- Email: [email protected]
The Effects of Fractions of Yellow Corn on the True Metabolizable Energy Value of Beef Tallow1
The Effects of Fractions of Yellow Corn on the True Metabolizable Energy Value of Beef Tallow1 I. R. SIBBALD and J.K.G. KRAMER Animal Research Institute, Agriculture Canada, Central Experimental Farm, Ottawa, Ontario, Canada K1A OC6 (Received for publication June 4, 1979)
1980 Poultry Science 59:1505-1509
INTRODUCTION T h e true metabolizable energy (TME) of beef tallow, as measured with adult cockerels, is n o t constant. In two r e p o r t s it was s h o w n t h a t t h e TME value of tallow was greater when fed in conjunction with a corn based diet t h a n with a wheat based diet (Sibbald a n d Kramer, 1 9 7 8 , 1 9 8 0 ) ; the difference attributable to the diets decreased as t h e a m o u n t of tallow increased relative t o basal diet. T h e c o n c e n t r a t i o n s of linoleic acid ( 1 8 : 2 ) and phospholipids (PL) in t h e basal diets appeared t o influence tallow utilization. T h e e x p e r i m e n t described in this r e p o r t was designed t o obtain additional information a b o u t t h e effect of t h e basal diet o n tallow utilization. Basal diets containing various fractions of yellow corn were used in an a t t e m p t t o identify t h e location in t h e corn kernel of t h e factor(s) which interacts with tallow. Lipid c o m p o n e n t s of t h e diets were identified and quantitated in an a t t e m p t t o identify t h e factor(s). MATERIALS AND METHODS
The e x p e r i m e n t was arranged as an 8 X 4
1 Contribution Institute.
Number
852, Animal
Research
factorial with 7 adult White Leghorn cockerels of t h e Kentville Control strain being assigned t o each t r e a t m e n t ; an additional 7 birds served as negative controls for t h e m e a s u r e m e n t of m e t a b o l i c plus e n d o g e n o u s energy excretion. Eight basal diets (Table 1), each fed at a level of 3 0 g per bird, and 4 levels of beef tallow (0, 1.5, 3.0, and 4.5 g per bird) were used. Basal Diets 1 and 2 had t h e same formulations as t h e wheat and corn based diets used in earlier experiments (Sibbald and Kramer, 1978, 1 9 8 0 ) . In t h e remaining 6 basal diets, wheat was replaced with a fraction of c o r n in an a m o u n t similar to t h a t which would be present in the corn p o r t i o n of Basal # 2 . T h e birds, individually housed in wire cages in a windowless r o o m where t h e y received 12 h r of light daily, were starved for 2 4 hr to ensure t h a t their alimentary canals were free of feed residues. T h e y were t h e n force-fed t h e experimental diets. T h e birds were treated in blocks with each diet being fed t o one bird before proceeding t o t h e n e x t block; t h e force feeding t o o k a b o u t o n e m i n u t e per bird. T h e feed i n p u t per bird was 30, 31.5, 33 and 34.5 g for the diets containing 0, 1.5, 3, and 4.5 g of tallow, respectively. Thus, each bird received 3 0 g of basal diet plus t h e appropriate a m o u n t of fat. T h e time of feeding was recorded for each bird, and t h e excreta voided during t h e
1505
Downloaded from http://ps.oxfordjournals.org/ by guest on April 14, 2015
ABSTRACT An experiment was made to study the effect of diet composition on the utilization of beef tallow by adult cockerels. The diets were based on wheat and soybean meal with portions of the wheat being replaced by either yellow corn, degermed corn, corn germ, extracted germ, crude corn oil, soapstock, or refined corn oil. The birds were starved for 24 hr and then force fed one of 8 basal diets (30 g) supplemented with 0, 1.5, 3.0, or 4.5 g of beef tallow. Excreta voided during the subsequent 24 hr were collected. The true metabolizable energy values (TME) of the tallow were measured. The TME value of tallow decreased with the level of input (P<.01). A corn based diet permitted greater TME values for tallow than did a wheat based diet at the lowest level of tallow inclusion. However, when corn products (degermed corn, germ, extracted germ, crude oil, soapstock, refined oil) were substituted in the wheat basal at levels similar to those in the corn basal, it appeared that all fractions except soapstock had some ability to enhance tallow utilization. Comparisons of TME values with lipid composition data failed to identify the factor(s) which increases tallow utilization.
