Utilization of Soybean Oil and Tallow in Young Turkeys Compared with Young Chickens

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1 Utilization of Soybean Oil and Tallow in Young Turkeys Compared with Young Chickens A. Mossab, 1 J. M. Hallouis, and M. Lessire Institut National de la Recherche Agronomique, Centre de Tours, Station de Recherches Avicoles 37380, Nouzilly, France ABSTRACT The experiment was conducted to determine system for fat utilization in turkeys than in young the apparent metabolizable energy and apparent fatty acid digestibility of tallow and soybean oil (8% of chickens. This efficient utilization of saturated fatty acids in turkeys seemed to depend more on the fat origin than on the basal diet) in young (1 and 3 wk of age) turkeys compared with young chickens. bird age, because it remained constant with age (91.4 At 1 wk of age, turkeys used fats, particularly saturated vs. 96%) when saturated fatty acids were provided by soybean oil, and decreased (particularly for C fats, more efficiently than young chickens (i.e., total fatty 18:0 : 5.08 vs. 35.8%) when saturated fatty acids were provided by acid digestibility was 96.5 vs. 86.4% for soybean oil and tallow. In turkeys, fluctuations in secretion of bile salts 75.0 vs. 49.1% for tallow). This difference between the or in lipase activity during the trial period may have two species disappeared at 3 wk of age, when there was caused the lower stearic acid digestibility at 3 wk of age. an increase (95.7 vs. 99.3% for soybean oil and 64.0 vs. The present study revealed a difference in fat utilization 69.7% for tallow) in fat utilization in young chickens, between turkeys and young chickens. For higher validity whereas in turkeys it remained constant (96.5 vs. 99.3% for soybean oil and 75 vs. 69.3% for tallow). This result suggests a greater and earlier maturity of the digestive of the digestibility of fats, it would be preferable to use turkeys to derive metabolizable energy and fatty acid digestibility of fat values in formulating turkey diets. (Key words: fats, digestibility, turkey, chicken, age) 2000 Poultry Science 79: INTRODUCTION Fats and oils are included in poultry diets primarily as high-energy ingredients, their energy value being at least twice as high as that of other ingredients. However, the chemical structures of fats and oils are extremely variable, with consequences for digestibility and the ultimate accuracy of diet formulation. Oils of plant origin, such as soybean oil (SO), contain high levels of unsaturated fatty acids and are more completely digested by fowl than animal fats such as lard and tallow (T), which contain higher proportions of saturated fatty acids (Sklan, 1979; Corino et al., 1980; Leeson and Atteh, 1995). In addition, the age of birds has a marked influence on the utilization of dietary fats. Birds physiological ability for fat utilization is poorly developed in the early growth stage, but greatly improves with age (Carew et al., 1972; Freeman, 1984). Nonetheless, most previous studies using the ME and digestibility bioassay of fats were performed with adult cockerels, although the commercial value is in the formulation of diets for broilers (Carew et al., 1972; Freeman, 1984; McNab and Blair, 1988; Wiseman and Salvador, 1989). Moreover, balance studies on growing turkeys are less common. The digestibility of T by 4- and 8-wkold poults was found to be higher than that of 2-wk-old birds, but the digestibility of lard and corn oil was not influenced by age (Whitehead and Fisher, 1975). Feeding beef fat, rapeseed oil, or combinations of the two fats to poults led to an improvement in absorbability of T from 1 to 3 wk, after which no further increase in absorbability occurred (Salmon, 1977). Halloran and Sibbald (1979) reported no significant effects on the ME of two fats (animal and blend fats) with male or female poults. In 6-wk-old poults, diets supplemented with vegetable oils (corn oil, SO, canola oil) were more efficiently utilized than control diets or diets supplemented with animal fat (Leeson and Atteh, 1995). Studies on fat utilization have generally been conducted on one species. Only a few studies (Slinger et al., 1964; Bayley et al., 1968; Fisher and Shannon, 1973; Leeson et al., 1974; Sibbald, 1976) have compared fat digestibility in young chickens and turkeys under the same experimental conditions. Comparison between the two Received for publication December 20, Accepted for publication May 8, To whom correspondence should be addressed: mossab@tours. inra.fr. Abbreviation Key: AFAD = apparent fatty acid digestibility; SO = soybean oil; T = tallow. 1326

