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Comparison of Lipoprotein Lipase Activities in Chickens and Turkeys
Comparison of Lipoprotein Lipase Activities in Chickens and Turkeys D. C. BORRON, L. S. JENSEN, M. G. McCARTNEY, and W. M. BRITTON Department of Poultry Science, University of Georgia, Athens, Georgia 30602 (Received for publication August 11, 1978) ABSTRACT Three experiments were conducted to compare the role of lipoprotein lipase in fatty acid metabolism in chickens and turkeys. An initial experiment to determine the effect of fasting on the enzyme activity of chicken and turkey muscle and adipose tissues demonstrated that fasting decreased the lipoprotein lipase activity of adipose tissue, while increasing the enzyme activity of muscle tissue in chickens only. Quantitatively, turkey samples showed a greater enzyme activity in both muscle and adipose tissue than the chicken samples. In a second experiment both insulin and epinephrine added in vitro significantly increased activity of lipoprotein lipase from chicken adipose tissue, but not from turkey adipose tissue. In a third experiment conducted to examine the effects of carbohydrate and fat feeding on lipoprotein lipase activity of chicken and turkey adipose tissue, fat feeding increased activity the greatest amount. In both species, refeeding, regardless of the energy source, produced a significant increase in the lipoprotein lipase activity of adipose tissue. Differences in lipoprotein lipase activity does not appear to be related to differences in rate of body fat deposition observed between broiler chickens and turkeys. 1979 Poultry Science 58:659-662 INTRODUCTION
One of the major problems in broiler production is the excess accumulation of adipose fat which reduces efficiency of production, creates problems in the processing plants, and elicits consumer complaints. An intergraded research effort involving nutritional, environmental, physiological, and genetic aspects appears to be needed to attempt to solve this problem. Lipid accumulation in broiler chickens and turkeys fed similar diets differ markedly with turkeys having considerable less depot fat than broilers at the same age. Although this difference in rate of fat deposition in extra-hepatic tissues is due to inherited differences, the biochemical mechanisms for the differences are unknown. Fatty acid synthesis in avian species occurs primarily in the liver (Leveille et al., 1975; and Borron and Britton, 1977). Therefore, the fatty acids stored in the adipose tissue must come from those transported to the adipose tissue as part of either low density lipoproteins (endogenous) or chylomicrons (exogenous). Since only free fatty acids can pass through the adipocyte membranes, the triacylglycerol carried to the adipose sight as part of lipoproteins must be hydrolyzed. This is accomplished by lipoprotein lipase (LPL, glycerol ester hydrolase EC 3.1.1.3). Kompiang et al. (1976) demonstrated the necessity of LPL for this purpose in chickens by injecting anti-LPL serum obtained from rabbits.
Since LPL is essential for uptake of fatty acids by adipose tissue, regulation of this enzyme might play a role in control of fat deposition and possibly account for species differences in lipid accumulation. The present studies were conducted to compare the activities of LPL in tissues from chickens and turkeys and to determine if differences in activity relate to the known differences in fat deposition of these species.
MATERIALS AND METHODS
Bird Preparation. Three experiments were conducted using commercial strain female broiler chickens, eight weeks of age, and Large White female turkeys, 12 weeks of age. Birds of both species were fed practical-type diets from one day of age to the treatment age. In the first experiment conducted to determine the effect of fasting on adipose tissue and muscle lipoprotein in lipase activity, three-bird replicates of each species were either full-fed, fasted 12 hr, or fasted 72 hr. After each treatment period, samples of abdominal adipose tissue and of breast muscle (pectoralis major) were obtained. A second experiment was conducted to determine the effect insulin and epinephrine have on adipose tissue lipoprotein lipase activity in vitro. Triplicate tissue samples used in this study were obtained from chickens and turkeys not fasted prior to tissue removal. In the third experiment,
659
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BORRON ET AL.
