200 ppm of the antioxidant ethoxyquin. Half of each sample collected was shipped to The Netherlands and the other half remained in Costa Rica. Altogether nine different fat products were used in the studies. The products from the palm oil studied were: crude palm oil (CPO), which is the main product of that industry; palm free fatty acids (PFFA) obtained after the distillation process applied for the deodorization of CPO; and full-fat palm kernel meal, a by-product with a high oil content that has great potential as a poultry feedstuff when its price is attractive for feed manufacturing [q.Residual palm oil (RPO) collected from oxidation lagoons, which consists of a mixture of crude oil and fatty acids, was also studied. This product is usually drained of excess water at the collection point and dehydrated in a processing plant to moisture content of less than 3%. The RPO sample was obtained from a local processor. A fat product commercially labeled soybean free fatty acids (SBFFA) was also included in the study. SBFFA, a blend of three by products: acidulated soapstock, gums, and distilled free fatty acids, is obtained after crude soybean oil is processed with hot water and phosphoric acid [8]. 'Ikro separate samples of yellow tallow were includedin the study. These were directly collected from two of the six rendering plants in Costa Rica. International quality standards and specifications are not usually used to class@ this local tallow for feed purposes. Almost 70% of it is used by the soap industry and the rest for animal feeding. The restaurant greases (RG) were collected from two different fast food restaurant chains. For frying purposes these restaurants

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and refining, several by-products and waste products are obtained that can be further processed for animal feeding purposes. Other fat products in the local market also require attention as potential ingredients. There has not been sufficient study of tallow, lard, and restaurant greases as potential feedstuffs, in contrast to the work of researchers in other countries [l, 2, 31; swine and poultry farmers already include those fats in the diets without a clear knowledge of their real quality, composition, and energy value. The growing world poultry industry requires large amounts of fats as an energy source in poultry diets to yield higher levels of metabolizable energy mainly for broilers at an economically justifiable price. Due to dissimilarities in processes and descriptions, by-productsobtained in different regions may not be of the same chemical composition as those reported in the literature. Thus the energy levels of the products for poultry available in a given area may not be the same as those reported by other researchers or included in feed composition tables. It is also important to consider that in some parts of the world, including the U.S. and the U.K.,feed fats are marketed with specific names such as "hydrolyzed vegetable and animal fat" or "white or yellow greases." Those are the result of different combinations of animal fats (tallow and lard), restaurant greases, acidulated soapstocks, and other residues of the oil refining industry. Some of these products have specifications for feed purposes as determined by their content of moisture, impurities (insoluble residues), and unsaponifiable matter (MIU), as well as free fatty acids. In many countries there is a need to know more about the composition of those fat products that may be useful for the feed industry. Such knowledge will allow a better understanding of how to produce blends with the highest digestibility and metabolizable energy levels. According to Renner and Hill [4] and other published research data [5,6], the best way to use some fats, especially more saturated fats such as tallow and palm fats, is by blending them with more unsaturated oils. Those researchers have usually found a synergism between fattyacids that improves the digestibility of the fat and its metabolizable energy content, particularly at high levels of dietary inclusion.

