Better breeds of common carp (Cyprinus carpio L.) for small-scale fish farmers

Ministry of Agriculture & Rural Development  
Collaboration for Agriculture & Rural Development  
002/04VIE Project  
Better Breeds of Common Carp (Cyprinus carpio L.)  
for Small-scale Fish Farmers  
Milestone 4: On-farm Trials and Uptake of Improved Breeds of  
Common Carp  
Christopher M Austin1, Tuan Anh Pham2, Binh Thanh Thai2, Hung Quang Le2  
1School of Science and Primary Industries, Charles Darwin University, Darwin Northern  
Territory 0909, Australia  
2Research Institute for Aquaculture No 1, Dinh Bang, Tu Son, Bac Ninh, Vietnam  
October, 2007  
2
Contents  
Contents...........................................................................................................2  
List of Figures .................................................................................................3  
List of Table ....................................................................................................4  
1. Introduction ................................................................................................6  
2. Materials and methods...............................................................................7  
2.1. Experimental Design..................................................................................................7  
2.2. Selection of common carp strains..............................................................................8  
2.3. Common carp rearing and experimental procedures .................................................9  
2.4. Data collection and analysis.....................................................................................11  
3. Results........................................................................................................14  
3.1. Fingerling growth rate..............................................................................................14  
3.2. Growth and survival of HP3 and LOC strains and effects of feed input .................14  
3.3. Growth rate and survival of HP3, H3B and LOC strains ........................................17  
3.4. Growth rate and survival for HP3, VNW and LOC Strains ....................................19  
3.5. Growth rate and survival of HP3, H3B, VNW and LOC strains in low feed input  
farms controlled for variation among farmer ponds ..................................................21  
3.6. Common carp biomass production in farms stocked with three common carp strain  
(HP3, H3B, LOC) ......................................................................................................23  
3.7. Common carp biomass production comparing farms stocked with two common  
carp strains (HP3 and LOC).......................................................................................25  
3.8. Demand of the improved common carp seed ..........................................................27  
4. Conclusion and Recommendations.........................................................29  
Appendices ....................................................................................................33  
Reference.......................................................................................................34  
3
List of Figures  
Fig 2.1. Rice field used for farm trials in Yen Bai province.................................................9  
Fig 2.2. Farmer’s pond in Thai Nguyen province.................................................................9  
Fig 2.3. Measuring common carp. ......................................................................................11  
Fig 2.4. Ethnic people harvesting common cap in rice field in Yen Bai province.............12  
Fig 2.5. Harvesting common carp in pond in Thai Nguyen................................................13  
Fig 2.6. A farmer is happy with common carp growth.......................................................13  
Fig 3.1. Daily growth rate of HP3 and LOC common carp strains in each of 18 farms.....15  
Fig 3.2. Example of relative growth of three strains of common carp in rice field in Yen  
Bai province after six months of culture.................................................................18  
Fig 3.3. Daily growth rate of HP3, H3B and LOC common carp strain in each of 11 farms  
in Yen Bai and Thai Nguyen provinces..................................................................18  
Fig 3.4. Daily growth rate of HP3, VNW and LOC common carp strain for a period of 10  
months in each farm in Yen Bai and Thai Nguyen provinces................................20  
Fig 3.5. Daily growth rate of HP3, H3B, VNW and LOC common carp strains in 3 farms.  
................................................................................................................................22  
Fig 3.6. Common carp from HP3 strain after seven months of cultured in a high input feed  
farm in Thai Nguyen province................................................................................23  
Fig 3.7. Proportion of genetically improved common carp fry and fingerlings cultured in  
Vinh Phuc, Thai Nguyen and Yen Bai provinces during 2004-2006. ....................29  
4
List of Table  
Table 2.1. Farms, pond type, and number of fish stocked of each strain (some farms were  
remove from the data set because fish escaped during flooding)...........................10  
Table 2.2. Data analyses for common carp culture farm trails...........................................13  
Table 3.1 Mean (± SD) of body length and weight of fingerling carp after 60 days of  
nursing ....................................................................................................................14  
Table 3.2. ANOVA table testing for differences in daily growth rate in relation to the  
effects of common carp strain (HP3 and LOC) and type of feed input..................15  
Table 3.3. Daily growth rate of HP3 and LOC common carp strain for period of 10 months  
in 18 farms in two type of feeding regimes in Yen Bai and Thai Nguyen provinces.  
Superscripts indicate significant differences among groups based on Tukey’s test.  
................................................................................................................................15  
Table 3.4. ANOVA table testing for differences in survival rate in relation to the effects of  
common carp strain (HP3 and LOC) and type of feed input..................................16  
Table 3.5. Survival rate of HP3 and LOC common carp strains grown for a period of 10  
months in 18 farms with two types of feeding rates in Yen Bai and Thai Nguyen  
provinces. Superscripts indicate significant differences among groups based on  
Tukey’s test.............................................................................................................16  
Table 3.6. ANOVA table testing for differences in daily growth rate in relation to the  
effects of common carp strain (HP3, H3B and LOC).............................................17  
Table 3.7. Daily growth rate of HP3, H3B and LOC common carp strains grown for a  
period of 10 months in 11 farms in Yen Bai and Thai Nguyen provinces.  
Superscripts indicate significant differences among groups based on Tukey’s test.  
................................................................................................................................17  
Table 3.8. ANOVA table testing for differences in survival rate in relation to the effects of  
common carp strains (HP3, H3B and LOC)...........................................................19  
Table 3.9. ANOVA table testing for differences in daily growth rate in relation to the  
effects of common carp strain (HP3, VNW and LOC)...........................................19  
Table 3.10. Daily growth rate of HP3, VNW and LOC common carp strains grown for a  
period of 10 months in 5 farms in Yen Bai and Thai Nguyen provinces.  
5
Superscripts indicate significant differences among groups based on Tukey’s test.  
................................................................................................................................20  
Table 3.11. ANOVA table testing for differences in survival rate in relation to the effects  
of common carp strains (HP3, VNW and LOC).....................................................21  
Table 3.12. ANOVA table testing for differences in daily growth rate in relation to the  
effects of common carp strain (HP3, H3B, VNW and LOC).................................21  
Table 3.13. Daily growth rate of HP3, H3B, VNW and LOC common carp strains for  
period of 10 months in 3 farms in Yen Bai and Thai Nguyen provinces.  
Superscripts indicate significant differences among groups based on Tukey’s test.  