SIBBALD AND KRAMER
1506
TABLE 1. Compositions of the basal diets (%) Diet number Ingredient1 68
76 68
71
72
72
72
68
3 20
28
28
20
20
21
21
21
3.84 3.13 .038
3.85 3.18 .033
3.79 3.21 .030
4.10 3.34 .028
3.88 3.05 .026
4.03 3.31 .036
3.90 3.24 .029
4.02 3.30 .034
a Constant ingredients: limestone 1.25%; dicalcium phosphate 1.5%; iodized salt .25%; vitamin premix .5%; ice mineral premix .5%. For compositions of premixes see Sibbald and Kramer (1978).
subsequent 24 hr were collected quantitatively. The negative control birds were treated similarly but were unfed. The frozen excreta samples were freezedried, equilibrated with atmopsheric moisture, weighed, and ground. Samples of diets, beef tallow, and excreta were assayed for gross energy in an adiabatic oxygen bomb calorimeter. The data were used to calculate TME values for the diets (Sibbald, 1976), and the TME values of the tallow were calculated by difference. The total lipids of the basal diets were extracted and quantitated with the use of internal standards as described previously (Sibbald and Kramer, 1980). The relative error was about 10%. A portion of total lipids was resolved into neutral and phospholipids using thin-layer chromatography (developing solvent, hexane: diethyl ether: acetic acid, 85:15:.5), and the respective lipid classes analyzed by gas-liquid chromatography (Sibbald and Kramer, 1978). The relative error of major fatty acids is less than 1% and less than 5% for minor fatty acids (less than 10% of total mixture). The relative composition of the neutral lipids (sterol esters, methyl esters, triglycerides, free fatty acids, diglycerides, free sterol) and total phospholipids were determined using an Iatroscan TH-10 analyzer (Iatron Laboratories, Inc., Tokyo, Japan). One microliter of total lipid extract, containing about 10
to 20 jug total lipid material, was applied onto the chromarod-S (mean thickness of active absorbant coating, 75 M) and then developed using the solvent hexane: diethyl ether: formic acid (85:15:.04). The scans were performed under the following conditions: hydrogen pressure, .71 kg/cm 2 (160 ml/min); air flowrate, 2 1/min; scanning speed, .38 cm/sec (gear #30); recorder sensitivity, 10 mV; and chart speed, .42 cm/sec. Peaks were identified by comparison to authentic standards and the areas corrected for the relative response determined for each lipid class. RESULTS AND DISCUSSION The TME values of the tallow are displayed as means in Table 2. The values declined with level of input, with overall means of 9.39 ± .18, 8.48 ± .12 and 8.00 + .05 kcal/g for inputs of 1.5, 3, and 4.5 g/bird, respectively. This observation confirms the findings of Sibbald and Kramer (1978, 1980). Two exceptions were observed. An increase in tallow input from 3 to 4.5 g/bird had little effect on the TME value of the tallow when fed in conjunction with basal Diet 2 (7.91 and 7.97 kcal/g) while with basal Diet 3 the TME value of the fat showed a small increase (7.81 and 8.04 kcal/g). At the lowest level of input, tallow had a lower TME value when fed with the wheat diet (Basal 1) than when fed with the corn diet
Downloaded from http://ps.oxfordjournals.org/ by guest on April 14, 2015
Wheat, ground Corn, ground Degermed corn Corn germ Extracted germ Crude corn oil Soapstock Refined corn oil Soybean meal (49% protein) By analysis Gross energy (kcal/g) TME (kcal/g) SEMofTME
UTILIZATION OF TALLOW
1507
TABLE 2. The mean TME values (kcal/g) of beef tallow fed at three levels with eight basal diets Basal diet number
Added tallow (g) 1.5 3.0 4.5
Mean SEM Mean SEM Mean SEM
1
2
3
4
8.72 b c .46 8.54 a b c .34 8.04 a .14
10.33 a .44 7.91bc .34 7.97 a .11
jyabc .57 7.81 c .10 8.04 a .11
9.42 a b c
9
5
•
51
K
ab .29 7.80 a .16
892
970 4 3
ab K
8.87 aDC .27 7.94 a .15
6
7
9.43ab .53 9.15 a .17 8.26 a .19
8.42 c
8
3 6
K
821abc
.21 7.96 a .18
9.73ab .55 8.46abc .50 8.02 a .13
' ' Means on a horizontal line which do not have a common letter in their superscripts are different at the 5% level of probability.
