Báo cáo nghiên cứu nông nghiệp " review of Common carp breeding program at RIA1-VN " docx

In the second phase 1986-1995 mass individual selection has been carried out among the three hybrid stocks obtained by crossing among Vietnamese white carp, Hungarian scale carp and Indo

review of Common carp breeding program at RIA1-VN

Mr Nguyen Huu Ninh, RIA1

Sumary

Common carp is one of the most important cultured species in Vietnam The goal of the carp breed program was creation of a common carp breed with stable genetic qualities such as fast growth, high survival rate and attractive appearance

In the first phase (1981-1985) the program focused on the assessment of the original carp varieties, which should be used as initial materials for selection In the second phase (1986-1995) mass individual selection has been carried out among the three hybrid stocks obtained by crossing among Vietnamese white carp, Hungarian scale carp and Indonesian yellow carp Despite the small size of the selected populations, the selection pressures for the first five generations in an average were severity of selection 19.8%, intensity of selection 1.52 and selection differential 93g

The realized heritability (h2) of body weight determined for carp of one of the three stocks was 0.29 in the first generation, 0.02 in the second generation, but this index declined to around 0 in the fourth generation The total genetic gain for body weight of selected common carp after five generations was 33%

Thus, it was recommended to move to family selection in the next phase (1996-2000) of breeding program however its results were unexpected due to very low realized heritability of almost 0.1 in second selected generation

Continuing third phase breeding program of common carp is also presented in these report which is undergoing at National Broodstocks Center, RIA1 by croosbreed between

6 carp populations in prospect to gain genetic variation from improved carp lines and pure carp lines

Background

According to the estimation of the Ministry of Fisheries (MOFI), the total fish production

of the country in 1998 was 1.67 million tonnes, of which around 538,000 tonnes came from aquaculture (MOFI, 1998), providing nearly 35 % of the total animal protein intake

of the nation The main cultured fish species in Vietnam are local and exotic carps

including common carp (Cyprinus carpio L), silver carp (Hypophthalmichthys harmandi and H molitrix), bighead carp (Aristichthys nobilis), mud carp (Cirihina molitorella),

grass carp (Ctenopharyngodon idella), black carp (Mylopharyngodon piceus), rohu (Labeo rohita), mrigal (Cirrhinus mrigala), silver barb (Puntius gonionotus) and some some species of Clarias, Pangasius and Tilapia (Oreochromis niloticus)

Aquaculture in Vietnam is facing with some problems, in the first instance should be indicate the deterioration of economically important traits, decreased growth rate, small maturation size, low survival and low disease resistance Obviously, improvement of genetic quality of cultured fish species is one of the most essential approaches to increase aquaculture production

Common carp is a traditional and important cultured species in Vietnam Among eight varieties of Vietnamese common carp white carp has been cultivated largely in many areas of the Country (Trong, 1983) However, white carp like other local varieties exhibited slow growth rate and early maturation In 1970 and 1975 the mirror and scale strains of Hungarian common carp were introduced to Vietnam Indonesian yellow carp was introduced to the South, Vietnam before 1975 and then transferred to the North in

1978 In the 70s the experiments on hybridization of the Vietnamese white carp with the Hungarian carps have been carried out (Tuong and Thien, 1979; Thien and Tuong, 1983; Thien, 1993) Hybrid carp (F1) showed fast growth and high survival The best productivity was obtained from raising hybrid carp However, due to importer breeding management, the base stocks of common carp in almost hatcheries over the country were gradually losing their purity, thus decreasing the effectiveness of commercial crossing for hybrids Since 1981, research programs have focused on selection of common carp with the intention of creating a fish breed with stable genetic qualities In the first phase (1981-1985) the program focused on the assessment of initial materials for selection In the second phase (1986-1995) mass individual selection has been carried out among the hybrid stocks over six generations Continued family selection were carried out over 2 generations in the period of 1996 to 2000

