Genetic Parameters For Body Weight Research Articles

Longitudinal genetic analysis of Nile tilapia ( Oreochromis niloticus L.) body weight using a random regression model

Genetic parameters for body weight at ages over approximately 120 days are scarce in Nile tilapia. In this study, genetic parameters for body weight in Nile tilapia were estimated for ages ranging from 100 to 326 days. To this end, five repeated observations of body weight were collected on 2483 pedigreed fish. The fish originated from a population descending from four different genetic backgrounds. Genetic parameters were estimated using a random regression model with covariance functions. The heritability of body weight was fairly constant around 0.2, which offers good prospects for selection on body weight. Genetic correlations were estimated between all ages (100–326 days). At higher ages, genetic correlations were clearly more stable: for example genetic correlations were over 0.9 between the age of 100 days and all ages up to 115 days of age; at higher ages genetic correlations were over 0.9 between the age of 223 days and all ages up to 326 days of age. The estimated genetic parameters showed that early selection results in higher selection response than direct selection, when the target trait is body weight at the age of 326 days. This is due to somewhat higher heritabilities at lower age and a shortened generation interval. Furthermore, evidence was found for genetic differences in growth patterns of fish of different strains. This means that the possibility to change the shape of body weight curves by selection exists and that the choice of strains should depend on the target market weight of the production chain. From the raw data we concluded that differences in body weight between male and female fish were significant already at early ages (100 days). Results from a bivariate genetic analysis, where body weight of male and female fish are treated as separate traits, suggest that body weight in male and female fish is most likely controlled by the same genes. Prospects to decrease the difference between mature male and female body weight by selection are therefore unfavorable in Nile tilapia.

Estimation of Genetic Parameters for Body Weight in Chinese Simmental Cattle Using Random Regression Model

The random regression model methodology was applied into the estimation of genetic parameters for body weights in Chinese Simmental cattle to replace the traditional multiple trait models. The variance components were estimated using Gibbs sampling procedure on Bayesion theory. The data were extracted for Chinese Simmental cattle born during 1980 to 2000 from 6 national breeding farms, where records from 3 months to 36 months were only used in this study. A 3 orders Legendre polynomial was defined as the submodel to describe the general law of that body weight changing with months of age in population. The heritabilities of body weights from 3 months to 36 months varied between 0.31 and 0.48, where the heritabilities from 3 months to 12 months slightly decreased with months of age but ones from 13 months to 36 months increased with months of age. Specially, the heritabilities at eighteenth and twenty-fourth month of age were 0.33 and 0.36, respectively, which were slightly greater than 0.30 and 0.31 from multiple trait models. In addition, the genetic and phenotypic correlations between body weights at different month ages were also obtained using regression model.

Genetic parameters of body weight and prolificacy in pigeons

Genetic parameters of body weight at weaning and of prolificacy were estimated in three commercial lines of pigeons selected by BLUP (Best Linear Unbiased Prediction) on both traits. The model of analysis took into account the direct genetic effects for both traits and the effect of parental permanent environment for body weight. Depending on the line considered, body weight varied from 556.7 g to 647.6 g and prolificacy ranged from 12.5 to 16.8 pigeons weaned per couple of parents per year. Heritability of body weight was high, varying between 0.46 and 0.60, and permanent environment was responsible for 6% to 9% of the total variability. On the contrary, prolificacy was poorly heritable (0.04 to 0.12). They were highly and negatively correlated (-0.77 to -0.82). Body weight showed significant genetic trends in lines B and C. No significant genetic difference could be observed between males and females for both traits.

Genetic parameters of body weight and prolificacy in pigeons.

