Heritability Of Body Weight Research Articles

Genetic and Phenotypic Parameters of Rabbit Individual Body Weight in the Preweaning Period.

The preweaning weight of kits has been related to their mortality during the suckling period. Selecting rabbit kits for individual body weight in the first days of life could be interesting; however, better knowledge of body weight's heritability during the preweaning period is necessary to determine the opportune moment for selection. A total of 1696 growth records of kits from 81 females of the ITLEV2006 synthetic line were analysed in order to estimate the genetic and non-genetic parameters for individual body weight at birth as well as at 5, 7, 14, 21, 28, and 35 days of age. The estimates of heritability (h2) for individual weight were between low (0.11 at birth, 0.16 at 5 days, and 0.17 at 7 days) and moderate (0.21, 0.21, 0.24, and 0.21 at 14, 21, 28, and 35 days, respectively). Weight at birth showed a strong and positive genetic correlation with weight at 5 days (+0.79) and 7 days of age (+0.78), but the correlation was low for the rest of the weight measurements (+0.41, +0.49, +0.54, and +0.54 with weight at 14, 21, 28, and 35 days, respectively). Weight at 5 days and 7 days displayed strong and positive genetic correlations with the rest of the weight measurements (higher than +0.83). The values of the common litter effect (c2) were high, and they increased with age from 0.43 at birth to 0.66 at 35 days of age. The values of the maternal permanent effect (p2) were low compared to those of the common litter effect (c2), varying between 0.04 and 0.11. In conclusion, opting to select for body weight at 5 or 7 days of age would yield a greater response compared to selecting for birth weight. This approach would indirectly increase the kits' weight at birth and at weaning, thereby reducing preweaning losses.

Heritability and genetic trend of body weight in dogs of different breeds in Sweden.

High body weight (BW) in dogs has been associated with developmental as well as degenerative diseases, but the heritability of BW in dog breeds is largely unknown. The aim of the current study was to estimate heritability and genetic change (genetic trend) for BW in a range of dog breeds in Sweden. Body weight registrations from 19 dog breeds (with n ranging from 412 to 4,710) of varying body size, type and usage were collected from 2007 to 2016. The average BW of the breeds was 8 to 56 kg. The BW registrations were performed when the dogs were 12 to 24 mo of age (18 to 30 mo for one large-sized breed) in connection with an official radiographic screening program for hip dysplasia. Collected weight records were used to estimate heritability and genetic trends for BW. Several statistical models were used. The preliminary model included the fixed effects of breed (P < 0.001), sex (P < 0.001), year of screening (P < 0.001), litter size (P = 0.06), parity of the dam (P = 0.03) and linear regression on age at screening (P < 0.001), the latter five effects all nested within breed, and the random effects of litter and dam. Season of birth and the quadratic effect of age were also tested, but were not significant (P > 0.10). For the genetic analysis, various mixed linear models were tested within breed with different combinations of random effects; the most complex model included random effects of litter, direct additive, and maternal genetic effects, and maternal permanent environmental effects. The average heritability for BW over all 19 breeds was 51%, with a range of 35% to 70%, and the additive genetic coefficient of variance was around 9%. Maternal heritability was 5% to 9% and litter variance was below 10% with one exception (15% in Shetland Sheepdogs). For nine breeds, there was a genetic trend of increasing BW, whereas seven breeds had a genetic trend of decreasing BW. The largest absolute genetic change over a 10-yr period was around 0.6 kg or about 2% of the mean. In conclusion, given the small genetic changes in spite of the high heritability, it seems that there is generally a very weak selection, if any, for BW in the included dog breeds.

