ism of Tsaiya Ducks When High Levels of Choline or Methionine are Added to the Ducks' Diet

(1)

1090

The Effect on ^나 le Lipid Metab

^이

ism of Tsaiya Ducks When High Levels of Choline or Methionine are Added to the Ducks' Diet

T. F. Lien* and D. F. Jan*1

* Address reprint request to T. F. Lien. Tel: 886-5-2750134, Fax: 88652782623

1 Department of Animal Science, National Chung Hsing University, Taichung, Taiwan, ROC.

Received November 11, 1998; Accepted March 10, 1999

Department of

Animal Science, National Chiayi Institute

of Technology,

Chiayi, Taiwan, ROC

ABSTRACT - In order to minimize the occurrence of fatty liver, this study investigated how adding a high level of dietary choline or methionine affected the lipid metabolism of Tsaiya ducks. Feeding trials were conducted with sixty Tsaiya ducks during their growing period, when they were 8-12 weeks old, and during their laying period, 10-14 weeks after the onset of laying when they were 26-30 weeks old. The ducks were randomly assigned to one of three groups: a control group (basal diet), a group in which methionine was added to the basal diet, and a group in which choline was added to the basal diet. The levels of methionine and choline added were twice as high as the levels recommended by the NRC for layer-type chickens. Experimental results indicated that adding choline to the basal diet of growing ducks significantly (p<0.05) increased their body weight, while adding methionine significantly (p<0.05) reduced their body weight. Adding either choline or methionine reduced the ducks' liver fat content in both the growing and the laying periods (p<0.05).

Ducks receiving added methionine or choline in their diets displayed enhanced egg production (p<0.05). Adding choline increased serum triacylglycerol (TG) in the laying period (p<0.05). Adding either choline or methionine did not significantly (p^그0.05) affect the 7 -globulin level. Adding methionine increased the activity of liver malic dehydrogenase in both the growing and the laying periods, and increased fatty acid synthetase in the laying period (p<0.05). While adding choline markedly (p그0，°5) increased VLDL and apo B in both the growing and the laying periods, it decreased HDL and apo A in the laying period (p<0.05). This study found that adding a high level of choline to the basal diets of Tsaiya ducks in both the growing and the laying periods had beneficial effects. Furthermore, adding methionine affected the lipid metabolism of Tsaiya ducks to a lesser extent than adding choline. (Asian-Aus. J. Anim. Set 1999. Vol. 12, No. 7 : 1090-1095)

Key Words : Choline, Methionine, Tsaiya Duck, Lij^d Metabolism, Serum Traits

INTRODUCTION

While duck

production

is an important

avian

industry

in

Taiwan, information about the

lipid

metabolism

of ducks

to fatty

liver syndrome, probably resulting

in carcinoma

(Rushmore et al.,

1984;

Yokoyama et al.,

1985;

Ru아"ore et al.,

1986;

Chandar and Lombardi, 1988).

Fatty

liver

syndrome is

induced not only

by insufficient VLDL production,

but

also by the

rate

of lipogenesis

since

lipogenesis is the main

source

of avian body

fat.

Furthermore, the

capacity

of lipogenesis

of chickens

during the

laying period differed from that

during the growing period. Laying birds follicles can

secrete estrogens that

stimulate lipogenesis, and resulting in a

relatively higher

level of

plasma and

liver TG in the laying

period

(Jensen, 1977;

Polin

and Wolford, 1977;

Hasegawa

et al.,

1980a;

Hasegawa et al., 1980b; Hasegawa et al., 1982;

Tanaka et

al.,

1986).

In

addition, the plasma lipoprotein

profiles

also

changed

during the laying period; the largest

population

of

lipoprotein

changed from high-density

lipoprotein

(HDL)

in growing

birds to

VLDL

in laying

birds

(Chapman, 1980; Hermier et al., 1985).

Tsiagbe et

al.

(1987)

reported

that adding methionine to

broiler diets

could

strengthen immuno

logical response.

One of

the

purposes

of this

study is

to determine

whether adding

dietary

choline or

methionine could have

similar results

in ducks.

Most

of

the

earlier

investigations concerning the

(2)

CHOLINE

AND

METHIONINE ADDITION

ON

LIPID METABOLISM OF

TSAIYA

DUCKS 1091

supplementation of choline and methionine in avian

diets

were aimed at the

effect

on performance or determined the requirements

for

use.

