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Utilization of Fats and Fatty Acids by Turkey Poults
Utilization of Fats and Fatty Acids by Turkey Poults S. LEESON and J. O. ATTEH1 Department of Animal and Poultry Science, University of Guelph, Guelph, Ontario, Canada, NIG 2W1
1995 Poultry Science 74:2003-2010
nondigestion of a fat is problematic in terms of energy metabolism, there is also Sources of fat used in poultry diets concern that such undigested fatty acids originate from either animals or vegeta- will complex with minerals to form unabbles. Animal products, and espedally sorbed soaps (Atteh and Leeson, 1984). tallow, are very saturated, and there is This is of particular relevance to the concern that young birds may not effec- young turkey, which is prone to skeletal tively utilize these fatty adds, mainly that can be caused by imbalance because of their inability to form mixed disorders of minerals, such as caldum. Two experimicelles in the lumen. However, mixtures ments were conducted to determine of saturated and unsaturated fatty adds, as exemplified by so-called animal- nutrient utilization by young turkeys vegetable blend fats, are fairly well uti- when fed various dietary fats or pure fatty lized, due to possible synergism in micelle adds varying in degree of saturation. formation (Atteh et al, 1989). Although INTRODUCTION
MATERIALS AND METHODS Received for publication February 7, 1995. Accepted for publication August 9, 1995. 1 Present address: Department of Animal Science, University Illorin, Illorin, Nigeria.
Experiment 1
Growth Study. Three hundred and sixty day-old Large White male turkey poults
2003
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ABSTRACT Two experiments were carried out with young, Large White male turkey poults maintained in either floor pens or metabolism cages. In Experiment 1, poults were fed isoenergetic diets containing either no supplemental fat, or 5% of either tallow, corn oil, soybean oil, animal-vegetable blend fat, or canola oil. Poults generally ate less of the fat-supplemented diets and showed improved feed utilization, although weight gain was little affected. There was improved fat retention when vegetable oils were used (P < .01) and this was reflected in a slight improvement in diet energy level (P > .05). Poults fed tallow or animal-vegetable blend fat also excreted most fat. Diet had no effect (P > .05) on apparent retention of caldum or phosphorus, although retention of magnesium was less with more saturated fats. In Experiment 2, poults were fed diets containing palmitic add, oleic acid, or a 50:50 (wt/wt) mixture of these fatty adds. There was a reduction (P < .05) in apparent retention of nitrogen, magnesium, caldum, and fat for poults fed palmitic add, oleic add, or the mixture. Mixing palmitic add with oleic add corrected some of these problems. However, reduced mineral retention was not reflected in any change in levels of bone ash, caldum, or phosphorus. Feeding palmitic add did result in the most dramatic reduction of bone magnesium content (P < .05). It is conduded that turkey poults, like chicks, are less able to digest saturated fatty acids, and that such undigested fats can lead to reduced retention of some minerals through increased soap formation. However, there is no direct evidence that such soap formation causes a major change in bone caldum or phosphorus content or in gross bone development or poult well-being. {Key words: turkey, fatty acid, fat saturation, soap, mineral retention)
2004
LEESON AND ATTEH TABLE 1. Percentage diet composition, Experiment 1 Diets
Ingredients and analysis
2
5
4
3
S
1°',,} \/ul
87.17 11.50 .85 .48
87.17 .87 6.96
87.17 .87 6.96
87.17 .87 6.96
87.17 .87 6.96
87.17 .87 6.96
5.00 5.00 5.00 5.00 100.00
100.00
100.00
100.00
100.00
5.00 100.00
90.02 29.44 1.72 1.17 .90 .13
89.97 29.74 6.47 1.16 .89 .14
90.53 29.88 6.64 1.15 .89 .14
90.70 29.23 6.39 1.23 .89 .14
90.60 29.67 6.70 1.23 .89 .14
90.55 29.62 6.51 1.14 .89 .14
JQmtained: corn, 30.00%; soybean meal, 46.5%; corn gluten meal, 3.00%; fish meal, 3.00%; limestone, 1.10%; calcium phosphate, 2.40%; DL-methionine, .12%; iodized salt, .30%; mineral-vitamin premix, .75% (provided per kilogram of diet); vitamin A, 8,000 IU (retinyl palmitate); cholecalciferol, 40 fig; vitamin E, 11IU (dl-a-tocopheryl acetate); riboflavin, 9.0 mg; biotin, .25 mg; pantothenic acid, 11.0 mg; vitamin B12,13 mg; niacin, 26 mg; choline, 900 mg; vitamin K, 1.5 mg; folic acid, 1.5 mg; ethoxyquin, 125 mg; manganese, 55 mg; zinc, 50 mg; copper, 5 mg; iron, 30 mg; and selenium, .1 mg. 2 Less .3% in the nutrient retention trial due to presence of .3% chromic oxide.
were brooded in floor pens in an environmentally controlled house and fed the experimental diets shown in Table 1. The diets were isonitrogenous and isoenergetic, the treatments being the substitution of 5% supplementary alphafloc (non-nutritive filler), animal-vegetable (AV) blend fat,2 animal tallow,2 corn oil,3 soybean oil,3 or canola oil3 for cornstarch in the control diet. Thus there were six diets, each fed to four replicate pens of 15 poults each. Growth rate was recorded to 6 wk of age. At this time, two poults per replicate were randomly selected, slaughtered, and processed at the University plant. The carcasses were then bisected longitudinally in order to
2 Rothsay, P.O. Box 8270, Dundas, ON, Canada, L9H 5G1. ^anamara Foods, P.O. Box 618, Hamilton, ON, Canada, L8N 3K7. 4 Kjel-foss Automatic, Model 16310, A/S N. Foss Electric, 69 Slangerupgade, DK 3400, Hillerod, Denmark. 5 Model 1241, Parr Instrument Co., Mowne, IL 61265.