replicates of three birds each were tube-fed by inserting a flexible rubber tube through the esophagus into the crop and injecting a meal. Isocaloric meals of either carbohydrate, fat, or an equal caloric mixture of carbohydrate and fat were fed. The carbohydrate source used was glucose monohydrate with an estimated metabolizable energy value of 3418 kcal/kg and the fat source used was corn oil with an estimated metabolizable energy (ME) value of 7938 kcal/ kg. The energy level fed was 774 kcal ME to the turkeys and 151 kcal ME to the chickens. These values were estimated to be one-half the normal daily ME consumption for the respective ages of each species. Water was added to the glucose to facilitate tube feeding with the corn oil being tube-fed undiluted. Tissue Removal, Preparation, and Assay for Lipoprotein Lipase Activity. After a 12-hr fast, 72-hr fast, or 1 hr post tube feeding, all birds were killed by cervical dislocation. Breast muscle (pectoralis major) or abdominal adipose tissue was immediately removed, placed in stoppered test tubes, and chilled on ice. Acetone powders were prepared according to the methods of Mayes and Felts (1968) with minor modifications by homogenizing 5 g of either adipose tissue or muscle tissue in 50 ml of icecold acetone in a ground-glass homogenizer. The homogenate was filtered on a Buchner funnel and the precipitate was washed with 25 ml of diethyl ether and air dried. At this stage, the acetone powders could be stored frozen in stoppered vials for up to 72-hr with no loss of enzyme activity. When the assays were conducted, .012 g of the acetone powders were rehomogenized, using a ground-glass homogenizer, in 8 ml of cold aqueous (.025N NH 3 ) solution, adjusted to pH 8.5 with HC1. After 5 min, the suspension was filtered through a fiber glass filter to remove large connective tissue. Portions of this filtrate were used for lipoprotein lipase activity assay. The assay system was a modification of that described by Robinson (1963). This assay was conducted in 1.35 M Tris buffer (pH 8.1) and the assay system contained 1.5 ml of 15% (W/V) bovine albumin (fraction V) in .15 M
'Vitrum, Stockholm, Sweden, distributed by Cutler Laboratories, Inc., Berkeley, CA. 2 Eli Lilly Co., Indianapolis, IN. 3 Sigma Chemical Company, St. Louis, MO.
NaCl; .2 ml of substrate, consisting of activated triglyceride emulsion (10 mg/ml); 1.0 ml of homogenate of tissue acetone powder; and .3 ml of .15 M NaCl containing additions where applicable. The substrate used was a 10% fat emulsion (Intralipid 1 ), that had been activated by incubation at 37 C for 30 min with an equal volume of serum from the respective species. This activated fat emulsion is reported to have substrate properties similar to chylomicrons (Mayes and Felts, 1968). Additions to the incubation mixture were insulin of bovine and porcine origin 2 and epinephrine 3 dissolved in .15 M NaCl. The concentration of additions used are indicated in Table 2. Incubations were carried out for 1 hr at 37 C. Lipoprotein lipase activity was determined according to the colorimetric micro-determination method of Duncombe (1963), as modified by Itaya and Ui (1965). Analysis of variance was used to determine statistical significance of all data (Remington and Schork, 1970). Fisher's least significant difference test was used to analyze differences in treatment means (Ostle, 1963). RESULTS AND DISCUSSION Table 1 shows the LPL activity of chicken and turkey muscle and adipose tissue after fasting. Fasting for 12 or 72 hr significantly decreased LPL activity of chicken adipose tissue. The change in enzyme activity for chicken adipose tissue during fasting from 12 to 72 hr was not statistically significant. Chicken muscle tis-
TABLE 1. Lipoprotein lipase activity of chicken and turkey adipose tissue and muscle after fasting /j moles FFA released/mg of acetone powder/min
Treatment
Chicken Adipose tissue Muscle
Turkey Adipose tissue Muscle
Fed Fasted 12 hr Fasted 72 hr
6.28a 4.15 b 3.69b
12.80a 8.50a . . ,<
1.08* 1.31a 2.47b
3.80a 3.80a ND2
' Values in the same column having the same superscripts are not significantly different (P<.05). 1 After a 72 hr fast, insufficient quantities of abdominal adipose tissue existed for analysis. 2 Non-detectable.