FAT BY-PRODUCTS

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FAT SOURCE

MOISIZTRE

I

FTA

MU

LIPIDS

%

PFFA

0.72

91.7

0.85

98.7

SBFFA CPO

0.90

50.6

0.98

99.7

0.62

4.9

0.82

99.9

Tallow 1

1.08

7.9

1.29

97.8

Tallow 2

0.7

2.4

1.06

98.9

RG1

0.82

6.0

1.32

97.8

RG2

0.10

2.2

0.26

100.0

RG3

0.60

1.1

1.05

100.0

Palm kernel meal

8.00

-

-

47.1

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was used to determine the digestibility and apparent metabolizable energy (corrected to nitrogen equilibrium) content of fat products for broilers. One of the main modifications was that excreta collection was performed at 25 days of age for 4 consecutive days (not alternate days) and after a feed restriction period of 6 hr. Basal diets with no fat added were prepared and 10% of the different fat products, either pure or in blends, were mixed with 90% of the basal diet (Table 1).In the case of palm kernel meal (47.1% fat), the ground product was added at the rate of 21% in the experimental diet to reach about the same 10% added fat as in the other diets. The composition of both basal diets is shown in Table 2. The procedures used at the University of Costa Rica (UCR) and at the Institute for Animal Science and Health (ID-DLO) in The Netherlands were made as uniform as possible, but the following differences existed. At ID-DLO the birds were housed in climatecontrolled houses where temperature was kept constant, and excreta was freeze-dried. At UCR birds were housed in Petersime batteries in conventional rooms and a forcedair oven was used to dry the excreta samples. After thawing, the excreta samples were homogenized and oven dried (UCR) or freeze-dried (ID-DLO). The feed and excreta samples were ground to pass through a %mesh sieve. Samples of ground materials were allowed to come into equilibrium with the air moisture, then stored in screw-top jars while awaiting further analysis.

use oleine, a product of palm oil (RG1 and RG2) or pure-refined soybean oil (RG3). These RG were collected in plastic containers and filtered through a 2-mm mesh screen to eliminate food particles. This is the procedure regularly used by restaurant grease processors in Costa Rica. A procedure to determine quality and composition was established for the nine experimental fat products within the study. Levels of moisture, impurities, and unsaponifiable matter (MIU)were determined. These are the main non-fat products that will dilute the energy value of a fat [9]. Fat content was determined [lo] for all fat products, although this is not an essential step when assessing the quality of a fat product, because fat content can be calculated as 100% minus M U . Free fatty acid content [lo] was measured. This may indicate the degree of deterioration in quality of some fats due to hydrolysis that could lead to oxidative rancidity. Fatty acid composition of all fat samples was determined by gas chromatography [ll,121. This is an important procedure, especially for fats that are expected to present a variable composition due to their by-product nature. The fatty acid profie of a fat indicates the ratio of unsaturated to saturated fatty acids, which is one of the main factors affecting the metabolizable energy content of a fat [3,4,5,6]. The last step in the evaluation of the fat products was the determination of the metabolizable energy content for feed formulation. The classical total excreta collection procedure [13], with some slight modifications,

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TABLE 2. ComDosition of the basal diets and the diet with full-fat Dalm kernel meal for AMEn determination

1&,

%inera1 remix ID-DLO xwided r of diet: monocalcium phos hate, 267 g; CaCO3, 573 g; NaCI, 125 g; CuS045&0,2 g; ZnS0.+7&0,3 g; &!3%.4H20,12 FeS0.+7H20,1%g; KI,50 mg; Se, 5 mg. 'Degussa AG, Feed Additives Division, Hanau, Germany.

Determination of crude fat in the fat products, diets, and excreta was carried out according to the Berntrop method (IS0 6492) with a pre-extraction step (IS0 6498) [141.The content of dried matter, nitrogen, and the heat of combustion were analyzed according to the AOAC [lo]. Tho methods were utilized to calculate the AME, of the pure fats or fat blends. AME values of the fat diets and the basal diet were obtained by using the heat of combustion values of the diets and excreta. AME was also calculated by using the digestibility coeffi-

I

cients multiplied by heat of combustion of the fats. The digestibilitycoefficients of the added fats in the diets were determined by comparing fat digestibility values in fat or experimental diets with fat digestibilityin the basal diet [14]. All calculations were determined on a dry matter basis. Weight gain, feed intake, and feed/gain ratio of the broilers were determined for the experimental period from 18 to 29 days of age in the ID-DLO trial. A randomized block design with three blocks of 18metabolic cages was used. Within a block each diet was

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*Vitamin (UCR and ID-DLO) and mineral remixes (VCR) sovided r kg of diet: vitamin A, 11,OOO IU; vitamin D3,2,200 IU; vitamin E, 15 I U vitamin 3 IU; thiamine, fmg; riboKvin, 45 mg;niacin, 30 m pantothenic acid (Ca-antothenateklo mg; pyridoxine, 1 mg; d-biotin, 0.05 mg; folic acid, 050 m& vltamin Biz, O h mg; choline chlonde &%, 400 m& n, 80 mg; Pe, 70 mg; Zn,80 m& Cu, 5 mg;I, 0.75 mg; and Se, 0.3 mg.

Research Report ZUMBADO et al.