HERITABILITY OF BODY WEIGHT AND LINEAR BODY MEASUREMENTS OF ISA BROWN x LOCAL CHICKEN GENOTYPES

Heritability of growth traits was studied at 2, 10 and 20 weeks using 531 day-old unsexed crossbred chickens belonging to six genotypes. Heritability estimates were obtained from variance components of sire ( ), dam ( ) and sire plus dam ( ) by analysis of variance in a nested design. The heritability of body weight was high (0.43-0.66) in frizzle feathered x Isa Brown (FxIB), Isa Brown x frizzle feathered (IBxF), Isa Brown x normal feathered (IBxN) and normal feathered x Isa Brown (NxIB) at 10 and 20 weeks, but low to moderate (0.02-0.38) in Isa Brown x naked neck (IBxNa) and naked neck x Isa Brown (NaxIB) at all ages from different variance components. The heritability of shank length was high at weeks 2 (0.45) in NaxIB, 10 (0.53-0.90) in IBxF, IBxN and NaxIB and 20 (0.40 - 0.53) in IBxNa and IBxN from . The heritability of drumstick length (0.40 - 0.46), body girth (0.54 - 0.62), body width (0.50 - 0.81) and keel length (0.72 - 1.50) was also high from different variance components and ages. Body length was highly heritable only in IBxN (0.50) from at 20 weeks. Wing length was lowly to moderately heritable (0.01 - 0.36) at all ages of the genotypes. There was large additive genetic variance for most of the traits in different genotypes and ages. Rapid genetic improvement of growth can be made in these chickens by individual selection, especially using shank length of IBxN from sire lines between 10 and 20 weeks of age.

The body weight heritability and the effect of non-genetic factors on the body measurement traits in Qinchuan cattle

This study aimed to understand the influence of the non-genetic factors that include breeding year, season, and sex of growth and development traits of Qinchuan cattle and to estimate the heritability of body weight at different growth stages. The Qinchuan cattle measurement records were by the Experiment farm of the National Beef Cattle Improvement Center (Yangling, China) from 2000 to 2017. SPSS and R software were used to analyze the influence of non-genetic factors on body size traits that include body weight (BW), withers height (WH), hip height (HH), body length (BL), chest circumference (CC), abdominal girth (AG), and calf girth (CG), at birth, 6, 12, 18, and 24 months of age. Meanwhile, the single-trait animal model of DMU software was used to estimate the variance component and the heritability of body weight. The results of GLM analysis showed as follows: sex, birth year, and birth season had effects on the body size traits of Qinchuan cattle at different growth stages. Respectively, the heritability of body weight at birth, 6, 12, 18, and 24 months of age were 0.43, 0.32, 0.37, 0.32, and 0.38.

Assessment the effect of genomic selection and detection of selective signature in broilers

Due to high selection advances and shortened generation interval, genomic selection (GS) is now an effective animal breeding scheme. In broilers, many studies have compared the accuracy of different GS prediction methods, but few reports have demonstrated phenotypic or genetic changes using GS. In this study, the paternal chicken line B underwent continuous selection for 3 generations. The chicken 55 k SNP chip was used to estimate the genetic parameters and detect genomic response regions by selective sweep analysis. The heritability for body weight (BW), meat production, and abdominal fat traits were ranged from 0.12 to 0.38. A high genetic correlation was found between BW and meat production traits, while a low genetic correlation (<0.1) was found between meat production and abdominal fat traits. Selection resulted in an increase of about 516 g in BW and 140 g in breast muscle weight. Percentage of breast muscle and whole thigh were increased 0.8 to 1.5%. No change was observed in abdominal fat percentage. The genomic estimated breeding value advances was positive for BW and meat production (except whole thigh percentage), while negative for abdominal fat percentage. By selective sweep analysis, 39 common chromosomal regions and 102 protein coding genes were found to be influenced, including MYH1A, MYH1B, and MYH1D of the MYH gene family. Tight junction pathway as well as myosin complex related terms were enriched. This study demonstrates the effective use of GS for improvements in BW and meat production in chicken line B. Further, genomic regions, responsive to intensive genetic selection, were identified to contain genes of the MYH family.

Insights into the genetic covariation between harvest survival and growth rate in olive flounder (Paralichthys olivaceus) under commercial production environment

In aquaculture, selective breeding for survival till harvest have become an alternative strategy for improving disease resistance and production. However, knowledge of genetic parameters of harvest survival, e.g., heritability and genetic correlations between survival and growth rate traits, is still scarce. The aims of this study were to estimate genetic parameters for harvest survival and growth rate traits under commercial farming conditions in olive flounder (Paralichthys olivaceus). Harvest survival was defined as a binary trait; growth traits were measured as average daily gain (ADG), specific growth rate (SGR), daily growth coefficient (DGC) and body weight (BW). Data from a population of 241 full-sib families (involving 39,904 individuals, four generations) were used. Heritabilities of survival were low but significant, which were 0.15 ± 0.04 and 0.22 ± 0.01 on observed and underlying scale, respectively. Heritability estimates for ADG, SGR and DGC were medium to high, which were 0.33 ± 0.06, 0.83 ± 0.07, 0.58 ± 0.07, respectively. While the heritability of BW is of low magnitude (0.17 ± 0.08). The genetic correlations between harvest survival and three growth rate traits (i.e., ADG, SGR and DGC) were very strong (ranging from 0.66 to 0.79), which is an exciting result. However, the genetic correlation between harvest survival and BW was much lower (0.17 ± 0.08). These results suggest that selection for harvest survival would consequentially result in concomitant increase of growth rate, and vice versa. Our findings revealed novel insights into the genetic improvement of growth rate and harvest survival through genetic selection in olive flounder.