LIPOPROTEIN LIPASE ACTIVITY TABLE 2. The in vitro effect of insulin and epinephrine on the lipoprotein lipase activity of chicken and turkey adipose tissue M moles of FFA released/mg acetone powder/min
Addition to incubation system'
Chicken
Turkey
Insulin Epinephrine No treatment
2.66 b 3.79 b 1.42 a
3.77 a 4.26 a 3.12 a
' Values in the same column having the same superscript are not significantly different (P<.05). 'Insulin—10 units per ml of incubation system. Epinephrine—10 jug per ml of incubation system.
sue showed a significant increase in LPL activity after 72 hr of fasting. There was no difference in e n z y m e activity b e t w e e n t h e fed state and 12 hr of fasting for chicken muscle tissue. Under each experimental condition, t h e activity of LPL was greater for chicken adipose tissue t h a n for muscle. E n z y m e activity for t u r k e y adipose tissue decreased as a result of a 12 hr fast, b u t this decrease was n o t significant. After 72 hr of fasting t h e t u r k e y s had w i t h d r a w n a major p o r t i o n of their a b d o m i n a l adipose deposits; consequently, a sample could n o t be o b tained for analysis. T u r k e y muscle LPL activity remained unchanged after 12 hr of fasting, b u t decreased t o non-detectable levels after 72 hr of
TABLE 3. Lipoprotein lipase activity in adipose tissue of chickens and turkey after isocaloric tube-fed meals of fat, carbohydrate, or an equal caloric mixture of fat and carbohydrate
, c ,. Tube-teeding treatment' T
Carbohydrate Fat Mixture (carbohydrate + fat) Fed (no fast) Fasted (12 hr)
H moles of FFA released/acetone powder/min r
Chicken c
4.66 4.96 c 4.37 c 3.57 b 1.70a
Turkey 3.03b 5.31 c 3.88 D 3.75 b 1.45 a
' ' Values in the same column having the same superscripts are not significantly different (P<.05). 'Turkeys receiving 774 ME kcal of carbohydrate, 774 ME kcal of fat, or a mixture of 387 ME kcal of each energy source. Chickens received 151 ME kcal of carbohydrate, 151 ME kcal of fat, or a mixture of 75.5 ME kcal of each energy source.
661
fasting. Quantitatively, b o t h t u r k e y adipose tissue and muscle contained greater quantities of LPL t h a n chicken tissues in this s t u d y . These results are consistent with those reported b y Husbands ( 1 9 7 2 ) , Evans ( 1 9 7 2 ) , and Hollenberg ( 1 9 6 0 ) w h o studied t h e effects of fasting on LPL activity of t h e chicken, d u c k , and rat adipose tissue and muscle. Each of these r e p o r t s d e m o n s t r a t e d t h a t longer periods of fasting d e creased adipose tissue LPL activity while increasing LPL activity of muscle. However, Husb a n d s ( 1 9 7 2 ) presented evidence showing t h a t t h e LPL activity of chicken adipose tissue increased from t h e fed state t o fasting state, t h e n decreased with increased d u r a t i o n of fasting. Results of t h e e x p e r i m e n t c o n d u c t e d to examine t h e effect in vitro of insulin and epinephrine on LPL o b t a i n e d from chicken and t u r k e y adipose tissue are s h o w n in Table 2. Insulin and epinephrine numerically increased t h e activity of t h e LPL from b o t h chickens and t u r k e y adipose tissue b u t only t h e differences for chicken were statistically significant. Again t h e relative activity of LPL for t u r k e y s were higher t h a n for chickens. T h e LPL activity of chicken and t u r k e y adipose tissue after isocaloric tube-fed meals of fat, c a r b o h y d r a t e , or an equal caloric m i x t u r e of fat and c a r b o h y d r a t e is shown in Table 3 . There were n o significant differences in t h e LPL activity of adipose tissues t a k e n from chickens which were fed t h e different energy source meals. Each t u b e feeding t r e a t m e n t increased LPL activity when c o m p a r e d to t h e ad libitum fed birds or fasted birds. Chickens fed t h e fat only meal t e n d e d t o have t h e greatest LPL activity. Adipose tissue LPL activity from t u r k e y samples was significantly greater for t h e birds fed t h e fat meal, followed by t h e carboh y d r a t e and fat m i x t u r e meal fed and ad libitum fed birds which were n o t significiantly different. LPL activity of fasted t u r k e y adipose tissue was significantly less t h a n t h e o t h e r feeding t r e a t m e n t s . These results indicate t h a t t h e response of LPL activity following meals of either carboh y d r a t e , fat, or a m i x t u r e thereof is similar in t h e chicken and t u r k e y adipose tissue. T h e results are in good agreement with t h o s e r e p o r t e d b y Delorme and Harris ( 1 9 7 5 ) and Pokrajac and Lossow ( 1 9 6 7 ) using adipose tissues from fasted rats. Results of t h e three e x p e r i m e n t s indicate t h e lipoprotein lipase is n o t a major factor in t h e differential c o n t r o l of fat deposition in chick-
BORRON ET AL.