2 FAT UTILIZATION IN YOUNG TURKEYS AND YOUNG CHICKENS 1327 TABLE 1. Fatty acid composition of added dietary fats Soybean oil Tallow Gross energy, kcal/kg 9 9 Acidity Iodine value Peroxide coefficient, meq 1 /kg Unsaponifiable, % (% TFA 2 ) Fatty acids C 14: C 16: C 16:1 n C 18: C 18:1 n C 18:2 n C 18:3 n meq = milli-equivalent. 2 TFA = total fatty acids. species is of considerable value from a scientific point of view, and because the data generated would guide decisions related to selection of fats in the case of differences between turkeys and young chickens. The aim of the current study was to determine and compare the AME n and apparent fatty acid digestibility (AFAD) of two fats differing in the degree of saturation of fatty acids (SO and T). The study was performed in very young (1- and 3-wk-old) turkeys compared with young chickens. MATERIALS AND METHODS Forty-eight, day-old male broiler Shaver chickens and 48, day-old male BUT9 turkeys were obtained from a commercial hatchery. They were fed experimental diets and reared in floored pens (three pens of 16 birds) until they were transferred to individual cages for balance trials (at 4 d of age for the first balance trial, and 18 d of age for the second). Cages ( cm) were in an environmentally controlled metabolism room where the initial temperature of 30 C was reduced by 1 C/wk as the experiment progressed to reach 27 C at 3 wk. Lighting was continuous except during the fasting period, when the birds were in the dark from 16 to 9 h. Two fats (Table 1) were selected for evaluation: T and SO. The basis of this selection was to provide fats with varying degrees of saturation according to their fatty acid composition. Eight percent of each fat was added (Lessire et al., 1982) at the expense of the basal diet (BD) (Table 2) so that the experimental diets were composed of 8% fat and 92% BD. The dietary treatments were: BD, BD + SO, or BD + T. Diets were presented as mash. Dietary fats were evaluated in balance trials by the total collection procedure (Lessire, 1990). Balance trials were conducted on young chickens and turkeys at 1 and 3 wk 2 IKA Laboratechnik Janke & Kunkel-STR 79219, Staufen, Germany. 3 GIRA, Rue des Bruyéres Cedex 21 Berlanne-Industriel 64160, Morlaas, France. of age (n = eight repetitions of two birds of the same weight at 1 wk and individual birds close to the mean group weight at 3 wk for each dietary treatment). Food and water were supplied ad libitum. After 4 d of adaptation to cages and experimental diets, young chickens and turkeys were fasted for 17 h, then fed experimental diets for 55 h and starved again for 17 h. Excreta were collected for the last 72 h; each 24-h output was totally collected and stored at 20 C until the end of the balance period. At the end of the collection period, feed intake was recorded precisely, and excreta output for each cage was freeze-dried, weighed, and ground through a hammer mill fitted with a 0.75-mm mesh. Diets and freeze-dried excreta were analyzed for gross energy (IKA isoperibol bomb calorimeter C700 2 ), nitrogen content (by Kjeldahl method: procedure V18-100; AFNOR, 1977), and lipid composition. Lipids were extracted by chloroform-methanol according to Folch et al. (1957) after acidification with 6 N HCl in order to liberate saponified fatty acids. The lipid extracts were esterified using H 2 SO 4 :methanol (5:95; vol:vol). The resulting fatty acid methyl esters were separated and quantified using a gas chromatograph (GIRA 180 GC2 3 ) equipped with a flame ionization detector (250 C), fused silica capillary column (SGE, BP 20 Phase, L: 25 m, internal diameter: 0.32 mm, thickness: 0.5 µ), and integrator. Helium was used as carrier gas. Identification of the different fatty acids was carried out by comparison with retention times of a known standard. Margaric fatty acid (C 17:0 ) was used as the internal standard (10 ml of 0.5 µg/ml solution of C 17:0 ). These analyses allowed the calculation of AFAD of C 16:0,C 18:0,C 18:1,C 18:2, and C 18:3 in the experimental diets and fats. Ingredients TABLE 2. Composition of the basal diet Composition (%) Wheat 39.2 Maize 30.0 Soybean meal 25.2 Isolate soybean proteins 1.47 DL-methionine 0.01 Calcium-carbonate 1.21 Dicalcium phosphate 1.91 Mineral-vitamin premix 1.00 Calculated analysis AME, kcal/kg 2,800 Crude protein, % Methionine + cystine, % 0.70 Lysine, % 1.00 Calcium, % 1.00 Available phosphorus, % 0.45 Measured analysis Fatty acids (% TFA 1 ) C 14: C 16: C 18: C 18:1 n C 18:2 n C 18:3 n TFA = total fatty acid (1.7% in the basal diet).