reduce sample size and one half ground and freeze-dried prior to chemical assay for fats and fatty acid profile. Nutrient Retention Study. One hundred and forty-four day-old turkey poults from the same hatch as used in the growth study were kept under similar environmental conditions but kept in metabolism cages that enabled excreta collection. Four replicate cages of six poults each were used for each of the six treatments. Chromic oxide, which acted as marker, replaced part of the cellulose in the experimental diets shown in Table 1 without affecting the nutrient content of the diets. Excreta samples were taken over a 72-h period when the birds were 2 wk old. The excreta samples were freeze-dried and ground prior to chemical analysis. Chemical Analysis. Nitrogen in both feed and excreta was determined by the Kjeldahl procedure4 and gross energy was determined by adiabatic oxygen bomb calorimetry.5 Total glycerides and fatty acids in feed, excreta, and carcass were determined by petroleum ether (boiling
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Basal* Cornstarch Alphafloc (cellulose)2 Linoleic acid Animal-vegetable fat Tallow Corn oil Soybean oil Canola oil Total Analyzed nutrient content Dry matter, % Crude protein, % Crude fat, % Calcium, % Total phosphorus, % Magnesium, %
1I
2005
TURKEY FAT DIGESTION TABLE 2. Percentage diet composition, Experiment 2 Diets Ingredients and analysis
1
4
3
2
_ (%) 87.85 11.49
87.85 .86 5.26
.66 100.00
6.03 100.00
5.60 5.69 100.00
87.85 .86 2.63 2.80 5.86 100.00
94.9 32.49 2.04 1.20 .62 .24
94.4 31.98 6.64 1.18 .62 .26
93.8 31.16 7.53 1.24 .62 .24
95.3 31.05 7.61 1.22 .61 .23
87.85 .86
iContained: com, 30%; soybean meal, 46.49%; corn gluten meal, 3%; fish meal, 3%; limestone, 1.1%; calcium phosphate, 2.4%; iodized salt, .3%; DL-methionine, .12%; linoleic acid, .09%; cornstarch, .3%; chromic oxide, .3%; mineral-vitamin premix (supplying/kg of diet), .75%; vitamin A, 8000 IU (retinyl palmitate); cholecalciferol, 40 /tg; vitamin E, 11 IU (dl-a-tocopheryl acetate); riboflavin, 9.0 mg; pantothenic acid, 11.0 mg; vitamin B12,13 pg; niacin, 26 mg; choline, 900 mg; vitamin K, 1.5 mg; folic acid, 1.5 mg; biotin, .25 mg; antioxidant (ethoxyquin), 125 mg; manganese, 55 mg; zinc, 50 mg; copper, 5 mg; iron, 30 mg; and selenium, .1 mg.
point = 40 to 60 C) extraction using a Technicon auto analyzer.7 Chromium in Soxhlet apparatus. To estimate the propor- feed and excreta samples was determined tion of the fatty acids in the excreta, samples using the method of Fenton and Fenton were subjected to a two-stage fat extraction (1979). (Atteh and Leeson, 1985). The fat extracted from the feed, and carcass, and that ex- Experiment 2 tracted from each of the two extractions One hundred and forty-four day-old from the excreta were esterified with .2 N Large White male turkey poults were methanolic trimethyl ammonium hydroxhoused in an electrically heated battery ide and the methyl esters analyzed for component fatty acids by gas-liquid chro- brooder and fed the experimental diets matography (Varian, Model 2100),6 using shown in Table 2. The control diet had no the method of Association of Official Ana- supplemental fat, but other diets contained palmitic, oleic, or a 50:50 mixture of oleic lytical Chemists (1980). and palmitic acids supplemented at 5% Feed and excreta samples were ashed at inclusion level, together with alphafloc, at 600 C, and the ash digested using the the expense of cornstarch in the control method of AOAC (1980) for preparation of diets. Thus, there were four treatments each a sample solution of inorganic materials for with six replicate cages of six poults. atomic absorption spectrophotometry. The The experimental diets and water were resulting solutions were then analyzed for available for ad libitum consumption during calcium and magnesium using a Varian a trial period that lasted 3 wk. At 2 wk of atomic absorption spectrophotometer age, excreta were collected over a (Model AA10)5 and phosphorus using a 72-h period for determination of nutrient retention. Chromic oxide was used as a marker. Samples were dried at 70 C and ground prior to chemical analysis. At 3 wk of age, feed intake and weight 6 Varian Canada Inc., Mississauga, ON, Canada, gain were determined. Two poults from L5N 5R9. TModel AA2, Technicon, Tarrytown, NY 10591. each replicate cage were selected at random
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Basal ingredients1 Cornstarch Palmitic acid (95%) Oleic acid (90%) Alphafloc (cellulose) Total Analyzed nutrient content Dry matter Crude protein Crude fat Calcium Total phosphorus Magnesium
2006
LEESON AND ATTEH
and killed by cervical dislocation. The left tibia was then removed and cleaned of adhering flesh, dried at 100 C, defatted using Soxhlet extraction apparatus, and dried again prior to ashing at 600 C for 16 h. Chemical analyses were as described in Experiment 1. Statistical Analysis
RESULTS Experiment 1
Experiment 2 From 0 to 6 wk of age, poults fed diets The performance of the poults as incontaining soybean oil consumed less feed (P < .01) than poults fed the control diet or fluenced by dietary treatment is shown in the diets supplemented with canola oil or Table 6. There was no effect of the treattallow (Table 3). Birds fed tallow were the ments on feed intake (P > .05), although the heaviest group at 6 wk of age, with this birds fed diets with supplemental oleic acid advantage being significant (P < .01) rela- consumed the least amount of feed. Diet tive to birds fed corn oil, soybean oil, or the had no effect on weight gain or feed:gain AV blend of fat. Except for corn oil, adding ratio (P > .05). There was no effect of the fat to the diet resulted in an improvement (P treatments on phosphorus retention (P > < .05) in feed efficiency (Table 2). There .05, Table 7). Poults fed the control diet were no effects of the dietary treatments on retained more nitrogen than did those fed apparent nitrogen, calcium, or phosphorus diets supplemented with free fatty acids (P retention (P > .05, Table 4). However, in < .05), although poults fed oleic acid diets supplemented with vegetable oils, retained more nitrogen than those fed the dietary fat was absorbed better than was fat diet supplemented with palmitic acid (P <
TABLE 3. Effects of dietary sources of fat on performance of turkey males to 6 wk, Experiment 1 Dietary sources of fat (5%)
Feed intake
Control AV-blend fat Tallow Corn oil Soybean oil Canola oil SD
2.994A 2.814*= 2.884AB 2.780BC 2.716C 2.897*8 .088
Weight gain -
(kg) 1.83ABC LSI 8 0 1.90* 1.76C 1.79C 1.87*8 .052
Feed:gain (kg:kg) 1.64* 1.56b 1.52t> 1.59* 1.52b 1.52b .047
"Means within a column with no common superscript differ significantly (P < .05). A-c Means within a column with no common superscript differ significantly (P < .01).
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Data collected from each experiment were subjected to analysis of variance using the model for completely randomized design (Steel and Torrie, 1980). Significant differences among treatments were determined by Duncan's multiple range test (Duncan, 1955).
in the control diet or those diets supplemented with tallow or AV-blend (P < .01). Supplementation of diets with fat, regardless of source, reduced magnesium retention (P < .05). There was increased ME for diets supplemented with vegetable oils and AV-blend compared to the control, although these effects were not significant. There was variation (P < .05) in excreta soap concentration; birds fed tallow showed the most excreta soap, whereas birds fed corn or soybean oil had less soap. As expected, the fatty acid profile of the carcass fat tended to mirror that seen in the diet (Table 5). Fatty acid profile of nonsoap fat in the excreta also resembles that seen in the diet, although fat present as soap tends to be less influenced by diet, and is found to be predominantly composed of saturated fatty acids (Table 5).