Estimasi Nilai Heritabilitas Lingkar Dada dan Panjang Badan pada Kambing Peranakan Etawah di BPTU dan HPT Pelaihari Kalimantan Selatan

Evaluation in standardization really needs to be carried out, including whether the livestock is in accordance with the SNI vital statistics standard (Indonesian national standard). The purpose of the study was to estimate heritability and breeding values of body weight and vital statistics in Etawah Grade (PE) goats in BPTU and HPT Pelaihari Kalimantan Selatan. The material used were the performance records of 220 PE goats, offsprings of 35 males and 71 females. The variables measured were body length and chest girth at birth, weaning, and 1 year of age. Variance componenet were analyzed using variance analysisrade. Heritability was estimated using the paternal half-sib correlation method by applying SPSS software. Breeding value was estimated using the progeny test model. The highest breeding value on body length at birth, at weaning age and at 1 year of age were sire 3315 KK, sire 4093 OK, and sire 4007 OK, respectively. The highest breeding Value on chest girth at birth, weaning age and 1 year of age were sire 3983 HH, 3315 HH, and 3971 HH. The conclusion of this study were the heritability for body weight were categorized high and for statistic vital were varied from medium to high value.

Genomic prediction of crossbred dairy cattle in Tanzania: A route to productivity gains in smallholder dairy systems

Selection based on genomic predictions has become the method of choice for genetic improvement in dairy cattle. This offers huge opportunity for developing countries with little or no pedigree data, and preliminary studies have shown promising results. The African Dairy Genetic Gains (ADGG) project initiated a digital system of dairy performance data collection, accompanied by genotyping in Tanzania in 2016. Currently, ADGG has the largest body of dairy performance data generated in East Africa from a smallholder dairy system. This study examines the use of genomic best linear unbiased prediction (GBLUP) and single-step (ss)GBLUP for the estimation of genetic parameters and accuracy of genomic prediction for daily milk yield and body weight in Tanzania. The estimates of heritability for daily milk yield from GBLUP and ssGBLUP were essentially the same, at 0.12 ± 0.03. The heritability estimates for daily milk yield averaged over the whole lactation from random regression model (RRM) GBLUP or ssGBLUP were 0.22 and 0.24, respectively. The heritability of body weight from GBLUP was 0.24 ± 04 but was 0.22 ± 04 from the ssGBLUP analysis. Accuracy of genomic prediction for milk yield from a forward validation was 0.57 for GBLUP based on fixed regression model or 0.55 from an RRM. Corresponding estimates from ssGBLUP were 0.59 and 0.53, respectively. Accuracy for body weight, however, was much higher at 0.83 from GBLUP and 0.77 for ssGBLUP. The moderate to high levels of accuracy of genomic prediction (0.53-0.83) obtained for milk yield and body weight indicate that selection on the basis of genomic prediction is feasible in smallholder dairy systems and most probably the only initial possible pathway to implementing sustained genetic improvement programs in such systems.

Genetic parameters for Photobacterium damselae subsp. piscicida resistance, immunological markers and body weight in gilthead seabream (Sparus aurata)

A challenge test for Photobacterium damselae subsp. piscicida (Phdp) resistance was carried out in two juvenile populations of gilthead seabream (Sparus aurata L.): F2_ATL and F0_MED. At 250 days post-hatching (dph), a fish plasma sample was collected to measure humoral immune markers (peroxidase activity, bactericidal activity, and IgM immunoglobulin levels), and at 272 dph fish were weighed and inoculated with bacteria Phdp. From that time onwards, surviving fish were recorded for nine days, and days to death was registered. Heritabilities for body weight and Phdp survival were moderate, although for days to death the heritability was low. Regarding humoral immune markers, for peroxidase activity it was moderate, and for IgM levels and for bactericidal activity it was low. Genetic correlations for body weight with Phdp survival and days to death were high and positive, while with peroxidase activity and IgM levels they tended to be positive, although these estimates were not accurate. Regarding genetic correlations between Phdp survival and humoral immune markers, they were very high, positive with peroxidase activity, and negative with IgM levels and bactericidal activity. Some humoral immune markers, particularly peroxidase activity, along with performance traits such as body weight and absence of deformities, are proposed to be included in a selective breeding program to raise fish that are capable of coping with diseases