However,

relatively

few

studies investigated the influence on lipid metabolism. Therefore, this

study

investigates how adding a

high

level of dietary

choline or methionine

to the basal diet

affects

the lipid

metabolism of ducks both

in the growing and

in

the laying periods.

MATERIALS AND METHODS Animal treatment:

Sixty Tsaiya

ducks

(Anas platyrhynchos var.

domestica),

which are

layer-type, were tested in

their

growing period (after they were 8 weeks

old)

and in

their

laying

period

(after they were 26 weeks old, 10 weeks after the onset of laying).

Each duck was

allocated

to one of three

groups: a control

group

fed

with

a basal

diet

(table 1),

a group in

which methionine was added

to

the

basal

diet, and

a

group

in which

choline was added to the basal

diet.

The amount

of methionine

added was

twice

the level

for

layer-type chickens (NRC, 1994). Methionine was determined

using

the

method

of

Gehrke

et

al.

(1968)

by

ion-exchange chromatography equipped with

an

amino acid analyzer (Biotronik AAA-LC 3000, Germany).

cleavage

enzyme

(EC 4.1.3.8,

CCE)

was assayed by the method

proposed

by Takada

et

al.

(1963); NADP-malic

dehydrogenase (EC 1.1.1.40,

MDH) was analyzed by the

method

proposed by Ochoa et

al. (1955); fatty acid

synthetase

(EC

2.3.1.85, FAS) was analyzed following the procedure proposed

by

Kumar et al. (1970);

and

liver cytosol

protein

content was

determined using

a kit equipped with

an

autoanalyzer (Roche

Co.

Switzerland).

Table 1. Composition

of basal diets

(%)

Ingredients Growing

period

Laying period

Yellow com meal 67.62 58.38

Soybean meal,

44% 14.63

26.26

Fish

meal,

65% 2.00 2.00

Wheat bran

12.00

^-

Dicalcium phosphate

1.83

2.48 Limestone, pulverized 0.61 4.53

Salt 0.30 0.40

Vitamin premix1 0.03

0.03 Mineral premix2

0.10 0.10

Soybean oil - 2.18

Oyster shells - 3.00

DL-Methionine

0.11

0.14

Choline chloride, 50% 0.76 0.50

Total

100.00 100.00

Calculated value

:

Crude protein, %

15.50 18.00

ME, kcal/kg ^一 2800 2760

Calcium, %

0.90

3.40

Available

phosphorus, % 0.50 0.45

Lysine, % 0.76

1.01

Methionine,

%

^0.27

0.30

Methionine+Cystine,

% 0.60 0.70

Choline, mg/kg 1274 1304

Analyzed

value:

Methionine

% 0.26

0.31

Choline mg/kg

1263 1326

Vitamin premix supplied the following per kilogram of diet : Vitamin A, 25000 IU ; Vitamin D3, 3125 ICU;

Vitamin E, 37.5 IU; Vitamin K3, 6.25 mg; Vitamin Bi, 3.75 mg; Vitamin B2, 12.5 mg; Vitamin B& 10.0 mg;

Pantothenate, 18.8 mg; Niacin, 50 mg; Biotin, 0.06 mg;

Folic acid, 1.25 mg; Vitamin 0.05 mg.

2 Mineral premix supplied the following per kilogram of diet: Cu (C11SO4 • 5H2O, 25.45 %Cu) 6 mg; Fe (FeSQ* • 7H2O, 20.29% Fe) 50 mg; Mn (MnSO4 • H2O, 32.49%

Mn) 40 mg; Zn (ZnO, 80.35% Zn) 60 mg; Se (NaSeOs, 45.56% Se) 0.075 mg.

Statistical analysis:

SAS software was

used in

the

experimental

data

to

analyze the variance. The significance

of differences

among groups was also

examined using

Tukey's

test

(3)

1092

^{LIEN AND} ^JAN

(SAS, 1990).

RESULTS Growing period (8-12 weeks ^이d)

Table 2

displays the effects on liver, and carcass traits

of Tsaiya

ducks

when

choline

or

methionine was added

to

the ration. While

adding

a

high

level

of

methionine

to basal diets

significantly (p<0.05)

decreased body

weight,

adding choline

significantly (p<0.05)

increased

body weight. Adding either choline

or methionine reduced liver

fat

contents (p<0.05).

Adding

choline tended

to

decrease

abdominal fat (p=0.35),

but not

significantly

(p

^그0.05).

