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Genetic and phenotypic variation in production traits in rainbow trout strains and strain crosses in Finland
Aquaculture, 33 (1983) 129-134 Elsevier Science Publishers B.V., Amsterdam -Printed
129 in The Netherlands
GENETIC AND PHENOTYPIC VARIATION IN PRODUCTION TRAITS IN RAINBOW TROUT STRAINS AND STRAIN CROSSES IN FINLAND
D. LINDER, 0. SUMARI*, K. NYHOLM* and S. SIRKKOMAA Department
of Animal Breeding,
University of Helsinki, Helsinki (Finland)
*Finnish Game and Fisheries Research Institute, Laukaa Fish Culture Research Station, Valkola (Finland) (Accepted
1 December 1982)
ABSTRACT Linder, D., Sumari, O., Nyholm, K. and Sirkkomaa, S., 1983. Genetic and phenotypic variation in production traits in rainbow trout strains and &rain crosses in Finland. Aquaculture, 33: 129-134. Variation in body weight was analyzed among 1979 1 -year-old fishes (progeny of four dams and five sires). The coefficient of variation was 0.39. The variance component estimated for dams by a least squares analysis of variance was lower than that estimated for sires. The heritability of body weight calculated from the dam component was 0.10 * 0.08, from the sire component 0.38 f 0.25. The variation in several characters (body weight, carcass quality) was studied in crosses between five strains of rainbow trout. The coefficients of variation ranged between 0.16 and 0.33. With regard to the pure strains the mean body weight at 2 years (24 months) and three summers (32 months) of age was significantly greater for the Kamloops strain than that for the most commonly used Danish strain. With regard to strain crosses the combinations containing Kamloops seemed to be slightly better than those without it. The analysis of variance with regard to carcass quality parameters showed significant differences between the strains at 2 years of age.
INTRODUCTION
An experiment with the stocks available at Laukaa Fish Culture Research Station (LFC) of the Finnish Game and Fisheries Research Institute, started in 1973. The objective of the study was to measure differences in growth rate in pure strains and in two-way crosses of the strains available. Differences in carcass quality parameters were also investigated. The strains at LFC were brought to the station during the late 1960’s. The “Kamloops” and the “Danish” strain were brought from Denmark, the others were from the United States. The populations were kept pure and the initial populations ranged from 50-300 individuals per strain. The succeeding generations were made by using lo-20 mature healthy big females per strain and approximately one-third as many males as females. 0044-8486/83/$03.00
0 1983 Elsevier Science Publishers B.V.
130 MATERIAL
AND METHODS
Five strains and their two-way crosses were evaluated. The strains were “Danish” (t), “Kamloops” (k), “Donaldson” (d), “American” (Am) and the originally autumn-spawning strain “A13”. The precise ancestry of the strains is not known except for the Donaldson strain (reported by Donaldson and Olson, 1957). The original intention was to produce purebred progeny and reciprocal crosses between all of the five stocks available at the LFC. The crosses were made by using six females and three males in each combination. The males used were different individuals in each combination in spite of a few that had to be used twice. Due to management difficulties only purebred progeny of the Danish and Kamloops strains were available at two years and three summers of age. In addition only progeny of the crosses between the Danish, Kamloops and Al3 were available at three summers of age. Some of the trials - those used for estimating slaughter traits - are very small and the results are therefore only indicative. Protein, fat and water contents were calculated on the basis of results for eight fish per stock. STATISTICAL
ANALYSES
The h2’s were estimated (Harvey, 1966) : Y..Ilk =
U -t
ai + bj +
eijk
(in the Danish strain) by least squares-procedure (model 1)
where Yijk = the observed weights of fishes; u = overall population mean when equal subclass numbers exist; ai = effect of the ith dam (+1,2,3,4); bj = effect of the jth sire &1,2,3,4,5), and C?ijk= random errors. The ai’s and bj’s are regarded as random effects. The comparisons between strains with regard to body weight at 2 years of age were estimated by least squares-procedure: Y.tk = U + ai + eik where Yik = observed weights of fishes; u = overall population mean when equal subclass numbers exist; ai = the effect of the ith strain (i=l ,,,,VV, 2 3 4 56 7 8,9), and eik = random errors. The comparison of strain differences was examined with the t-test of least squares deviations between class means (Snedecor and Cochran, 1967). The comparisons between strains with regard to body weight at three summers of age were estimated by least squares-procedure: Yijk = U + Cli+ bj + eijk
(model 3)
where Yijk = observed weights of fishes; u = overall population mean when equal subclass numbers exist; ai = effect of the ith strain (i=1,2,3,4,5,6); bj = effect of the male sex u=l) and females and juveniles 0=2), and C?ijk= random errors.