267

randomly allocated to two cages. Results achieved with the fat-containing diets were analyzed with ANOVA (Genstat 5 or SAS) [fi,161.

acids present in the final product are free; the other half form triglycerides. Most of the other fat products collected showed values below 10% FFA. The fatty acid profiles of most of the fats utilized in this experiment are summarized in AND Table 3. As expected, palm kernel fat is the Table 1summarizesthe average composi- most saturated of the products analyzed. PFFA contains an even higher amount of sattion of the different fat products studied and urated fatty acids (SFA) than CPO. The preanalyzed at ID-DLOand UCR. Most of the dominant fatty acids in these palm fats are products showed a low moisture content, palmitic and oleic acid; in the kernel fat the which indicates that processing at the different short-chain fatty acids lauric and myristic repplants is well controlled to avoid excess moisresent nearly 60% of the total fat content. ture and further oxidation problems. The sum Tallow showed an SFA content similar to that of moisture, impurities, and unsapodables in of the oils from palm (around 50%), with steamost samples was close to 1%.Only tallow and restaurant greases showed values above 1%, ric and palmitic as the main saturated fatty acids. but even these samples have MIU values As expected, soybean fatty acids obtained within the accepted range for feed fats [lq. from crude soybean oil are very high in unsatThe main foreign materials found were bone urated fatty acids (UFA), with a high level of particles in tallow and unfiltered food residues linoleic acid. Very little difference in fatty acid in RG. composition existed between the two soybean Free fatty acid content was, as expected, oils. The fatty acid composition of RG varied very high in PFFA. This product is obtained by dependmg on the original frying oil used. The an efficient physical distillationprocess during origin of RG1 and RG2 is oleine, a refined oil refining of crude palm oil; only small amounts produced from palm oil specially for food of neutral oil and triglycerides are released frying; consequently, these two RG are more during this industrial procedure. SBFFA had a lower free fatty acid content, as it is produced saturated than RQ, which is produced from by a less efficient chemical process. The oil is soybean oil. combined with caustic soda to neutralize the The determined M E n levels of the fats free fatty acids. A soapstock is formed which and blends from both labs are summarized in emulsifies approximately its own weight in Table 4. Accordmg to these results, the lowest neutral oil, so that only about half of the fatty AME, values occurred in both fats from the

RESULTS

DISCUSSION

*PFFA = Palm free fat acids; SBFFA = soybean free fatty acids +acidulated soa stock; CPO =Crude palm oil; Tallow 1 and Tallow2 = k e f tallow samples provided by two different renderers;RG and RG2 = Restaurant greases from oleine palm oil; and RG3 = Restaurant grease from soybean oil.

f

Iv a l u e s for full-fat palm kernel meal are for the fat portion (47.1%) of this product.

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TABLE 3. Fatty acid composition of experimental fat products

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268

TABLE 4. Nitrogencorrected metabolizable energy of experimental products calculated directly or by

rent metabolizable energy (calculated by digestibilitycoefficient).

oil palm, CPO and its main by-product PFFA, and Tallow 1. This is in agreement with the high saturated fatty acid composition and low UFASFA ratio of these fats. PFFA showed the lowest value among the saturated fats, which is also explained by its high free fatty acid (FFA) level. In fact, WEeman and Salvador [18] confirmed that the combination of high saturation and high free fatty acid content reduces the digestibility and AME content of fats. A high FFA level, which indicates that the fat has a high FFAglyceride ratio, reduces the formation of micelles. Reduced micelle formation mainly affects absorption of SFA of longer carbon chains, such as those predominant in palm oil and tallow. The energy levels for CPO and tallow are very close to those values reported by the NRC [2]. These figures are based on research conducted in several parts of the world, particularly the work of Sibbald [6], Sibbald and Kramer [q, and Huyghebaert et al. [3]. The values reported for refined palm fat are 5300 and 5800 kcaVkg [3]. Wiseman and Salvador [18] found AME, values ranging from 6620 k&g for 2.5-wk-old broilers and

7720 kcal/kg (7.5-wk-old) for crude palm oil with 5.75% FFA content to 3537 (2.5 wk) and 6573 kcaVkg (7 wk) for PFFA with 91.75% FFA. Tallow showed a digestibility and AME, close to that of CPO and higher than those values for PFFA (5980 and 6112 kcal/kg). Huyghebaert et al. [3] reported an average of 6205 kcaVkg for refined tallow; Wiseman and Salvador [19] found values from 6238 k&g for tallow with 54.5% FFA to 7385 k&g for a 13.8% FFA content. On the other hand, SBFFA showed values of 8349 to 8598 kcal/kg associated with its high fat digestibility, which results from a high UFASFA ratio. Values calculated from digestibility coefficients were somehow lower (8014 to 8252 kcal/kg). A product similar to this with a content of 51.6% FFA was determined to have 8341 k&g [18]. On the other hand, values of 6118 kcalflrg determined by direct method and 6865 kcal/kgby digestibility had been reported for acidulated soapstock and 8806 and 8376 k&g for crude soybean oil [3].

