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Poult Sci 2008. 87:506-513. doi:10.3382/ps.2007-00354
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METABOLISM AND NUTRITION

Fatty Acid Digestion and Deposition in Broiler Chickens Fed Diets Containing Either Native or Randomized Palm Oil

W. Smink*,1, W. J. J. Gerrits{dagger}, R. Hovenier{ddagger}, M. J. H. Geelen{ddagger}, H. W. J. Lobee§, M. W. A. Verstegen{dagger} and A. C. Beynen{ddagger}

* Feed Innovation Services BV, Generaal Foulkesweg 72, 6703 BW, Wageningen, the Netherlands; {dagger} Wageningen University, Animal Nutrition Group, PO Box 338, 6700 AH, Wageningen, the Netherlands; {ddagger} Utrecht University, Faculty of Veterinary Medicine, Department of Nutrition, 3508 TD, Utrecht, the Netherlands; and § Cargill Refined Oils Europe, Jan van Galenstraat 4, 3115 JG, Schiedam, the Netherlands

1 Corresponding author: smink{at}fisbv.nl


   ABSTRACT
TOP
 ABSTRACT
INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 REFERENCES
 
The hypothesis tested was that randomization of palm oil would increase its digestibility, especially that of its palmitic acid (C16:0) component, with subsequent changes in the fatty acid composition in body tissues. Broiler chickens were fed diets containing either native or randomized palm oil. Diets with either native or a 50/50 mix of native and hydrogenated sunflower oil were also fed. Randomization of palm oil raised the fraction of C16:0 at the sn-2 position of the glycerol molecule from 14 to 32%. Hydrogenation of sunflower oil reduced fat and total saturated fatty acid digestibility, whereas no change in digestibility of total unsaturated fatty acids was found. Randomization of palm oil raised the group mean apparent digestibility of C16:0 by 2.6 and 5.8% units during the starter and grower-finisher phase, respectively. On the basis of the observed digestibilities in the grower-finisher period, it was calculated that the digestibility for C16:0 at the sn-2 and sn-1,3 position was 90 and 51%, respectively. The feeding of randomized instead of native palm oil significantly raised the palmitic acid content of breast meat and abdominal fat and lowered the ratio of unsaturated to saturated fatty acids. It is concluded that randomized palm oil may be used as vegetable oil in broiler nutrition with positive effect on saturated fatty acid digestibility when compared with native palm oil and positive effect on firmness of meat when compared with vegetable oils rich in unsaturated fatty acids.

Key Words: chicken • palm oil • fatty acid • digestibility


   INTRODUCTION
TOP
 ABSTRACT
 INTRODUCTION
MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 REFERENCES
 
There is increasing interest to replace animal fats by vegetable fat sources in the diet for broiler chickens. Animal fats such as tallow and lard are rich in long-chain saturated fatty acids. Most vegetable fat sources have a high content of unsaturated fatty acids. The use of unsaturated dietary fats decreases the melting point of the fat in the broiler carcass (Bavelaar and Beynen, 2003), diminishing the firmness or consistency of the fat (Gläser et al., 2004).

Palm oil is of vegetable origin but is rich in the saturated fatty acid palmitic acid (C16:0); the content is about 45% of the total fatty acids. The use of palm oil in broiler diets is attractive, because it is a saturated source that may be associated with a positive influence on meat firmness. However, saturated fats rich in long-chain fatty acids (> 14 C atoms) are less digestible than fats high in medium-chain fatty acids or unsaturated fatty acids (Renner and Hill, 1961; Young, 1961; Garrett and Young, 1975; Vila and Esteve-Garcia, 1996). In addition, a high fraction of C16:0 in palm oil is bound at the sn-1 or sn-3 position of the glycerol molecule (Breckenridge, 1978; Mu and Høy, 2004). Long-chain saturated fatty acids on the sn-1 and sn-3 positions are thought to be absorbed less efficiently than those bound on the sn-2 position. This is because of the more hydrophilic character of the monoglyceride in comparison with, by lipase hydrolyzed, fatty acids from the sn-1 or sn-3 position of the glycerol backbone.