Description of issue or practice

The materials for selection were preliminarily selected among 8 local and 5 exotic varieties of common carp They were Vietnamese white carp (V), Hungarian scale carp (H) and Indonesian yellow carp (Y) To bring together a number of positive qualities from these varieties and to improve the genetic variability of the initial materials for selection, at first three stocks of single hybrids were obtained by crossing Vietnamese carp with Hungarian carp (VH), Vietnamese carp with yellow carp (VY) and Hungarian carp with yellow carp (HY) Then the males of each single hybrid are crossed with

females of the third variety The double hybrids obtained in these crossings have been evaluated and used as materials for further selection (Fig 1)

Assessment of initial materials for selection was made by comparing some morphological, physiological and biochemical characteristics among the above mentioned pure common carp varieties and their hybrids

In order to carry out mass individual selection about 5-10 families (one family included 1 female and 3-4 males) of each stock were bred at the same day Their eggs were incubated under the same conditions The rearing of fry and fingerlings and culturing them to marketable size were done under similar environmental conditions On an average, about 20% of total number marketable fish in each stock were selected based on the body weight and appearance (big body and small head) The selection effectiveness was estimated according to Falconer (1960)

R= Sh2 = iδh2 R: effectiveness of selection i: intensive of selection

S: selection differential δ: average square variation

h2: heritability of the trait (body weight)

To estimate the coefficient of realized heritability of fish body weight in each selected generation, the experiments were implemented according to the schema in figure 2 Before mass selection of marketable fish was done, a randomly collected control population was kept Then another group was collected by selecting for big body weight (experimental group) Deduction of the average body weight between experimental group and control group was a selection differential (S) In the next year the offsprings of the two groups were obtained by the same method and the fingerlings of control experimental groups were reared by communal stocking in the same pond to a marketable size The deduction of the average body weight between two offspring groups had to be the effectiveness of selection for one generation (R) The heritability was calculated according to formula:

H= - = -

Vietnamese (white)

Common carp

Hungarian (scale) Common carp

(Indonesian) Yellow Common carp H

F1

(Double)

1986

F2

1988

F3

1989

F4

1991

F5

1993

F6

1995

F1 (Single)

Fig 1- Mass selection of Hybrid Common carp

Research and development

Morphological characterization of common carp varieties and their hybrids

There are 8 local and 3 introduced varieties of common carp in Vietnam The local varieties, identified on basic of morphology and coloration, are white scaled, Bac Can,

Ho Tay, South Hai Van, Red, Violet, High Body Depth and Scattered Scale varieties (Trong, 1983) The introduced common carps are Hungarian scaled, Hungarian mirror and Indonesian yellow varieties

Crossing between Hungarian carp and Vietnamese carp, Hungarian carp and Indonesian carp, Vietnamese carp and Indonesian carp was carried out in the 1980’s for investigation

of their hybrid growth performance Morphological study on Vietnamese, Hungarian, Indonesian and hybrid common carps (Table 1) was also conducted by Research Institutes for Aquaculture No.1 and the University of Hanoi in the same period (Thien and Tuong, 1983; Thien 1990)

Table 1 Morphology and morphometrics of common carp varieties and their hybrids (H = Hungarian; Y = Indonesian Yellow; V = Vietnamese White)

Varieties Hybrids Descriptions

Body weight (g)

Standard length (Cm)

24.3 ± 1.41 8.2 ± 0.16

22.2 ± 1.27 8.3 ± 0.18

16.3 ± 0.61 7.9 ± 0.09

21.2 ± 0.91 8.1± 0.11

22.8± 1.21 8.2 ± 0.15

12.9 ± 0.89 6.9 ± 0.15

As % of standard length:

Maximal body height

Minimal body height

Length of head

Dorsal spine to tip most

dorsal ray (DSR)

Intestine length

As % of head length:

Diameter of eye

Length of barbell

38.1 ± 0.19 14.3 ± 0.13 34.1 ± 0.24 36.3 ± 0.24

174.0 ± 1.6

26.6 ± 0.32 17.8 ± 0.29

35.1 ± 0.32 13.0 ± 0.13 31.9 ± 0.13 36.6 ± 0.25

185.7± 1.8

24.0 ± 0.37 18.6 ± 0.25

30.9 ± 0.25 11.9 ± 0.10 31.6 ± 0.16 33.5 ± 0.16

145.0 ± 1.3

29.6 ± 0.49 18.0 ± 0.21

35.5 ± 0.25 14.5 ± 0.16 34.4 ± 0.38 36.6 ± 0.38

175 ± 1.4

25.9 ± 0.45 19.2 ± 0.21

37.3± 0.28 13.9± 0.17 33.1± 0.30 34.4± 0.14

186 ±2.2

25.4± 0.3 18.2± 0.26

32.2 ± 0.30 14.4 ± 0.17 32.1 ± 0.40 37.1 ± 0.30

165.8 ± 2.1

27.9 ± 0.50 17.4 ± 0.30

No of lateral line scales

No of Dorsal rays

No of Anal rays

No of branched stamens in

first bow

No of vertebrae

37.7 ± 0.20 18.9 ± 0.12

5

24.9 ± 0.20

35.8 ± 0.12

32.9 ± 0.25 18.3 ± 0.16

5

19.7 ± 0.17

35.1 ± 0.08

32.0 ± 0.14 20.4 ± 0.16

5

20.7 ± 0.18

34.1 ± 0.08

32.6 ± 0.12 18.0 ± 0.08

5

20.2 ± 0.20

34.4 ± 0.13

33.8± 0.16 18.2± 0.26

5

22.7± 0.23

35.0± 0.16

33.4 ± 0.15 19.0 ± 0.15

5

20.2 ± 0.18

34.7 ± 0.20

Genetic characterization of common carp populations

Transferrin of pure common carp varieties and their hybrids was analysed using 12 % starch gel electrophoresis Four banding patterns were observed, designated as A,B,C and

D, with 8 different phenotypes (Thien and Tuong, 1983: Thien 1990) (Table 2)

Table 2 Distribution (%) of Transferrin phenotypes in different common carp varieties

(HS = Hungarian scaled; HM = Hungarian mirror; Y = Indonesian yellow; V = Vietnamese white; HS x V = hybrid Hungarian x Vietnamese)

Carp

varieties

n AA AB AC BB BC BD CC DD

HS

HM

Y

V

HS x V

58

9

33

28

33

1.72 11.1 3.58 3.02

-

- 88.9 9.1

-

-

74.14

- 39.39 92.84 93.96

1.72

- 12.12

-

-

13.8

- 27.27 3.58

-

5.17

-

-

- 3.02

1.72

- 12.12

-

-

1.72

-

-

-

-

Two banding patterns of serum esterase were obtained, designated as F (fast) and S (slow) There were three esterase phenotypes in pure varieties and their hybrids (Table 3)

Two banding patterns with two phenotypes of pre-albumin were observed in pure and hybrid common carp varieties (Table 4) Serum proteins were also analysed in these strains and the H x V crossbred (Table 5)

Table 3 Distribution (%) of esterase phenotypes in different common carp varieties (HS

= Hungarian scaled; HM = Hungarian mirror; Y = Indonesian yellow; V = Vietnamese

white; HxV = hybrid Hungarian x Vietnamese)

Carp varieties N FF FS SS

HM

Y

V

H x V

9

33

28

33

100.0

- 28.58 42.42

-

100 71.42 42.42

-

-

- 3.03

Table 4 Distribution (%) of pre-albumin phenotypes in different common carp varieties (HS = Hungarian scaled; HM = Hungarian mirror; Y = Indonesian yellow; V = Vietnamese white; HxV = hybrid Hungarian x Vietnamese)