131
The comparison of strain differences was examined with the t-test of least squares deviations between class means. The comparisons between strains with regard to carcass quality parameters were estimated by least squares-procedure (Harvey, 1966) and was performed by using the following model: yik = u + ai + eik
(model 4)
where yik = the lipid, protein and water percentage of fishes; u = overall population mean when equal subclass numbers exist; ai = the effect of the ith strain (i=1,2), and eik = random errors. RESULTS AND DISCUSSION
The effect of sire and dam on body weight at 1 year of age is given in Table I. TABLE I Least squares analysis of the effect of dam and sire on the body weights of progeny. Model 1 Source of variation
Degrees of freedom
Mean square
Proportion of total variation
Dam Sire Error
3 4 1971
1922.6176 5414.3345 126.3161
0.026 0.095 0.879
P< 0.01 significant at the 0.1% level.
The variance component estimated for dams is lower than that estimated for sires. This result is in good agreement with the results obtained by Aulstad et al. (1972) for 280 days old fishes. In the present study the sire X dam interaction component was not estimated. In the study of Aulstad et al. (1972) the sire X dam component was negative. The heritability calculated from the dam component is O.lO+O.OS, from the sire component 0.3820.25. The higher value for the heritability calculated from the sire component is in agreement with Aulstad et al. (1972). Together with the high coefficient of variation (0.39) the estimated heritability indicates, that there are fairly good prospects for genetic improvement with regard to body weight of the Danish (t) rainbow trout strain in Finland. The averages and standard deviations in the different materials for differences in weight are given in Table II. The differences between strains and strain crosses were significantly different from each other at both 2 years and three summers of age. The difference in size was significant between the Danish and Kamloops strains (Z’
132
TABLE II The means and standard deviations model 3 : age three summers
in the different
material.
Used stock
Weight (g)
Standard deviation
Number of fish
Age 2 years txt kxk kxt dxk kxAl3 txk txA13 Al3xAm A13xk
531.5 603.8 510.6 616.5 554.4 504.9 473.2 574.1 554.9
174.5 188.8 159.2 174.3 158.7 167.4 182.6 129.0 156.7
250/stack
Age three summers kxk 1713 kxA13 1711 Al3xk 1649 kxt 1603 txk 1561 txt 1547
515.9 462.7 351.5 382.6 349.8 419.5
226 236 245 248 252 241
txt txt kxk kxk kxt kxt kxAl3 kxA13 txk txk Al3xk Al3xk
1515 1644 1587 2005 1567 1681 1619 2043 1501 1801 1648 1780
452.82 365.78 504.47 415.88 401.17 323.45 476.98 384.77 351.20 274.71 342.06 335.40
155 86 161 65 174 74 155 81 181 71 164 81
1631
419.5
1446
1782
365.7
457
1561
419.52
989
O8 lb 0 1 0 1 0 1 0 1 0 1
Total weight Total weight of males Total weight of females and juveniles
“0 = females and juveniles. bl = males. Kamloops Danish = t; Donaldson = d; LFC American = Am.