The position of fatty acids in triacylglycerols can be manipulated by hydrolysis and chemical reesterification (Mukherjee and Warwel, 1997). Randomization is a process of nonspecific random esterification of fatty acids at the 3 positions of the glycerol molecule. In lard, the C16:0 is mainly bound at the sn-2 position of the glycerol molecule (Breckenridge, 1978; Mu and Høy, 2004). Randomization of lard does decrease the digestibility of C16:0 in broilers (Renner and Hill, 1961). A higher digestibility of long-chain saturated fatty acids at the sn-2 position is probably also responsible for a higher deposition rate of these fatty acids in broilers (Scheeder et al., 2003).

As far as known, the effect of randomization of palm oil on C16:0 digestibility and deposition in broiler chickens has not yet been quantified. We hypothesized that randomization of palm oil would increase its digestibility, in particular that of its C16:0 component. In this study, our hypothesis was put to the test. Broiler chickens were fed diets containing either native or randomized palm oil, and the digestibility and deposition of fatty acids were measured.

In addition to studying the effect of randomization of palm oil, we also assessed the effect on digestibility of the degree of fatty acid saturation and chain length of fatty acids. Mathematical models used to calculate the ME of fat sources in broiler nutrition are generally based on the contents of long-chain unsaturated and saturated fatty acids without taking into account chain length differences between C16:0 and C18:0 (Ketels, 1994; Wiseman et al., 1998). It is well known that saturation of unsaturated fatty acids will decrease their digestibility and that of the oils they are components of (Ketels, 1994; Wiseman et al., 1998). As far as we know, it is not known to what extent the total digestibility of oils varies when their saturated fatty acid constituents have different chain lengths. As a positive control in this study, we determined the effect of saturation by comparing sunflower oil and a 50/50 mix of fully hydrogenated sunflower oil and sunflower oil. To assess effect of chain length in the form of C16:0 vs. C18:0, we used the comparison of randomized palm oil vs. the mixture of hydrogenated and native sunflower oil.


   MATERIALS AND METHODS
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
RESULTS
 DISCUSSION
 REFERENCES
 
Birds and Housing

One-day-old female broilers (Ross 308) were purchased from a local hatchery. On arrival, they were wing-banded, weighed, and housed in wire-floor, suspended cages. Each of the 4 experimental groups contained 12 replicates (cages). The experiment started with 6 birds per cage during the starter period of 2 wk. Then up to 2 randomly chosen birds in each cage were removed, so there were 4 birds for the grower-finisher period. Continuous lighting was provided throughout the experiment. The temperature in the cage at arrival was 32°C and was decreased gradually to ambient temperatures during the course of the experiment.

Diets

The birds received a starter feed until d 14 and a grower-finisher feed between d 15 to 35. The composition of the diets is presented in Table 1Go. Four different fat sources were used in the starter and grower-finisher diets. The fat sources were delivered by Cargill (Rotterdam-Botlek, the Netherlands). The diets were in pelleted form (2.5 mm). The diets were fed on an ad libitum basis, and the birds had free access to water. The inclusion level of experimental fat was 4 and 8% (wt/wt) in the starter and grower-finisher period, respectively (Table 1Go). The inclusion levels are in agreement with European high-energy and fat diets for broiler chickens. The 4 experimental fats consisted of sunflower oil (SO), a 50/50 mix of fully hydrogenated sunflower oil and sunflower oil (HSO + SO), palm oil (PO), and chemical randomized palm oil (RPO). The analyzed fatty acid composition of the experimental fats is presented in Table 2Go. The macronutrient and fatty acid composition of the diets are presented in Table 3Go. The experimental fats allow assessment of the effect of saturation (HSO + SO vs. SO or C18:0 vs. C18:1 + C18:2), the effect of the chain length (HSO + SO vs. RPO or C18:0 vs. C16:0), and the effect of the position of long-chain saturated fatty acids on the glycerol molecule (PO vs. RPO or 20 vs. 45% of C16:0 at the sn-2 position) in a situation with a high fat intake.