Carp varieties N FS SS

HS

HM

Y

V

H x V

58

9

33

28

33

8.64

- 12.12 3.58 9.09

91.36 100.0 87.88 96.42 90.91

Table 5 Serum protein of various common carp varieties (HS = Hungarian scaled; HM = Hungarian mirror; Y = Indonesian yellow; V = Vietnamese white; H x V = hybrid Hungarian x Vietnamese)

Varieties Total protein

(g%)

Albumin (g%)

α-globulin (g%)

β-globulin (g%)

δ-globulin (%)

V

HS

HM

Y

H x V

2.60 ± 0.041 3.03 ± 0.044 3.06 ± 0.033 3.51 ± 0.033 2.84 ± 0.022

0.85 ± 0.034 1.05 ± 0.066 1.06 ± 0.072 1.18 ± 0.048 0.90 ± 0.034

0.63 ± 0.036 0.69 ± 0.029 0.70 ± 0.025 0.84 ± 0.039 0.71 ± 0.026

0.56 ± 0.036 0.63 ± 0.029 0.68 ± 0.036 0.75 ± 0.033 0.64 ± 0.022

0.56 ± 0.041 0.66 ± 0.04 0.62 ± 0.033 0.74 ± 0.033 0.59 ± 0.022

Heterosis in intraspecific crossbreeds of common carp

Eight varieties of local common carp were investigated, of which white carp, a variety with high viability is the most popular (Trong 1983) However, this carp and other varieties of Vietnamese common carp presented slow growth and early maturity Attempts aimed at obtaining heterosis by crossing among these varieties were not successful

Two Hungarian common carp strains (mirror and scale carps) were introduced in Vietnam in 1970 and 1975 respectively Under Vietnamese conditions, the Hungarian carps showed fast growth and late maturation but were easily infected with diseases and possessed low viability The first hybrid generation (F1) crossing between Vietnamese white carp and Hungarian carp showed the best characteristics from their parents i.e high survival rate, fast growth and attractive appearance The survival rate of hybrid fry and fingerling was much higher than that of Hungarian carp (Table 6) At the same time survival rate of the hybrids and Vietnamese carp was similar

Table 6 Survival rate (%) of fry and fingerling of Vietnamese common carp (V), Hungarian common carp and their reciprocal hybrids (VH, HV)

Survival rate (%) Stage Crossing

1974 1975 1976

Fry

V

VH

HV

H

51.6 61.6 60.4 22.3

- 70.0 44.3 40.0

71.2 80.0 78.0 37.6

Fingerling

V

VH

HV

H

85.9 ± 9.4 94.9 ± 1.9 81.4 ± 7.5 45.7 ± 5.2

- 76.2 ± 2.9 76.7 ± 2.3 38.6 ± 2.4

78.3 ± 0.2 90.0 ± 3.3 73.0 ± 11.3 46.3 ± 5.1

Mass selection of common carp

The data collected during process of mass selection showed that the number of experimental fish in each stock was limited due to a limited number of ponds Even though the scale of selection is small (Table 8) the indices obtained proved to be acceptable

Thus in first generation the number of fish obtained for mass selection in one of stocks was 1720, in each of two other stocks was 400 where as in second generation the number

of fish in each stock was only 250 but the selection differential in second generation was even higher than that in F1 In the F3 generation field trials, due to poaching of some stocked fishes the total number of fish obtained for selection was reduced So around 33% of fishes in each stock was selected It led to declining of the selection intensity and the selection differential In the next generations following the recommendation of some

geneticist-selectionists (Kirpichnikov, 1987) about 20% of fishes was kept to established the broodstocks As a result the selection indices were stabilized in an acceptable level After five selected generations the common carps of all three stocks have been clearly improved in growth rate and appearance However, in order to estimate the genetic gain it was necessary to know the coefficient of heritability The data obtained in the experiments to determining the realized heritability of body weight showed that the indices in the first two generations were suitable for individual selection, but they were decreased from F1 to F4 generation