Genetic parameters of body weight at weaning and of prolificacy were estimated in three commercial lines of pigeons selected by BLUP (Best Linear Unbiased Prediction) on both traits. The model of analysis took into account the direct genetic effects for both traits and the effect of parental permanent environment for body weight. Depending on the line considered, body weight varied from 556.7 g to 647.6 g and prolificacy ranged from 12.5 to 16.8 pigeons weaned per couple of parents per year. Heritability of body weight was high, varying between 0.46 and 0.60, and permanent environment was responsible for 6% to 9% of the total variability. On the contrary, prolificacy was poorly heritable (0.04 to 0.12). They were highly and negatively correlated (-0.77 to -0.82). Body weight showed significant genetic trends in lines B and C. No significant genetic difference could be observed between males and females for both traits.

Genetic parameters and genetic trends in the Chinese x European Tiameslan composite pig line. I. Genetic parameters.

Genetic parameters of body weight at 4 (W4 w), 8 (W8 w) and 22 (W22 w) weeks of age, days from 20 to 100 kg (DT), average backfat thickness at 100 kg (ABT), teat number (TEAT), number of good teats (GTEAT), total number of piglets born (TNB), born alive (NBA) and weaned (NW) per litter, and birth to weaning survival rate (SURV) were estimated in the Chinese × European Tiameslan composite line using restricted maximum likelihood methodology applied to a multiple trait animal model. Performance data from a total of 4 881 males and 4 799 females from 1 341 litters were analysed. Different models were fitted to the data in order to estimate the importance of maternal effects on production traits, as well as genetic correlations between male and female performance. The results showed the existence of significant maternal effects on W4w, W8w and ABT and of variance heterogeneity between sexes for W22w, DT, ABT and GTEAT. Genetic correlations between sexes were 0.79, 0.71 and 0.82, respectively, for W22w, DT and ABT and above 0.90 for the other traits. Heritability estimates were larger than (ABT and TEAT) or similar to (other traits) average literature values. Some genetic antagonism was evidenced between production traits, particularly W4w, W8w and ABT, and reproductive traits.

Genetic parameters of body weight of broiler chickens measured at 22°C or 32°C

1. Male broilers (n = 1521) from 247 families were reared from 4 to 6 weeks of age at 22° or 32°C. 2. Genetic correlations between measurements recorded at 22°C and 32°C were 0.73 ± 0.12 for weight gain between 4 and 6 weeks and 0.74 ± 0.08 for food conversion ratio (FCR). Genes controlling weight gain at both temperatures differed to some extent. 3. Heritability of weight gain from 4 to 6 weeks was much lower at 32°C than at 22°C (0.13 ± 0.03 vs 0.24 ± 0.04): selection for increased body weight will thus be much less efficient at 32°C than at 22°C. 4. Conversely, heritabilities of the FCR were very similar at the 2 temperatures (0.28 ± 0.04 at 22°C and 0.27 ± 0.04 at 32°C). Selecting for FCR would thus be efficient at 32°C too. 5. These results justify, at least under our experimental conditions, selecting broiler lines for improved growth performance at 22°C. However, it could be more efficient if broilers are to be reared in hot climates to select for improved FCR rather than for increased body weight.

Genetic analysis of a selection experiment on increased body weight and breast muscle weight as well as on limited abdominal fat weight

1. Genetic parameters of body weight (BW), breast meat weight or yield (BRW, BRY) and abdominal fat weight or yield (FTW, FTY) were estimated in males and females originated from an experimental line selected for improving broiler carcase quality and its control line. 2. Mean heritabilities over both sexes of BW, FTW and FTY were 0.43, 0.56 and 0.63 respectively. Those of BRW and BRY were 0.53 and 0.65 respectively. 3. BW was unfavourably correlated with FTW (rg of 0.40) and to a lesser extent with FTY (rg of 0.12). BW was, as expected, highly correlated with BRW (rg 0.77), but a poor correlation was obtained with BRY (rg of 0.15). Selection for more breast yield should not reduce the leanness of the birds, with a genetic correlation between BRY and FTY of -0.15. 4. The variance explained by the maternal effects accounted for a rather small part of the total phenotypic variance (from 3% to 8% according to the trait), but ignoring these effects led to a significant overestimation of the heritabilities (by 11% to 19%). 5. Except for BRY, the heritability estimates differed between sexes, only moderately for BW but more for BRW, FTW and FTY. However, estimated genetic correlations between sexes were high (between 0.94 and 0.99) and in turn heritabilities of sexual dimorphism of the various traits very low (between 0.02 and 0.07). 6. A significant improvement of the genetic level for growth and carcase composition had been obtained in the selected line, with a mean genetic gain per generation of 0.12 sigma g, 0.13 sigma g and -0.30 sigma g for BW, BRY and FTY respectively.