Genetic parameters of caviar yield, color, size and firmness using parentage assignment in an octoploid fish species, the Siberian sturgeon Acipenser baerii

Aquaculture is presently the only sustainable way of enhancing sturgeon caviar production as the use of wild stocks is banned throughout the world. Hence sustainable management and efficient genetic improvement of domesticated populations are major challenges for the development of farmed caviar. We estimated genetic parameters of caviar yields and quality traits (size, color and firmness) in the polyploid Siberian sturgeon A. baerii, one of the major sturgeon species farmed for meat and caviar worldwide. This study was performed in commercial breeding conditions, where two factorial mating plans were created to produce 77 families. Larvae were pooled at hatching and reared in common environment until the age of caviar production. We phenotyped 494 females, which were successfully assigned to their parents with microsatellite markers using a newly developed software, designed to manage genotypes with varying ploidy levels, up to 8 N. The genetic parameters were estimated using heteroscedastic multi-trait BLUP animal models. Heritability of body weight, ovary weight, caviar weight, caviar (egg) size, caviar yield, caviar firmness and caviar color were moderate to high (0.13 to 0.66) depending on the trait. Moderate negative genetic correlations were estimated between growth and caviar yields (−0.28 to −0.37) while genetic correlations between caviar (egg) size and caviar yield were more negative (−0.70 to −0.76). These results provide favorable grounds to improve the efficiency of farmed caviar production by selective breeding.

Genetic parameter estimates for important traits on the fifth generation in red tilapia in Vietnam

Genetic parameters comprising heritability, genetic correlation and genotype by environment interaction (GxE) for growth survival rate and body colour at harvest were estimated on the 5th selective generation of red tilapia grown in two environments, freshwater and brackishwater ponds. A total of 116 full-half-sib families was produced as well as 4,432 and 3,811 tagged individuals were tested in freshwater and brackishwater ponds, respectively. Genetic parameters were estimated by ASReml 4.1 software. The heritability for body weight and survival rate was high while medium heritability for body colour in freshwater was observed. The heritability for those traits of red tilapia in brackishwater. Together with the figures in earlier publication on previous generations (G1 to G4) in the same selective population, the expected medium to high response acquires if selection is done for each trait. Genetic correlations among harvest body weight, survival rate and body colour are insignificantly different and ranging from -0.25 to 0.37 (P &gt; 0.05). These results implied that selection on one trait do not influence on responses of the other traits. GxE interaction for body weight and body colour between two tested environments is mostly negligible with genetic correlations ranging from 0.63 - 0.80 while it is important for survival trait (rg = -0.17 ± 0.40).

Genetic parameters for weight, morphometry and oviposition of Africanized honeybee queens using simulated data

ABSTRACT This study aimed to estimate genetic parameters for simulated data of body weight (BW), abdominal width (AW), abdominal length (AL), and oviposition. Simulation was performed based on real data collected at apiaries in the region of Campo das Vertentes, Minas Gerais, Brazil. Genetic evaluations were performed using single- and two-trait models and (co)variance components were estimated by the restricted maximum likelihood method. The heritability for BW, AW, AL and oviposition were 0.54, 0.47, 0.31 and 0.66, respectively. Positive genetic correlations of high magnitude were obtained between BW and AW (0.80), BW and oviposition (0.69), AW and oviposition (0.82), and AL and oviposition (0.96). The genetic correlations between BW and AL (0.11) and between AW and AL (0.26) were considered moderate and low. In contrast, the phenotypic correlations were positive and high between BW and AW (0.97), BW and AL (0.96), and AW and AL (0.98). Phenotypic correlations of low magnitude and close to zero were obtained for oviposition with AL (0.02), AW (-0.02), and BW (-0.03). New studies involving these characteristics should be conducted on populations with biological data in order to evaluate the impact of selection on traits of economic interest.