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  		Table 1. Ingredient composition of the diets (g/kg)
 

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  		Table 2. Fatty acid composition (% of methyl esters) of the total fatty acids in the experimental fats1 and the composition of fatty acids at the sn-2 position of the glycerol molecule of palm oil and randomized palm oil
 

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  		Table 3. Analyzed macronutrient content (%) and fatty acid profile (% of methyl esters) of the experimental diets1 in the starter and grower-finisher period
 
Sampling and Analysis

Excreta were collected in the starter period from d 10 to 14 and in the growing-finishing period from d 31 to 33. It is known that fat digestibility in broiler chickens is lower during the starter than grower-finisher period (Katangole and March, 1980; Ketels, 1994). Thus, we collected excreta during the 2 periods to determine apparent fecal digestibility of total fat and individual fatty acids. Excreta were collected quantitatively per cage, dried at 60°C, weighed, and ground. On d 35, two broilers per pen were used to determine the fatty acid composition of breast meat and abdominal fat. Crude fat determination of diets and excreta were determined with the acid hydrolysis method (AOAC, 1975). To determine the fatty acid composition of the diets, breast meat, and feces, a 10-g sample was extracted with a choloroform:methanol (2:1, vol/vol) mixture according to the method of Folch et al. (1957). Then, 20 to 25 mg of the extracted fat was saponified with 0.5 M methanolic sodium hydroxide and methylated with boronitrifluoride in methanol according to the method of Metcalfe et al. (1966). The fatty acid methyl esters obtained were separated and analyzed by gas chromatography. The fat of abdominal fat was directly saponified and methylated and the fatty acid composition determined with gas chromatography. The concentration of fatty acids at the sn-2 position of PO and RPO was determined by gas-liquid chromatography after hydrolysis with pancreas lipase. The diets were analyzed according to the Dutch Normalization Institute for DM (NEN 3332), ash (NEN 3329), crude fiber (NEN 3326), N. The N in the diets was analyzed with the Kjeldahl method (NEN 3145). Crude protein (g) was calculated as 6.25 x N (g).

Statistical Analysis

Cage served as the experimental unit so that there were 12 units per diet. The effect of diet on digestibility of fat and fatty acids, profiles of breast meat, and adipose tissue were statistically analyzed by 1-way ANOVA with diet as factor. In case of a significant diet effect, the effects of dietary fatty acid saturation (HSO + SO vs. SO), chain length (HSO + SO vs. RPO), and position on the glycerol molecule (RPO vs. PO) were analyzed via a least square means contrast test. The level of statistical significance was preset at P < 0.05. Results are presented as least square means and a pooled SEM. Statistical analysis was done with the SAS program (SAS JMP, 2000).


   RESULTS
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
DISCUSSION
 REFERENCES
 
The effect of dietary fat source on BW gain, feed intake, and feed conversion is presented in Table 4Go. The weight gain was not affected by the diet. The feed-to-gain ratio was significantly lower in the SO group in comparison with the HSO + SO group in both starter and grower-finisher period.


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  		Table 4. Effect of dietary fat characteristics on feed intake, daily weight gain, and feed conversion during the starter (d 1 to 14) and grower-finisher (d 15 to 33) period
 
The effects of treatment on the apparent fecal digestibility of total fat and individual fatty acids are presented in Tables 5Go and 6Go. The digestibility of crude fat in broilers fed the HSO + SO was significantly (P < 0.001) lower than in those fed the SO in both the starter and grower-finisher period. The digestibilities of C18:0, C16:0, and total saturated fatty acids (S) were highest in the SO group, irrespective of the age of the broilers. There was no significant difference in the digestibility of total unsaturated fatty acids (U) between the HSO + SO and SO or RPO groups. During the age period of 31 to 33 d, almost all differences between digestibility of saturated fatty acids in HSO + SO and RPO were significant. During the age period of 10 to 14 d, the significant higher digestibility of total S was mainly based on a higher digestibility of C18:0 (Table 5Go). The difference for the digestibility of total U was not significant. The randomization of palm oil (RPO vs. PO) did not significantly affect fat and fatty acid digestibility. However, a numerical increase (P < 0.1) of the digestibility of C16:0, C18:0, and total S for the growing-finishing birds fed with RPO in comparison with the PO group was found.