................................................................................................................................22  
Table 3.14. ANOVA table testing for differences in survival rate in relation to the effects  
of common carp strains (HP3, H3B, VNW and LOC) and culture types (low and  
high feed input).......................................................................................................23  
Table 3.15. Biomass of common carp strains in 11 farms with 3 strains (HP3, H3B and  
LOC) and cultured for 300 days in Yen Bai and Thai Nguyen provinces..............24  
Table 3.16. ANOVA analyses of biomass of HP3, H3B, and LOC common carp strains.25  
Table 3.17. ANOVA analysis of biomass of HP3 and LOC common carp strains............25  
Table 3.18. Biomass of common carp strains in 18 farms with 2 strains (HP3 and LOC)  
cultured for 300 days. Superscripts indicate significant differences among groups  
based on Tukey’s test..............................................................................................26  
Table 3.19. Biomass of HP3 and LOC common carp strains grown for a period of 10  
months in 18 farms with two types of feed input in Yen Bai and Thai Nguyen  
provinces.................................................................................................................27  
Table 3.20. Number of hatcheries and fry nursing farmers in 3 provinces. .......................27  
Table 3.21. Number of common carp fry produced in five hatcheries in Thai Nguyen, Yen  
Bai and Vinh Phuc provinces in 2006.....................................................................28  
Table 3.22. Proportion of fry produced from genetically improved common carp lines in  
five hatcheries in Thai Nguyen, Yen Bai, and Vinh Phuc provinces in 2006. .......28  
6
1. Introduction  
In Vietnam aquaculture plays a very important role in economic development and food  
security for small scale farmers and contributes 35% of Vietnamese protein consumption.  
Aquaculture production is increasing at rate of 10% per year and contributes significantly  
to the country’s export income (MOFI, 2007).  
Common carp is one of the most popular freshwater aquaculture species in Vietnam and is  
cultured in pond, cages, reservoir and rice field for household consumption and income  
generation. A recent survey of 133 carp farmers indicated that pond and rice field  
production are the preferred form of culture systems (98%) with the pond culture the most  
common (Austin et al., 2007a). Most farmers culture common carp with up to 8 other fish  
species, both indigenous (silver carp, black carp) and exotic (silver grass carp, bighead,  
rohu, mrigal, pirapitinga, Tilapia). In polyculture ponds, common carp is the predominate  
species making up 30.1% of the biomass based on a recent survey (Austin et al., 2007a).  
The level of culture intensity for common carp varies from small scale extensive farming,  
with fish deriving all their nutrition from natural pond productivity, through semi-  
intensive farming using fertilization from organic material such as bran, agriculture by-  
products and household wastes to high intensive culture system with high stocking  
densities and the use of manufactured fish foods. Semi-intensive culture systems are the  
most popular in Vietnam using ponds or a combination of ponds and rice field cultivation  
(Austin et al., 2007a).  
There are many factors that affect production and yield of farmed fish species, including  
seed (fry and fingerlings) quality, feed type and rate, fertilisation and pond management,  
including water exchange. Of these, seed quality, which is directly related to the genetic  
quality of the broodstock used to produce the fry and fingerlings, has been identified as  
being of major concern to researchers (Thai et al., 2006; 2007), but which is not generally  
understood by farmers to be a potential issue affecting farm productivity (Austin et al.,  
2007a).  
7
In Vietnam there are many different local varieties of common carp that have been used  
by farmers but they usually have small size and low growth rate (Tran, 1983). Over recent  
times the Research Institute for Aquaculture No.1 (RIA-I) has bred genetically improved  
common carp strains to enhance the productivity of small scale fish farms that utilise this  
species. This program has used crossbreeding and mass and family selection  
methodologies to produce genetically improved strains and is considered to have achieved  
an average increase of 5% in growth rate per generation over a number of generations  
(Thien and Thang, 1992). However, all the selective breeding and associated growth trials  
have been conducted in research ponds, often without the availability of unselected lines  
as control populations for comparative studies.  
As a consequence, on-farm growth trials of different strains were undertaken to allow for a  
more effective analysis of carp growth under environments directly relevant to small scale  
carp farmers and as a strategy to encourage uptake by farmers of genetically improved  
strains. This report presents, firstly, a report on the statistical analysis of growth and  
production of different common carp strains in small scale farmer ponds in Yen Bai and  
Thai Nguyen provinces. The farmers participating in this research project included those  
using both pond and rice field culture from mostly highland environments. All farmers  
had previously participated in the socio-economic survey and one of two workshops on  
fish breeding and genetic improvement conducted as part of this project. Secondly, a  
survey of the uptake of improved breeds by producers is presented.  
2. Materials and methods  
2.1. Experimental Design  
The original objective of the on-farm trials was to compare a genetically improve carp  
strain and a local strain communally reared in six ponds owned by different farmers. With  
additional support from the Research Institute of Aquaculture No. 1 (RIA1), the  
experimental objectives were scaled up to include 37 separate farmers and four strains.  
The majority (34) of farmers used ponds as their culture systems with six farmers using  
8
rice field systems, which reflects the proportion of these different farming systems in these  
provinces based on the socio-economic survey (Austin et al., 2007a) (Fig 2.1&2.2). Farms  
were classified according to their levels of feed inputs as either high or low to determine if  
this important management aspect influenced the relative performance of the different  
carp strains. Farmers who did not provide food more than once per month were classified  
as having “Low” input pond systems and those who fed at least once per week or more  
frequently were classified as having “High” input pond systems. The experiment was  
conducted over a 12 months period from March 2006 to March 2007, which included  
spawning and fry rearing March – May, 2006 and fingerling grow out May 2006 to March  
2007, which largely coincides with the normal carp farming culture cycle. The trials were  
conducted in pond systems owned by 20 households in each of the Thai Nguyen and Yen  
Bai provinces. Representatives of these households were interviewed for the socio-  
economic survey and participated in one of the farmer workshops on fish breeding and  
selection held as part of this project.  
As described in more detail below the experimental design could not be achieved due to  
differential reproduction and survival of fry. Thus different farms were stocked with  
different numbers of strains and in varying combinations. Further, fish could not be  
harvested from several farms due to flooding and other management problems. Appendix  
1 lists the farms that participated in the project, and details of their culture systems and  
fish that were stocked and if data collection at harvest was possible.  