2007
TURKEY FAT DIGESTION TABLE 4. Effects of dietary sources of fat on apparent nutrient retention of turkeys. Experiment 1 Dietary of fat
Nutrient retention Nitrogen
Calcium
Magnesium
Phosphorus
Fat
Diet ME
soap fat
75.3B 78.3B 76.5B 87.7A 88.0* 86.8* 2.7
(kcal/kg) 3,101 3,217 3,032 3,244 3,279 3,263 44.6
(%)i
33.9 34.2 33.0 33.1 36.1 33.8 .5
/o/\
Control AV-blend Tallow Corn oil Soybean oil Canola oil SD
57.0 57.7 55.5 60.2 61.3 57.5 .9
57.5 54.9 52.7 57.3 57.4 59.2 .9
45.1" 35.6b 30.8b 35.1b 36.7b 34.5b 1.9
12.6bc 16.5»b 20.8" 10.2< 11.9c 14.8b 1.6
TABLE 5. Comparison of fat in diet, digesta, and carcass Fatty acid Variable
Cl4:0
C
16:0
Cl8:0
Cl8:l
Q&2
Cl8:3
(%1 Fatty acid profile Control AV-blend Tallow Corn oil Soybean oil Canola oil Fatty acid profile Control AV-blend Tallow Com oil Soybean oil Canola oil Fatty acid profile Control AV-blend Tallow Corn oil Soybean oil Canola oil Fatty acid profile Control AV-blend Tallow Corn oil Soybean oil Canola oil
of dietary fat .1 2.9 4.0 trace .2 .1
14.5 13.2 22.3 13.2 8.9 5.8
2.8 9.4 20.6 2.6 5.2 2.0
26.9 29.1 33.4 27.3 24.8 56.3
45.8 29.6 6.2 54.1 49.4 23.4
3.6 4.5 1.1 1.4 7.7 9.3
trace trace .1 trace trace trace
14.9 20.8 27.8 13.8 10.5 10.4
4.0 15.8 23.2 3.3 8.2 2.9
22.6 27.7 28.4 23.6 21.1 48.8
53.1 26.2 5.7 52.4 53.1 28.4
2.8 1.4 1.5 1.9 4.3 1.3
.1 .6 .8 trace trace trace
25.7 26.7 29.6 29.2 13.8 22.9
9.4 20.3 31.8 13.1 13.8 10.0
37.6 27.1 13.6 34.0 36.3 39.1
14.0 16.7 15.5 16.0 17.0 20.0
.7 .9 .7 .9 trace 1.5
1.6 1.9 2.4 1.6 1.3 1.4
20.6 19.2 24.5 20.4 19.8 20.9
14.7 13.0 16.6 9.4 8.9 9.2
39.7 40.7 38.8 37.7 38.2 43.1
14.1 16.0 9.3 23.7 23.9 17.8
1.5 2.1 1.2 .9 1.3 1.7
of non-soap fat in excreta
of soap fat in excreta
of carcass fat
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"-•Means within column with no common superscript differ significantly (P < .05). A_B Means within a column with no common superscript differ significantly (P < .01). 1 As a proportion of total excreta fat.
2008
LEESON AND ATTEH TABLE 6. Effects of dietary saturated and unsaturated fatty acids on performance of turkey poults to 3 wk of age, Experiment 2
Dietary treatments
Feed intake
Control Palmitic acid (P) Oleic acid (O) 50:50 O and P mixture SD
728.1 758.7 680.6 788.1 99.4
Body weight gain (g/bird)
—
Feed:gain ratio
teg) 1.53 1.68 1.45 1.58 .17
474.9 452.5 469.8 500.3 35.1
TABLE 7. Effects of dietary saturated and unsaturated fatty acids on nutrient retention by turkey poults, Experiment 2 Nutrient retention Diet treatment
Nitrogen
Phosphorus
Control Palmitic acid (P) Oleic acid (O) 50:50 O and P mixture SD
75.4a 68.7<: 72.9b 70.6C 3.4
43.0 41.6 40.9 42.6 5.1
Magnesium
Calcium
Fat
68.9a 54.0a 62.3' 60.4" 3.9
72.1" 63.2"1 87.2a 77.2C 5.6
— (%) 47.8b 32.6C 43.1" 40.4a 4.6
ME (kcal/kg)
a-dMeans within a column with no common superscript differ significantly (P < .05).
2,890" 2,640c 2,994a 2,722c 105.9
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.05). There was also variation in fat reten- diet (P < .05). Birds fed palmitic acid had the tion (P < .05), with birds fed diets sup- lowest bone magnesium content. plemented with oleic acid retaining more fat than those fed supplemental palmitic DISCUSSION acid. Fat retention by birds fed diets supplemented with the palmitic-oleic mixThe variation in feed intake observed ture was intermediate between values for with the different sources of fat used in birds fed either fatty acid alone (P < .05). Experiment 1 may be associated with Dietary ME followed a trend similar to that variation in fat retention and overall diet of fat retention, with the diet supplemented ME. Thus birds tended to consume more with oleic acid having the highest ME, of the control diet although differences whereas the diet with supplemental were significant only for birds fed AVpalmitic acid had the lowest ME (P < .05). blend fat, corn oil, and soybean oil. Fatty acid supplementation reduced magNitrogen, magnesium, and calcium nesium and calcium retention (P < .05) and retention were reduced (P < .05) by among acid diets supplemented with fatty dietary fatty acid supplementation. The acids, retention was least for birds fed reduction was more pronounced when palmitic acid (Table 7). palmitic acid was used in the diet. This is Dietary fatty acid did not affect bone ash, thought to be associated with the reduced calcium, or phosphorus contents (P > .05, absorption of saturated fatty acids (HamilTable 8). However, dietary fatty acid sup- ton and McDonald, 1969; Sibbald and plementation reduced bone magnesium Kramer, 1980). The trend in protein retencontent relative to that seen with the control tion confirms earlier observations by
2009
TURKEY FAT DIGESTION TABLE 8. Effects of dietary saturated and unsaturated fatty acids on bone ash and bone minerals of turkey poults, Experiment 2 Diet treatment
Bone ash1
Calcium2
Control Palmitic acid (P) Oleic acid (O) 50:50 O and P mixture SD
43.5 42.9 44.8 43.7 3.4
32.9 31.9 33.2 32.0 1.5
Magnesium2
Phosphorus2
.75» .67' .70b .71b .04
13.6 15.2 14.0 15.5 1.1
(%)
'-•Means within a column with no common superscript differ significantly (P < .05). *On dry, fat-free basis. Percentage of bone ash.