3 1328 MOSSAB ET AL. Diet AFAD was calculated as the difference between fatty acids ingested and fatty acids excreted. The AFAD of each fat was adjusted for the fat intake and fat excretion attributable to the BD (Wiseman and Lessire, 1987). The AME n of the experimental diets were calculated using the gross energy values of the food and droppings and corrected to zero nitrogen balance (Hill and Anderson, 1958). The AME values of added fats were calculated by the product of total fatty acid digestibility and gross energy of added fat. Two- or three-way analyses of variance for AME and AFAD of diets and fats using the Statview 4 program were performed to identify variations caused by fat, species, and bird age. Statistical differences among means were measured by Newman-Keuls test and were considered to be significant when P RESULTS Birds Performances (Table 3) At the beginning of the first digestibility trial, bird weight was the same regardless of diet; at the end of the trial, bird weight, weight gain, and feed conversion ratio differed according to species and diet, and significant diet species interaction was detected. In chicks, growth parameters were almost independent of diet; however, on the contrary, the best performances were observed in turkeys fed BD. In the second digestibility trial, chicks were heavier and gained more weight than turkeys. Significant diet species interactions were detected for weight, weight gain, and feed intake because there was no diet effect in turkeys and a significant diet effect in chicks. Basal Diet (Table 4) There was a significant interaction between species and age in relation to the AME n of the BD. At 1 wk of age, the AME n value was higher in young chickens than in turkeys, and then from 1 to 3 wk AME n increased in both species. Because this increase was more pronounced in turkeys than in young chickens, AME n values at 3 wk were identical in both species. Significant interactions between species and age of birds were also measured for the digestibility of total and unsaturated fatty acids. At 1 wk of age, unsaturated fatty acids that predominated in the BD (80%) were used more efficiently by turkeys than by young chickens. Digestibility of total and unsaturated fatty acids increased with age only in young chickens and remained constant in turkeys. Digestibility of saturated fatty acids was also higher in turkeys than in young chickens, but did not increase significantly with age in either species. Digestibility of C 16:0 was fairly similar to that of unsaturated fatty acids in all 4 Abacus Concepts, Inc., Berkeley, California TABLE 3. Growth performance of turkeys and chicks during the trial period 1 Turkeys Chickens Probability BD 2 BS + SO 2 BD + T 2 BD BD + SO BD + T Diet Species Diet species 1st Digestibility trial Weight Day 8, g 96 ± 7 90 ± 4 86 ± 8 93 ± 5 89 ± 5 90 ± NS 3 NS Weight Day 12, g 123 ± 9 b 102 ± 5 c 103 ± 10 c 137 ± 8 a 135 ± 8 a 135 ± 10 a < Weight gain Days 8 to 12, g 27 ± 4 b 12 ± 4 c 17 ± 5 c 45 ± 3 a 47 ± 4 a 45 ± 8 a < < Feed intake Days 8 to 12, g 64 ± 5 b 46 ± 2 c 46 ± 5 c 80 ± 4 a 76 ± 5 a 79 ± 6 a < < < Feed conversion ratio 2.39 ± 0.25 bc 4.18 ± 1.55 a 2.87 ± 0.69 b 1.80 ± 0.13 cd 1.63 ± 0.06 d 1.82 ± 0.33 cd < nd Digestibility trial Weight Day 22, g 354 ± 43 c 324 ± 19 c 346 ± 29 c 490 ± 37 b 561 ± 42 a 497 ± 27 b NS < Weight Day 26, g 434 ± 51 c 397 ± 26 c 412 ± 33 c 615 ± 47 b 698 ± 55 a 618 ± 34 b NS < Weight gain Days 22 to 26, g 80 ± ± ± ± ± ± 16 NS < NS Feed intake Days 22 to 26, g 167 ± 18 c 144 ± 17 c 150 ± 12 c 241 ± 11 ab 256 ± 27 a 252 ± 17 b NS < Feed conversion ratio 2.11 ± ± ± ± ± ± NS a d Means in the same line for each factor measured with no common superscripts are significantly different (P < 0.05). 1 Results are mean ± standard deviation for 8 birds (mean of 8 2 birds at 1st trial, mean of 8 birds at 2nd trial) in each group. 2 BD = basal diet, SO = soybean oil, and T = tallow. 3 NS = P > 0.05.