Table 2. The effects of choline

or

methionine addition on liver

and

carcass traits

of Tsaiya

ducks during growing period

____________________________

Treatment

Control Methionine Choline Body weight, kg 1.27±0.01

b

1.14±0.01

c

^1.31±0.01

a Abdominal fat,

%

0.96

±0.07

0.95 ±0.11 0.78 ±0.09 Liver fat,

% 4.98±0.43

a 3.67±0.16b 3.92±0.14b

Mean + SE (n=20).

Abdominal fat and liver fat expressed as per 100 g of body weight.

a,b,c Mean in the same row with no common superscript are significantly different (p<0.05).

Table

3

lists the effects on serum traits. Although the level of phospholipids did

not

significantly

(p

^그0.05) differ among groups, this table revealed an inclination

to increase when

either methionine or

choline

was added to the diets. The level

of

serum albumin

decreased when choline

was added

(p<0.05).

However, adding choline

or

methionine did

not

significantly

(p

^그0.05)

affect

y

-globulin

levels.

Table 4

displays the

effects

of the experiment on the activity

of

lipogenic-related

enzymes in

the liver.

Adding

methionine

markedly (p<0.05) increased the activity

of

MDH, while adding choline reduced the activity

of CCE (p<0.05).

Table

5

presents

the

effects of

the experiment on the

lipoprotein profile and

apolipoprotein A

and B concentrations.

Adding choline significantly (p<0.05)

elevated

VLDL

and apo

B

concentration.

nmole/mg

protein/niin.

Table 4. The effects

of

choline or methionine addition on

liver lipogenesis-related enzymes

activities

of

Tsaiya ducks during growing

27.22±

4.56b MDH 274.12 ±30.47b 499,34 ±29.64a 342.00±27.61b

ACC: Acetyl-CoA carboxylase, FAS: Fatty acid synthetase, CCE: Citrate cleavage enzyme, MDH: NADP-Malic dehydrogenase.

Mean + SE (n=20).

Table 5. The

effects of

choline or

methionine addition

on serum lipoproteins profile

and apolipoproteins

A

and

B

of

Tsaiya

ducks

during growing period

_______

Treatment Control Methionine Choline

HDL,

%

55.77

±1.87

54.30±1.16

55.31

±1.20

VLDL, % 7.12±0.47

b 8.39±0.90b 12.27 ±0.60a

LDL, % 36.85±1.64

35.41

±1.63

32.67

±0.94 Apo

A,

mg/비

10.10±0.38 9.81

±1.30 9.25

±0.46

Apo B, mg/^비 5.60±0.56

b 5.67 ±0.3

^俨 7.60±0.79

a

Mean±SE (n=20).

Laying period (26-30 weeks ^에10-14 weeks after the onset of laying)

Table

6

summarizes the effects of the experiment on the liver fat,

and egg

production. Adding choline

or

methionine significantly (p<0.05) reduced the liver fat

content.

The ducks

in

the methionine group

and

in the choline group laid more

eggs

(p<0.05).

Table

7 displays

the effects

of

the

experiment

on serum traits. There was significantly (p<0.05) more serum TG

when

choline was added to the diets. The effect on other traits was

not significant

(p그

0.05),

however phospholipids

had

the

potency

to increase Table 3. The

effects of choline or

methionine addition on serum traits of

Tsaiya

ducks during

growing

period

Cholesterol

Phospholipids Triacylglycerol Albumin

/-Globulin

---

mg/dl

---

143.95

± 5.02

129.76

± 3.69

134.75

±

5.49 139.73

± 5.44

150.76

±

4.91 149.42

± 4.83

148.19±9.36

158.65±

16.15

166.10 ±12.60

2300.00^土36.8(^沪 2164.80^土49.6(^严 2152.00

±39.60b

502.40^土32.0 576.40

±

60.80 527.20

±

35.20 Mean ± SE (n=20).

(4)

CHOLINE AND

METHIONINE ADDITION ON LIPID METABOLISM

OF TSAIYA

DUCKS 1093

(p=0.21)

and

cholesterol

had

the potency to decrease (p=0.14)

when

choline

was added.

Table 6. The

effects

of choline

or

methionine addition on liver fat and

egg production

of Tsaiya ducks during laying

period

Body weight, kg

1.39±0.01 1.39±0.01

1.37 ±0.01

Liver

fat, %

9.24±0.85

a

^6.52±0.30

b 4.71

±0.29

b

Egg production,

egg/hen

81.63

+

1.79b 90.42 ±0.44a 86.60 ±1.14a

Mean±SE (n=20).