supplemented with animal fat. This is thought to be related to the higher proportion of unsaturated fatty acids in vegetable oils than in animal fat. There is a positive correlation between the degree of unsaturation of component fatty acids of fats and their retention (Sklan, 1979; Corino et al, 1980). A larger proportion of the unabsorbed (excreta) fat was present as soap for birds fed diets supplemented with AVblend and tallow. Thus, soap formation may be a factor acting against optimum retention of fat from tallow and AV-blend for the young poult. Atteh et al (1989) made similar observations in broiler chicks fed different fat sources. The reduction in magnesium retention associated with fat supplementation suggests that it may be the main cation involved in soap formation. Calcium and magnesium are usually the predominant cations involved in the formation of insoluble soap (West et al, 1966). Although the fatty acid profile of the carcass fat of the birds tended to follow the fatty acid profile of the diet fat, there was substantial modification. There was a general tendency to increase palmitic and stearic acid content of the carcass fat relative to the dietary content (Table 5). The oleic acid content of the carcass fat was also relatively constant regardless of dietary sources of fat. The carcass fat of poults fed diets with supplemental vegetable oils was more unsaturated than that of birds fed the control diet and those fed diets supplemented with tallow or AVblend fat. Oleic acid was the dominant
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Kusaibati et al. (1983) that protein retention is enhanced in the presence of unsaturated rather than saturated lipids. The reduced retention of calcium and magnesium (Experiment 2) associated with fatty acid supplementation of the diets is thought to be due to soap formation, which has been observed with chickens (Dewar et al, 1975; Gardiner and Whitehead, 1976). The relative retention of palmitic acid is much lower than retention of oleic acid. Young and Garret (1963) reported that increasing the amount of oleic acid in relation to palmitic acid resulted in a linear increase in the absorption of palmitic acid. Cullen et al. (1962) and Jensen et al. (1970) have also reported cases of fatty acid synergism between saturated and unsaturated fatty acids. The detrimental effects of supplemental palmitic acid observed on calcium and magnesium retention were reflected in analysis of bone. Although bone ash and bone calcium of birds fed palmitic acid were lower than those of birds fed oleic acid, these differences were not significant. The reduction in bone magnesium content seen with palmitic acid supplementation is thought to be associated with reduced magnesium absorption. Dewar et al. (1975) and Atteh and Leeson (1983) considered soap formation to be the cause of decrease in bone cations of birds fed high-fat diets. However, compared with chickens, bone mineralization in poults seem to be less adversely affected by dietary fat inclusion. Fats present in diets supplemented with vegetable oils were more efficiently utilized than those in the control diet or diets
2010
LEESON AND ATTEH
ACKNOWLEDGMENTS
This work was supported by the Ontario Ministry of Agriculture, Food and Rural Affairs, Toronto, ON, Canada, M7A 2B2 and British United Turkeys of America, Lewisburg, WV 24901. Fat samples were kindly donated by Rothsay, P.O. Box 8270, Dundas, ON, Canada, L9H 5G1 and Canamara Foods, P.O. Box 618, Hamilton, ON, Canada, L8N 3K7. REFERENCES Association of Official Analytical Chemists, 1980. Official Methods of the AOAC. Association of Official Analytical Chemists, Washington, DC. Atteh, J. O., and S. Leeson, 1983. Effects of dietary fatty acids and calcium levels on performance and mineral metabolism of broiler chickens. Poultry Sci. 62:2412-2419. Atteh, J. O., and S. Leeson, 1984. Effects of dietary saturated or unsaturated fatty acids and calcium levels on performance and mineral metabolism of broiler chicks. Poultry Sci. 63:2252-2260. Atteh, J. O., and S. Leeson, 1985. Influence of age, dietary cholic acid, and calcium levels on
performance, utilization of free fatty acids and bone mineralization in broilers. Poultry Sci. 64: 1959-1971. Atteh, J. O., S. Leeson, and J. D. Summers, 1989. Effects of dietary sources and levels of fat on performance, nutrient retention and bone mineralization of broiler chicks fed two levels of calcium. Can. J. Anim. Sci. 69:459-467. Corino, C, V. Dell'orto, and O. Pedron, 1980. Effect of fatty acid composition of fats and oils on the nutritive efficiency of broiler feeds. Rev. Zootec. Vet. 2:94-98. Cullen, M. P., O. G. Rasmussen and O.H.M. Wilder, 1962. Metabolizable energy value and utilization of different types and grades of fat by the chick. Poultry Sci. 41:360-367. Dewar, W. A., C. C. Whitehead, J. N. Downie, and E. Potter, 1975. The retention of calcium, iron, magnesium, and zinc in chicks fed on diets containing metal soaps. Proc. Nutr. Soc. 34: 5A-6A. Duncan, D. B., 1955. Multiple range and multiple Ftests. Biometrics, 11:1-42. Fenton, T. W., and M. Fenton, 1979. An improved procedure for determination of chromic oxide in feed and feces. Can. J. Anim. Sci. 59:631-634. Gardiner, E. E., and C. C. Whitehead, 1976. Effect of dietary palmitic acid on broiler chicks fed on various concentrations of calcium. Br. Poult. Sci. 17:241-244. Hamilton, R.M.G., and B. E. McDonald, 1969. Effect of dietary fat source on the apparent digestibility of fat and the composition of fecal lipids of the young pig. J. Nutr. 97:33-41. Jensen, L. S., G. W. Schumaier, and J. D. Lathshaw, 1970. "Extra caloric" effect of dietary fat for developing turkeys as influenced by calorie: protein ratio. Poultry Sci. 49:1697-1704. Kusaibati, R., B. Leclerq, and J. Guillaume, 1983. Effects of calcium, magnesium and bile salts on apparent metabolizable energy and digestibility of lipids, starch and proteins in growing chicks. Anal. Zootechnie 32:7-20. Sibbald, I. R. and J.K.G. Kramer, 1980. The effect of the basal diet on the utilization of fat as a source of true metabolizable energy, lipid and fatty acids. Poultry Sci. 59:316-324. Sklan, D., 1979. Digestion and absorption of lipids in chicks fed triglycerides or free fatty acid. Synthesis of monoglycerides in the intestine. Poultry Sci. 58:885-889. Steel, R.G.D., and J. H. Torrie, 1980. Principles and Procedures of Statistics: A Biomethcal Approach. 2nd ed. McGraw-Hill Book Co. New York, NY. West, E. S., W. R. Todd, H. S. Mason, and J. T. Van Bruggen, 1966. Textbook of Biochemistry. 4th ed. MacMillan Co., London, UK. Young, R. J., and R. L. Garrett, 1963. Effect of oleic and linoleic acids on the absorption of saturated fatty acids in the chick. J. Nutr. 81:321-329. Young, R. J., R. L. Garret, and M. Griffith, 1963. Factors affecting the absorbability of fatty acid mixtures high in saturated fatty acids. Poultry Sci. 42:1146-1154.
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carcass fatty acid regardless the dietary fat source. Experiments with chickens (Atteh and Leeson, 1984, 1985) showed significant increases in feed intake in the presence of saturated fatty acid supplementation. This was thought to be due to the fact that palmitic and stearic acids contributed very little energy to broiler diets. Observations in Experiment 2 show that in terms of performance, turkey poults were able to utilize palmitic acid. However, like chickens (Young et al, 1963; Corino et al, 1980; Atteh and Leeson, 1984), saturated fatty acids are metabolized less efficiently by turkeys than are unsaturated fatty acids (Table 7). It is concluded that unsaturated fatty acids are better utilized by poults than are the more inexpensive saturates as found in tallow and tallow blends. Such reduced digestibility results in lower energy utilization, although resultant excreta soap formation does not seem to have any major effects on bone mineralization. It seems unlikely that poor fat utilization is responsible for skeletal problems related to abnormal bone calcification, as often seen in young poults.