2.2. Selection of common carp strains  
Fours common carp strains were used for growth trials and included one strain (HP3)  
recently produced through hybridization between the three blood Hungarian strain and a  
recently imported pure line of Hungarian carp, the three blood Hungarian strain (H3B), an  
unselected Vietnamese strain (VNW) and a locally available strain (LOC) produced from  
broodstock available from the Yen Bai provincial hatchery. Genetic analysis of this strain  
(Thai et al., 2006: 2007) indicates it represented a mixture of Indonesian, Hungarian and  
Vietnamese strains with the latter strain predominating.  
9
.
Fig 2.1. Rice field used for farm trials in Yen Bai province  
Fig 2.2. Farmer’s pond in Thai Nguyen province  
2.3. Common carp rearing and experimental procedures  
Common carp breeding was undertaken at the National Broodstock Centre Hai Duong.  
Broodstock of each experimental strain were induced to breed on the same day, using  
standard practices for gamete stripping and fertilization (Thai and Ngo, 2004). Between 10  
-12 families of fish were obtained from each strain. After fertilization eggs produced from  
10  
different families of the one strain were pooled and raised in 200l upwelling incubators.  
After 4-5 days when larvae had reached 8-12 mm they were transferred to four ponds and  
stocked at a rate of 100 larvae/m2 and grown for a period of two months. Every effort was  
made to keep the conditions under which the fry and fingerlings of each strain were raised  
as similar as possible, especially in relation to stocking density and feeding regime. When  
the fingerlings had reached of 3-5g, they were tagged by using Coded Wire Tag (CWT).  
The strains of common carp lines were marked by placing the CWTs on different  
locations on the body. The tagged fish were stocked into 40 ponds or pond-rice field  
systems over a two day period. Communally stocked fish were in equal proportions with  
the exception of three ponds. The details of the fish stocked in farms is given Table 2.1.  
Table 2.1. Farms, pond type, and number of fish stocked of each strain (some farms were remove  
from the data set because fish escaped during flooding).  
Farm  
Provinces Culture Area  
Feed  
Strain and No of fish stocked  
HP3 H3B VNW LOC Total  
(m2)  
systems  
input  
HF  
LF  
LF  
HF  
LF  
HF  
LF  
LF  
HF  
LF  
LF  
LF  
HF  
LE  
LE  
HF  
LF  
LF  
LF  
LF  
LF  
LF  
Hoan  
Ly  
Thuan Yen Bai  
Tap  
Tuan  
Yen Bai  
Yen Bai  
Ricefield 1000  
100 100  
120 120  
100 100  
120  
100 100  
100  
113 113 113 113  
80  
75 75  
100  
113 113 113 113  
145 55  
60  
100 100  
113 113 113 113  
100  
300  
240  
300  
240  
300  
300  
450  
240  
150  
200  
450  
300  
120  
300  
450  
150  
300  
240  
180  
300  
150  
120  
Pond  
Pond  
800  
1000  
800  
100  
120  
100  
Thai Nguyen Pond  
Thai Nguyen Pond  
1000  
1000  
Chung Yen Bai  
Pond  
100 100  
Lien  
Hom  
Tho  
Dieu  
Ha  
Lieu  
Canh  
Luat  
Nhan  
Yen Bai  
Yen Bai  
Yen Bai  
Thai Nguyen Pond  
Thai Nguyen Pond  
Thai Nguyen Pond  
Thai Nguyen Pond  
Thai Nguyen Pond  
Ricefield 1500  
Ricefield  
Pond  
800  
450  
80 80  
100  
600  
1500  
1000  
400  
100  
60  
100  
1000  
1500  
500  
Yen Bai  
Pond  
Truong Thai Nguyen Pond  
75  
75  
150  
80  
90  
100  
75  
Que  
Vinh  
Ke  
Thai Nguyen Pond  
Thai Nguyen Pond  
Thai Nguyen Pond  
1000  
800  
550  
100 50  
80 80  
90  
100 100  
75  
Thong Yen Bai  
Lich Thai Nguyen Pond  
Trung Thai Nguyen Pond  
Pond  
1000  
500  
400  
60 60  
HF: High feeding rate LF: Low feeding rate.  
11  
Each farm pond or rice field was stocked at a rate of 0.3 fish/m2 and was classified as  
either “Low Feed” or “High Feed” based on the level of food inputs into the ponds. Rice  
field systems fed less than once per week were classified as low input systems and more  
than once per week as high input.  
All experimental ponds and rice fish fields were managed by farmers. Fish in ponds and  
rice fields were fed by available foods from farmers’ households such as rice bran, corn  
and cassava. A log book was provided to each farmer to keep a record of food inputs into  
their experimental pond and other relevant information and this information was used to  
classified ponds into high and low feed input. The farmers were visited on a monthly basis  
by project staff to assist in record keeping (Fig 2.3).  
Fig 2.3. Measuring common carp.  
2.4. Data collection and analysis  
Inequalities in fry weight among strains after the three month nursing period was tested by  
weighing a sample of 30 individuals to the nearest 0.1 g and analysed using a one –way  
ANOVA. Prior to this analysis the FMax test was used to determine if variances amongst  
strains were homogenous.  
12  
Pond trials were conducted for 300 – 330 days. Fish were harvesting by draining and by  
netting. Data from were collected as fish wet weight to the nearest 0.1 g and length (snout  
– caudal) measured to the nearest mm (Fig 2.4, 2.5 & 2.6). Fish were allocated to strain  
based on the identification of the position of the CWT using a detector scanner (North  
West Marine technology, Shaw Island, WA, American). To compare growth between  
strains, fish weights were converted to daily growth rate (DGR) after first subtracting the  
mean fingerling weight for that strain.  
The appropriate statistical procedure for the experimental design for analyzing for  
differences in growth rate is a three-way ANOVA with nesting. The first level of the  
analysis allows partitioning of variance due to Feed Input as either low (LF) or high (HF),  
the second level is Farmer, which is nested within level 1 and the third level is Fish Strain.  
Due to the unequal numbers fry available for each of the four carp strains and their  
stocking in different combinations into farms and the unavailability of data from a number  
farms, several kinds of ANOVA were conducted. The number of farms with different  
combinations of stocked strains is given in Table 2.2 together with the type of ANOVA  
conducted.  