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metabolizable energy nitrogen corrected (direct determination using heat of combustion values of

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ZUMBADO et al.

determine fat content [I 41. This method stimulates hydrolysis of soaps before the process of extraction. However, some saturated fatty acids may not be extracted, which can yield high AME values for saturated fats, a result that occurs with most methods of extraction. Table 5 shows the chemical composition of full-fat palm kernel meal on a dry matter basis. This product contains a large amount of fat (47.1%) and 8.7% crude protein. In this sample, the level of crude fiber is rather low compared to values above 10% reported in the literature [7, 21, 22). This is probably due to a lower content of hull residues in the final meal. The oil in full-fat palm kernel meal showed a digestibility of 83.3% and an AME value of 4230 kcal/kg. This AME value is in close agreement with previous reports by Zumbado and Jackson [21], who found a content of 4420 k&g TME, for kernel with no hull contamination, and a decrease of 21.45 kcal/kg for every 1% hulls present in the kernel as foreign material.The high digestibility of kernel oil is attributed to its high content of short-chain fatly acids despite its high saturation.This is an0 ther example of the effect of the fatty acid composition of a fat upon its utilization by poultry [23,24]. Broiler performance jiom 18 to 29 days (Table 6) shows highly significant differences between treatments (P e .05), especially for feed conversion. Birds fed 1he SBFFA diet had the best feed conversion ratio (FCR), as was expected considering its high digestibility and AME, content. On the other hand, broilers that received the PFFA diet showed the lowest weight gain and worst FCR among all treatments; these results are at1ributable to its low digestibility (Table 4). An intermediate re-

COMPONENT

Dly matter Crude protein Crude fat

%

93.6

8.7 47.1

Ash

1.9

Crude fiber

8.8

AM%, kcavkg DM AM&, kcalkg As Is

4230 3960

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Restaurant grease obtained from restaurants using soybean oil (RG3) also had a higher AME, value. In the case of RG1 the AME, value is more than 1Mcal below the value for RG3 because of the higher saturation and higher FFA content of RG1 (Tables 1and 3). As was mentioned before, RG1 was obtained from restaurants that use oleine from palm oil. Blends of fats, mainly those with SBFFA, produced interesting results related to synergism of fats. The blends of PFFA, tallow, or RG with SBFFA showed AME, values higher than expected based on the arithmetic mean calculated from the individual AM& values of the two components of the blends. This higher AME, occurs because the presence of UFA during micelle formation increases the digestibility of the SFA [5, 61. The blend of SBFFA with Tallow or PFFA improved the AME, by 383 and 1051kcal/kg, respectively, from the expected value. A synergistic effect was also noticed for the CPO +PFFA blend ( + 319 kcalkg), even thou both are saturated fats. These results are in agreement with previous preliminary findings from our laboratories [19,20]. Differences in digestibility and AME, between the values determined at UCR and ID-DLO exist for PFFA, PFFA + SBFFA, and SBFFA + Tallow. These differences may be explained in part by the composition of the basal diets (Table 2). The ID-DLO diet contained about 9% less corn than the UCR basal diet and 10% cornstarch, an ingredient not included in the UCR diet. The UCR diet thus contains more corn oil and, in turn, more unsaturated fatty acids than the ID-DLO diet, which may have improved the absorption of the more saturated fats such as PFFA and Tallow. These effects of the basal diets have been previously reported [13]. The results also show that AME values of saturated fats calculated from digestibility values are generally higher than values of fats as determined by the direct method. This may occur because saturated fatty acids react with calcium in the digestive tract, forming soaps that are less solvable in extraction solvents than soaps from unsaturated fatty acids. The solvents used for extraction and analysis of excreta fats thus tended to extract more unsaturated than saturated fats, even though a special method was used to