4 FAT UTILIZATION IN YOUNG TURKEYS AND YOUNG CHICKENS 1329 TABLE 4. Metabolizable energy value and apparent fatty acid digestibility of basal diet in young chicks and turkeys 1 Apparent digestibility 2 AME n Species Age (kcal/kg) TFA 2 C 16:0 C 18:0 C 18:1 C 18:2 n-6 Chicks 1 wk 2,597 ± 29 b 64.7 ± 5.7 c 61.8 ± ± ± 5.8 c 68.4 ± 5.8 b 3 wk 2,673 ± 37 a 70.3 ± 3.0 ab 67.2 ± ± ± 3.0 b 73.3 ± 3.8 a Turkeys 1 wk 2,492 ± 56 c 75.0 ± 2.2 a 71.6 ± ± ± 2.5 a 76.5 ± 3.4 a 3 wk 2,677 ± 65 a 73.2 ± 3.6 a 71.3 ± ± ± 3.6 a 74.9 ± 3.7 a (Probability) Source of variation Species < < Age < NS 3 NS NS NS NS Species age NS NS a e Means in the same column with no common superscripts are significantly different (P < 0.05). 1 Results are mean ± standard deviation for 8 birds (mean of 8 2 birds at 1 wk, mean of 8 birds at 3 wk) in each group. 2 TFA = total fatty acids; AME n = apparent metabolizable energy corrected for nitrogen balance. 3 NS = P > groups, whereas that of C 18:0 was lower, especially in young chickens. Fats (Table 5) Significant fat species age, fat species, fat age, and species age interactions were measured on the AME n of fats. At 1 wk, the AME n of the fats studied was higher in turkeys than in young chickens, especially with the saturated fatty acid-rich T. Indeed, in 1-wk-old birds, the AME n of T in turkeys was about twice that obtained in young chickens and almost reached the AME n of SO recorded in young chickens of the same age. From 1 to 3 wk, the AME of fats increased in young chickens, particularly with T. In contrast, the AME n of fats remained constant with age in turkeys. Therefore, no differences between the two species were detected in AME n of fats at 3 wk of age. As for AME n, significant interactions were measured on AFAD of SO and T. At 1 wk of age, fatty acids were digested more efficiently in turkeys than in young chickens. Fatty acid digestibility increased with age in young chickens, particularly for T. However, in turkeys fatty acid digestibility remained constant with age except for the C 18:0 digestibility of T, for which there was a significant decrease from 1 to 3 wk. Therefore, no differences between turkeys and young chickens were detected at 3 wk of age. DISCUSSION The live weight and feed consumption recorded during the trial periods were lower than those commonly obtained in turkey and chick growth. It should be noted that these growth performances should be considered with caution, because they were measured during a short period (3 d) and under particular conditions. Indeed, cage housing, two fasting periods during digestibility trial (5 d), and mash diets are known (%) to decrease growth performance. Moreover, the BD was deficient in protein and amino acids, particularly for turkeys, but the balance between amino acids was correct. The low recorded performances, particularly in turkeys, may be attributed to the protein deficiency. Kouba et al. (1992) showed that the diet formulated for chicken requirements decreased turkey s live weight but didn t affect carcass composition. In contrast, the carcass fat fraction decreased when chickens were fed turkey diets that were high in protein. The higher AME n and fatty acid digestibility of SO compared with T, due to the