Fig 2.4. Ethnic people harvesting common cap in rice field in Yen Bai province  
13  
Fig 2.5. Harvesting common carp in pond in Thai Nguyen  
Fig 2.6. A farmer is happy with common carp growth  
Table 2.2. Data analyses for common carp culture farm trails  
Type of analysis  
Strains  
Farm input  
Low High Total  
Three way Anova  
Two way Anova  
Two way Anova  
Two way Anova  
(HP3,  
LOC) 14  
LOC) 10  
4
1
1
18  
11  
5
(HP3, H3B,  
(HP3,  
VNW, LOC)  
4
3
(HP3, H3B, VNW, LOC)  
3
Percentage of recovered fish and harvested fish biomass of each common carp strain were  
analyzed as a 2-way ANOVA. The biomass of fish harvested in ponds with unequal  
14  
stocking rates was adjusted to the average stocking rate to allow for statistical comparison.  
All analyses were conducted using the Excel and SPSS software packages.  
3. Results  
3.1. Fingerling growth rate  
The average weight of common carp fingerlings after 60 days of nursing was 3.18 g. The  
average weight of each common carp strain is given in Table 3.1. However, the difference  
in body weigh among strains was not significantly different (P>0.05).  
Table 3.1 Mean (± SD) of body length and weight of fingerling carp after 60 days of nursing  
Carp strain  
HP3  
Length (cm)  
4.72 ± 0.70  
4.57 ± 0.56  
5.36 ± 1.28  
4.27 ± 0.74  
4.73 ± 0.82  
Weight (g)  
3.38 ± 1.50  
2.82 ± 1.66  
4.21 ± 2.84  
2.29 ± 1.32  
3.18 ± 1.83  
H3B  
VNW  
LOC  
Total  
3.2. Growth and survival of HP3 and LOC strains and effects of feed input  
Growth rate for the HP3 and LOC strains were compared in 18 farms which included both  
low and high feed input systems. Significant differences were observed for all factors and  
for the interaction between production systems and strain (Table 3.2) (P<0.01). The mean  
daily growth rate of HP3 strain (0.48g) was 60% higher than that of local strain (LOC)  
(0.30g) (Table 3.3). Daily growth rate of each fish farm is present in Fig 3.1.  
15  
Table 3.2. ANOVA table testing for differences in daily growth rate in relation to the effects of  
common carp strain (HP3 and LOC) and type of feed input.  
Source  
Type III Sum of Squares  
df Mean Square  
F
Sig.  
Corrected Model  
Intercept  
Farm  
209.18  
213.32  
76.76  
9.52  
9.49  
5.27  
25.81 814  
367.36 835  
234.99 834  
20  
1
17  
1
1
1
10.46 329.90 0.00  
213.32 6728.53 0.00  
4.52 142.42 0.00  
9.52 300.13 0.00  
9.49 278.62 0.00  
5.27 166.26 0.00  
0.03  
Strain  
Feed input  
Strain * Feed input  
Error  
Total  
Corrected Total  
Table 3.3. Daily growth rate of HP3 and LOC common carp strain for period of 10 months in 18  
farms in two type of feeding regimes in Yen Bai and Thai Nguyen provinces. Superscripts  
indicate significant differences among groups based on Tukey’s test.  
Strain  
Feed input  
Low  
High  
0.22 ± 0.02a 1.13 ± 0.03c  
HP3  
0.16 ± 0.02b 0.79 ± 0.04d  
LOC  
3.00  
HP3  
LOC  
2.50  
2.00  
1.50  
1.00  
0.50  
0.00  
Luat  
Ha  
Ke  
Vinh  
Tuan  
Lieu  
Dieu  
Que  
Lich  
Lien  
Hom Nhan Thong Thuan Truong Hoan  
Tap Chung  
Low feeding rate  
High feeding rate  
Farm  
Fig 3.1. Daily growth rate of HP3 and LOC common carp strains in each of 18 farms.  
This last finding is particularly significant as it indicates that while there is a significant  
difference among strains, this difference is greatly diminished in production systems with  
low feed inputs. Table 3.3 gives the average daily growth rate for the 2 strains in each  
16  
system and it can be seen there is only a 0.06g difference in average daily growth in low  
feed input systems compared with a 0.36 in high input system.  
The results from an analysis of survival rate of two strains are shown in Table 3.4 and  
Table 3.5. There is a significant difference in survival rate between low and high feed  
input farms but no significant difference between strains. The survival rate of HP3 and  
LOC strains is 24.77% and 22.76% respectively and it is 62% higher in High feed input  
ponds compared to Low feed input ponds.  
Table 3.4. ANOVA table testing for differences in survival rate in relation to the effects of  
common carp strain (HP3 and LOC) and type of feed input.  
Source  
Corrected Model  
Intercept  
Type III Sum of Squares  
3366.45  
df Mean Square  
F
Sig  
14.88 0.00  
19547.55 1641.80 0.00  
19  
1
177.18  
19547.55  
36.13  
Strain  
1
1
36.13  
772.99  
3.18  
3.03 0.10  
9.44 0.00  
0.27 0.61  
Feed input  
Strain * Feed input  
Error  
Total  
Corrected Total  
772.99  
3.18  
190.50  
23894.81  
3556.95  
1
16  
36  
35  
11.91  
Table 3.5. Survival rate of HP3 and LOC common carp strains grown for a period of 10 months  
in 18 farms with two types of feeding rates in Yen Bai and Thai Nguyen provinces. Superscripts  
indicate significant differences among groups based on Tukey’s test.  
Feed input  
Low  
N
28  
8
Mean  
21.29a  
32.44b  
26.90a  
Std  
Min  
Max  
0.86 11.72 29.33  
6.31 14.17 62.00  
3.58 12.95 45.67  
High  
Total  
36  
17  
3.3. Growth rate and survival of HP3, H3B and LOC strains  
Growth data from three strains, HP3, H3B and LOC were compared in 11 farms which  
included 10 low and 1 high feed input systems. Significant differences were observed for  
strain and farmer as presented Table 3.6. Table 3.7 gives the average growth rate for the 3  
strains. The effect of the level of feed input could not be tested statistically due lack of  
replicates. The differences between strains can be seen from Figure 3.2 and Table 3.7. The  
daily growth rate of common carp in each farm is presented in Fig 3.3. Each strain was  
significantly different on the basis of Tukey’s test with HP3>H3B>LOC.  
Table 3.6. ANOVA table testing for differences in daily growth rate in relation to the effects of  
common carp strain (HP3, H3B and LOC).  
Source  
Type III Sum of Squares  
df Mean Square  
F
Sig.  