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270

Broilers fed full-fat palm kernel meal did not perform as well as its AMEnlevel led us to expect. This may be explained by the lower AM& content of the diet compared to most of the other experimental diets except for the diet with PFFA (Table 4). The palm kernel meal diet may have had more problems related to the amino acid content and balance and to having a higher crude fiber content than the diets with pure fats. These aspects require further study as little information is available on total and digestible amino acid content of full-fat palm kernel meal.

sponse occurred with RG1, CPO, and tallow. When tallow, and especially PFFA, were mixed with SBFFA, bird performance was greatly improved even beyond the expected values. This response is probably due to the fatty acid synergism mentioned before [23,24]. Blending PFFA with CPO showed only a sllght beneficial effect compared to the results obtained with the two fats fed separately. This means that synergism between these two fats, as in acid palm oil [q, does not occur as efficiently as in blends where one component is clearly more unsaturated.

SBFFA

CPO Tallow 1

I I

106Sa

1130"

I I

1132'

636' 634'

1

dg

I I

1.68a

1.7P

629'

1.80'

RG1

1112"

62T

I.?

+ PFFA +SBFPA

1121"

S d

1.88=

PFFA CPO

I

1088ab

I

622'

SBFFA +Tallow 1

1102"

637

Palm kernel meal

1121"

594b

Effect of diet (P-value)

LSD (P <

0.012

33

<0.001 22

I

1.7SbC 1.73b 1.89e

< 0.001 0.042

CONCLUSIONS AND APPLICATIONS 1. The oil and fat products that are available in a region or country must be properly analyzed

by chemical and biological means to obtain the best use of them and produce the right blends for animal feeding purposes. 2. The fat blends with the w e s t AMEn level are those that include unsaturated fat products, such as acidulated soybean soapstock, soybean distilled fatty acid, and/or restaurant greases. When these are mixed with palm free fatty acids, tallow, or crude palm oil a synergistic effect occurs, yielding a higher AMEn level in the blend. Restaurant greases from soybean oil showed up to 20% more AMEn than restaurant greases from palm oleine. 3. Nutritionists may choose for feed formulation the higher AMEn values f o b d in this research, as the level of the fats in the experimental diets (10%) was much higher than the levels regularly used in practical diets. The large differences in AMEn values for PFFA obtained by the two laboratories indicate the need for more research on this substance.

I I

I

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%bird

%bird

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REFERENCESAND Noms 1. Dale, N.M., 1988. Defming the value of fats in ultry diets. Pages 26-33 in: Proc. ArkansasNutr. Conf., Kyettcville, AR. 2. National Research Council, 1994. Nutrient Re-

uirements of Poult . 9th Rev. Edition. Natl. Acad. $res, Washington, D Z

3.Huyghebaert, G., G. De Munter, and G. De G m ( e , 1988.The metabolizable energy of fats for broilers in relation to their chemical composition. Anim. Feed Sci. Tech. m45-58.

4.Renner, R And F.W. Hill, 1960.The utilization of corn oil,lard, and tallow by chicks of variousages. Poultry Sci. 39849-854.

6.Sibbald, 1.R ,1978.The true metabolizable energy value of mixtures of tallowwith either soybean oil or lard. Poultry Sci. 57473477.

7.Zumbado, M.,1990,Utilizaci6n de productos de la alma africana en la alimentaci6n avlar. Avicultura rofesional7:137-146.

f : ’

8.The gums from crude saybean oil are hyd,X”d by using steam and chemical solutions (NaCl and 6 0 4 ) . Dehydration and centrifugation then render hydrolyzed soybean oil. On the other hand, the soa stock obtained from the deodorization of crude oil by &OH and water is treated with sulfuric acid and steam, then centrifuged and dehydrated. The final product is the acidulated soapstock, mainly free fattyacids,which is combined with the other two products to obtain SBFFA or hydrolyzed soybean oil. 9. Moisture in fat arises from slight emulsification during processing or storing. High moisture levels will cause the fat to be more easily oxidized. Impurities are mainly meat, bone particles, metals, or food residues that remain after processing or are picked u during stora e of the fat. Unsaponifiables are any solubfe material in k t that will not convert into soap when mixed with an alkali.