662
ens and t u r k e y s . E n z y m e activity of t u r k e y samples was as high, or higher, t h a n samples from broiler chickens, y e t rate of fat deposition is less in t u r k e y s .
REFERENCES Borron, D. C , and W. M. Britton, 1977. The significance of adipose tissue and liver as sites of lipid biosynthesis in the turkey. Poultry Sci. 56:353— 355. Delorme, C. L. W., and K. L. Harris, 1975. Effects of diet on lipoprotein lipase activity in the rat. J. Nutr. 105:447-451. Duncombe, W. G., 1963. The colorimetric microdetermination of long chain fatty acids. Biochem. J. 8 8 : 7 - 1 0 . Evans, A. J., 1972. Lipoprotein lipase activity in adipose tissues of the domestic duck: The effect of age, sex, and nutritional state. Int. J. Biochem. 3: 199-206. HoUenberg, C. H., 1960. The effect of fasting on the lipoprotein lipase activity of rat heart and diaphragm. J. Clin. Invest. 39:1282-1287. Husbands, D. R., 1972. The distribution of lipoprotein lipase in tissues of the domestic fowl and the effects of feeding and starving. Brit. Poultry Sci. 13: 85-90.
Itaya, K., and M. Ui, 1965. Colorometric determination of free fatty acids in biological fluids. J. Lipid Res. 6:16-20. Kompiang, I. P., A. Bensadoun, and M. W. Yong, 1976. Effect of an anti-lipoprotein lipase serum on plasma triglyceride removal. J. Lipid Res. 1 7 : 4 9 8 505. Leveille, G. A., D. R. Ramos, Y. Yen, and E. K. O'Hea, 1975. Lipid biosynthesis in the chick. A consideration of site of synthesis, influence of diet and possible regulatory mechanisms. Poultry Sci. 54:1075-1093. Mayes, P. A., and J. M. Felts, 1968. The functional status of lipoprotein lipase in rat liver. Biochem. J. 108:483-487. Ostle, B., 1963. Statistics in research. The Iowa State University Press, Ames, IA. Pokrajac, N., and W. J. Lossow, 1967. The effect of tube feeding of glucose or corn oil on adipose tissue lipoprotein lipase activity and uptake of ' 4 Clabeled palmitic acid of chyle triglycerides in vitro. Biochem. Biophys. Acta. 137:291-295. Remington, R. D., and M. A. Schork, 1970. Statistics with applications to biological and health sciences. Prentice-Hall Inc., Englewood Cliffs, NJ. Robinson, D. S., 1963. The clearing factor lipase and its action in the transport of fatty acids between the blood and the tissues. Adv. in Lipid Res. 1: 133-182.
One of the major problems in broiler production is the excess accumulation of adipose fat which reduces efficiency of production, creates problems in the processing plants, and elicits consumer complaints. An intergraded research effort involving nutritional, environmental, physiological, and genetic aspects appears to be needed to attempt to solve this problem. Lipid accumulation in broiler chickens and turkeys fed similar diets differ markedly with turkeys having considerable less depot fat than broilers at the same age. Although this difference in rate of fat deposition in extra-hepatic tissues is due to inherited differences, the biochemical mechanisms for the differences are unknown. Fatty acid synthesis in avian species occurs primarily in the liver (Leveille et al., 1975; and Borron and Britton, 1977). Therefore, the fatty acids stored in the adipose tissue must come from those transported to the adipose tissue as part of either low density lipoproteins (endogenous) or chylomicrons (exogenous). Since only free fatty acids can pass through the adipocyte membranes, the triacylglycerol carried to the adipose sight as part of lipoproteins must be hydrolyzed. This is accomplished by lipoprotein lipase (LPL, glycerol ester hydrolase EC 3.1.1.3). Kompiang et al. (1976) demonstrated the necessity of LPL for this purpose in chickens by injecting anti-LPL serum obtained from rabbits.
Since LPL is essential for uptake of fatty acids by adipose tissue, regulation of this enzyme might play a role in control of fat deposition and possibly account for species differences in lipid accumulation. The present studies were conducted to compare the activities of LPL in tissues from chickens and turkeys and to determine if differences in activity relate to the known differences in fat deposition of these species.