Model 2: age 2 years;
= k; LFC autumn
spawning = A13;
However, the strain crosses were intermediate to the pure strains at three summers of age. Kamloops seems to have positive additive effects as females, The coefficient of variation within strains ranged between 0.28-0.33 at 2 years of age and 0.22-0.30 at three summer-a of age. The coefficient of
133
variation ranged between 0.16-0.22 for the males and between 0.22-0.32 for the females and the fishes of undetermined sex (juveniles). The proportion of mature males was 0.28-0.36 in all strains at three summers of age. The mature males at three summers of age were significantly bigger (P
Protein fresh weight
Protein dry weight
Lipids fresh weight
Lipids dry weight
k s.d.
71.8 0.75
20.1 0.29
71.2 2.12
7.1 0.85
25.0 2.41
t s.d.
71.01 0.99
19.8 0.44
68.4 2.59
8.2 1.05
28.0 2.70
txk s.d.
70.0 1.43
19.3 0.29
64.6 2.99
9.3 1.46
31.0 3.42
kxt s.d.
71.1 1.06
20.0 0.48
69.1 3.28
7.9 1.31
27.1 3.61
Total means s.d .
71.0 1.21
19.8 0.47
68.3 3.55
8.1 1.4
27.8 3.65
k = Kamloops; t = Danish.
REFERENCES Aulstad, D., Gjedrem, T. and Skjervold, H., 1972. Genetic and environmental sources of variation in length and weight of rainbow trout (Salmo gairdneri). J. Fish. Res. Board Can., 29: 237-241. Ayles, G.B., Bernard, D. and Hendzel, M., 1979. Genetic differences in lipid and dry matter content between strains of rainbow trout (Salmo gairdneri) and their hybrids. Aquaculture, 18: 253-262.
134 Donaldson, L.R. and Olson, P.R., 1957. Development of rainbow trout brood stock by selective breeding. Trans. Am. Fish. Sot., 85: 93-101. Gjedrem, T., 1976. Possibilities for genetic improvement in salmonids. J. Fish. Res. Board Can., 33: 1094-1099. Harvey, W.R., 1966. Least squares analysis of data with unequal subclass numbers. ARS 20-3, Agric. Res. Serv., US Dep. Agric., 157 pp. Snedecor, G.W. and Cochran, G.W., 1967. Statistical Methods. The Iowa State University Press, Ames, IA, 593 pp.
129 in The Netherlands
GENETIC AND PHENOTYPIC VARIATION IN PRODUCTION TRAITS IN RAINBOW TROUT STRAINS AND STRAIN CROSSES IN FINLAND
D. LINDER, 0. SUMARI*, K. NYHOLM* and S. SIRKKOMAA Department
of Animal Breeding,
University of Helsinki, Helsinki (Finland)
*Finnish Game and Fisheries Research Institute, Laukaa Fish Culture Research Station, Valkola (Finland) (Accepted
1 December 1982)
ABSTRACT Linder, D., Sumari, O., Nyholm, K. and Sirkkomaa, S., 1983. Genetic and phenotypic variation in production traits in rainbow trout strains and &rain crosses in Finland. Aquaculture, 33: 129-134. Variation in body weight was analyzed among 1979 1 -year-old fishes (progeny of four dams and five sires). The coefficient of variation was 0.39. The variance component estimated for dams by a least squares analysis of variance was lower than that estimated for sires. The heritability of body weight calculated from the dam component was 0.10 * 0.08, from the sire component 0.38 f 0.25. The variation in several characters (body weight, carcass quality) was studied in crosses between five strains of rainbow trout. The coefficients of variation ranged between 0.16 and 0.33. With regard to the pure strains the mean body weight at 2 years (24 months) and three summers (32 months) of age was significantly greater for the Kamloops strain than that for the most commonly used Danish strain. With regard to strain crosses the combinations containing Kamloops seemed to be slightly better than those without it. The analysis of variance with regard to carcass quality parameters showed significant differences between the strains at 2 years of age.