1995 Poultry Science 74:2003-2010
nondigestion of a fat is problematic in terms of energy metabolism, there is also Sources of fat used in poultry diets concern that such undigested fatty acids originate from either animals or vegeta- will complex with minerals to form unabbles. Animal products, and espedally sorbed soaps (Atteh and Leeson, 1984). tallow, are very saturated, and there is This is of particular relevance to the concern that young birds may not effec- young turkey, which is prone to skeletal tively utilize these fatty adds, mainly that can be caused by imbalance because of their inability to form mixed disorders of minerals, such as caldum. Two experimicelles in the lumen. However, mixtures ments were conducted to determine of saturated and unsaturated fatty adds, as exemplified by so-called animal- nutrient utilization by young turkeys vegetable blend fats, are fairly well uti- when fed various dietary fats or pure fatty lized, due to possible synergism in micelle adds varying in degree of saturation. formation (Atteh et al, 1989). Although INTRODUCTION
MATERIALS AND METHODS Received for publication February 7, 1995. Accepted for publication August 9, 1995. 1 Present address: Department of Animal Science, University Illorin, Illorin, Nigeria.
Experiment 1
Growth Study. Three hundred and sixty day-old Large White male turkey poults
2003
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ABSTRACT Two experiments were carried out with young, Large White male turkey poults maintained in either floor pens or metabolism cages. In Experiment 1, poults were fed isoenergetic diets containing either no supplemental fat, or 5% of either tallow, corn oil, soybean oil, animal-vegetable blend fat, or canola oil. Poults generally ate less of the fat-supplemented diets and showed improved feed utilization, although weight gain was little affected. There was improved fat retention when vegetable oils were used (P < .01) and this was reflected in a slight improvement in diet energy level (P > .05). Poults fed tallow or animal-vegetable blend fat also excreted most fat. Diet had no effect (P > .05) on apparent retention of caldum or phosphorus, although retention of magnesium was less with more saturated fats. In Experiment 2, poults were fed diets containing palmitic add, oleic acid, or a 50:50 (wt/wt) mixture of these fatty adds. There was a reduction (P < .05) in apparent retention of nitrogen, magnesium, caldum, and fat for poults fed palmitic add, oleic add, or the mixture. Mixing palmitic add with oleic add corrected some of these problems. However, reduced mineral retention was not reflected in any change in levels of bone ash, caldum, or phosphorus. Feeding palmitic add did result in the most dramatic reduction of bone magnesium content (P < .05). It is conduded that turkey poults, like chicks, are less able to digest saturated fatty acids, and that such undigested fats can lead to reduced retention of some minerals through increased soap formation. However, there is no direct evidence that such soap formation causes a major change in bone caldum or phosphorus content or in gross bone development or poult well-being. {Key words: turkey, fatty acid, fat saturation, soap, mineral retention)
2004
LEESON AND ATTEH TABLE 1. Percentage diet composition, Experiment 1 Diets
Ingredients and analysis
2
5
4
3
S
1°',,} \/ul
87.17 11.50 .85 .48
87.17 .87 6.96
87.17 .87 6.96
87.17 .87 6.96
87.17 .87 6.96
87.17 .87 6.96
5.00 5.00 5.00 5.00 100.00
100.00
100.00
100.00
100.00
5.00 100.00
90.02 29.44 1.72 1.17 .90 .13
89.97 29.74 6.47 1.16 .89 .14
90.53 29.88 6.64 1.15 .89 .14
90.70 29.23 6.39 1.23 .89 .14
90.60 29.67 6.70 1.23 .89 .14
90.55 29.62 6.51 1.14 .89 .14
JQmtained: corn, 30.00%; soybean meal, 46.5%; corn gluten meal, 3.00%; fish meal, 3.00%; limestone, 1.10%; calcium phosphate, 2.40%; DL-methionine, .12%; iodized salt, .30%; mineral-vitamin premix, .75% (provided per kilogram of diet); vitamin A, 8,000 IU (retinyl palmitate); cholecalciferol, 40 fig; vitamin E, 11IU (dl-a-tocopheryl acetate); riboflavin, 9.0 mg; biotin, .25 mg; pantothenic acid, 11.0 mg; vitamin B12,13 mg; niacin, 26 mg; choline, 900 mg; vitamin K, 1.5 mg; folic acid, 1.5 mg; ethoxyquin, 125 mg; manganese, 55 mg; zinc, 50 mg; copper, 5 mg; iron, 30 mg; and selenium, .1 mg. 2 Less .3% in the nutrient retention trial due to presence of .3% chromic oxide.
were brooded in floor pens in an environmentally controlled house and fed the experimental diets shown in Table 1. The diets were isonitrogenous and isoenergetic, the treatments being the substitution of 5% supplementary alphafloc (non-nutritive filler), animal-vegetable (AV) blend fat,2 animal tallow,2 corn oil,3 soybean oil,3 or canola oil3 for cornstarch in the control diet. Thus there were six diets, each fed to four replicate pens of 15 poults each. Growth rate was recorded to 6 wk of age. At this time, two poults per replicate were randomly selected, slaughtered, and processed at the University plant. The carcasses were then bisected longitudinally in order to
2 Rothsay, P.O. Box 8270, Dundas, ON, Canada, L9H 5G1. ^anamara Foods, P.O. Box 618, Hamilton, ON, Canada, L8N 3K7. 4 Kjel-foss Automatic, Model 16310, A/S N. Foss Electric, 69 Slangerupgade, DK 3400, Hillerod, Denmark. 5 Model 1241, Parr Instrument Co., Mowne, IL 61265.