The lipid compositions of and basal diets are displayed tallow was mainly composed with palmitic, stearic, and oleic
the beef tallow in Table 3. The of triglycerides acids accounting
for about 86% of the total fatty acids. The lipid contents of the basal diets ranged from .9% for the degermed corn diet to 4.5% for the corn germ diet. Some marked differences were found between diets among the lipid subclasses. The lipid of the soapstock diet consisted primarily of free fatty acids with relatively little triglyceride. Among the other diets, the lipids were largely composed of triglycerides plus phospholipids. The lipid of the degermed corn diet was particularly rich in phospholipids, followed by the wheat and corn germ diets. However, in absolute terms, the differences between phospholipid concentrations were small because of the variability in total lipid content. The degermed corn and crude corn oil diets (Basals 3 and 6) contained .409 and .414% of phospholipid, respectively. In relative terms the fatty acid compositions of the neutral and phospholipids were similar, but the absolute values tended to parallel the total lipid values. The wheat diet (Basal 1) contained more phospholipid and less linoleic acid than the corn diet (Basal 2). Thus, the difference in TME values of the tallow at the 1.5 g level of input might be attributed to the differences in the concentrations of these components. Young (1961) observed that the absorption of certain saturated fatty acids was influenced by the amounts of unsaturated fatty acids in the diet, and there are numerous other reports of interactions between fats (see Sibbald and Kramer, 1977). Sibbald and Kramer (1980) obtained data indicating that both linoleic acid and phospholipid exerted beneficial effects on tallow utilization under similar experimental conditions. To explore this, a series of analyses were made in which the mean TME values at the 1.5 g level of input were regressed on total
Downloaded from http://ps.oxfordjournals.org/ by guest on April 14, 2015
(Basal 2); this observation is in agreement with earlier work. However, at inputs of 3 and 4.5 g/bird the TME values of the tallow did not differ between the two basal diets (P>.05). When tallow was fed in conjunction with basal Diets 3 to 8 there were very few differences among the TME values. At an input of 1.5 g, the soapstock diet (Basal 7) permitted the lowest utilization, whereas at the 3 g input the degermed corn diet (Basal 3) was the least effective. When the input was 4.5 g the differences between diets were minor. An analysis of variance confirmed that the tallow TME values declined with input (P<.01). The differences between diets were not significant (P>.05), but the fat level X diet interaction was significant (P<.05). This latter observation confirmed that the diet differences were greatest at the lowest level of tallow input and provided justification for the application of a multiple range test (Robinson, 1959) within fat input levels. The results of the test which are incorporated in Table 2 confirm the existence of a few significant (P<.05) differences. At the 1.5 g input of tallow the corn diet (Basal 2) permitted better utilization than either the wheat diet or the soapstock diet (Basals 1 and 7). The diets containing corn oil (Basals 6 and 8) gave higher TME values than the soapstock diet (Basal 7). At the 3 g input the crude corn oil diet (Basal 6) allowed better utilization than the corn and degermed corn diets (Basals 2 and 3); the latter was inferior to the corn germ diet (Basal 4). No significant differences were observed at the 4.5 g level of input.
1508
SIBBALD AND KRAMER TABLE 3. Lipid analysis of the beef tallow and eight basal diets Beef tallow
Basal diet number 1
2
4
3
5
6
7
8
2.4
.9
4.5
1.5
3.6
2.9
3.9
Lipid subclasses (% of total) Sterol esters Triglycerides 98.8 Free fatty acids Diglycerides .7 Cholesterol Phospholipid .5
3.4 44.6 16.1 2.8 2.6 30.6
1.4 68.7 12.8 1.8 1.1 14.3
5.4 35.2 9.3 2.9 1.8 45.4
1.3 73.1 8.4 2.4 3.1 11.6
2.4 54.0 11.7 3.2 2.1 26.5
1.0 59.3 20.6 4.7 2.9 11.5
2.0 11.3 62.8 4.7 1.5 17.7
1.9 65.2 14.4 4.1 3.2 11.3
Fatty acid composition of neutral lipids 3 14:0 15:0 16:0 16:1 17:0 18:0 18:1 18:2 18:3 20:0 20:1 20:2
3.2 .7 25.9 3.3 1.6 26.1 34.1 2.6 .3 .4 .5 .2
.7 .4 17.3 .5 .2 3.8 19.9 50.4 4.3 1.5 .9 .1
.4 .2 12.2 .7 .4 3.2 25.9 54.5 1.9 .7 .4 .1
.6 .3 13.3 .6 .4 5.0 22.8 51.0 3.6 1.3 .4 .3
.4 .2 11.3 .7 .2 2.3 23.6 57.6 1.8 .6 .6 .2
.5 .2 14.6 .7 .2 2.7 20.6 55.4 4.0 .4 .8 .1