INTRODUCTION
An experiment with the stocks available at Laukaa Fish Culture Research Station (LFC) of the Finnish Game and Fisheries Research Institute, started in 1973. The objective of the study was to measure differences in growth rate in pure strains and in two-way crosses of the strains available. Differences in carcass quality parameters were also investigated. The strains at LFC were brought to the station during the late 1960’s. The “Kamloops” and the “Danish” strain were brought from Denmark, the others were from the United States. The populations were kept pure and the initial populations ranged from 50-300 individuals per strain. The succeeding generations were made by using lo-20 mature healthy big females per strain and approximately one-third as many males as females. 0044-8486/83/$03.00
0 1983 Elsevier Science Publishers B.V.
130 MATERIAL
AND METHODS
Five strains and their two-way crosses were evaluated. The strains were “Danish” (t), “Kamloops” (k), “Donaldson” (d), “American” (Am) and the originally autumn-spawning strain “A13”. The precise ancestry of the strains is not known except for the Donaldson strain (reported by Donaldson and Olson, 1957). The original intention was to produce purebred progeny and reciprocal crosses between all of the five stocks available at the LFC. The crosses were made by using six females and three males in each combination. The males used were different individuals in each combination in spite of a few that had to be used twice. Due to management difficulties only purebred progeny of the Danish and Kamloops strains were available at two years and three summers of age. In addition only progeny of the crosses between the Danish, Kamloops and Al3 were available at three summers of age. Some of the trials - those used for estimating slaughter traits - are very small and the results are therefore only indicative. Protein, fat and water contents were calculated on the basis of results for eight fish per stock. STATISTICAL
ANALYSES
The h2’s were estimated (Harvey, 1966) : Y..Ilk =
U -t
ai + bj +
eijk
(in the Danish strain) by least squares-procedure (model 1)
where Yijk = the observed weights of fishes; u = overall population mean when equal subclass numbers exist; ai = effect of the ith dam (+1,2,3,4); bj = effect of the jth sire &1,2,3,4,5), and C?ijk= random errors. The ai’s and bj’s are regarded as random effects. The comparisons between strains with regard to body weight at 2 years of age were estimated by least squares-procedure: Y.tk = U + ai + eik where Yik = observed weights of fishes; u = overall population mean when equal subclass numbers exist; ai = the effect of the ith strain (i=l ,,,,VV, 2 3 4 56 7 8,9), and eik = random errors. The comparison of strain differences was examined with the t-test of least squares deviations between class means (Snedecor and Cochran, 1967). The comparisons between strains with regard to body weight at three summers of age were estimated by least squares-procedure: Yijk = U + Cli+ bj + eijk
(model 3)
where Yijk = observed weights of fishes; u = overall population mean when equal subclass numbers exist; ai = effect of the ith strain (i=1,2,3,4,5,6); bj = effect of the male sex u=l) and females and juveniles 0=2), and C?ijk= random errors.
131
The comparison of strain differences was examined with the t-test of least squares deviations between class means. The comparisons between strains with regard to carcass quality parameters were estimated by least squares-procedure (Harvey, 1966) and was performed by using the following model: yik = u + ai + eik
(model 4)
where yik = the lipid, protein and water percentage of fishes; u = overall population mean when equal subclass numbers exist; ai = the effect of the ith strain (i=1,2), and eik = random errors. RESULTS AND DISCUSSION
The effect of sire and dam on body weight at 1 year of age is given in Table I. TABLE I Least squares analysis of the effect of dam and sire on the body weights of progeny. Model 1 Source of variation
Degrees of freedom
Mean square
Proportion of total variation
Dam Sire Error
3 4 1971
1922.6176 5414.3345 126.3161
0.026 0.095 0.879
P< 0.01 significant at the 0.1% level.
The variance component estimated for dams is lower than that estimated for sires. This result is in good agreement with the results obtained by Aulstad et al. (1972) for 280 days old fishes. In the present study the sire X dam interaction component was not estimated. In the study of Aulstad et al. (1972) the sire X dam component was negative. The heritability calculated from the dam component is O.lO+O.OS, from the sire component 0.3820.25. The higher value for the heritability calculated from the sire component is in agreement with Aulstad et al. (1972). Together with the high coefficient of variation (0.39) the estimated heritability indicates, that there are fairly good prospects for genetic improvement with regard to body weight of the Danish (t) rainbow trout strain in Finland. The averages and standard deviations in the different materials for differences in weight are given in Table II. The differences between strains and strain crosses were significantly different from each other at both 2 years and three summers of age. The difference in size was significant between the Danish and Kamloops strains (Z’
132
TABLE II The means and standard deviations model 3 : age three summers
in the different
material.