Mink dam weight changes during the lactation period I. Genetic and Environmental Effects

Records from 570 scanblack mink dams with 786 lactations in the period 1989–94 were used to estimate genetic parameters for body weight and weight changes during the lactation period from parturition to 6 weeks post‐partum. Direct additive effects and effects of permanent environment were estimated using restricted maximum likelihood (REML) in univariate and bivariate models. During the first 6 weeks of lactation, the dam lost around 15% (169 g) of the body weight at parturition, the main part, 10% (112 g), during the last 2 weeks. Older dams lost more weight than yearling dams, especially during the late part of the lactation period. Dams fed ad libitum had a higher body weight during the last part of the lactation period. The litter size, the sex of the kits and the litter weight influenced weight loss of the dam, especially in the late part of the lactation period. The heritability of the direct additive effect was intermediate to high for body weight (h2 a ∼ 0.39–0.58), but lower for weight changes (h2 a ∼ 0.15–0.38). The permanent environmental effect was important for the total body weight (c2 ∼ 0.23–0.30) and less important for weight changes (c2 ∼ 0.13), but still significant. The repeatability for weight changes between parities was intermediate to high (r ∼ 0.19–0.52).

Mink kit growth performance in the suckling period

Records of 4103 scanblack mink kits born in 1989–94 were used to estimate genetic parameters for body weight and body length during the growth season with special emphasis on the suckling period. Maternal additive and direct additive effects and effects of permanent maternal and specific litter environment were estimated, using restricted maximum likelihood (REML) in univariate and bivariate animal models. The maternal additive effect was constant during the first 4 weeks after parturition at h2 m ≈ 0.30 for weight, and decreased thereafter. The heritability estimate for direct additive effect for body weight decreased from h2 a ≈ 0.19 at birth to h2 a ≈ 0.12 at 4 weeks but increased to h2 a ≈ 0.50 in August to December. The maternal permanent environment was important only at 2 and 4 weeks, c2 p ≈ 0.10. The specific environment, common within the litter, increased from c2 s ≈ 0.24 at birth to c2 s≈ 0.40 at 2 and 4 weeks, but decreased thereafter to c2 s ≈ 0.10 in December. Estimates for body length showed a slightly different pattern, h2 a varying from 0.07 to 0.17 in the lactation period, but increased to 0.46 at pelting. The heritability of maternal additive effect (h2 m) for body length varied from 0.17 to 0.24 during the lactation period and decreased thereafter to 0.06 at pelting. The results indicate that selection for maternal traits should be based on kit body weight, or body length within 4 weeks after birth, or on growth from 2 to 4 weeks. The largest direct response for body weight would be obtained by selection on body weight in August‐December.

Genetic parameters for body weight, fleece weight and fibre diameter in South African Angora goats