0.00  
0.00  
0.00  
0.00  
Corrected Model  
Intercept  
Strain  
Farm  
Error  
60.13  
49.36  
1.84  
58.78  
9.86  
13  
1
4.63 387.22  
49.36 4132.25  
2
0.92  
77.08  
10  
5.34 447.32  
0.01  
825  
839  
838  
Total  
Corrected Total  
133.38  
69.99  
Table 3.7. Daily growth rate of HP3, H3B and LOC common carp strains grown for a period of  
10 months in 11 farms in Yen Bai and Thai Nguyen provinces. Superscripts indicate significant  
differences among groups based on Tukey’s test.  
Strain  
HP3  
N
301  
282  
256  
839  
Mean  
0.33a  
0.26b  
0.23c  
0.27d  
Std  
0.34  
0.27  
0.23  
0.28  
Min  
0.05  
0.04  
0.02  
0.03  
Max  
1.90  
1.51  
1.05  
1.49  
H3B  
LOC  
Total  
18  
HP3  
LOC  
H3B  
Fig 3.2. Example of relative growth of three strains of common carp in rice field in Yen Bai  
province after six months of culture.  
1.400  
1.200  
1.000  
0.800  
0.600  
0.400  
0.200  
0.000  
HP3  
H3B  
LOC  
Luat  
Ha  
Vinh Tuan Lieu Que Lien Hoan Nhan Thuan Thong  
Farm  
Fig 3.3. Daily growth rate of HP3, H3B and LOC common carp strain in each of 11 farms in Yen  
Bai and Thai Nguyen provinces.  
ANOVA analyses of survival rate of common carp showed that there was a significant  
difference between farms, while survival rate between common carp strains was not  
different (Table 3.8). The average survival rate of HP3, H3B and LOC was 24.28%,  
25.78%, and 23.45% respectively.  
19  
Table 3.8. ANOVA table testing for differences in survival rate in relation to the effects of  
common carp strains (HP3, H3B and LOC).  
Source  
Type III Sum of Squares  
3890.87  
df Mean Square  
F
Sig.  
0.00  
0.00  
0.00  
0.30  
Corrected Model  
Intercept  
Farm  
Strain  
Error  
13  
1
299.30 15.10  
17183.84 866.98  
349.90 17.65  
25.09 1.27  
19.82  
17183.84  
3848.88  
50.18  
376.59  
23859.09  
4267.46  
11  
2
19  
33  
32  
Total  
Corrected Total  
3.4. Growth rate and survival for HP3, VNW and LOC Strains  
Growth data from three strains, HP3, VNW and LOC were compared in 5 farms which  
included 4 low and 1 high feed input systems. Significant differences were observed for  
both strain and farmer factors as presented Table 3.9. Table 3.10 gives the average growth  
rate for the 3 strains. While the effect of production system could not be tested statistically  
due to lack of replicates for this effect and the differences between strains and farms can  
be seen from Figure 3.4. Each strain was significantly different on the basis of Tukey’s  
test with HP3>VNW>LOC.  
Table 3.9. ANOVA table testing for differences in daily growth rate in relation to the effects of  
common carp strain (HP3, VNW and LOC).  
Source  
Type III Sum of Squares  
df Mean Square  
F
Sig.  
55.05 0.00  
17.22 1381.20 0.00  
Corrected Model  
Intercept  
Farm  
Strain  
Error  
4.12  
17.22  
3.13  
1.08  
3.74  
6
1
0.69  
4
2
300  
307  
306  
0.78  
0.54  
0.01  
62.84 0.00  
43.40 0.00  
Total  
Corrected Total  
25.74  
7.86  
.
20  
Table 3.10. Daily growth rate of HP3, VNW and LOC common carp strains grown for a period  
of 10 months in 5 farms in Yen Bai and Thai Nguyen provinces. Superscripts indicate significant  
differences among groups based on Tukey’s test.  
Strain  
HP3  
N
112  
96  
Mean  
0.31a  
0.22b  
0.18c  
0.24c  
Std  
0.20  
0.12  
0.10  
0.14  
Min  
0.10  
0.03  
0.02  
0.05  
Max  
1.50  
0.66  
0.78  
0.98  
VNW  
LOC  
Total  
99  
307  
0.60  
HP3  
VNW  
LOC  
0.50  
0.40  
0.30  
0.20  
0.10  
0.00  
Ha  
Lien  
Hom  
Nhan  
Chung  
Farm  
Fig 3.4. Daily growth rate of HP3, VNW and LOC common carp strain for a period of 10 months  
in each farm in Yen Bai and Thai Nguyen provinces.  
The results of the survival rate of three common carp strains (HP3, VNW and LOC)  
showed no significant differences between farms (Table 3.11). Although survival rate of  
HP3 was the highest (20.57%) there had no significant difference comparing with other  
two strains (VNW = 17.98% and LOC = 18.49%).  
21  
Table 3.11. ANOVA table testing for differences in survival rate in relation to the effects of  
common carp strains (HP3, VNW and LOC).  
Source  
Type III Sum of Squares  
df Mean Square  
F
2.28  
Sig.  
0.14  
0.00  
0.11  
0.28  
Corrected Model  
Intercept  
Farm  
Strain  
Error  
87.19  
5417.29  
68.18  
6
1
14.53  
5417.29 850.77  
4
2
8
17.04  
9.51  
6.37  
2.68  
1.49  
19.01  
50.94  
Total  
Corrected Total  
5555.42  
138.13  
15  
14  
3.5. Growth rate and survival of HP3, H3B, VNW and LOC strains in low feed input  
farms controlled for variation among farmer ponds  
Growth data from all four strains, HP3, H3B, VNW and LOC were compared in 3 low  
input farms in which they were raised communally. Significant differences were observed  
for both strain and farmer as presented Table 3.12. Table 3.13 gives the average growth  
rate for the 4 strains. Post hoc tests indicated significant differences among strains with  
HP3 > H3B = VIET > LOC. Daily growth rate of each strain and farm are presented in Fig  
3.5.  
Table 3.12. ANOVA table testing for differences in daily growth rate in relation to the effects of  
common carp strain (HP3, H3B, VNW and LOC)  
Source  
Type III Sum of Squares  
df Mean Square  
F
Sig.  