Table

8 shows the

effects of

the experiment on the activities of lipogenesis-related enzymes

in

the liver.

The activities of FAS

and

MDH

in

the methionine addition

group

were significantly (p<0.05) increased.

Table 8. The effects

of

choline

or

methionine addition on

liver

lipogenesis-related enzymes activities

of

Tsaiya ducks duing laying

period______________

Treat Control Methionine Choline ment

mg/^시

ACC 1.33± 0.12 1.42± 0.14

1.15±

0.10

FAS

14.36± 1.52

b 22.83 ±

2.02즈

14.83

±

1.14b

CCE

37.70 + 8.71

60.88土

9.98 34.28 +

6.66

MDH

811.30±40.26

b

1034.13±37.96

a

846.53±54.03

b

ACC: Acetyl-CoA carboxylase, FAS: Fatty acid synthetase, CCE: Citrate cleavage enzyme, MDH: NADP-Malic dehydrogenase.

Mean±SE (n=20).

Table

9

presents the effects

of

the experiment on the

lipoprotein profile

and apolipoprotein

A

and

B concentrations.

When

choline

was added

to

the diets, the VLDL

and apo

B concentrations were marke^시y (p<0.05) stronger, but the HDL and apo A

concentra

tions

were

weaker (p<0.05).

Adding methionine

had

a

similar

result,

though with

less effective.

Table 9. The

effects of

choline or methionine addition

on serum lipoprotein

profile

and apolipo

proteins

A

and

B

concentration of

Tsaiya ducks

duHng

laying

period

Treatment Control Methionine Choline HDL,

%

25.50 ± 2.10

a

21.58 ±1.58ab 17.12±1.53

b

VLDL,

%

74.50

±

2.

10

b 78.42±1.58ab 82.88

±1.53a

Apo

A,

mg/dl

7.95

±0.9

^여 _7.10土 1.09"

4.53 ± 0.7

^裂 Apo B,

mg/dl

11.40±0.52b

17.48 +3.16ab 27.65

±4.47a

Mean±SE (n=20).

DISCUSSION

Most

studies

indicated

that

adding

choline

or methionine

to

avian

diets had

a positive effect;

hens

produced more

eggs

(Keshavarz

and

Austic, 1985;

Miles et al.,

1986; Pourreza and

Smith, 1988; Hams et al.,

1990;

Tsiagbe et al., 1992).

This study

found similar results.

Katz and

Baker (1975)

indicated

that adding a

high

level of methionine (1.25%)

in

the diet of growing

chickens

might decrease body

weight

gain.

The level of methionine added

to

the

diet of

growing ducks in this

study

also

decreased

body weight gain.

In

this

experiment,

some

of

the laying ducks

in

the control group exhibited

fatty liver

(liver fat

content was

over 10%). Schexnailder

and Griffith

(1973) indicated

that

adding choline in the

diet of

laying

hens

would reduce

liver

fat content. Adding choline or methionine

to

the diets

of both

growing

and

laying ducks

in

this experiment also

reduced

their liver fat

content. Because

choline can

undergo phosphorylation

to form phosphocholine,

and

then

synthesize

lecithin via cho-cytidine diphosphocholine,

methionine

could also synthesize lecithin via phosphotidylethanolamine.

Although choline can be

synthesized

from the lysophosphatidylcholine

that is secreted

by the

liver,

the amount would

not

be

sufficient to

satisfy body requirements. This is particularly true

for animals

such as

ducks in

which

lipid synthesis

occurs

primarily in

the liver;

that is

why choline

needs

to be

added to

a Table 7. The effects of

choline or

methionine

addition

on serum

traits

of

Tsaiya

ducks during laying period

Cholesterol Phospholipids Triacylglycerol Albumin

/-Globulin

---mg/dl ---

131.65±

14.86

114.52± 11.11 97.95±

7.66

80.62 ± 2.92 77.43

± 3.03

85.78

±

2.94

1188.00 ±83.70b

1255.50

±104.95b

1579.30

±83.70a

2121.70

+

28.70 2169.30+ 42.00

2044.00

±39.20

380.10±

12.60 344.75

± 14.00

372.05 +

17.50

Mean±SE (n=20).