.2 .1 12.0 .5 .2 2.1 23.3 58.0 2.1 .7 .6 .2
1.0 .2 13.6 .6 .3 2.2 22.1 55.0 2.6 .7 .6 .2
.2 .1 12.0 .5 .2 2.3 23.3 58.0 2.2 .5 .7 .1
Fatty acid composition o f phospholipids 2 14:0 15:0 16:0 16:1 17:0 18:0 18:1 18:2 18:3 20:0 20:1 20:2
6.5 5.0 23.8 15.4 8.0 12.8 15.3 4.3 .1 .4 .3 .6
.7 .5 18.1 .5
.7 .6 13.0 .4 .1 4.7 12.9 54.3 5.1 .3 .4 .3
1.6 .3 19.0 .5
.7 .4 15.4 1.1 .4 2.8 15.0 58.1 5.4 .3 .3 .4
.4 .2 16.7 .6 .4 2.4 13.6 59.1 5.9 .2
.4 .3 14.7 .4 .5 2.5 17.8 57.9 4.1 .2 .5 .3
.4 .4 16.5 .4
.4 .4 13.9 .5
2.9 14.9 58.2 5.4 .1 .3 .2
2.6 17.6 59.6 4.2 .3 .3 .1
3.3 12.3 57.6 6.3 .2 .4 .1
4.8 10.8 56.4 6.9
.3
Traces of methyl esters of equivalent chain length 15.4 and 17.4 were present in beef tallow.
lipids, phospholipids, and linoleic acid concentrations in the basal diets; none of the resulting correlation coefficiencts was significant (P >.05). The independent variables may have exerted small effects, but the analyses indicate that they were not prime determinants of differences. In earlier experiments of this series, the same wheat and corn diet formulations permitted substantial differences in beef tallow utilization both at the 1.5 and 3 g levels of input. The failure to elicit a response at the 3 g level in the present experiment may have been due to
differences in the compositions of the tallows. A comparison of the major lipid components of the three tallows revealed no large differences which could account for the difference in response. A comparison of the major lipid components of the diets used in the present experiment with those of the diets used by Sibbald and Kramer (1980) revealed only minor differences. Therefore, lipid composition did not appear to be the cause of the difference in response. However, the possibility remains that lipid structure may have been involved, because Renner and Hill (1961) demonstrated
Downloaded from http://ps.oxfordjournals.org/ by guest on April 14, 2015
1.4
Lipid (%)
UTILIZATION OF TALLOW ACKOWLEDGMENTS
The authors are indebted to the St. Lawrence Starch Company, Port Credit, for the corn and fractions thereof and to Canada Packers Ltd., Toronto, for the beef tallow. Able technical support was provided by S. Tobin and R. C. Fouchard.
REFERENCES Renner, R., and F. W. Hill, 1961. Factors affecting the absorbability of saturated fatty acids in the chick. J. Nutr. 74:254-258. Robinson, P., 1959. Tests of significance for use in comparisons of several means with particular reference to Duncan's multiple range test. Processed Publ. No. 4, Canada Dept. Agr. Stat. Res. Serv. Ottawa. Sibbald, I. R., 1976. A bioassay for true metabolizable energy in feedingstuffs. Poultry Sci. 55:303-308. Sibbald, I. R., and J.K.G. Kramer, 1977. The true metabolizable energy values of fats and fat mixtures. Poultry Sci. 56:2079-2086. Sibbald, I. R., and J.K.G. Kramer, 1978. The effect of the basal diet on the true metabolizable energy value of fat. Poultry Sci. 57:685-691. 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. Young, R. J., 1961. The energy value of fat and fatty acids for chicks. 1. Metabolizable energy. Poultry Sci. 40:1225-1233.
Downloaded from http://ps.oxfordjournals.org/ by guest on April 14, 2015
that the absorption of fatty acids varies with the point of attachment in the triglyceride molecule. The results of this work clearly demonstrate that the composition of the basal diet can affect the utilization of supplementary tallow, particularly at low levels of inclusion. As the level of tallow inclusion increased the effect of the diet decreased, which suggests a dilution of die factor(s) stimulating utilization. It was found that the corn diet permitted greater utilization of the tallow than did the wheat diet at the low level of inclusion. However, substitution of wheat with fractions of corn, in amounts similar to those present in the corn diet, failed to identify the location of the active factor(s). The soapstock diet was no better than the wheat diet. The diets containing degermed corn, corn germ, extracted germ, crude corn oil, and refined corn oil yielded TME values for tallow, at the low level of inclusion, which were numerically intermediate between those of the corn and wheat diets and not significantly (P>.05) different from either one. When the diets contained 3 g of added tallow, the data are more confusing. However, it seems probable that the factor(s) responsible for enhancing tallow utilization was present in each of the corn fractions but not in the soapstock which is a byproduct of the corn oil industry.