MATERIALS AND METHODS
Bird Preparation. Three experiments were conducted using commercial strain female broiler chickens, eight weeks of age, and Large White female turkeys, 12 weeks of age. Birds of both species were fed practical-type diets from one day of age to the treatment age. In the first experiment conducted to determine the effect of fasting on adipose tissue and muscle lipoprotein in lipase activity, three-bird replicates of each species were either full-fed, fasted 12 hr, or fasted 72 hr. After each treatment period, samples of abdominal adipose tissue and of breast muscle (pectoralis major) were obtained. A second experiment was conducted to determine the effect insulin and epinephrine have on adipose tissue lipoprotein lipase activity in vitro. Triplicate tissue samples used in this study were obtained from chickens and turkeys not fasted prior to tissue removal. In the third experiment,
659
660
BORRON ET AL.
replicates of three birds each were tube-fed by inserting a flexible rubber tube through the esophagus into the crop and injecting a meal. Isocaloric meals of either carbohydrate, fat, or an equal caloric mixture of carbohydrate and fat were fed. The carbohydrate source used was glucose monohydrate with an estimated metabolizable energy value of 3418 kcal/kg and the fat source used was corn oil with an estimated metabolizable energy (ME) value of 7938 kcal/ kg. The energy level fed was 774 kcal ME to the turkeys and 151 kcal ME to the chickens. These values were estimated to be one-half the normal daily ME consumption for the respective ages of each species. Water was added to the glucose to facilitate tube feeding with the corn oil being tube-fed undiluted. Tissue Removal, Preparation, and Assay for Lipoprotein Lipase Activity. After a 12-hr fast, 72-hr fast, or 1 hr post tube feeding, all birds were killed by cervical dislocation. Breast muscle (pectoralis major) or abdominal adipose tissue was immediately removed, placed in stoppered test tubes, and chilled on ice. Acetone powders were prepared according to the methods of Mayes and Felts (1968) with minor modifications by homogenizing 5 g of either adipose tissue or muscle tissue in 50 ml of icecold acetone in a ground-glass homogenizer. The homogenate was filtered on a Buchner funnel and the precipitate was washed with 25 ml of diethyl ether and air dried. At this stage, the acetone powders could be stored frozen in stoppered vials for up to 72-hr with no loss of enzyme activity. When the assays were conducted, .012 g of the acetone powders were rehomogenized, using a ground-glass homogenizer, in 8 ml of cold aqueous (.025N NH 3 ) solution, adjusted to pH 8.5 with HC1. After 5 min, the suspension was filtered through a fiber glass filter to remove large connective tissue. Portions of this filtrate were used for lipoprotein lipase activity assay. The assay system was a modification of that described by Robinson (1963). This assay was conducted in 1.35 M Tris buffer (pH 8.1) and the assay system contained 1.5 ml of 15% (W/V) bovine albumin (fraction V) in .15 M
'Vitrum, Stockholm, Sweden, distributed by Cutler Laboratories, Inc., Berkeley, CA. 2 Eli Lilly Co., Indianapolis, IN. 3 Sigma Chemical Company, St. Louis, MO.
NaCl; .2 ml of substrate, consisting of activated triglyceride emulsion (10 mg/ml); 1.0 ml of homogenate of tissue acetone powder; and .3 ml of .15 M NaCl containing additions where applicable. The substrate used was a 10% fat emulsion (Intralipid 1 ), that had been activated by incubation at 37 C for 30 min with an equal volume of serum from the respective species. This activated fat emulsion is reported to have substrate properties similar to chylomicrons (Mayes and Felts, 1968). Additions to the incubation mixture were insulin of bovine and porcine origin 2 and epinephrine 3 dissolved in .15 M NaCl. The concentration of additions used are indicated in Table 2. Incubations were carried out for 1 hr at 37 C. Lipoprotein lipase activity was determined according to the colorimetric micro-determination method of Duncombe (1963), as modified by Itaya and Ui (1965). Analysis of variance was used to determine statistical significance of all data (Remington and Schork, 1970). Fisher's least significant difference test was used to analyze differences in treatment means (Ostle, 1963). RESULTS AND DISCUSSION Table 1 shows the LPL activity of chicken and turkey muscle and adipose tissue after fasting. Fasting for 12 or 72 hr significantly decreased LPL activity of chicken adipose tissue. The change in enzyme activity for chicken adipose tissue during fasting from 12 to 72 hr was not statistically significant. Chicken muscle tis-
TABLE 1. Lipoprotein lipase activity of chicken and turkey adipose tissue and muscle after fasting /j moles FFA released/mg of acetone powder/min
Treatment
Chicken Adipose tissue Muscle
Turkey Adipose tissue Muscle
Fed Fasted 12 hr Fasted 72 hr
6.28a 4.15 b 3.69b
12.80a 8.50a . . ,<
1.08* 1.31a 2.47b
3.80a 3.80a ND2
' Values in the same column having the same superscripts are not significantly different (P<.05). 1 After a 72 hr fast, insufficient quantities of abdominal adipose tissue existed for analysis. 2 Non-detectable.