reduce sample size and one half ground and freeze-dried prior to chemical assay for fats and fatty acid profile. Nutrient Retention Study. One hundred and forty-four day-old turkey poults from the same hatch as used in the growth study were kept under similar environmental conditions but kept in metabolism cages that enabled excreta collection. Four replicate cages of six poults each were used for each of the six treatments. Chromic oxide, which acted as marker, replaced part of the cellulose in the experimental diets shown in Table 1 without affecting the nutrient content of the diets. Excreta samples were taken over a 72-h period when the birds were 2 wk old. The excreta samples were freeze-dried and ground prior to chemical analysis. Chemical Analysis. Nitrogen in both feed and excreta was determined by the Kjeldahl procedure4 and gross energy was determined by adiabatic oxygen bomb calorimetry.5 Total glycerides and fatty acids in feed, excreta, and carcass were determined by petroleum ether (boiling
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Basal* Cornstarch Alphafloc (cellulose)2 Linoleic acid Animal-vegetable fat Tallow Corn oil Soybean oil Canola oil Total Analyzed nutrient content Dry matter, % Crude protein, % Crude fat, % Calcium, % Total phosphorus, % Magnesium, %
1I
2005
TURKEY FAT DIGESTION TABLE 2. Percentage diet composition, Experiment 2 Diets Ingredients and analysis
1
4
3
2
_ (%) 87.85 11.49
87.85 .86 5.26
.66 100.00
6.03 100.00
5.60 5.69 100.00
87.85 .86 2.63 2.80 5.86 100.00
94.9 32.49 2.04 1.20 .62 .24
94.4 31.98 6.64 1.18 .62 .26
93.8 31.16 7.53 1.24 .62 .24
95.3 31.05 7.61 1.22 .61 .23
87.85 .86
iContained: com, 30%; soybean meal, 46.49%; corn gluten meal, 3%; fish meal, 3%; limestone, 1.1%; calcium phosphate, 2.4%; iodized salt, .3%; DL-methionine, .12%; linoleic acid, .09%; cornstarch, .3%; chromic oxide, .3%; mineral-vitamin premix (supplying/kg of diet), .75%; vitamin A, 8000 IU (retinyl palmitate); cholecalciferol, 40 /tg; vitamin E, 11 IU (dl-a-tocopheryl acetate); riboflavin, 9.0 mg; pantothenic acid, 11.0 mg; vitamin B12,13 pg; niacin, 26 mg; choline, 900 mg; vitamin K, 1.5 mg; folic acid, 1.5 mg; biotin, .25 mg; antioxidant (ethoxyquin), 125 mg; manganese, 55 mg; zinc, 50 mg; copper, 5 mg; iron, 30 mg; and selenium, .1 mg.
point = 40 to 60 C) extraction using a Technicon auto analyzer.7 Chromium in Soxhlet apparatus. To estimate the propor- feed and excreta samples was determined tion of the fatty acids in the excreta, samples using the method of Fenton and Fenton were subjected to a two-stage fat extraction (1979). (Atteh and Leeson, 1985). The fat extracted from the feed, and carcass, and that ex- Experiment 2 tracted from each of the two extractions One hundred and forty-four day-old from the excreta were esterified with .2 N Large White male turkey poults were methanolic trimethyl ammonium hydroxhoused in an electrically heated battery ide and the methyl esters analyzed for component fatty acids by gas-liquid chro- brooder and fed the experimental diets matography (Varian, Model 2100),6 using shown in Table 2. The control diet had no the method of Association of Official Ana- supplemental fat, but other diets contained palmitic, oleic, or a 50:50 mixture of oleic lytical Chemists (1980). and palmitic acids supplemented at 5% Feed and excreta samples were ashed at inclusion level, together with alphafloc, at 600 C, and the ash digested using the the expense of cornstarch in the control method of AOAC (1980) for preparation of diets. Thus, there were four treatments each a sample solution of inorganic materials for with six replicate cages of six poults. atomic absorption spectrophotometry. The The experimental diets and water were resulting solutions were then analyzed for available for ad libitum consumption during calcium and magnesium using a Varian a trial period that lasted 3 wk. At 2 wk of atomic absorption spectrophotometer age, excreta were collected over a (Model AA10)5 and phosphorus using a 72-h period for determination of nutrient retention. Chromic oxide was used as a marker. Samples were dried at 70 C and ground prior to chemical analysis. At 3 wk of age, feed intake and weight 6 Varian Canada Inc., Mississauga, ON, Canada, gain were determined. Two poults from L5N 5R9. TModel AA2, Technicon, Tarrytown, NY 10591. each replicate cage were selected at random
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Basal ingredients1 Cornstarch Palmitic acid (95%) Oleic acid (90%) Alphafloc (cellulose) Total Analyzed nutrient content Dry matter Crude protein Crude fat Calcium Total phosphorus Magnesium
2006
LEESON AND ATTEH
and killed by cervical dislocation. The left tibia was then removed and cleaned of adhering flesh, dried at 100 C, defatted using Soxhlet extraction apparatus, and dried again prior to ashing at 600 C for 16 h. Chemical analyses were as described in Experiment 1. Statistical Analysis
RESULTS Experiment 1
Experiment 2 From 0 to 6 wk of age, poults fed diets The performance of the poults as incontaining soybean oil consumed less feed (P < .01) than poults fed the control diet or fluenced by dietary treatment is shown in the diets supplemented with canola oil or Table 6. There was no effect of the treattallow (Table 3). Birds fed tallow were the ments on feed intake (P > .05), although the heaviest group at 6 wk of age, with this birds fed diets with supplemental oleic acid advantage being significant (P < .01) rela- consumed the least amount of feed. Diet tive to birds fed corn oil, soybean oil, or the had no effect on weight gain or feed:gain AV blend of fat. Except for corn oil, adding ratio (P > .05). There was no effect of the fat to the diet resulted in an improvement (P treatments on phosphorus retention (P > < .05) in feed efficiency (Table 2). There .05, Table 7). Poults fed the control diet were no effects of the dietary treatments on retained more nitrogen than did those fed apparent nitrogen, calcium, or phosphorus diets supplemented with free fatty acids (P retention (P > .05, Table 4). However, in < .05), although poults fed oleic acid diets supplemented with vegetable oils, retained more nitrogen than those fed the dietary fat was absorbed better than was fat diet supplemented with palmitic acid (P <
TABLE 3. Effects of dietary sources of fat on performance of turkey males to 6 wk, Experiment 1 Dietary sources of fat (5%)
Feed intake
Control AV-blend fat Tallow Corn oil Soybean oil Canola oil SD
2.994A 2.814*= 2.884AB 2.780BC 2.716C 2.897*8 .088
Weight gain -
(kg) 1.83ABC LSI 8 0 1.90* 1.76C 1.79C 1.87*8 .052
Feed:gain (kg:kg) 1.64* 1.56b 1.52t> 1.59* 1.52b 1.52b .047
"Means within a column with no common superscript differ significantly (P < .05). A-c Means within a column with no common superscript differ significantly (P < .01).
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Data collected from each experiment were subjected to analysis of variance using the model for completely randomized design (Steel and Torrie, 1980). Significant differences among treatments were determined by Duncan's multiple range test (Duncan, 1955).
in the control diet or those diets supplemented with tallow or AV-blend (P < .01). Supplementation of diets with fat, regardless of source, reduced magnesium retention (P < .05). There was increased ME for diets supplemented with vegetable oils and AV-blend compared to the control, although these effects were not significant. There was variation (P < .05) in excreta soap concentration; birds fed tallow showed the most excreta soap, whereas birds fed corn or soybean oil had less soap. As expected, the fatty acid profile of the carcass fat tended to mirror that seen in the diet (Table 5). Fatty acid profile of nonsoap fat in the excreta also resembles that seen in the diet, although fat present as soap tends to be less influenced by diet, and is found to be predominantly composed of saturated fatty acids (Table 5).