fatty acid composition, is in accordance with previous results (Renner and Hill, 1960, 1961; Whitehead and Fisher, 1975; Blanch et al., 1995). Birds, particularly when young, use vegetable fats, such as SO, more efficiently because they are predominantly unsaturated, compared with animal fats such as T that are predominantly saturated (Young, 1961; Wiseman and Salvador, 1989, 1991). Fat utilization is positively correlated with the degree of saturation (Sklan, 1979; Corino et al., 1980; Leeson and Atteh, 1995). AME n and fatty acid digestibility may be affected by factors that are not necessarily associated with fat quality, such as species and age of birds, but may be slightly related to bird performance. In the present experiment, turkeys used fats, especially saturated fats, at 1 wk of age more efficiently than young chickens. Fat utilization was not affected by age in turkeys, but was increased greatly with age in young chickens. Thus, no difference in fat utilization was detected between the two species at 3 wk of age. The low fat utilization measured at 1 wk of age in young chickens may be attributed to limited bile salt secretion, as observed by Krogdhal (1985a), and low lipase activity (Nitsan et al., 1991). Improved bile salt secretion and lipase activity with age in young chickens resulted in increased fat utilization at 3 wk by making their digestive systems more fully functional to solubilize and hydrolyze dietary lipids (Carew et al., 1972).

5 1330 MOSSAB ET AL. TABLE 5. Metabolizable energy value and apparent fatty acid digestibility of soybean oil (SO) and tallow (T) in young chicks and turkeys 1 AME n 2 (kcal/kg) Apparent digestibility TFA 2 C 16:0 C 18:0 C 18:1 C 18:2 n-6 Species Age SO T SO T SO T SO T SO T SO T (%) Chicks 1 wk 8,158 ± 135 b 3,966 ± 415 e 86.4 ± 1.4 b 41.9 ± 4.4 e 81.8 ± 2.0 b 35.4 ± 3.9 e 72.5 ± 2.4 c 5.5 ± 4.7 f 84.6 ± 1.8 b 65.5 ± 4.0 c 88.5 ± 0.3 c 57.3 ± 13.6 d 3 wk 9,029 ± 151 a 6,051 ± 191 d 95.7 ± 1.6 a 64.0 ± 2.0 d 94.2 ± 2.3 a 53.9 ± 2.3 d 87.5 ± 2.4 b 30.9 ± 3.5 e 95.3 ± 1.9 a 87.4 ± 1.1 b 96.7 ± 1.3 bc ± 4.8 ab Turkeys 1 wk 9,103 ± 49 a 7,093 ± 195 c 96.5 ± 0.5 a 75.0 ± 2.1 c 95.9 ± 0.7 a 64.6 ± 2.6 c 91.4 ± 0.7 ab 50.8 ± 3.7 d 96.8 ± 0.5 a 93.2 ± 0.8 a 96.8 ± 0.5 bc ± 3.7 a 3 wk 9,368 ± 32 a 6,588 ± 100 cd 99.3 ± 0.3 a 69.7 ± 1.1 cd 99.4 ± 0.5 a 58.9 ± 1.7 cd 96.0 ± 0.4 a 35.8 ± 1.8 e 99.9 ± 0.4 a 93.6 ± 0.5 a 99.3 ± 0.3 bc ± 1.4 a (Probability) Source of variation Fat < < < < < NS Species < < < < < < Age < < < < Fat species < < Fat age NS 3 NS NS NS NS Species age < < < < < Fat species age a f Means in the two fats column for each factor measured with no common superscripts are significantly different (P < 0.05). 1 Results are mean ± standard deviation for 8 birds (mean of 8 2 birds at 1 wk, mean of 8 birds at 3 wk) in each group. 2 TFA = total fatty acids; AME = apparent metabolizable energy corrected for nitrogen balance. 3 NS = P > The present study indicated that fat utilization in young turkeys is more efficient and greater than that of young chickens. Results may indicate that turkeys have higher bile salt secretion and lipase activity from 1 wk of age. However, compared with young chickens, in which bile salt secretion and lipase activity increased with age, turkey bile salt secretion and lipase activity might be constant or increase slowly with age, at least until 3 wks of age (Krogdahl and Sell, 1989). Consequently, turkeys showed only small changes in fatty acid digestibility between 1 and 3 wk, except for C 18:0 digestibility of T, which decreased with age. The digestibility of saturated