LIPOPROTEIN LIPASE ACTIVITY TABLE 2. The in vitro effect of insulin and epinephrine on the lipoprotein lipase activity of chicken and turkey adipose tissue M moles of FFA released/mg acetone powder/min
Addition to incubation system'
Chicken
Turkey
Insulin Epinephrine No treatment
2.66 b 3.79 b 1.42 a
3.77 a 4.26 a 3.12 a
' Values in the same column having the same superscript are not significantly different (P<.05). 'Insulin—10 units per ml of incubation system. Epinephrine—10 jug per ml of incubation system.
sue showed a significant increase in LPL activity after 72 hr of fasting. There was no difference in e n z y m e activity b e t w e e n t h e fed state and 12 hr of fasting for chicken muscle tissue. Under each experimental condition, t h e activity of LPL was greater for chicken adipose tissue t h a n for muscle. E n z y m e activity for t u r k e y adipose tissue decreased as a result of a 12 hr fast, b u t this decrease was n o t significant. After 72 hr of fasting t h e t u r k e y s had w i t h d r a w n a major p o r t i o n of their a b d o m i n a l adipose deposits; consequently, a sample could n o t be o b tained for analysis. T u r k e y muscle LPL activity remained unchanged after 12 hr of fasting, b u t decreased t o non-detectable levels after 72 hr of
TABLE 3. Lipoprotein lipase activity in adipose tissue of chickens and turkey after isocaloric tube-fed meals of fat, carbohydrate, or an equal caloric mixture of fat and carbohydrate
, c ,. Tube-teeding treatment' T
Carbohydrate Fat Mixture (carbohydrate + fat) Fed (no fast) Fasted (12 hr)
H moles of FFA released/acetone powder/min r
Chicken c
4.66 4.96 c 4.37 c 3.57 b 1.70a
Turkey 3.03b 5.31 c 3.88 D 3.75 b 1.45 a
' ' Values in the same column having the same superscripts are not significantly different (P<.05). 'Turkeys receiving 774 ME kcal of carbohydrate, 774 ME kcal of fat, or a mixture of 387 ME kcal of each energy source. Chickens received 151 ME kcal of carbohydrate, 151 ME kcal of fat, or a mixture of 75.5 ME kcal of each energy source.