2007
TURKEY FAT DIGESTION TABLE 4. Effects of dietary sources of fat on apparent nutrient retention of turkeys. Experiment 1 Dietary of fat
Nutrient retention Nitrogen
Calcium
Magnesium
Phosphorus
Fat
Diet ME
soap fat
75.3B 78.3B 76.5B 87.7A 88.0* 86.8* 2.7
(kcal/kg) 3,101 3,217 3,032 3,244 3,279 3,263 44.6
(%)i
33.9 34.2 33.0 33.1 36.1 33.8 .5
/o/\
Control AV-blend Tallow Corn oil Soybean oil Canola oil SD
57.0 57.7 55.5 60.2 61.3 57.5 .9
57.5 54.9 52.7 57.3 57.4 59.2 .9
45.1" 35.6b 30.8b 35.1b 36.7b 34.5b 1.9
12.6bc 16.5»b 20.8" 10.2< 11.9c 14.8b 1.6
TABLE 5. Comparison of fat in diet, digesta, and carcass Fatty acid Variable
Cl4:0
C
16:0
Cl8:0
Cl8:l
Q&2
Cl8:3
(%1 Fatty acid profile Control AV-blend Tallow Corn oil Soybean oil Canola oil Fatty acid profile Control AV-blend Tallow Com oil Soybean oil Canola oil Fatty acid profile Control AV-blend Tallow Corn oil Soybean oil Canola oil Fatty acid profile Control AV-blend Tallow Corn oil Soybean oil Canola oil
of dietary fat .1 2.9 4.0 trace .2 .1
14.5 13.2 22.3 13.2 8.9 5.8
2.8 9.4 20.6 2.6 5.2 2.0
26.9 29.1 33.4 27.3 24.8 56.3
45.8 29.6 6.2 54.1 49.4 23.4
3.6 4.5 1.1 1.4 7.7 9.3
trace trace .1 trace trace trace
14.9 20.8 27.8 13.8 10.5 10.4
4.0 15.8 23.2 3.3 8.2 2.9
22.6 27.7 28.4 23.6 21.1 48.8
53.1 26.2 5.7 52.4 53.1 28.4
2.8 1.4 1.5 1.9 4.3 1.3
.1 .6 .8 trace trace trace
25.7 26.7 29.6 29.2 13.8 22.9
9.4 20.3 31.8 13.1 13.8 10.0
37.6 27.1 13.6 34.0 36.3 39.1
14.0 16.7 15.5 16.0 17.0 20.0
.7 .9 .7 .9 trace 1.5
1.6 1.9 2.4 1.6 1.3 1.4
20.6 19.2 24.5 20.4 19.8 20.9
14.7 13.0 16.6 9.4 8.9 9.2
39.7 40.7 38.8 37.7 38.2 43.1
14.1 16.0 9.3 23.7 23.9 17.8
1.5 2.1 1.2 .9 1.3 1.7
of non-soap fat in excreta
of soap fat in excreta
of carcass fat
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"-•Means within column with no common superscript differ significantly (P < .05). A_B Means within a column with no common superscript differ significantly (P < .01). 1 As a proportion of total excreta fat.
2008
LEESON AND ATTEH TABLE 6. Effects of dietary saturated and unsaturated fatty acids on performance of turkey poults to 3 wk of age, Experiment 2
Dietary treatments
Feed intake
Control Palmitic acid (P) Oleic acid (O) 50:50 O and P mixture SD
728.1 758.7 680.6 788.1 99.4
Body weight gain (g/bird)
—
Feed:gain ratio
teg) 1.53 1.68 1.45 1.58 .17
474.9 452.5 469.8 500.3 35.1
TABLE 7. Effects of dietary saturated and unsaturated fatty acids on nutrient retention by turkey poults, Experiment 2 Nutrient retention Diet treatment
Nitrogen
Phosphorus
Control Palmitic acid (P) Oleic acid (O) 50:50 O and P mixture SD
75.4a 68.7<: 72.9b 70.6C 3.4
43.0 41.6 40.9 42.6 5.1
Magnesium
Calcium
Fat
68.9a 54.0a 62.3' 60.4" 3.9
72.1" 63.2"1 87.2a 77.2C 5.6
— (%) 47.8b 32.6C 43.1" 40.4a 4.6
ME (kcal/kg)
a-dMeans within a column with no common superscript differ significantly (P < .05).
2,890" 2,640c 2,994a 2,722c 105.9
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.05). There was also variation in fat reten- diet (P < .05). Birds fed palmitic acid had the tion (P < .05), with birds fed diets sup- lowest bone magnesium content. plemented with oleic acid retaining more fat than those fed supplemental palmitic DISCUSSION acid. Fat retention by birds fed diets supplemented with the palmitic-oleic mixThe variation in feed intake observed ture was intermediate between values for with the different sources of fat used in birds fed either fatty acid alone (P < .05). Experiment 1 may be associated with Dietary ME followed a trend similar to that variation in fat retention and overall diet of fat retention, with the diet supplemented ME. Thus birds tended to consume more with oleic acid having the highest ME, of the control diet although differences whereas the diet with supplemental were significant only for birds fed AVpalmitic acid had the lowest ME (P < .05). blend fat, corn oil, and soybean oil. Fatty acid supplementation reduced magNitrogen, magnesium, and calcium nesium and calcium retention (P < .05) and retention were reduced (P < .05) by among acid diets supplemented with fatty dietary fatty acid supplementation. The acids, retention was least for birds fed reduction was more pronounced when palmitic acid (Table 7). palmitic acid was used in the diet. This is Dietary fatty acid did not affect bone ash, thought to be associated with the reduced calcium, or phosphorus contents (P > .05, absorption of saturated fatty acids (HamilTable 8). However, dietary fatty acid sup- ton and McDonald, 1969; Sibbald and plementation reduced bone magnesium Kramer, 1980). The trend in protein retencontent relative to that seen with the control tion confirms earlier observations by
2009
TURKEY FAT DIGESTION TABLE 8. Effects of dietary saturated and unsaturated fatty acids on bone ash and bone minerals of turkey poults, Experiment 2 Diet treatment
Bone ash1
Calcium2
Control Palmitic acid (P) Oleic acid (O) 50:50 O and P mixture SD
43.5 42.9 44.8 43.7 3.4
32.9 31.9 33.2 32.0 1.5
Magnesium2
Phosphorus2
.75» .67' .70b .71b .04
13.6 15.2 14.0 15.5 1.1
(%)
'-•Means within a column with no common superscript differ significantly (P < .05). *On dry, fat-free basis. Percentage of bone ash.