Used stock
Weight (g)
Standard deviation
Number of fish
Age 2 years txt kxk kxt dxk kxAl3 txk txA13 Al3xAm A13xk
531.5 603.8 510.6 616.5 554.4 504.9 473.2 574.1 554.9
174.5 188.8 159.2 174.3 158.7 167.4 182.6 129.0 156.7
250/stack
Age three summers kxk 1713 kxA13 1711 Al3xk 1649 kxt 1603 txk 1561 txt 1547
515.9 462.7 351.5 382.6 349.8 419.5
226 236 245 248 252 241
txt txt kxk kxk kxt kxt kxAl3 kxA13 txk txk Al3xk Al3xk
1515 1644 1587 2005 1567 1681 1619 2043 1501 1801 1648 1780
452.82 365.78 504.47 415.88 401.17 323.45 476.98 384.77 351.20 274.71 342.06 335.40
155 86 161 65 174 74 155 81 181 71 164 81
1631
419.5
1446
1782
365.7
457
1561
419.52
989
O8 lb 0 1 0 1 0 1 0 1 0 1
Total weight Total weight of males Total weight of females and juveniles
“0 = females and juveniles. bl = males. Kamloops Danish = t; Donaldson = d; LFC American = Am.
Model 2: age 2 years;
= k; LFC autumn
spawning = A13;
However, the strain crosses were intermediate to the pure strains at three summers of age. Kamloops seems to have positive additive effects as females, The coefficient of variation within strains ranged between 0.28-0.33 at 2 years of age and 0.22-0.30 at three summer-a of age. The coefficient of
133
variation ranged between 0.16-0.22 for the males and between 0.22-0.32 for the females and the fishes of undetermined sex (juveniles). The proportion of mature males was 0.28-0.36 in all strains at three summers of age. The mature males at three summers of age were significantly bigger (P
Protein fresh weight
Protein dry weight
Lipids fresh weight
Lipids dry weight
k s.d.
71.8 0.75
20.1 0.29
71.2 2.12
7.1 0.85
25.0 2.41
t s.d.
71.01 0.99
19.8 0.44
68.4 2.59
8.2 1.05
28.0 2.70
txk s.d.
70.0 1.43
19.3 0.29
64.6 2.99
9.3 1.46
31.0 3.42
kxt s.d.
71.1 1.06
20.0 0.48
69.1 3.28
7.9 1.31
27.1 3.61
Total means s.d .
71.0 1.21
19.8 0.47
68.3 3.55
8.1 1.4
27.8 3.65
k = Kamloops; t = Danish.
REFERENCES Aulstad, D., Gjedrem, T. and Skjervold, H., 1972. Genetic and environmental sources of variation in length and weight of rainbow trout (Salmo gairdneri). J. Fish. Res. Board Can., 29: 237-241. Ayles, G.B., Bernard, D. and Hendzel, M., 1979. Genetic differences in lipid and dry matter content between strains of rainbow trout (Salmo gairdneri) and their hybrids. Aquaculture, 18: 253-262.
134 Donaldson, L.R. and Olson, P.R., 1957. Development of rainbow trout brood stock by selective breeding. Trans. Am. Fish. Sot., 85: 93-101. Gjedrem, T., 1976. Possibilities for genetic improvement in salmonids. J. Fish. Res. Board Can., 33: 1094-1099. Harvey, W.R., 1966. Least squares analysis of data with unequal subclass numbers. ARS 20-3, Agric. Res. Serv., US Dep. Agric., 157 pp. Snedecor, G.W. and Cochran, G.W., 1967. Statistical Methods. The Iowa State University Press, Ames, IA, 593 pp.