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  		Table 5. Effect of dietary fat characteristics on the apparent fecal digestibility (%) of DM, crude fat, and fatty acids in the starter period (d 10 to 14)
 

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  		Table 6. Effect of dietary fat characteristics on the apparent fecal digestibility (%) of DM, crude fat, and fatty acids in the grower-finisher period (d 31 to 33)
 
The effect of the dietary fat source on the fatty acid profile of breast meat and abdominal fat is presented in Table 7Go and 8Go. The differences in fatty acid composition for the birds fed the HSO + SO and SO diets were nearly all significant. Broilers fed the SO diet had higher concentrations of unsaturated fatty acids in breast meat and abdominal fat. The calculated U/S ratio was highest in the SO group. The differences in fatty acid profile for broilers fed either the RPO diet or HSO + SO diet were significant for most fatty acids. The concentrations of C16:0 and C18:1 were higher and those of C18:0 and C18:2 were lower in the RPO group. The U/S ratio of breast meat and abdominal fat was lowest in broiler chickens fed the RPO diet. Feeding of RPO instead of PO resulted in significantly increased C16:0 in abdominal fat and breast meat. The U/S ratio of both breast meat and abdominal fat was significantly lower in the RPO group when compared with the PO group.


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  		Table 7. Effect of dietary fat characteristics on the fatty acid profile (% of methyl esters) of breast meat in broilers
 

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  		Table 8. Effect of dietary fat characteristics on the fatty acid profile (% of methyl esters) of abdominal fat in broilers
 

   DISCUSSION
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
REFERENCES
 
This study with broiler chickens confirms that saturated fatty acids are less digestible than unsaturated fatty acids. It also confirms that the intake of C18:2 is reflected in the fatty acid profiles of breast meat and of abdominal fat. The broilers fed with the SO diet instead of the HSO + SO diet, which in essence is consumption of C18:0 at the expense of C18:1 and C18:2, had a higher fat digestibility. This outcome corroborates earlier studies (Renner and Hill, 1961; Katangole and March, 1980; Wiseman and Salvador, 1991; Ketels, 1994). It is known that in broiler chickens, the digestibility of medium-chain saturated fatty acids is higher than that of long-chain saturated fatty acids (Renner and Hill, 1961; Young, 1961; Kussaibati et al., 1982; Dänicke et al., 2000; Knarreborg et al., 2004). There was a significantly higher crude fat digestibility for the RPO diet in comparison with the HSO + SO diet. Deduced from this and different other studies with broiler chickens (Young, 1961; Kussaibati et al., 1982; Ketels and De Groote, 1989; Smits et al., 2000), the differences in digestibility between poly- and monounsaturated fatty acids with a chain length of 18 C atoms are low. For the digestibility, the relevant difference in dietary fat composition between HSO + SO and RPO is therefore the C16:0 and the C18:0 concentration.