1509
1980 Poultry Science 59:1505-1509
INTRODUCTION T h e true metabolizable energy (TME) of beef tallow, as measured with adult cockerels, is n o t constant. In two r e p o r t s it was s h o w n t h a t t h e TME value of tallow was greater when fed in conjunction with a corn based diet t h a n with a wheat based diet (Sibbald a n d Kramer, 1 9 7 8 , 1 9 8 0 ) ; the difference attributable to the diets decreased as t h e a m o u n t of tallow increased relative t o basal diet. T h e c o n c e n t r a t i o n s of linoleic acid ( 1 8 : 2 ) and phospholipids (PL) in t h e basal diets appeared t o influence tallow utilization. T h e e x p e r i m e n t described in this r e p o r t was designed t o obtain additional information a b o u t t h e effect of t h e basal diet o n tallow utilization. Basal diets containing various fractions of yellow corn were used in an a t t e m p t t o identify t h e location in t h e corn kernel of t h e factor(s) which interacts with tallow. Lipid c o m p o n e n t s of t h e diets were identified and quantitated in an a t t e m p t t o identify t h e factor(s). MATERIALS AND METHODS
The e x p e r i m e n t was arranged as an 8 X 4
1 Contribution Institute.
Number
852, Animal
Research
factorial with 7 adult White Leghorn cockerels of t h e Kentville Control strain being assigned t o each t r e a t m e n t ; an additional 7 birds served as negative controls for t h e m e a s u r e m e n t of m e t a b o l i c plus e n d o g e n o u s energy excretion. Eight basal diets (Table 1), each fed at a level of 3 0 g per bird, and 4 levels of beef tallow (0, 1.5, 3.0, and 4.5 g per bird) were used. Basal Diets 1 and 2 had t h e same formulations as t h e wheat and corn based diets used in earlier experiments (Sibbald and Kramer, 1978, 1 9 8 0 ) . In t h e remaining 6 basal diets, wheat was replaced with a fraction of c o r n in an a m o u n t similar to t h a t which would be present in the corn p o r t i o n of Basal # 2 . T h e birds, individually housed in wire cages in a windowless r o o m where t h e y received 12 h r of light daily, were starved for 2 4 hr to ensure t h a t their alimentary canals were free of feed residues. T h e y were t h e n force-fed t h e experimental diets. T h e birds were treated in blocks with each diet being fed t o one bird before proceeding t o t h e n e x t block; t h e force feeding t o o k a b o u t o n e m i n u t e per bird. T h e feed i n p u t per bird was 30, 31.5, 33 and 34.5 g for the diets containing 0, 1.5, 3, and 4.5 g of tallow, respectively. Thus, each bird received 3 0 g of basal diet plus t h e appropriate a m o u n t of fat. T h e time of feeding was recorded for each bird, and t h e excreta voided during t h e
1505
Downloaded from http://ps.oxfordjournals.org/ by guest on April 14, 2015
ABSTRACT An experiment was made to study the effect of diet composition on the utilization of beef tallow by adult cockerels. The diets were based on wheat and soybean meal with portions of the wheat being replaced by either yellow corn, degermed corn, corn germ, extracted germ, crude corn oil, soapstock, or refined corn oil. The birds were starved for 24 hr and then force fed one of 8 basal diets (30 g) supplemented with 0, 1.5, 3.0, or 4.5 g of beef tallow. Excreta voided during the subsequent 24 hr were collected. The true metabolizable energy values (TME) of the tallow were measured. The TME value of tallow decreased with the level of input (P<.01). A corn based diet permitted greater TME values for tallow than did a wheat based diet at the lowest level of tallow inclusion. However, when corn products (degermed corn, germ, extracted germ, crude oil, soapstock, refined oil) were substituted in the wheat basal at levels similar to those in the corn basal, it appeared that all fractions except soapstock had some ability to enhance tallow utilization. Comparisons of TME values with lipid composition data failed to identify the factor(s) which increases tallow utilization.