(5)

1094

LIEN AND JAN

duck's

diet.

The

liver

needs

sufficient

lecithin to synthesize VLDL;

if there is

an insufficient amount of choline, the level

of

synthesized

lecithin

will drop,

resulting in a

corresponding

reduction in

VLDL synthesis

and

secretion.

Lipoprotein is

a glycoprotein,

in which phosphorylcholine

could

accelerate

the glucosamine bind

to

protein.

Thus,

if there

is

a choline deficiency,

there might not

be sufficient synthesis

of apolipoprotein for

VLDL formation. The

function

of VLDL

is to carry liver TG

into the

blood

stream, when

there is

a VLDL shortage; TG will

largely accumulate

in the

liver

and,

will

ultimately lead

to

fatty

liver

(Lombardi, 1970).

Yao

and

Vance (1988) reported

that liver

VLDL

secretion

was significantly reduced

when

rats were deficient

in

choline,

and that

the component of TG and lecithin in

VLDL

will be

higher

when choline or

methionine is

added

to

the diet.

In

humans

or rats,

adding

lecithin

could result in

increased

VLDL

concentration and

VLDL-TG (Beil

and

Grundy, 1980;

Murata

et al., 1985). Simila뢰y, results

in

this study

demonstrated that

duck VLDL

concentration

was

enhanced,

and that serum phospholipids was a trend

associated with

choline

addition in both

growing

and laying

periods;

however,

the

effects

of methionine addition were

not

so apparent.

In addition,

choline

can also supply the methyl

group for

carnitine synthesis.

Thus adding

sufficient

choline

may

accelerate

fatty acid

B

-oxidation

and facilitate a decrease in liver

fat

content.

Supplementation of

lecithin reduced rat serum apo A-l and elevated apo B concentration (Imaizumi et al.,

1983; Murata

et

at,

1985). The

results in

this study also

demonstrate that

adding

choline to

the diet

of

growing

ducks

could

lead

to markedly elevated levels of

apo B in both

growing and laying periods,

and

reduced

levels of apo

A

in

the laying period.

Some

reports

have

indicated

that,

in

humans

or rats,

supplementation

of lecithin

could

reduce

serum cholesterol

and lipoprotein (Beil and

Grundy, 1980;

Rampone

and Machida, 1981;

Imaizumi et al., 1983),

because it could

reduce cholesterol absorption and increase excretion. In this study, although the levels of cholesterol did

not differ

significantly

in

ducks

of

different groups, there was

a similar

trend.

Takahashi

and

Akiba (1995)

pointed out that

a supplement of

methionine

could

affect

lipogenesis.

When amino

acids in

the

diet became

unbalanced, more amino

acids were used

as an

energy

source, and

consequently

lipogenesis increased.

In

this experiment, twice the level

of

methionine recommended by NRC

for

layer-type

chickens

was added

in

the diet. When there was more

methionine

than the body needed, the

methyl

group of

methionine

could combine

with glycine

to form N-methylglycine by glycine-N-

methyItransferase;

N-methylglycine could then convert

to glycine. On the other hand,

homocysteine

could be condensed

with serine to convert

into

cystathionine

by

cystathionine

B -synthase;

cystationine

is then hydrolyzed into glycine

and a -ketobutyrate

by the /

-cystationase

(Frontiera et al., 1994).

Therefore, as

methionine exceeds the

requirements of

the animals, amino

acids could

become

unbalanced;

that

would

affect utilization of amino

acids (Katz and

Baker,

1975;

Takahashi and Akiba,

1995) and this situation

could

depress

the body weight

of ducks and

increase lipogenesis. However,

that

did

not

enhance liver fat

content.

Tsiagbe et

al.

(1987) reported that supplementation of methionine could enhance

broiler

immune response, and

thus

lead to

higher levels of

total

antibodies

and stronger IgG

concentration.

However, this

study found

no significant

difference

in /

-globulin

concentrations

when either

methionine

or choline

was

added

to the ducks* diet

in either

the growing period

or

the laying

period.

In conclusion, this trial indicated that adding high levels

of choline had beneficial effects

on

growing and

laying ducks.

Moreover,

adding

methionine had

a

lesser effect

than adding

choline on the lipid

metabolism

of

Tsaiya ducks.

REFERENCES

Beil, F. U. and S. M. Grundy. 1980. Studies on plasma lipoproteins during absorption of exogenous lecithin in man. J. Lipid Res. 21:525-536.