Birds fed the HSO + SO diet in comparison with those fed with the SO diet had a significant lower digestibility for the predominant long-chain saturated fatty acids (C16:0 and C18:0) but not for the unsaturated fatty acids. This agrees with results of studies in which tallow was compared with soybean oil (Dänicke et al., 1999; Knarreborg et al., 2004). However, Dänicke et al. (2000) estimated a significant linear dose-dependent decrease for digestibility of both the saturated and unsaturated fatty acids after replacing soybean oil by tallow. The digestibility of saturated fat may be improved by the addition of an unsaturated fat source (Sibbald, 1978), but according to Wiseman et al. (1998), it is not plausible to suggest a synergy between dietary unsaturated and saturated fat in broiler chickens. There might be a dose effect and a limiting digestibility for the amount of long-chain saturated fat. Ketels and De Groote (1989) showed that the inclusion of increasing levels of a saturated fat source like tallow decreased its digestibility, but no such effect was seen with soybean oil. The dose level of long-chain saturated fatty acids in the HSO + SO group was relatively high, being approximately 3 and 6% of the diet in the starter and grower-finisher period, respectively. This dietary long-chain saturated fat content corresponds with a dietary dose level of 7 and 14% of a saturated fat source like tallow in the starter and the grower-finisher period, respectively. Thus, the low digestibility of C18:0 in the HSO + SO group may relate to the high inclusion level of C18:0. However, a high intake itself tends to raise the apparent digestibility because of the diminishing effect of the relatively constant excretion of endogenous origin will be smaller. The calculated C18:0 digestibility was negative for the HSO + SO group in the starter period. This is probably caused by the combination of a low digestibility and endogenous C18:0 production in the lower gut. In addition, the C18:0 digestibility coefficient may be underestimated due to biohydrogenation of C18:1 and C18:2 in the large intestine.

In calculation models, the dietary U/S ratio is used to predict the digestibility, ME value (Ketels, 1994; Wiseman et al., 1998), or both. The S in the formulas mainly reflects the sum of C16:0 and C18:0. The U/S ratios of the HSO + SO and RPO diets were similar. The S digestibility was significantly lower in the HSO + SO group compared with the RPO group, but there was no difference in total U digestibility between the groups. The S fraction consists of C18:0 with relatively low digestibility and C16:0 with higher digestibility, as was shown earlier (Kussaibati et al., 1982; Dänicke et al., 2000; Smits et al., 2000).

Palm oil contains a high content of C16:0 that is predominantly located at the sn-1 and sn-3 positions of the glycerol molecule. Randomization yielded palm oil with one-third of the C16:0 at the sn-2 position. As indicated in the introduction section, we hypothesized that randomization of palm oil would increase its digestibility, in particular that of its C16:0 component. There was no statistically significant effect of randomization on crude fat digestibility and the digestibility of individual fatty acids. Thus, our hypothesis would be rejected. However, we did find a systematic (P-value between 0.05 and 0.1) increase in the group mean digestibilities of C16:0, C18:0, and S during the growing-finisher period. Randomization of palm oil had increased the group mean digestibility of C16:0 by 5.8% units. The randomization-induced increase of C16:0 digestibility is in line with results found in rats (Renaud et al., 1995). The effect of randomization of palm oil on the digestibility of C16:0 is also supported by significantly higher concentration of C16:0 in breast meat and abdominal fat. It is not known to what extent the increase in C16:0 in breast meat and abdominal fat is caused by increased digestion of C16:0 or increased de novo synthesis. A large part of deposition of S in broiler chickens fed with lipid-rich diets does not originate from the de novo production (Villaverde et al., 2006). The deposition of C16:0 will come predominantly from dietary C16:0. It is concluded that the raised level of C16:0 in breast meat and abdominal fat of the birds fed the RPO diet was caused by the increased digestibility of C16:0. Scheeder et al. (2003) have also reported that the position of saturated fatty acids in the glycerol molecule influence their position in the body of poultry. Triacyglycerols are hydrolyzed in the lumen of the gastrointestinal tract in free fatty acids and 2-monoglycerides. Free fatty acids have a lower digestibility than monoglycerides (Garrett and Young, 1975). Due to a randomization of palm oil, the composition of free fatty acids in the lumen of the intestine will be changed. The amount of free S decreased and free U increased. The decrease of the fat digestibility by increasing the amount of dietary free fatty acids is higher in case of saturated fat in comparison with an unsaturated fat source (Wiseman and Salvador, 1991). The increased content of unsaturated fatty acids at the sn-1,3 position after randomization did not affect its digestibility.