SIBBALD AND KRAMER
1506
TABLE 1. Compositions of the basal diets (%) Diet number Ingredient1 68
76 68
71
72
72
72
68
3 20
28
28
20
20
21
21
21
3.84 3.13 .038
3.85 3.18 .033
3.79 3.21 .030
4.10 3.34 .028
3.88 3.05 .026
4.03 3.31 .036
3.90 3.24 .029
4.02 3.30 .034
a Constant ingredients: limestone 1.25%; dicalcium phosphate 1.5%; iodized salt .25%; vitamin premix .5%; ice mineral premix .5%. For compositions of premixes see Sibbald and Kramer (1978).
subsequent 24 hr were collected quantitatively. The negative control birds were treated similarly but were unfed. The frozen excreta samples were freezedried, equilibrated with atmopsheric moisture, weighed, and ground. Samples of diets, beef tallow, and excreta were assayed for gross energy in an adiabatic oxygen bomb calorimeter. The data were used to calculate TME values for the diets (Sibbald, 1976), and the TME values of the tallow were calculated by difference. The total lipids of the basal diets were extracted and quantitated with the use of internal standards as described previously (Sibbald and Kramer, 1980). The relative error was about 10%. A portion of total lipids was resolved into neutral and phospholipids using thin-layer chromatography (developing solvent, hexane: diethyl ether: acetic acid, 85:15:.5), and the respective lipid classes analyzed by gas-liquid chromatography (Sibbald and Kramer, 1978). The relative error of major fatty acids is less than 1% and less than 5% for minor fatty acids (less than 10% of total mixture). The relative composition of the neutral lipids (sterol esters, methyl esters, triglycerides, free fatty acids, diglycerides, free sterol) and total phospholipids were determined using an Iatroscan TH-10 analyzer (Iatron Laboratories, Inc., Tokyo, Japan). One microliter of total lipid extract, containing about 10
to 20 jug total lipid material, was applied onto the chromarod-S (mean thickness of active absorbant coating, 75 M) and then developed using the solvent hexane: diethyl ether: formic acid (85:15:.04). The scans were performed under the following conditions: hydrogen pressure, .71 kg/cm 2 (160 ml/min); air flowrate, 2 1/min; scanning speed, .38 cm/sec (gear #30); recorder sensitivity, 10 mV; and chart speed, .42 cm/sec. Peaks were identified by comparison to authentic standards and the areas corrected for the relative response determined for each lipid class. RESULTS AND DISCUSSION The TME values of the tallow are displayed as means in Table 2. The values declined with level of input, with overall means of 9.39 ± .18, 8.48 ± .12 and 8.00 + .05 kcal/g for inputs of 1.5, 3, and 4.5 g/bird, respectively. This observation confirms the findings of Sibbald and Kramer (1978, 1980). Two exceptions were observed. An increase in tallow input from 3 to 4.5 g/bird had little effect on the TME value of the tallow when fed in conjunction with basal Diet 2 (7.91 and 7.97 kcal/g) while with basal Diet 3 the TME value of the fat showed a small increase (7.81 and 8.04 kcal/g). At the lowest level of input, tallow had a lower TME value when fed with the wheat diet (Basal 1) than when fed with the corn diet
Downloaded from http://ps.oxfordjournals.org/ by guest on April 14, 2015
Wheat, ground Corn, ground Degermed corn Corn germ Extracted germ Crude corn oil Soapstock Refined corn oil Soybean meal (49% protein) By analysis Gross energy (kcal/g) TME (kcal/g) SEMofTME
UTILIZATION OF TALLOW
1507
TABLE 2. The mean TME values (kcal/g) of beef tallow fed at three levels with eight basal diets Basal diet number
Added tallow (g) 1.5 3.0 4.5
Mean SEM Mean SEM Mean SEM
1
2
3
4
8.72 b c .46 8.54 a b c .34 8.04 a .14
10.33 a .44 7.91bc .34 7.97 a .11
jyabc .57 7.81 c .10 8.04 a .11
9.42 a b c
9
5
•
51
K
ab .29 7.80 a .16
892
970 4 3
ab K
8.87 aDC .27 7.94 a .15
6
7
9.43ab .53 9.15 a .17 8.26 a .19
8.42 c
8
3 6
K
821abc
.21 7.96 a .18
9.73ab .55 8.46abc .50 8.02 a .13
' ' Means on a horizontal line which do not have a common letter in their superscripts are different at the 5% level of probability.