0.00  
0.00  
0.00  
0.00  
Corrected Model  
Intercept  
Farm  
Strain  
Error  
1.53  
7.89  
0.92  
0.62  
0.55  
10.65  
2.08  
5
1
0.31  
7.89 3480.33  
135.15  
2
3
242  
248  
247  
0.46  
0.21  
0.00  
203.09  
91.25  
Total  
Corrected Total  
22  
Table 3.13. Daily growth rate of HP3, H3B, VNW and LOC common carp strains for period of 10  
months in 3 farms in Yen Bai and Thai Nguyen provinces. Superscripts indicate significant  
differences among groups based on Tukey’s test.  
Strain  
HP3  
N
71  
Mean  
0.26a  
0.17b  
0.17b  
0.13c  
0.18C  
Std  
0.08  
0.09  
0.07  
0.06  
0.08  
Min  
0.10  
0.04  
0.03  
0.02  
0.05  
Max  
0.46  
0.38  
0.38  
0.24  
0.37  
H3B  
62  
VNW  
LOC  
Total  
58  
57  
248  
0.40  
HP3  
H3B  
VNW  
LOC  
0.35  
0.30  
0.25  
0.20  
0.15  
0.10  
0.05  
0.00  
Lien  
Ha  
Nhan  
Farm  
Fig 3.5. Daily growth rate of HP3, H3B, VNW and LOC common carp strains in 3 farms.  
The results of survival rate comparisons among four common carp strains (HP3, H3B,  
VNW and LOC) are showed in Table 3.14. There are significant differences between fish  
survival rate among farms (P<0.05) with survival rate of fish in the farms ranged from  
20.94 to 16.81 %. There was no significant differences in survival rate between common  
carp strains (P>0.05).  
23  
Table 3.14. ANOVA table testing for differences in survival rate in relation to the effects of  
common carp strains (HP3, H3B, VNW and LOC) and culture types (low and high feed input).  
Source  
Type III Sum of Squares  
df Mean Square  
F
4.33  
991.99  
6.82  
Sig.  
0.05  
0.00  
0.03  
0.14  
Corrected Model  
Intercept  
Farm  
90.87  
4161.47  
57.19  
5
1
2
18.17  
4161.47  
28.60  
Strain  
33.68  
3
11.23  
2.68  
Error  
25.17  
6
4.20  
Total  
Corrected Total  
4277.52  
116.04  
12  
11  
Fig 3.6. Common carp from HP3 strain after seven months of cultured in a high input feed farm  
in Thai Nguyen province.  
3.6. Common carp biomass production in farms stocked with three common carp  
strain (HP3, H3B, LOC)  
Common carp production was compared for 3 strains in 11 farms. Biomass of common  
carp from 11 farms is presented in Table 3.23. Significant differences were observed  
between farms and strains of common carp (Table 3.24). The pair-wise comparison  
indicated difference in biomass of common carp between farms and between strains using  
Tukey’s test. Biomass of three common carp strains ranged from 3.16g/m2 (LOC) to  
4.80g/m2 (HP3).  
24  
Table 3.15. Biomass of common carp strains in 11 farms with 3 strains (HP3, H3B and LOC) and  
cultured for 300 days in Yen Bai and Thai Nguyen provinces.  
Farm  
Area Culture Strains  
Stocking  
Harvesting  
Biomass Adjusted  
(m2)  
(g/m2)  
19.30  
17.84  
13.74  
1.61  
1.29  
1.06  
1.46  
1.05  
1.22  
1.96  
0.58  
0.30  
0.09  
0.03  
0.05  
1.80  
0.46  
1.43  
1.23  
0.73  
1.05  
0.74  
0.64  
0.56  
1.14  
0.57  
0.66  
1.11  
0.91  
0.62  
0.58  
0.01  
0.03  
(g/m2)  
29.72  
27.45  
20.96  
2.92  
2.36  
1.94  
2.69  
2.01  
2.17  
2.53  
2.01  
0.79  
0.64  
0.47  
0.41  
3.20  
1.79  
1.77  
2.35  
1.52  
1.92  
1.62  
1.39  
1.18  
2.79  
1.56  
1.66  
2.73  
2.23  
1.58  
1.67  
0.44  
0.40  
systems  
N Weight (g)  
3.38  
NWeight (g) Sur (%) DGR  
Hoan  
1000  
1000  
1000  
1000  
1000  
1000  
800  
HF HP3 100  
51  
62  
56  
20  
19  
19  
30  
26  
29  
40  
10  
12  
15  
14  
17  
36  
11  
33  
20  
15  
22  
22  
21  
22  
25  
20  
30  
20  
21  
22  
21  
16  
19  
385.08  
292.33  
249.49  
97.43  
82.82  
67.90  
59.87  
51.43  
49.89  
61.88  
70.55  
44.82  
28.61  
22.45  
16.10  
59.35  
56.74  
53.68  
62.73  
53.78  
46.51  
49.00  
44.00  
35.67  
83.96  
58.72  
41.66  
102.67  
79.93  
54.24  
59.88  
20.61  
15.66  
51.00 1.28  
62.00 0.97  
56.00 0.83  
20.00 0.32  
19.00 0.28  
19.00 0.23  
30.00 0.20  
26.00 0.17  
29.00 0.17  
27.27 0.21  
19.00 0.24  
11.72 0.15  
15.00 0.10  
14.00 0.07  
17.00 0.05  
36.00 0.20  
21.00 0.19  
22.00 0.18  
25.00 0.21  
18.89 0.18  
27.50 0.16  
22.00 0.16  
21.00 0.15  
22.00 0.12  
22.12 0.28  
17.70 0.20  
26.55 0.14  
17.70 0.34  
18.58 0.27  
19.47 0.18  
18.58 0.20  
14.16 0.07  
16.81 0.05  
H3B 100  
2.82  
2.29  
3.38  
2.82  
2.29  
3.38  
2.82  
2.29  
3.38  
2.82  
2.29  
3.38  
2.82  
2.29  
3.38  
2.80  
2.29  
3.38  
2.82  
2.29  
3.38  
2.82  
2.29  
3.38  
2.82  
2.29  
3.38  
2.82  
2.29  
3.38  
2.82  
2.29  
LOC 100  
LF HP3 100  
H3B 100  
LOC 100  
LF HP3 100  
H3B 100  
LOC 100  
LF HP3 145  
H3B 55  
LOC 100  
LF HP3 100  
H3B 100  
LOC 100  
LF HP3 100  
H3B 50  
LOC 150  
LF HP3 80  
H3B 80  
Thuan  
Tuan  
Lieu  
Luat  
Que  
Vinh  
Thong  
Lien  
Ha  
LOC 80  
1000  
1500  
1500  
1500  
LF HP3 100  
H3B 100  
LOC 100  
LF HP3 113  
H3B 113  
LOC 113  
LF HP3 113  
H3B 113  
LOC 113  
LF HP3 113  
H3B 113  
Nhan  
LOC 113  
25  
Table 3.16. ANOVA analyses of biomass of HP3, H3B, and LOC common carp strains  
Source  
Type III Sum of Squares  
1634.65  
df Mean Square  
F
Sig  
0.00  
0.00  
0.00  
0.02  
Corrected Model  
Intercept  
Farm  
Strain  
Error  
12  
1
10  
2
136.22 81.95  
519.00 312.23  
161.98 97.45  
519.00  
1619.77  
14.88  
33.24  
2186.89  
1667.90  
7.44  
1.66  
4.48  
20  
33  
32  
Total  
Corrected Total  
3.7. Common carp biomass production comparing farms stocked with two common  
carp strains (HP3 and LOC).  