Bogin, E., Y. Avidar, M. Merom, B. A. Israeli, M.

Malkinson, S. Soback and Y. Kudler, 1984. Bio^아lemical changes associated with fatty liver in geese. Avian Pathol. 13:683-701.

Chandar, N. and B. Lombardi. 1988. Liver cell proliferation and incidence of hepatocellular carcinomas in rats fed consecutively a choline-devoid and a choline-supplemented diet. Carcinogenesis 9(2):259-263.

Chapman, M. T. 1980. Animal lipoproteins: chemistry, structure, and comparative aspects. J. Lipid Res.

21:789-852.

Evans, A. J. 1972. In vitro lipogenesis in the liver and adipose tissues of the female Aylesbury duck at different ages. Br. Poult. Sci. 13:595-602.

Folch, T., M. Lees and G. H. S. Stanley. 1957. A simple method for the isolation and purification of total lipids from animal tissues. J. Biol. Chem. 226:499-509.

Frontiera, M. S., S. P. Stabler, J. F. Koihouse and R. H.

Allen, 1994. Regulation of methionine metabolism:

Effects of nitrous oxide and excess dietary methionine. J.

Nutr. Biochem, 5:28-39.

Gabarrow, J. F., M. R. Salichon, G. Guy and J. C. Blum.

1996. Hybrid ducks overfed with boiled com develop an accute hepatic steatosis with decreased choline and polyunsaturated fatty acid level in phospholipids. Reprod.

Nutr. Dev. 36(5):473-484.

(6)

CHOLINE

AND METHIONINE ADDITION ON LIPID METABOLISM

OF TSAIYA

DUCKS

1095

Gehrke, C. W., L. L. Wall, Sr., J. S. Ab^아leer, F. E. Kaeser and R. W. Zumwalt. 1968. Focus: amino acid analysis for chromatography of amino acids: acid hydrolysis of protein. J. Assoc. Off. Anal. Chem. 198:811-821.

Harms, R. H., N. Ruiz and R. D. Mile. 1990. Research note: conditions necessary for a response by the commercial laying hen to supplemental choline and sulfate. Poult. Sci. 69:1226-1229.

Hasegawa, S., K. Sato, Y.

Effect of estrogen on chicks, with reference composition and lipase 51(5):360-367.

Hasegawa, S., K. Sato, Y.

Effect of estrogen on

Hikami and T. Mizuno. 1980a.

adipose tissue accumulation in to changes in its chemical activity. Jpn. J. Zootech Sci.

Hikami and T. Mizuno. 1980b.

adipose tissue accumulation in chicks, with reference to changes in triglyceride synthesis and fatty acid oxidation. Jpn. J. Zootech Sci.

51(9):673-679.

Hasegawa, S., T. Nimori, K. Sato, Y. Hikami and T.

Mizuno, 1982. Effect of estrogen on triglyceride metabolism in chick liver. Jpn. J. Zootech Sci.

53(10):699-706.

Hermier, D., P. Forges and M. T. Chapman. 1985. A density gradient study of the lipoprotein and apolipoprotein distribution in the chicken, Gallus domesticus. Biochimica, et Biophy. Acta 836:105-108.

Imaizumi, K., K. Masakazu, M. Murata, I. Ikeda and M.

Sugano. 1983. The contrasing effect of dietary phosphatidylethanolamine and phosphatidylcholine on serum lipoproteins and liver lipids in rats. J. Nutr.

113:2403-2411.

Jensen, L. S. 1977. Control of liver lipid accumulation in laying birds. Fed Proc. 38(12):2631-2634.

Katz, R. S and D. H. Baker. 1975. Methionine toxicity in the chick: nutritional and metabolic implications. J. Nutr.

105:1168-1175.

Keshavarz, K. and R. E. Austic. 1985. An investigation concerning the possibility of replacing supplemental methionine with choline in practical laying rations. Poult.

Sci. 64:114-118.

Kumar, S., T. A. Dorsey, R. A. Muesing and J. W. Porter.

1970. Comparative studies of the pigeon liver fatty acid synthetase complex and its subunit. J. Biol. Chem.

245(18):4732-4736.

Lim, F. and E. D. Schall. 1964. Determination of choline in feeds. J. Assoc. Off. Anal. Chem. 43:501-503.