The lipid compositions of and basal diets are displayed tallow was mainly composed with palmitic, stearic, and oleic
the beef tallow in Table 3. The of triglycerides acids accounting
for about 86% of the total fatty acids. The lipid contents of the basal diets ranged from .9% for the degermed corn diet to 4.5% for the corn germ diet. Some marked differences were found between diets among the lipid subclasses. The lipid of the soapstock diet consisted primarily of free fatty acids with relatively little triglyceride. Among the other diets, the lipids were largely composed of triglycerides plus phospholipids. The lipid of the degermed corn diet was particularly rich in phospholipids, followed by the wheat and corn germ diets. However, in absolute terms, the differences between phospholipid concentrations were small because of the variability in total lipid content. The degermed corn and crude corn oil diets (Basals 3 and 6) contained .409 and .414% of phospholipid, respectively. In relative terms the fatty acid compositions of the neutral and phospholipids were similar, but the absolute values tended to parallel the total lipid values. The wheat diet (Basal 1) contained more phospholipid and less linoleic acid than the corn diet (Basal 2). Thus, the difference in TME values of the tallow at the 1.5 g level of input might be attributed to the differences in the concentrations of these components. Young (1961) observed that the absorption of certain saturated fatty acids was influenced by the amounts of unsaturated fatty acids in the diet, and there are numerous other reports of interactions between fats (see Sibbald and Kramer, 1977). Sibbald and Kramer (1980) obtained data indicating that both linoleic acid and phospholipid exerted beneficial effects on tallow utilization under similar experimental conditions. To explore this, a series of analyses were made in which the mean TME values at the 1.5 g level of input were regressed on total
Downloaded from http://ps.oxfordjournals.org/ by guest on April 14, 2015
(Basal 2); this observation is in agreement with earlier work. However, at inputs of 3 and 4.5 g/bird the TME values of the tallow did not differ between the two basal diets (P>.05). When tallow was fed in conjunction with basal Diets 3 to 8 there were very few differences among the TME values. At an input of 1.5 g, the soapstock diet (Basal 7) permitted the lowest utilization, whereas at the 3 g input the degermed corn diet (Basal 3) was the least effective. When the input was 4.5 g the differences between diets were minor. An analysis of variance confirmed that the tallow TME values declined with input (P<.01). The differences between diets were not significant (P>.05), but the fat level X diet interaction was significant (P<.05). This latter observation confirmed that the diet differences were greatest at the lowest level of tallow input and provided justification for the application of a multiple range test (Robinson, 1959) within fat input levels. The results of the test which are incorporated in Table 2 confirm the existence of a few significant (P<.05) differences. At the 1.5 g input of tallow the corn diet (Basal 2) permitted better utilization than either the wheat diet or the soapstock diet (Basals 1 and 7). The diets containing corn oil (Basals 6 and 8) gave higher TME values than the soapstock diet (Basal 7). At the 3 g input the crude corn oil diet (Basal 6) allowed better utilization than the corn and degermed corn diets (Basals 2 and 3); the latter was inferior to the corn germ diet (Basal 4). No significant differences were observed at the 4.5 g level of input.
1508
SIBBALD AND KRAMER TABLE 3. Lipid analysis of the beef tallow and eight basal diets Beef tallow
Basal diet number 1
2
4
3
5
6
7
8
2.4
.9
4.5
1.5
3.6
2.9
3.9
Lipid subclasses (% of total) Sterol esters Triglycerides 98.8 Free fatty acids Diglycerides .7 Cholesterol Phospholipid .5
3.4 44.6 16.1 2.8 2.6 30.6
1.4 68.7 12.8 1.8 1.1 14.3
5.4 35.2 9.3 2.9 1.8 45.4
1.3 73.1 8.4 2.4 3.1 11.6
2.4 54.0 11.7 3.2 2.1 26.5
1.0 59.3 20.6 4.7 2.9 11.5
2.0 11.3 62.8 4.7 1.5 17.7
1.9 65.2 14.4 4.1 3.2 11.3
Fatty acid composition of neutral lipids 3 14:0 15:0 16:0 16:1 17:0 18:0 18:1 18:2 18:3 20:0 20:1 20:2
3.2 .7 25.9 3.3 1.6 26.1 34.1 2.6 .3 .4 .5 .2
.7 .4 17.3 .5 .2 3.8 19.9 50.4 4.3 1.5 .9 .1
.4 .2 12.2 .7 .4 3.2 25.9 54.5 1.9 .7 .4 .1
.6 .3 13.3 .6 .4 5.0 22.8 51.0 3.6 1.3 .4 .3
.4 .2 11.3 .7 .2 2.3 23.6 57.6 1.8 .6 .6 .2
.5 .2 14.6 .7 .2 2.7 20.6 55.4 4.0 .4 .8 .1
.2 .1 12.0 .5 .2 2.1 23.3 58.0 2.1 .7 .6 .2
1.0 .2 13.6 .6 .3 2.2 22.1 55.0 2.6 .7 .6 .2
.2 .1 12.0 .5 .2 2.3 23.3 58.0 2.2 .5 .7 .1
Fatty acid composition o f phospholipids 2 14:0 15:0 16:0 16:1 17:0 18:0 18:1 18:2 18:3 20:0 20:1 20:2
6.5 5.0 23.8 15.4 8.0 12.8 15.3 4.3 .1 .4 .3 .6
.7 .5 18.1 .5
.7 .6 13.0 .4 .1 4.7 12.9 54.3 5.1 .3 .4 .3
1.6 .3 19.0 .5
.7 .4 15.4 1.1 .4 2.8 15.0 58.1 5.4 .3 .3 .4
.4 .2 16.7 .6 .4 2.4 13.6 59.1 5.9 .2
.4 .3 14.7 .4 .5 2.5 17.8 57.9 4.1 .2 .5 .3
.4 .4 16.5 .4
.4 .4 13.9 .5
2.9 14.9 58.2 5.4 .1 .3 .2
2.6 17.6 59.6 4.2 .3 .3 .1
3.3 12.3 57.6 6.3 .2 .4 .1
4.8 10.8 56.4 6.9
.3
Traces of methyl esters of equivalent chain length 15.4 and 17.4 were present in beef tallow.