fatty acids in turkeys depends more on the origin of the dietary fat than the age of the bird, although in young chickens the digestibility of saturated fatty acids depends on the origin of the fat and the age of the bird. In turkeys, the digestibility of saturated fatty acids did not change with age when they were provided with SO, but decreased with age (particularly for C 18:0 ) when saturated fatty acids originated from T. The digestibility of stearic acid in young chickens follows the concentration of bile acids (Krogdahl, 1985b), which shows temporal fluctuations with age (Green and Kellog, 1987), such as lipase activity (Nitsan et al., 1991). The unusual decrease in stearic acid digestibility observed in 3-wk-old turkeys fed T was probably related to the coincidence of the balance trial period with a slight decrease in bile acid secretion or lipase activity, which are both essential for efficient fat digestibility, particularly for saturated fats. When turkeys were provided with unsaturated fats (SO), these fluctuations did not occur with saturated fatty acids, because unsaturated fatty acids improve the solubility of saturated fatty acids and, as a consequence, their digestibility. The apparent digestibility of linoleic acid calculated for T varied between 105 and 117%. These high values might have arisen as a result of an improvement in the digestibility of linoleic acid from the BD (Vila and Esteve-Garcia, 1996). Or, more likely, the T contained only a small amount of linoleic acid (1.4% of total fatty acids) and thus, small errors in the total amount of fatty acid might have resulted in very large errors in the digestibility of the added linoleic acid, because the results were calculated by difference (Ketels and De Groote, 1987). In conclusion, the present study shows that, at 1 wk of age, turkeys use fats, and especially saturated fats, more efficiently than young chickens. Fat utilization was not affected by age in turkeys, but increased greatly with age in young chickens. Thus, at 3 wk of age no difference in fat utilization was detected between the two species. These results suggest earlier and greater maturity of the digestive system for fat utilization in turkeys than in young chickens. It is common practice at the present time for feed manufacturers to use nutritive values derived from chick trials for the formulation of diets for other species. The results of this experiment suggest that it would be desirable to derive a separate set of values for fats and, perhaps, for other ingredients used in feed manufacture for turkeys.

6 FAT UTILIZATION IN YOUNG TURKEYS AND YOUNG CHICKENS 1331 The results also suggest that fluctuations in secretion of bile acids and lipase activity may have influenced saturated fatty acid digestibility in turkeys, particularly at 3 wk of age and when saturated fatty acids were provided by T. It may, therefore, be advisable to choose the right fat for each species at an early age (i.e., at 1 wk). In addition to the above approaches related to fat allocation to birds that use them efficiently, it would be valuable to evaluate and compare bile salt secretion and lipase activity in young chickens and turkeys from hatch to slaughter age using different fat origins. ACKNOWLEDGMENTS We would like to thank G. M. Pesti (University of Georgia, 30602, U.S.A.), M. Picard, and D. Hermier (I.N.R.A. Tours, 37380, France) for their critical reading of the manuscript. Furthermore, acknowledgement goes to K. Gerard (I.N.R.A. Tours, 37380, France) for animal care. 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