supplemented with animal fat. This is thought to be related to the higher proportion of unsaturated fatty acids in vegetable oils than in animal fat. There is a positive correlation between the degree of unsaturation of component fatty acids of fats and their retention (Sklan, 1979; Corino et al, 1980). A larger proportion of the unabsorbed (excreta) fat was present as soap for birds fed diets supplemented with AVblend and tallow. Thus, soap formation may be a factor acting against optimum retention of fat from tallow and AV-blend for the young poult. Atteh et al (1989) made similar observations in broiler chicks fed different fat sources. The reduction in magnesium retention associated with fat supplementation suggests that it may be the main cation involved in soap formation. Calcium and magnesium are usually the predominant cations involved in the formation of insoluble soap (West et al, 1966). Although the fatty acid profile of the carcass fat of the birds tended to follow the fatty acid profile of the diet fat, there was substantial modification. There was a general tendency to increase palmitic and stearic acid content of the carcass fat relative to the dietary content (Table 5). The oleic acid content of the carcass fat was also relatively constant regardless of dietary sources of fat. The carcass fat of poults fed diets with supplemental vegetable oils was more unsaturated than that of birds fed the control diet and those fed diets supplemented with tallow or AVblend fat. Oleic acid was the dominant
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Kusaibati et al. (1983) that protein retention is enhanced in the presence of unsaturated rather than saturated lipids. The reduced retention of calcium and magnesium (Experiment 2) associated with fatty acid supplementation of the diets is thought to be due to soap formation, which has been observed with chickens (Dewar et al, 1975; Gardiner and Whitehead, 1976). The relative retention of palmitic acid is much lower than retention of oleic acid. Young and Garret (1963) reported that increasing the amount of oleic acid in relation to palmitic acid resulted in a linear increase in the absorption of palmitic acid. Cullen et al. (1962) and Jensen et al. (1970) have also reported cases of fatty acid synergism between saturated and unsaturated fatty acids. The detrimental effects of supplemental palmitic acid observed on calcium and magnesium retention were reflected in analysis of bone. Although bone ash and bone calcium of birds fed palmitic acid were lower than those of birds fed oleic acid, these differences were not significant. The reduction in bone magnesium content seen with palmitic acid supplementation is thought to be associated with reduced magnesium absorption. Dewar et al. (1975) and Atteh and Leeson (1983) considered soap formation to be the cause of decrease in bone cations of birds fed high-fat diets. However, compared with chickens, bone mineralization in poults seem to be less adversely affected by dietary fat inclusion. Fats present in diets supplemented with vegetable oils were more efficiently utilized than those in the control diet or diets
2010
LEESON AND ATTEH
ACKNOWLEDGMENTS
This work was supported by the Ontario Ministry of Agriculture, Food and Rural Affairs, Toronto, ON, Canada, M7A 2B2 and British United Turkeys of America, Lewisburg, WV 24901. Fat samples were kindly donated by Rothsay, P.O. Box 8270, Dundas, ON, Canada, L9H 5G1 and Canamara Foods, P.O. Box 618, Hamilton, ON, Canada, L8N 3K7. REFERENCES Association of Official Analytical Chemists, 1980. Official Methods of the AOAC. Association of Official Analytical Chemists, Washington, DC. Atteh, J. O., and S. Leeson, 1983. Effects of dietary fatty acids and calcium levels on performance and mineral metabolism of broiler chickens. Poultry Sci. 62:2412-2419. Atteh, J. O., and S. Leeson, 1984. Effects of dietary saturated or unsaturated fatty acids and calcium levels on performance and mineral metabolism of broiler chicks. Poultry Sci. 63:2252-2260. Atteh, J. O., and S. Leeson, 1985. Influence of age, dietary cholic acid, and calcium levels on
performance, utilization of free fatty acids and bone mineralization in broilers. Poultry Sci. 64: 1959-1971. Atteh, J. O., S. Leeson, and J. D. Summers, 1989. Effects of dietary sources and levels of fat on performance, nutrient retention and bone mineralization of broiler chicks fed two levels of calcium. Can. J. Anim. Sci. 69:459-467. Corino, C, V. Dell'orto, and O. Pedron, 1980. Effect of fatty acid composition of fats and oils on the nutritive efficiency of broiler feeds. Rev. Zootec. Vet. 2:94-98. Cullen, M. P., O. G. Rasmussen and O.H.M. Wilder, 1962. Metabolizable energy value and utilization of different types and grades of fat by the chick. Poultry Sci. 41:360-367. Dewar, W. A., C. C. Whitehead, J. N. Downie, and E. Potter, 1975. The retention of calcium, iron, magnesium, and zinc in chicks fed on diets containing metal soaps. Proc. Nutr. Soc. 34: 5A-6A. Duncan, D. B., 1955. Multiple range and multiple Ftests. Biometrics, 11:1-42. Fenton, T. W., and M. Fenton, 1979. An improved procedure for determination of chromic oxide in feed and feces. Can. J. Anim. Sci. 59:631-634. Gardiner, E. E., and C. C. Whitehead, 1976. Effect of dietary palmitic acid on broiler chicks fed on various concentrations of calcium. Br. Poult. Sci. 17:241-244. Hamilton, R.M.G., and B. E. McDonald, 1969. Effect of dietary fat source on the apparent digestibility of fat and the composition of fecal lipids of the young pig. J. Nutr. 97:33-41. Jensen, L. S., G. W. Schumaier, and J. D. Lathshaw, 1970. "Extra caloric" effect of dietary fat for developing turkeys as influenced by calorie: protein ratio. Poultry Sci. 49:1697-1704. Kusaibati, R., B. Leclerq, and J. Guillaume, 1983. Effects of calcium, magnesium and bile salts on apparent metabolizable energy and digestibility of lipids, starch and proteins in growing chicks. Anal. Zootechnie 32:7-20. Sibbald, I. R. and J.K.G. Kramer, 1980. The effect of the basal diet on the utilization of fat as a source of true metabolizable energy, lipid and fatty acids. Poultry Sci. 59:316-324. Sklan, D., 1979. Digestion and absorption of lipids in chicks fed triglycerides or free fatty acid. Synthesis of monoglycerides in the intestine. Poultry Sci. 58:885-889. Steel, R.G.D., and J. H. Torrie, 1980. Principles and Procedures of Statistics: A Biomethcal Approach. 2nd ed. McGraw-Hill Book Co. New York, NY. West, E. S., W. R. Todd, H. S. Mason, and J. T. Van Bruggen, 1966. Textbook of Biochemistry. 4th ed. MacMillan Co., London, UK. Young, R. J., and R. L. Garrett, 1963. Effect of oleic and linoleic acids on the absorption of saturated fatty acids in the chick. J. Nutr. 81:321-329. Young, R. J., R. L. Garret, and M. Griffith, 1963. Factors affecting the absorbability of fatty acid mixtures high in saturated fatty acids. Poultry Sci. 42:1146-1154.
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carcass fatty acid regardless the dietary fat source. Experiments with chickens (Atteh and Leeson, 1984, 1985) showed significant increases in feed intake in the presence of saturated fatty acid supplementation. This was thought to be due to the fact that palmitic and stearic acids contributed very little energy to broiler diets. Observations in Experiment 2 show that in terms of performance, turkey poults were able to utilize palmitic acid. However, like chickens (Young et al, 1963; Corino et al, 1980; Atteh and Leeson, 1984), saturated fatty acids are metabolized less efficiently by turkeys than are unsaturated fatty acids (Table 7). It is concluded that unsaturated fatty acids are better utilized by poults than are the more inexpensive saturates as found in tallow and tallow blends. Such reduced digestibility results in lower energy utilization, although resultant excreta soap formation does not seem to have any major effects on bone mineralization. It seems unlikely that poor fat utilization is responsible for skeletal problems related to abnormal bone calcification, as often seen in young poults.