lipids, phospholipids, and linoleic acid concentrations in the basal diets; none of the resulting correlation coefficiencts was significant (P >.05). The independent variables may have exerted small effects, but the analyses indicate that they were not prime determinants of differences. In earlier experiments of this series, the same wheat and corn diet formulations permitted substantial differences in beef tallow utilization both at the 1.5 and 3 g levels of input. The failure to elicit a response at the 3 g level in the present experiment may have been due to
differences in the compositions of the tallows. A comparison of the major lipid components of the three tallows revealed no large differences which could account for the difference in response. A comparison of the major lipid components of the diets used in the present experiment with those of the diets used by Sibbald and Kramer (1980) revealed only minor differences. Therefore, lipid composition did not appear to be the cause of the difference in response. However, the possibility remains that lipid structure may have been involved, because Renner and Hill (1961) demonstrated
Downloaded from http://ps.oxfordjournals.org/ by guest on April 14, 2015
1.4
Lipid (%)
UTILIZATION OF TALLOW ACKOWLEDGMENTS
The authors are indebted to the St. Lawrence Starch Company, Port Credit, for the corn and fractions thereof and to Canada Packers Ltd., Toronto, for the beef tallow. Able technical support was provided by S. Tobin and R. C. Fouchard.
REFERENCES Renner, R., and F. W. Hill, 1961. Factors affecting the absorbability of saturated fatty acids in the chick. J. Nutr. 74:254-258. Robinson, P., 1959. Tests of significance for use in comparisons of several means with particular reference to Duncan's multiple range test. Processed Publ. No. 4, Canada Dept. Agr. Stat. Res. Serv. Ottawa. Sibbald, I. R., 1976. A bioassay for true metabolizable energy in feedingstuffs. Poultry Sci. 55:303-308. Sibbald, I. R., and J.K.G. Kramer, 1977. The true metabolizable energy values of fats and fat mixtures. Poultry Sci. 56:2079-2086. Sibbald, I. R., and J.K.G. Kramer, 1978. The effect of the basal diet on the true metabolizable energy value of fat. Poultry Sci. 57:685-691. 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. Young, R. J., 1961. The energy value of fat and fatty acids for chicks. 1. Metabolizable energy. Poultry Sci. 40:1225-1233.
Downloaded from http://ps.oxfordjournals.org/ by guest on April 14, 2015
that the absorption of fatty acids varies with the point of attachment in the triglyceride molecule. The results of this work clearly demonstrate that the composition of the basal diet can affect the utilization of supplementary tallow, particularly at low levels of inclusion. As the level of tallow inclusion increased the effect of the diet decreased, which suggests a dilution of die factor(s) stimulating utilization. It was found that the corn diet permitted greater utilization of the tallow than did the wheat diet at the low level of inclusion. However, substitution of wheat with fractions of corn, in amounts similar to those present in the corn diet, failed to identify the location of the active factor(s). The soapstock diet was no better than the wheat diet. The diets containing degermed corn, corn germ, extracted germ, crude corn oil, and refined corn oil yielded TME values for tallow, at the low level of inclusion, which were numerically intermediate between those of the corn and wheat diets and not significantly (P>.05) different from either one. When the diets contained 3 g of added tallow, the data are more confusing. However, it seems probable that the factor(s) responsible for enhancing tallow utilization was present in each of the corn fractions but not in the soapstock which is a byproduct of the corn oil industry.
1509