Abstract Data obtained through the Angora goat performance testing pilot scheme, run by the Department of Agriculture at the Grootfontein Agricultural Development Institute, were analyzed. Data of kids born from 1990 until 1993 in 17 studs were used in the analysis. Traits analyzed were body weight (BW; n = 6240), greasy fleece weight (FW; n = 6239) and mean fibre diameter (FD; n = 6195). Heritability estimates were obtained for each trait employing REML-procedures under univariate animal models. By ignoring or including maternal genetic or environmental effects, four different models of analysis were fitted for each trait. Log likelihood ratio tests indicated that the model including a direct as well as a maternal genetic effect was the most suitable model for all traits. For the estimation of correlations between traits, bivariate analysis was carried out fitting direct effects only. Direct heritability estimates for BW [0.292 (with SE 0.047)] and FD [0.257 (0.046)] were higher than that estimated for FW [0.192 (0.038)]. Maternal heritability estimates of 0.090 (0.071), 0.049 (0.075) and 0.083 (0.068) were obtained for BW, FW and FD, respectively. Positive phenotypic correlations were obtained between BW and FW [0.572 (0.010)], BW and FD [0.548 (0.010)] and FW and FD [0.568 (0.010)]. Estimates of genetic correlations were 0.668 (0.058) between BW and FW, 0.558 (0.057) between BW and FD and 0.551 (0.068) between FW and FD.

Estimation of Genetic Parameters by Restricted Maximum Likelihood under Multi-trait Animal Models in Selected Layer Lines.

Genetic parameters for body weight at 256 days (BW), age at first egg (SM), egg weight at 252 days (EW) and egg production efficiencies between 169-280 days (EPA) and between first egg and 280 days (EPB) were estimated in five layer chicken lines selected at the National Livestock Improvement Center, Okazaki Station, between 1986 and 1994. The lines were three White Leghorn lines (E1, E4 and S46), one recessive White Rock line (L17) and one Rhode Island Red line (Y8). Parameters were estimated by restricted maximum likelihood procedure under the expectation maximization algorithm using multiple trait animal models. The model included year and house as fixed effects, inbreeding as a covariate and random additive genetic effects.Estimates of heritability differed slightly between lines and, for BW, SM, EW, EPA and EPB were between 0.51-0.65, 0.35-0.47, 0.51-0.60, 0.13-0.19 and 0.20-0.27 respectively with weighted average heritabilities of 0.58, 0.44, 0.56, 0.17 and 0.23 respectively. Genetic correlations between EPA and EPB were expectedly high at between 0.80 and 0.93 while the genetic correlations between these two traits and the other traits were low and negative except with BW where the correlations were low but positive. Estimated heritabilities and, especially, the correlations were different among lines and from those assumed at the station for making the desired gain indices which indicates the importance of estimating variance and covariance components in each line for use in making selection decisions.

Rates of change of genetic parameters of body weight in selected mouse lines

A method based on the animal model is described which allows the estimation of continuous changes in variance components over time using restricted maximum likelihood (REML). The method was applied to the analysis of a selection experiment in which a foundation population formed from a cross between two inbred strains of mice (C57BL/6J and DBA/2J) was divergently selected for 6 week body weight over 20 generations. The analysis suggested that there was an increase in phenotypic variance of about 50% in the low selected lines over the course of the experiment which was attributed to increases in the environmental and additive variance components. Variance changes in the High selected lines were generally smaller than in the Low lines, although there was an estimated 20% increase in the environmental variance. Simple models to explain these effects involving dominance, linkage and epistasis were explored. Testing which of these was responsible for the variance changes noted in this experiment (if any) is difficult, although the epistasis and dominance models require less stringent conditions than the linkage model, and the dominance model is supported by evidence of heterosis in the F1.

Genetic parameters for body weight and growth in Dutch Black and White replacement stock

Abstract Genetic parameters for body weight and growth were estimated using data on 631 Black and White growing dairy heifers, from 60 sires, and born between 1982 and 1990. Body weights were collected monthly and by linear interpolation adjusted to weights at 10, 20, 30, 40 and 50 weeks of age, at breeding, at 26 and 13 weeks before calving and at calving. Also weight at 2 days after calving was recorded. Heifers were fed a restricted amount of concentrate and ad libitum roughage. Data were analyzed using an animal model, considering year-season, parity of dam, and genetic group as fixed effects. Average age and weight at calving were 733 days and 508 kg, respectively. Unadjusted average daily gains from birth to 50 weeks of age and from breeding to calving were 731 (SD 68) and 527 (SD 107) g day −1 , respectively. Heifers born from second and third parity dams were on average 3.1 and 5.2 kg heavier than heifers born from first parity dams. Heifers with > 80–100% HF genes were nearly 30 kg heavier at calving than 100% DF heifers. Heritabilities for body weights ranged from 0.41 to 0.64. Growth from birth to 50 weeks had a heritability of 0.48, while growth during pregnancy had a heritability of 0.19.