Feed competition reduces heritable variation for body weight in Litopenaeus vannamei

BackgroundCompetition is a common social interaction among shrimp and depending on its intensity, it can affect heritable variation and response to selection. Little is known about the variance of indirect genetic effects (IGE) under competitive and non-competitive conditions in shrimp. In this study, we used extended mixed linear models to estimate genetic parameters for the direct genetic effect (DGE) and IGE on body weight in Litopenaeus vannamei raised under ad libitum (AF, non-competitive environment) and restricted (RF, competitive environment) feeding regimes.ResultsEstimates of heritabilities for body weight obtained with a traditional animal model (i.e. without accounting for IGE) were 0.11 ± 0.09 under AF and 0.25 ± 0.11 under RF. With extended animal models that accounted for IGE, the corresponding estimates for body weight were 0.07 ± 0.08 and 0.34 ± 0.11. Thus, heritabilities were higher under the RF regime than under the AF regime, regardless of whether IGE was accounted for or not. The log-likelihood ratio test revealed significant IGE under the RF regime. Although estimates of indirect genetic variance were low (0.0023 ± 0.0013 for AF and 0.0028 ± 0.0012 for RF), they contributed substantially to the total heritable variance: 66.8% for AF and 692.2% for RF. The total heritable variance was smaller under the RF regime (0.7 ± 1.3) than under the AF regime (5.8 ± 2.6) because of the high contribution of the negative covariance between DGE and IGE (− 7.03). Estimates of the correlation between DGE and IGE were 0.32 ± 0.47 under AF and − 0.93 ± 0.15 under RF, those of DGE and IGE for body weight between both regimes were 0.94 ± 0.07 and 0.67 ± 0.20, respectively, and those of IGE for body weight with DGE for survival were − 0.12 ± 0.22 under AF and − 0.58 ± 0.20 under RF.ConclusionsThese results indicate that strong competitive interactions occurred under the RF regime in L. vannamei. Significant reranking and variation in IGE of individuals were observed between the two feeding regimes. Strong competitive interactions reduced the total heritable variation for body weight when food was restricted. These results indicate that the extent of competition among L. vannamei depends on the feeding regime applied and that this competition affects the genetic basis of body weight.

Genetic variation among full-sib families and the effect of non-genetic factors on growth traits at harvest in Clarias magur (Hamilton, 1822)

Magur (Clarias magur) is an Indian catfish species with a good potential for aquaculture. The expansion of magur aquaculture is hindered because of low reproductive and survival rates. Furthermore, males need to be sacrificed to collect milt for artificial fertilization. At present, magur seed production mainly depends on the wild-caught juveniles and to a smaller extent, from broodfish whose genetic potential is unknown. The availability of high-quality seeds in a sustainable way can be ensured through the selective breeding program for magur. The knowledge of factors influencing growth traits and their genetic parameters is a pre-requisite for implementing a genetic selection program. The present study aimed to quantify the performance of C.magur reared in a two-year class and estimate their heritabilities at stocking and harvest and also to estimate the genetic and phenotypic correlations among them. The growth traits such as Body Weight (BW), Total Length (TL), Body Depth (BD), Head Width (HW), and Average Daily Gain (ADG) were recorded from 1413 animals belonging to 78 fullsib families produced by adopting single pair mating design, after one year of pond culture (traits at harvest). Genetic parameters were also estimated for body weight (BW0) and total length (TL0) measured from 2328 fish from 78 fullsib families at the time of stocking. Magur attained an average BW of 135 g and 24.5 cm TL after one year culture period. The heritabilities of BW, TL, and ADG were 0.44 ± 0.07, 0.32 ± 0.06, and 0.42 ± 0.07, respectively and may be biased upwardly due to the single pair mating design. Genetic correlations between harvest traits were all positive and varied in magnitude between traits (0.74 to 0.99). The results obtained from the current study indicate the presence of genetic variation in magur population for growth traits and selection based on genetic merit can produce improvement in these traits.