ANOVA analysis of biomass of common carp showed that there were significant  
differences in biomass between farms, feed input, and the 2 strains (Table 3.25). The  
biomass of common carp in two feed input systems are given in Table 3.26 and Table  
3.27. The average common carp biomass for each strain in both high and low feed input  
systems is given in Table 3.27.  
Table 3.17. ANOVA analysis of biomass of HP3 and LOC common carp strains.  
Source  
Corrected Model  
Intercept  
Farm  
Strain  
Feed input  
Strain * Feed input  
Error  
Total  
Corrected Total  
Type III Sum of Squares  
1416.77  
1478.65  
557.10  
df Mean Square  
F
Sig  
0.00  
0.00  
0.00  
0.23  
0.00  
0.20  
19  
1
74.57  
1478.65 725.34  
36.58  
16  
1
1
34.82  
14.75  
844.86  
3.69  
17.08  
7.24  
45.84  
1.81  
14.75  
844.86  
3.69  
32.62  
2198.60  
1449.39  
1
16  
36  
35  
2.04  
26  
Table 3.18. Biomass of common carp strains in 18 farms with 2 strains (HP3 and LOC) cultured  
for 300 days. Superscripts indicate significant differences among groups based on Tukey’s test.  
Farm  
Hoan  
Area CultureStrains  
Stocking  
Harvesting  
Biomass Adjusted  
(m2)  
(g/m2)  
19.30  
13.74  
1.61  
1.06  
15.57  
17.12  
1.46  
1.22  
2.66  
1.63  
1.14  
0.66  
1.22  
0.99  
2.93  
1.05  
1.11  
0.62  
1.96  
0.30  
0.09  
0.05  
0.58  
0.03  
8.32  
8.13  
1.80  
1.43  
1.23  
1.05  
1.70  
3.27  
0.74  
0.56  
1.81  
1.61  
(g/m2)  
29.72  
21.15  
2.92  
1.94  
16.07  
17.47  
2.69  
2.17  
4.50  
2.79  
2.79  
1.66  
2.34  
1.83  
3.14  
1.29  
2.73  
1.58  
2.53  
0.79  
0.64  
0.41  
1.67  
0.40  
8.83  
8.47  
3.20  
1.77  
2.35  
1.92  
2.06  
3.34  
1.62  
1.18  
2.32  
1.95  
systems  
N Weight (g)  
3.38  
NWeight (g) Sur (%) DGR  
1000  
HF HP3 100  
51  
385.08 51.00 1.28  
249.49 56.00 0.83  
97.43 20.00 0.32  
67.90 19.00 0.23  
756.38 14.17 2.52  
465.74 25.00 1.55  
59.87 30.00 0.20  
49.89 29.00 0.17  
166.64 18.00 0.56  
98.03 19.00 0.33  
83.96 22.12 0.28  
41.66 26.55 0.14  
64.88 24.00 0.22  
58.09 21.00 0.19  
95.20 22.00 0.32  
37.40 23.00 0.12  
102.67 17.70 0.34  
54.24 19.47 0.18  
61.88 27.27 0.21  
44.82 11.72 0.15  
28.61 15.00 0.10  
16.10 17.00 0.05  
59.88 18.58 0.20  
15.66 16.81 0.05  
200.71 29.33 0.67  
156.85 36.00 0.52  
59.35 36.00 0.20  
53.68 22.00 0.18  
62.73 25.00 0.21  
46.51 27.50 0.16  
61.88 22.22 0.21  
87.15 25.56 0.29  
49.00 22.00 0.16  
35.67 22.00 0.12  
57.99 26.67 0.19  
44.39 29.33 0.15  
LOC 100  
LF HP3 100  
LOC 100  
2.29  
3.38  
2.29  
3.38  
2.29  
3.38  
2.29  
3.38  
2.29  
3.38  
2.29  
3.38  
2.29  
3.38  
2.29  
3.38  
2.29  
3.38  
2.29  
3.38  
2.29  
3.38  
2.29  
3.38  
2.29  
3.38  
2.29  
3.38  
2.29  
3.38  
2.29  
3.38  
2.29  
3.38  
2.29  
56  
20  
19  
17  
30  
30  
29  
18  
19  
25  
30  
19  
16  
22  
23  
20  
22  
40  
12  
15  
17  
21  
19  
22  
27  
36  
33  
20  
22  
20  
23  
22  
22  
20  
22  
Thuan 1000  
Tap  
800  
HF HP3 120  
LOC 120  
Tuan  
1000  
LF HP3 100  
LOC 100  
Chung 1000  
HF HP3 100  
LOC 100  
Lien  
Hom  
Dieu  
Ha  
1500  
800  
LF HP3 113  
LOC 113  
LF HP3  
LOC  
80  
80  
600  
LF HP3 100  
LOC 100  
1500  
1000  
1000  
1500  
LF HP3 113  
LOC 113  
LF HP3 145  
LOC 100  
LF HP3 100  
LOC 100  
LF HP3 113  
LOC 113  
Lieu  
Luat  
Nhan  
Truong 500  
HF HP3  
LOC  
75  
75  
Que  
Vinh  
Ke  
1000  
800  
LF HP3 100  
LOC 150  
LF HP3  
LOC  
80  
80  
90  
90  
550  
LF HP3  
LOC  
Thong 1000  
Lich 500  
LF HP3 100  
LOC 100  
LF HP3  
LOC  
75  
75  
27  
Table 3.19. Biomass of HP3 and LOC common carp strains grown for a period of 10 months in  
18 farms with two types of feed input in Yen Bai and Thai Nguyen provinces.  