In F1 generation the realized heritability was 0.29 In F2 generation experiments, the results were analyzed and adjusted according to the methodology of Wohlfath and Moav (1972), because of the difference in body weight between two groups of fingerling when stocked (Table 9)

The realized heritability of body weight was 0.20 for the F2 generation In the F4 generation this index was declined even to around 0 In fact, the effectiveness of individual selection of common carp in the last two generations was low The experiment

of comparison of growth rate of carps obtained from breeders in F3 and F5 selected generation (Table 10) showed that the difference in body weight was 7% only It is expected that improvement of selection effectiveness in the next phase of the breeding program should be done by applying another method, for example, family selection

An average coefficient of realized heritability calculated for each generation was 0.16

So, based on average index of selection differential, the response to selection for increasing body weight in each generation could be estimated and it should be around 15g or 6.6% So, the total genetic gain for body weight in the common carp breeding program after 5 selected generations was 33%

Decrease of the genetic gain could be caused by inbreeding To avoid the inbred depression it was recommended to cross among the three stocks to producing hybrid seed for grow-out farmers Preliminary data obtained in the experiments following this direction (Table 11) showed that the heterosis effect has found out in both experiments but it was more significant in the experiment No.2

Decline of realized heritability in these selection program might be caused by reducing in variability of selected trait With intention of understanding the genetic structure of the selected common carp stocks in 5th generation, some isozymes namely Lactat dehydrogenase (LDH), Malat dehydrogenase (MDH), Aspartat aminotransferase (AAT) and Esterase (EST) located in blood, heart, liver and muscle of the fishes were studied by electrophoresis in 6% polyacrylamide gel All the above mentioned isozymes were

polymorphic and the electrophoregrams included from 2 to 6 bands The data on comparison of three stocks showed that LDH in muscle, heart and liver, MDH in liver and muscle, as well as AAT in blood, heart and muscle of the carps in all the stocks were identical The electrophoretic patterns of AAT in liver, EST in heart and muscle were also similar but there were some differences between the stocks in frequency of the bands Identification of the fish stocks could be done only by using parallel analysis of LDH, MDH and EST in blood

For the fishes in each stocks the identity of above mentioned isozymes was in very high level Thus, genetic variability of the fishes within the stocks after 4-5 generations has been possibly declined

Table 7 Presentative data of the mass individual selection of the hybrid stocks of common carp (V-Vietnamese, H-Hungarian and Y-Indonesian Yellow common carp) Year Stocks Total Body Indices collected through selection generation

and place

fish

weight (g)

Severity

V (%)

Intensity i (S/δ )

Differenti

al S (g)

1986

F1

RIA.1

H x (YxV)

V x (YxH)

Y x (HxV)

400

400

1720

162±6 178±4 187±8

12.5 12.5 7.5

2.77 1.66 1.94

99

84

82

1988

F2

RIA.1

H x (YxV)

V x (YxH)

Y x (HxV)

248

258

253

152±7 104±5 148±9

10.1 9.7 9.9

1.76 2.03 1.60

117

177

164

1989

F3

RIA.1

H x (YxV)

V x (YxH)

Y x (HxV)

75

243

74

149±8 155±12 310±16

33.3 32.9 33.8

1.25 0.80 0.77

52

62

41

1991

F4

RIA.1

H x (YxV)

V x (YxH)

Y x (HxV)

200

209

189

260±6 197±5 299±6

20.0 19.1 25.9

1.26 1.75 1.24

74

124

47

1992

F5

RIA.1

H x (YxV)

V x (YxH)

Y x (HxV)

229

235

175

314±12 300±9 350±10

21.8 21.3 22.0

1.28 1.72 1.72

97

69

93

1993

F5

H x (YxV)

V x (YxH)

257

263

226±10 300±14

19.5 20.9

1.39 1.06

85

101