Reducing the Common Environmental Effect on Litopenaeus vannamei Body Weight by Rearing Communally at Early Developmental Stages and Using a Reconstructed Pedigree

Heritability estimates may be severely biased when a large common environmental effect on a family arises from a long-lasting separate rearing at early stages (SRES) in traditional selective breeding programs, especially when bred populations have weak genetic ties. Communal rearing at early stages (CRES) may reduce common environmental effect since all families are reared in the same environment immediately after hatching. Here, we compared the effects of CRES and SRES strategies on genetic parameter estimation for harvest body weight in a selective breeding population of Litopenaeus vannamei with a small number of half-sib families. Genetic parameters of each strategy were estimated by using animal models excluding and including the common environmental effect (Model 1 and Model 2, respectively). Heritability estimates for body weight were 0.21±0.06 (P 0.05) in Model 2. The ratio of common environmental variance to phenotypic variance was 0.002 ±0.000 and 0.071 ±0.112 for CRES and SRES, respectively. Neither strategy precisely partitioned the common environmental variance according to likelihood ratio test. Lower heritability for body weight in CRES than in SRES implied that a large common environmental variance was confounded with additive genetic variance and was not effectively partitioned in SRES. Moreover, genetic correlation of body weight between the two strategies was 0.75±0.15, indicating that family rankings truly changed. The CRES should be followed in the selective breeding program of shrimp, especially in a population with a shallow pedigree and weak genetic ties between families.

Genomic partitioning of growth traits using a high-density single nucleotide polymorphism array in Hanwoo (Korean cattle).

ObjectiveThe objective of this study was to characterize the number of loci affecting growth traits and the distribution of single nucleotide polymorphism (SNP) effects on growth traits, and to understand the genetic architecture for growth traits in Hanwoo (Korean cattle) using genome-wide association study (GWAS), genomic partitioning, and hierarchical Bayesian mixture models.MethodsGWAS: A single-marker regression-based mixed model was used to test the association between SNPs and causal variants. A genotype relationship matrix was fitted as a random effect in this linear mixed model to correct the genetic structure of a sire family. Genomic restricted maximum likelihood and BayesR: A priori information included setting the fixed additive genetic variance to a pre-specified value; the first mixture component was set to zero, the second to , the third , and the fourth to . BayesR fixed a priori information was not more than 1% of the genetic variance for each of the SNPs affecting the mixed distribution.ResultsThe GWAS revealed common genomic regions of 2 Mb on bovine chromosome 14 (BTA14) and 3 had a moderate effect that may contain causal variants for body weight at 6, 12, 18, and 24 months. This genomic region explained approximately 10% of the variance against total additive genetic variance and body weight heritability at 12, 18, and 24 months. BayesR identified the exact genomic region containing causal SNPs on BTA14, 3, and 22. However, the genetic variance explained by each chromosome or SNP was estimated to be very small compared to the total additive genetic variance. Causal SNPs for growth trait on BTA14 explained only 0.04% to 0.5% of the genetic varianceConclusionSegregating mutations have a moderate effect on BTA14, 3, and 19; many other loci with small effects on growth traits at different ages were also identified.

Selection response and genetic parameters for growth in North African catfish, Clarias gariepinus (Burchell, 1822)

The North African catfish, Clarias gariepinus (Cga) is economically important and has been cultured worldwide. There had previously been no genetic improvement programs for this species, and thus its genetic potential had not been explored or utilized. A selection program to improve growth of Cga has now been established in Thailand and the response to one generation of selection and genetic parameters are presented in this study. The selection was performed by selecting the 17 families that had the highest average EBV (estimated breeding value) for body weight at harvest, while fish from 17 families with medium family EBV were kept as the control group. When they reached maturation, mating was done within groups following a partial factorial mating design which eventually resulted in 51 full-sib (14 paternal-, 13 maternal half-sib families) for the selected group, and 62 full-sib (16 families each of paternal- and maternal half-sibs) for the control group. The families were tagged by family at 100 DAH and communally reared in two 400 m2 earthen ponds. The dataset at 160 DAH (n = 6920) was used to estimate variance components using a multiple-traits animal model by an Average-Information Restricted Maximum Likelihood procedure. Heritability for body weight (BW), total length (TL) and standard length (SL) was low and almost equal (range of 0.128–0.129) and heritability for condition factor (K) was 0.155. Genetic correlations between growth traits ranged from 0.966 to 0.996 and between growth traits and K were 0.294–0.509. Selection response, measured as the difference between least squares mean of the selected and the control groups was 28.00 g (10.37%). Selection resulted in 3.65, 3.77, and − 0.95% correlated response for TL, SL and K, respectively. Despite of a desirable selection response, there is a concern that apparent reduction of heritability may result in low selection response in succeeding generations.