661
fasting. Quantitatively, b o t h t u r k e y adipose tissue and muscle contained greater quantities of LPL t h a n chicken tissues in this s t u d y . These results are consistent with those reported b y Husbands ( 1 9 7 2 ) , Evans ( 1 9 7 2 ) , and Hollenberg ( 1 9 6 0 ) w h o studied t h e effects of fasting on LPL activity of t h e chicken, d u c k , and rat adipose tissue and muscle. Each of these r e p o r t s d e m o n s t r a t e d t h a t longer periods of fasting d e creased adipose tissue LPL activity while increasing LPL activity of muscle. However, Husb a n d s ( 1 9 7 2 ) presented evidence showing t h a t t h e LPL activity of chicken adipose tissue increased from t h e fed state t o fasting state, t h e n decreased with increased d u r a t i o n of fasting. Results of t h e e x p e r i m e n t c o n d u c t e d to examine t h e effect in vitro of insulin and epinephrine on LPL o b t a i n e d from chicken and t u r k e y adipose tissue are s h o w n in Table 2. Insulin and epinephrine numerically increased t h e activity of t h e LPL from b o t h chickens and t u r k e y adipose tissue b u t only t h e differences for chicken were statistically significant. Again t h e relative activity of LPL for t u r k e y s were higher t h a n for chickens. T h e LPL activity of chicken and t u r k e y adipose tissue after isocaloric tube-fed meals of fat, c a r b o h y d r a t e , or an equal caloric m i x t u r e of fat and c a r b o h y d r a t e is shown in Table 3 . There were n o significant differences in t h e LPL activity of adipose tissues t a k e n from chickens which were fed t h e different energy source meals. Each t u b e feeding t r e a t m e n t increased LPL activity when c o m p a r e d to t h e ad libitum fed birds or fasted birds. Chickens fed t h e fat only meal t e n d e d t o have t h e greatest LPL activity. Adipose tissue LPL activity from t u r k e y samples was significantly greater for t h e birds fed t h e fat meal, followed by t h e carboh y d r a t e and fat m i x t u r e meal fed and ad libitum fed birds which were n o t significiantly different. LPL activity of fasted t u r k e y adipose tissue was significantly less t h a n t h e o t h e r feeding t r e a t m e n t s . These results indicate t h a t t h e response of LPL activity following meals of either carboh y d r a t e , fat, or a m i x t u r e thereof is similar in t h e chicken and t u r k e y adipose tissue. T h e results are in good agreement with t h o s e r e p o r t e d b y Delorme and Harris ( 1 9 7 5 ) and Pokrajac and Lossow ( 1 9 6 7 ) using adipose tissues from fasted rats. Results of t h e three e x p e r i m e n t s indicate t h e lipoprotein lipase is n o t a major factor in t h e differential c o n t r o l of fat deposition in chick-
BORRON ET AL.
662
ens and t u r k e y s . E n z y m e activity of t u r k e y samples was as high, or higher, t h a n samples from broiler chickens, y e t rate of fat deposition is less in t u r k e y s .
REFERENCES Borron, D. C , and W. M. Britton, 1977. The significance of adipose tissue and liver as sites of lipid biosynthesis in the turkey. Poultry Sci. 56:353— 355. Delorme, C. L. W., and K. L. Harris, 1975. Effects of diet on lipoprotein lipase activity in the rat. J. Nutr. 105:447-451. Duncombe, W. G., 1963. The colorimetric microdetermination of long chain fatty acids. Biochem. J. 8 8 : 7 - 1 0 . Evans, A. J., 1972. Lipoprotein lipase activity in adipose tissues of the domestic duck: The effect of age, sex, and nutritional state. Int. J. Biochem. 3: 199-206. HoUenberg, C. H., 1960. The effect of fasting on the lipoprotein lipase activity of rat heart and diaphragm. J. Clin. Invest. 39:1282-1287. Husbands, D. R., 1972. The distribution of lipoprotein lipase in tissues of the domestic fowl and the effects of feeding and starving. Brit. Poultry Sci. 13: 85-90.
Itaya, K., and M. Ui, 1965. Colorometric determination of free fatty acids in biological fluids. J. Lipid Res. 6:16-20. Kompiang, I. P., A. Bensadoun, and M. W. Yong, 1976. Effect of an anti-lipoprotein lipase serum on plasma triglyceride removal. J. Lipid Res. 1 7 : 4 9 8 505. Leveille, G. A., D. R. Ramos, Y. Yen, and E. K. O'Hea, 1975. Lipid biosynthesis in the chick. A consideration of site of synthesis, influence of diet and possible regulatory mechanisms. Poultry Sci. 54:1075-1093. Mayes, P. A., and J. M. Felts, 1968. The functional status of lipoprotein lipase in rat liver. Biochem. J. 108:483-487. Ostle, B., 1963. Statistics in research. The Iowa State University Press, Ames, IA. Pokrajac, N., and W. J. Lossow, 1967. The effect of tube feeding of glucose or corn oil on adipose tissue lipoprotein lipase activity and uptake of ' 4 Clabeled palmitic acid of chyle triglycerides in vitro. Biochem. Biophys. Acta. 137:291-295. Remington, R. D., and M. A. Schork, 1970. Statistics with applications to biological and health sciences. Prentice-Hall Inc., Englewood Cliffs, NJ. Robinson, D. S., 1963. The clearing factor lipase and its action in the transport of fatty acids between the blood and the tissues. Adv. in Lipid Res. 1: 133-182.