From the results of the grower-finisher period (Table 6Go), the digestibility of C16:0 at the sn-2 and sn-1,3 positions can be calculated using the following formulas:


Formula 1([1])


Formula 2([2])

Multiplying the first formula by 1/0.67 gives the value for sn-1,3 being:


Formula 3([3])

The digestibility of C16:0 at the sn-2 position can be calculated by using formula [2] and [3]:


Formula 4([4])

The digestibility of C16:0 at sn-2 is calculated to be 89.5%. The use of this value in formula [1] gives a calculated digestibility of 51.0% for C16:0 at the sn-1,3 position.

Randomization also resulted in a numerically (P = 0.09) increased digestibility of C18:0 during d 31 to 33. The calculated digestibility for C18:0 at the sn-2 and sn-1,3 positions was 84 and 37%, respectively. Thus, the positions of C16:0 and C18:0 at the glycerol molecule are important factors to determining the digestibility of palm oil.

In conclusion, the present data support the idea that randomization of palm oil, which raises the content of C16:0 at the sn-2 position, improves the digestibility of its C16:0 component. Randomization of palm oil increased the group mean C16:0 digestibility by 5.8% units during the grower-finisher period. It was calculated that C16:0 at the sn-2 position was digested much more efficiently than C16:0 at the sn-1,3 position. Randomization of palm oil increased the incorporation of C16:0 into breast meat and abdominal fat and lowered the U/S ratios in these tissues. Thus, randomized palm oil may be used as a vegetable oil in broiler nutrition with positive effects on saturated fat digestibility and firmness of meat compared with native palm oil. For the determination of the digestibility or metabolic energy value of palm oil to replace animal fat, both the differences between C16:0 and C18:0 and the position C16:0 on the glycerol molecule are relevant.

Received for publication August 23, 2007. Accepted for publication November 25, 2007.


   REFERENCES
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 REFERENCES
 
AOAC. 1975. Official Methods of Analysis of Official Analytical Chemists. 12th ed. Assoc. Off. Anal. Chem., Washington, DC.

Bavelaar, F. J., and A. C. Beynen. 2003. Relationships between dietary fatty acid composition and either melting point or fatty acid profile of adipose tissue in broilers. Meat Sci. 64:133–140.[CrossRef]

Breckenridge, W. C. 1978. Stereospecific analysis of triacylglycerols. Pages 197–232 in Handbook of Lipid Research. Fatty Acids and Glycerides. A. Kuksis, ed. Plenum Press, New York, NY.

Dänicke, S., H. Jeroch, W. Böttcher, M. R. Bedford, and O. Simon. 1999. Effect of dietary fat type, pentosan level, and xylanases on digestibility of fatty acids, liver lipids, and vitamin E in broilers. Lipids 101:90–100.

Dänicke, S., H. Jeroch, W. Böttcher, and O. Simon. 2000. Interactions between dietary type and enzyme supplementation in broiler diets with high pentosan contents: Effects of precaecal and total tract digestibility of fatty acids, metabolisability of gross energy, digesta viscosity and weights of small intestine. Anim. Feed Sci. Technol. 84:279–294.[CrossRef]

Folch, J., M. Lees, and G. H. S. Stanley. 1957. A simple method for the isolation and purification of total lipids from animal tissues. J. Biol. Chem. 226:497–509.[Free Full Text]

Garrett, R. L., and R. J. Young. 1975. Effect of micelle formation on the absorption of neutral fat and fatty acids by the chicken. J. Nutr. 105:827–838.[Abstract/Free Full Text]

Gläser, K. R., C. Wenk, and M. R. L. Scheeder. 2004. Evaluation of pork backfat firmness and lard consistency using several different physicochemical methods. J. Sci. Food Agric. 84:853–862.[CrossRef][Web of Science]

Katangole, J. B. D., and B. E. March. 1980. Fat utilization in relation to intestinal fatty acid binding protein and bile salts in chicks of different ages and different genetic sources. Poult. Sci. 59:819–827.[Web of Science][Medline]

Ketels, E. 1994. The metabolizable energy values of fats in poultry diets. PhD Thesis. Univ. Gent, Belgium.