PSVIII-29 Analysis of genotype by environment interaction across time for Nile tilapia reared in different production systems

Abstract Nile tilapia is the second most important freshwater fish for human consumption worldwide and it is produced under many different conditions. Even though genotype by environment interaction (GEI) can arise due to many factors, most studies with tilapia have focused on water quality on pond and cage systems. Therefore, the objective of the current work was to evaluate GEI on body weight (BW) of Nile tilapia raised in biofloc technology (BFT), Cage, and recirculation aquaculture systems (RAS) from 100 to 350 days of age. A Bayesian multi-trait random regression model (MTRRM) with age as random regression covariable was employed to evaluate the temporal trend of GEI. Estimated genetic correlations between BFT and RAS were above 0.7 for almost any combination of ages evaluated (Figure 1). However, genetic correlations between Cage at ages below 150 days with either BFT or RAS at any other age were positive but below 0.5. The posterior means of heritability for BW were found to reach peaks of 0.40, 0.38 and 0.29 around 230 days for RAS, BFT, and Cage respectively (Figure 2). Conversely, the ratio between common family environment and phenotypic variances presented an overall decreasing trend with minimums around 0.22, 0.15 and 0.10 at 230 days for Cage, RAS, and BFT, respectively. The MTRRM has shown to be a powerful statistical tool to assess changes across time for genetic parameters of interest. In conclusion, GEI was found to be dynamic across time, with stronger effects between Cage and both BFT and RAS if selection is promoted prior to 150 days. However, GEI is negligible for most of the situations considered if selection is performed after 200 days of age in either BTF or RAS, with the possibility of achieving better indirect selection results if selection is performed around 230 days.

Genetic parameters of egg production trait in Alabio and Mojosari ducks under selection

Genetic parameters for egg production traits in Alabio and Mojosari ducks were estimated. Egg production data were collected from 530 Alabio and 461 Mojosari ducks. The ducks were 6th generation of selection program for egg production trait at the BPTU-HPT Pelaihari. Heritability values were estimated using paternal half-sib correlation method in a one-way analysis of variance. The result showed that heritability estimates for body weight at 16 weeks of age were high, in Alabio ducks (0.63±0.242) and in Mojosari duck (0.88±0.269). Heritability for body weight at first egg was 0.55±0.23 in Alabio duck and 0.44±0.222 in Mojosari duck. The heritability estimates for number of eggs from months 1-3 (EN3) and 1-6 (EN6), ranging from 0.30 to 0.46. The heritability for number of eggs from months 1-12 (EN12) was high in Alabio duck (0.62) and moderate in Mojosari duck (0.46). The EN12 had high genetic correlation with EN3 and EN6 (ranging from 0.80 to 0.99). EN12 had a negative genetic correlation with body weight and age at first egg (between -0.81 and -0.21). This finding indicates that EN3 could be used as a selection criteria to increase EN12 in Alabio and Mojosari ducks.

Genetic heterogeneity of residual variance of hatch weight in Mazandaran native chicken

ABSTRACT 1. In current breeding programmes, uniformity of end products and producing animals that are robust to environmental challenges are desirable. Several studies have provided evidence of the presence of genetic heterogeneity of residual variance and proposed that it could be possible to increase uniformity of livestock productions by selection. The present study aimed to define the micro environmental sensitivity of dual-purpose chickens for body weight at hatch. 2. The data set consisted of 24,321 female and 21,547 male chickens’ records of hatch weight from 19 consecutive generations of Mazandaran fowl. The statistical analysis was carried out in a two-step approach: first, an animal model was fitted to the data and then, the impact of additive genetic effects on the residual variance of the studied trait was investigated. 3. The estimate of heritability for body weight at hatch was in the range of 0.23–0.25 for female and 0.14–0.16 for male offspring, respectively. The proportion of maternal environmental variance to phenotypic variance ranged from 0.24 to 0.27 for female and 0.17 to 0.24 for male offspring. Heritabilities in females were higher than males. Estimates of the heritability of residual variance ranged between 0.067 and 0.090. The genetic coefficients of variation were high ranging between 0.83 and 0.86. Genetic correlations between hatch weight and its residual variance estimates from bivariate analysis were −0.39 and −0.44 in females and males, respectively. 4. The results suggest that there is an opportunity to simultaneously improve body weight and the uniformity of body weight by selecting for lower residual variance in native chickens.