Genetic parameters of body weight, egg production and shell quality traits in the Brown Tsaiya laying duck

Parametres genetiques des caracteres de poids corporels, de production d'œufs, et de qualite de la coquille chez la cane pondeuse Tsaiya Brune. Les heritabilites et correlations genetiques ont ete estimees pour 5575 pondeuses Tsaiya Brune, sur la base de performances concernant les 5 premieres generations d'une experience de selection par la methode du REML-MM (maximum de vraisemblance restreinte-multivariate multimodele) appliquee a un modele animal sur 12 caracteres: la longueur de la plume a l'âge de 20 sem (FL20), le poids corporel a 20 et 40 sem (BW20; B W40), l'âge au premier œuf (AGE1EGG), les nombres d'œufs a 40 et 52 sem (NEGG40; NEGG52), la solidite de la coquille a 30 et 40 sem (ES30; ES40), le poids des œufs a 30 et 40 sem (EW30; EW40), le poids des jaunes d'œufs a 40 sem (EYW40) et le rapport du poids de l'œuf au poids corporel a 40 sem (EW40/BW40). Les femelles adultes etaient plus lourdes que les mâles (BW40: 1 391 vs 1 310 g). ES40 etait inferieure a ES30 (3,5 vs 3,8 kg/cm 2 ). Les valeurs d'heritabilite d'ES40, ES30, NEGG52, NEGG40, FL20, EYW40 et AGE1EGG etaient faibles: 0,094; 0,107; 0,118; 0,160; 0,169; 0,191 et 0,201 respectivement. Elles etaient de 0,327; 0,329; 0,353; 0,425 et 0,499 pour EW40/BW40, EW40, EW30, BW20 et BW40. Cinquante correlations genetiques sont tabulees. NEGG52 etait fortement correle avec NEGG40 (rg = 0, 948), mais n'etait pas correle avec les poids corporels et etait correle negativement avec AGE1EGG (rg = -0, 749), EW40 (rg = -0, 323), EW30 (rg = -0,200), EYW40 (rg = -0,340), ES30 (rg = -0,194), ES40 (rg = -0,203), FL20 (rg = -0,131) et EW40/BW40 (rg = -0, 259). Les poids des œufs, les poids corporels et les caracteres de la solidite de la coquille etaient positivement correles entre eux. Les resultats suggerent qu'une selection sur un index lineaire pour NEGG52 avec des contraintes pour EW40, BW40 et ES40 pourrait etre efficace pour ameliorer les performances de la production d'œuf de la cane Tsaiya Brune.

Genetic parameters of body weight, egg production and shell quality traits in the Brown Tsaiya laying duck

Genetic parameters of body weight, egg production and shell quality traits in the Brown Tsaiya laying duck

The genetics of body weight and its effect on early maturity based on individually tagged rainbow trout ( Oncorhynchus mykiss)