Ketels, E., and G. De Groote. 1989. Effect of ratio of unsaturated to saturated fatty acids of the dietary lipid fraction on utilization and metabolizable energy of added fats in young chicks. Poult. Sci. 68:1506–1512.[Web of Science][Medline]

Knarreborg, A., C. Lauridsen, R. M. Engberg, and S. K. Jensen. 2004. Dietary antibiotic growth promoters enhance the bio-availability of {alpha}-tocopherol acetate in broilers by altering lipid absorption. J. Nutr. 134:1487–1492.[Abstract/Free Full Text]

Kussaibati, R., J. Guillaume, and B. Leclerq. 1982. Effects of intestinal microflora and added bile salts on the metabolisable energy and digestibility of saturated fats in the chicken. Arch. Geflugelkd. 46:42–46.

Metcalfe, L. D., A. A. Schmitz, and J. R. Pelka. 1966. Rapid preparation of fatty acid esters from lipids for gaschromatographic analysis. Anal. Chem. 193:514–515.

Mu, H., and C. E. Høy. 2004. The digestion of dietary triacylglycerols. Prog. Lipid Res. 43:105–133.[CrossRef][Web of Science][Medline]

Mukherjee, K. D., and S. Warwel. 1997. Strukturierte Triglyceride. Schriftenreihe des Bundesministeriums fur Ernahrung, Landwirtschaft und-Forsten Reihe A. Angew. Wiss. 464:69–90.

Renaud, S. C., J. C. Ruf, and D. Petithory. 1995. The positional distribution of fatty acids in palm oil and lard influences their biological effects in rats. J. Nutr. 125:229–237.[Abstract/Free Full Text]

Renner, R., and F. W. Hill. 1961. Factors affecting the absorbability of saturated fatty acids in the chick. J. Nutr. 74:254–258.[Abstract/Free Full Text]

SAS JMP. 2000. JMP® Design of Experiments. Version 4. SAS Inst. Inc., Cary, NC.

Scheeder, M. R. L., D. Gumy, R. Messikommer, C. Wenk, and P. Lambelet. 2003. Effect of PUFA at sn-2 position in dietary triacylglycerols on the fatty acid composition of adipose tissues in non-ruminant farm animals. Eur. J. Lipid Sci. Technol. 105:74–82.[CrossRef]

Sibbald, I. R. 1978. The true metabolizable energy values of mixtures of tallow with either soybean oil or lard. Poult. Sci. 57:473–477.[Web of Science]

Smits, C. H. M., P. J. Moughan, and A. C. Beynen. 2000. The inhibitory effect of a highly viscous carboxymethylcellulose on dietary fat digestibility in the growing chickens is dependent on the type of fat. J. Anim. Physiol. Anim. Nutr. (Berl.) 83:231–238.

Vila, B., and E. Esteve-Garcia. 1996. Studies on acid oils and fatty acids for chickens. I. Influence of age, rate of inclusion and degree of saturation on fat digestibility and metabolisable energy of acid oils. Br. Poult. Sci. 37:105–117.[CrossRef][Web of Science][Medline]

Villaverde, C., M. D. Baucells, L. Cortinas, and A. C. Barroeta. 2006. Effect of dietary concentration and degree of polyunsaturation of dietary fat on endogenous synthesis and deposition of fatty acids in chickens. Br. Poult. Sci. 47:173–179.[CrossRef][Web of Science][Medline]

Wiseman, J., J. Powles, and F. Salvador. 1998. Comparison between pigs and poultry in the prediction of dietary energy value of fats. Anim. Feed Sci. Technol. 71:1–9.[CrossRef]

Wiseman, J., and F. Salvador. 1991. The influence of free fatty acid content and degree of saturation on the apparent metabolizable energy value of fats fed to broilers. Poult. Sci. 70:573–582.[Web of Science][Medline]

Young, R. 1961. The energy value of fats and fatty acids for chicks. Poult. Sci. 41:1225–1233.[Web of Science]




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