10. Association of Omcia1 Analytical Chemists, 1982. Official Methods of Analysis. Assn. Offic. Anal. Chemists, Washington, DC.

11. A f t e r addition of an internal standard (heptadecanoicacid),theboundand freefattyacids in the fat samplesweremethylated by a two-stepprocedure.The fatty aad methyl esters were analyzed by gas chromato raphy on a Carlo Erba Mega GC with automatic c o g on-column injector, flame ionization detector, and capilData acqulsilary column (ChromapackCP-wax 52 a). tion and processing was performed with a Hewlett Packard Labdata System. The fat in the palm kernel was isolated by the solvent extraction method, but with the other products this step was omitted. 12.Badings, H.T.and C. De Jong, 1983.Glass capillaly gas chromatography of fatty acids methyl esters. A study of condihons for the quantitativeanalysis of shortand long-chain fatty acids in lipids. J. Chromatography 279:49>506. 13.Sibbald,I.R, 1982.Measurement of bioavailable energ: in poultIy feedingstuffs: A review. Can. J. Anim. Sci. 983-1048.

15.Genstal 5 Committee, 1587.Genstat 5 Reference Manual. Release 3.1.Rothamsttd Experimental Station. Clarendon Press, Oxford, England.

16. SAS Inslitule, Inc, 1988. SAS/STAT User’s Guide. SAS Institute, Inc., Cary NC. 17.National Renderers Asstciation, 1993/94.Pocket Information Manual. A Buyer‘s Guide to Rendered Products. AsbuIy Publication LId., U.K. 18.WLscman, J. and F. Salvridor, 1991.The influence of free fatty acid content and degree of saturation on the apparent metabolizable energy value of fats fed to broilers. Poultry Sci. 70573-582. 19. Kwakernaak, C., C.W. Scheele, A.C.J.M. Smulders, and M. Zumbado, 1595.Synergistic effect of a blend with soybean free fatty acids and palm free fatty acids on the rformance of brlilers. Pages 242-243 in: PrOC.XIXwgeSA Meeting, Antalya, Turkey. 20. Smolders, A.C.J.M., C. Kwakernaak, R.P. Kwakkel, and M. Zumbado, 1996. Energy values of ergistic effects of blends different vegetable fats and in broiler diets. Page 3 in: X x . XX WPSA Meeting, New Delhi, India. 21. Zumbado, M. and F. Jackson, 1996.Efecto de la presencia de endocarpo en el palmiste integral )sobre su valor nutritilro. I. Nivel de endocarpo, caractenzacidnde la fibra cruds y contenido de energ’a metabolizable. Agronomia Costamcense 20:141-144.

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22. Jackson, F. and M. Zmibado, 1996. Efecto de la presencia de endocarpo en el palmiste integral sobre su valor nutritivo. 11. Rendimientos de pollos de en orde en iiiiciacibn. Agronomia Costarricense 201h-149.

(w

23. Ketels, E and G. De Grtmte, 1989.Effect of ratio of saturated fatty acids of the dietary li id fraction on utilization and metabolizable mer ofadded fats in young chicks. Poultry Sci. 68:lSM-l&. 24. Scheele, C.W. and H.AJ Verskegb, 1987.Synergistic effects of different supplementaryoils and fats on the energy of animal fat in broiler diets. Pages 22-24 in: 6th European Symp. on Poultrr. Nutr., World’s PoultIy Sci. Assn., Konigslutter, Germany. 25. Acid Im oil marketed in Central America is a commercial Eend of about 55% crude palm oil with a content of 5% FFA and 45% PFFA (90% FFA). The result is a product with around r13% FFA.

ACKNOWLEDGEMENTS This research was supported by the International ScientificCooperation Programme of the Commission of the European Communities (Contract CIl*-(JT0319). The authorswishto thank Pilxua Poultry Corporation S.A., Numar S.A. @alm oil company), and Industrias Cerdas S.A. (oil by-products company) of Costa Rica for their help in providing experimental materials and technical support.

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5. Sibbald, LR and J.K. Knuner, lW7. The true metabolizable energy value of fats and fat mixtures. Poultry Sci. 562079-2086.

14.Berntrop IS0 6498,Official Journal of the European Communities, 1984.No L 15. pp. 29-30.