Lombardi, B. 1970. Effect of choline deficiency on rat hepatocytes. Fed. Proced. 30(1):139-142.

Miles, R. D., N. Ruiz and R. H. Harms, 1986. Response of laying hens to choline when fed practical diets devoid and supplemental sulfur amino acids. Poultry Sci.

65:1760-1764.

Murata, M., K. Imaizumi and M. Sugano. 1985. Catabolism of newly formed triglyceride-rich lipoproteins and serum high density lipoproteins in rats fed soybean phospholipid and soybean oil. J. Nutr. 115:994-1004.

National Research Council. 1994. Nutrient requirements of poultry. (9th Ed.). Academy Press, Wa아lington, DC.

Numa, S. 1969. Acetyl-CoA carboxylase from chicken and rat liver. In : Methods in enzymology (Vol. xiv. lipids).

Academic press Inc. New York. pp:9-17.

Ochoa, S. 1955. Malic enzyme In: Methods enzymology.

Vol. 1: Acadamic press Inc. New York. pp:739.

Polin, D. and J. H. Wolford, 1977. Role of estrogen as a cause of fatty liver hemorrhagic syndrome. J. Nutr.

107(5):873-886.

Pourreza, J. ar^너W. K. Smith. 1988. Performance of laying hens fed on low sulphur amino acids diets supplemented with choline and methionine. Poult. Sci. 29:605-611.

Rampone, A. J. and C. M. Machida. 1981. Model of action of lecithin in suppressing cholesterol absorption. J. Lipid Res. 22:744-752.

Rouvier, R., G. Guy, D. Rousselot-Paillet and B. Poujardieu.

1994. Genetic parameters from factorial cross breeding in two duck strains (Anas platyrhynchos) Brown Tsaiya and Pekin, for growth and fatty liver traits. Br. Poultry Sci.

35(4):509-517.

Rushmore, T. H., Y. P. Lim, E. Farber and A. K. Ghoshal.

1984. Rapid lipid peroxidation in the nuclear fraction of rat liver induced by a diet deficient in choline and methionine. Cancer Letters 24:251-255.

Ru아imore, T. H., E. Farber, A. K. Ghoshal, S. Parodi, M.

Paia and M. A. Taningher, 1986. A choline-devcHd diet, carcinogenic in the rat, induces DNA damage and repair.

Carcinogenesis 7(10):1677-1680.

SAS. 1990. Users guide. Statistical Analysis System Institute, Inc., Cary, NC.

Schexnailder, R. and M. Griffith. 1973. Liver fat and egg production of laying hen as influenced by choline and other nutrients. Poult. Sci. 52:1188-1194.

Takada, Y., F. S. Zuki and H. Inoue. 1963. Citrate-cleavage enzyme. In: Methods in enzymology. Academic press Inc New York. pp:154.

Takahashi, K. and Y. Akiba. 1995. Effect of methionine supplementation on lipogenesis and lipolysis in broiler chicks. Jpn. Poult. Sci. 32:99-106.

Tanaka, K., J. C. Hsu, S. Ohtani and C. M. Collado. 1986.

Changes in the activities of hepatic lipogenic related enzymes and in the concentrations of various plasma and liver lipid fractions in hens before and after the onset of laying. Jpn. Poult. Sci. 23(4):203-210.

Tsiagbe, V. K., M. E. Cook, A. E. Harper and M. L.

Sunde. 1987. Enhanced immune responses in broiler chicks fed methionine-supplemented diets. Poult. Sci.

66:1147-1154.

Tsiagbe, V. K., A. E. Harper and M. L. Sunde. 1992. A feather-strain of laying hens was more responsive to dietary supplements of choline and methionine than a vent-sexed strain. Poult. Sci. 71:1271-1276.

Yao, Z. ar너 D. E. Vance. 1988. The active synthesis of phosphatidylcholine is required for very low density lipoprotein secretion from rat hepatocytes. J. Biol. Chem.

263:2998-3004.

Yokoyama, S., M. A. Sells, T. V. Reddy and B. Lombard.

1985. Hepatocarcinogenic and promoting action of a choline-devoid diet in the rat. Cancer Res. 45:2834-2842.

Zeisel, S. H. and D. J. Canty. 1993. Choline phospholipids:

molecular mechanisms for human diseases: a meeting report. Nutr. Biochem. 4:258-263.

ism of Tsaiya Ducks When High Levels of Choline or Methionine are Added to the Ducks' Diet

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