Strains  
Feed input  
Low (g/m2)  
2.36 ± 1.15a  
1.59 ± 1.15a  
High (g/m2)  
14.78 ± 2.15b  
12.47 ± 2.15b  
HP3  
LOC  
3.8. Demand of the improved common carp seed  
A survey on demand for genetically improved common carp strain was conducted in three  
provinces (Yen Bai, Thai Nguyen and Vinh Phuc) which have a high level of common  
carp aquaculture. In these provinces common carp are cultured mostly in two different  
farming systems consisting of ponds and flooded rice fields. The provinces differ in that  
Yen Bai is a mountainous region, Thai Nguyen is partly mountainous with midlands while  
Vinh Phuc is a delta area. A total of 25 common carp hatcheries and nursery producers  
were surveyed. Details of interviewees are presented in Table 3.30.  
Table 3.20. Number of hatcheries and fry nursing farmers in 3 provinces.  
Provinces  
Yen Bai  
Interviewee Hatchery producer Nursery farmer  
8
10  
7
2
2
1
5
6
8
Thai Nguyen  
Vinh Phuc  
Total  
6
25  
20  
The results of the survey showed the number of common carp seed produced was highly  
variable among fish hatcheries. The proportion of common carp produced ranged from  
10.0% to 66.7% with an average of 37.4% of the total freshwater fish species produced  
(Table 3.31). Most of hatcheries surveyed have produced both local (VNW) and  
genetically improved common carp (three blood lines) (Table 3.32). It can be seen from  
Table 3.32 the proportion of genetically improved common carp produced in hatcheries  
ranged from 16.7% to 100% and the average proportion of improved genetically common  
carp was 48.7%.  
28  
Table 3.21. Number of common carp fry produced in five hatcheries in Thai Nguyen, Yen Bai  
and Vinh Phuc provinces in 2006.  
Hatchery  
No of fry  
(x 1000)  
No of common carp fry Proportion of carp fry  
(x 1000) (%)  
Dong Ly  
Van Chan  
Phu Binh  
Cu Van  
Vu Di  
1,200  
500  
30,000  
24,000  
20,000  
12,000  
86,500  
41.67  
50.00  
20.00  
66.67  
9.92  
60,000  
120,000  
30,000  
120,999  
332,199  
Total  
26.04  
Table 3.22. Proportion of fry produced from genetically improved common carp lines in five  
hatcheries in Thai Nguyen, Yen Bai, and Vinh Phuc provinces in 2006.  
Hatchery  
Province  
No of carp fry  
(x 1000)  
No of Local strain Improved strain Propotion of improved strain  
(x 1000) (x 1000) (%)  
Dong Ly  
Yen Bai  
500  
500  
100.00  
16.67  
40.00  
100.00  
58.33  
48.67  
Van Chan Yen Bai  
30,000  
24,000  
20,000  
12,000  
86,500  
25,000  
5,000  
9,600  
Phu Binh Thai Nguyen  
24,000  
Cu Van  
Vu Di  
Total  
Thai Nguyen  
Vinh Phuc  
20,000  
7,000  
5,000  
54,000  
42,100  
Hybrid (Hungary x Vietnamese) and stocks derived from the genetically improved three  
blood lines (Hungarian, Vietnamese and Indonesian) with faster growth performance are  
preferred by most of the nursery farmers interviewed in three provinces. However, many  
of the nursery farmers are not confident in identifying differences between hybrid and  
other genetically improved and local Vietnamese strains. The main basis for determining  
the quality of common carp seed is the perceived reputation of the hatchery based on the  
farmers evaluation of the survival and growth performance of their fish in grow-out  
systems. The results of a 2006 survey of 20 carp nursery farmers indicated that 95% of  
farmers cultured genetically improved strains.  
29  
Based on data collected in earlier surveys it can be seen that demand for genetically  
improved common carp by nursery farmers is increasing in the three provinces, over the  
period 2004-2006 (Fig 3.9). While the demand for genetically improved common carp  
seed by nursery farmers in the three provinces investigated has been increasing it varies  
greatly between provinces. The demand for seed from genetically improved carp strains  
was found to be very high in Thai Nguyen (>80%), and much lower in Vinh Phuc and Yen  
Bai (<25%).  
100  
90  
80  
70  
60  
VinhPhuc  
50  
ThaiNguyen  
40  
YenBai  
30  
20  
10  
0
2004  
2005  
2006  
Fig 3.7. Proportion of genetically improved common carp fry and fingerlings cultured in Vinh  
Phuc, Thai Nguyen and Yen Bai provinces during 2004-2006.  
4. Conclusion and Recommendations  
There are some very significant conclusions from this study that related directly to the use  
of genetically improved common carp in farmers ponds and the management of cultured  
fish that are highlighted below.  
Significant differences in growth rate of common carp strains were found  
30  
This is the first on-farm growth trial to report difference in growth between strains of  
common carp. Specifically the overall findings were the growth rate of the HP3 strain was  
superior to the H3B and VNW strains, which in turn were superior to the local strain  
(LOC). At the extremes the difference between the worst strains and best strains was 44%.  
However, very importantly, the significance of this difference in growth performance was  
dependent on the level of feed input into the culture system. In low input systems the  
average differences between the best and worst strains was a growth rate of 0.06 grams  
per day, where as in high input systems the average difference in growth rate was 0.34  
grams per day.  
Very large difference in growth, survival and biomass production were apparent  
between farms  
The difference in daily growth rate between farms was much greater than between strains.  
The best performing farm had from a 31 and 12.6 fold difference in growth rate for the  
LOC and HP3 strains respectively. A significant factor explaining these differences can be  
attributed to feed input but it is likely that other environmental and husbandry aspects  
contribute to these very substantial differences.  
The production of genetically improved common carp by hatcheries and their  
demand in different provinces are highly variable  
A barrier to the dissemination of genetically improved carp strains is that many hatcheries  
breed local (unselected) strains and that demand for genetically improved strains is low in  
some provinces. An added complication is that it is difficult, if not impossible, for  
hatchery operators and farmers to distinguish between genetically improved and  
unselected local strains at the point of purchase.  
The following key recommendations emerge from the studies reported in the document  
and earlier reports associated with this project.  

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