The effect of sex and temperature on body weight, the effect of body weight on age of maturity, and genetic parameters for body weight at ten ages were investigated for progeny from 18 two-year females and 54 yearling males through 740 days post-fertilization. Sexes were classified into three categories: females, early maturing males (E-males), and other males (T-males). E-males were significantly heavier than T-males and formed a disproportionate percentage of the heaviest males at ages prior to maturity the first year. However, T-males were significantly heavier than E-males after the E-males passed first maturity, and they were heavier than females between 362 and 628 days. Members of each full-sib family were placed into low and high temperature treatments. Temperature significantly influenced body weight at all ages except 278, 362, and 740 days. By increasing body weight, the high temperature treatment produced almost three times the proportion of E-males as the low temperature treatment. Genetic parameter estimates were obtained using derivative-free restricted maximum likelihood techniques to analyze a mixed, additive genetic and maternal model. Additive genetic, maternal, and residual variances were estimated as well as the additive genetic-maternal covariance. Heritability estimates ranged from 0.21 to 0.53 and were highest at young ages and lowest at later ages. The ratio of maternal to phenotypic variance was consistent and low, ranging between 0.02 and 0.03. However, additive genetic-maternal correlations varied considerably with age. They were all positive and ranged from 0.28 to 1.00; only three estimates, at 278, 398 and 740 days, were above 0.53. Genetic correlations between body weights at seven ages ranged from 0.19 to 0.95 and phenotypic correlations ranged from 0.29 to 0.94. Genetic and phenotypic correlations were consistently high between contiguous ages (0.74 to 0.95) and generally decreased as the difference between ages increased. The evidence supported the hypothesis of a strong positive relationship between body weight and early maturity based on numerous genetic parameters estimated for body weight. The availability of such information will facilitate genetic decision making.

Estimation of changes in genetic parameters in selected lines of mice using REML with an animal model. 2. Body weight, body composition and litter size.

Restricted Maximum Likelihood (REML) with an animal model was used to estimate genetic parameters of body weight, body consumption and litter size of lines of mice selected for 20 generations on an index of lean mass at 10 weeks in males, highly correlated with body weight, and for a further 18 generations on body weight at 10 weeks in males and females. Univariate and multivariate estimates of heritability were about 0.5 and those of common environment correlations were about 0.25 for both body weight and composition. Body weight and fat pad weight had genetic and phenotypic correlations of about 0.5. The heritability estimate of litter size was about 0.15 from univariate analysis, rather lower from multivariate, and the estimate of its genetic correlation with body weight was about 0.25. There were reductions in heritability of both body weight and litter size in later generations, even though full pedigrees were fitted and inferences made to the base population, but a plateau in response to selection for increased body weight could not be explained by a complete attenuation of genetic variance.

Genetic parameters for body weight, scrotal circumference, and serving capacity in beef cattle

Abstract Data from a large Hereford bull breeding herd in South Canterbury, New Zealand, were analysed to estimate genetic parameters for liveweights and three reproductive traits. The records comprised yearling weight (YW) in both sexes, 18-month (final) weight (FW) on bulls, scrotal circumference (SC), and serving capacity of bulls recorded in two ways, first as the number of serves in a standard time (serving number, SN), and second as a grade (serving grade, SG). There were 8 years of data available (1982–89 calf crops), comprising 2414 YW records from both sexes (progeny of 63 sires) and 1090 and 923 SC and SN records respectively. Restricted maximum likelihood (REML) procedures were applied to each trait, with a numerator-relationship matrix to incorporate pedigrees of paternal grand-sires. Univariate heritability estimates were 0.17 ± 0.06 (YW), 0.21 ± 0.09 (FW), 0.36 ± 0.13 (SC), 0.15 ± 0.07 (SN), and 0.14 ± 0.07 (SG). Phenotypic and genetic correlations were about 0.5 between liveweights (YW or F...

Estimates of genetic parameters of body weight in descendants of X-irradiated rat spermatogonia.

Effects of nine generations of 450r per generation of ancestral spermatogonial X irradiation of inbred rats on genetic parameters of body weight at 3, 6, and 10 weeks of age and of weight gains between these periods were studied. Covariances among relatives were estimated by mixed model and regression techniques in randomly selected lines with (R) and without (C) radiation history. Analyses of the data were based on five linear genetic models combining additive direct, additive indirect (maternal), dominance and environmental effects. Parameters in these models were estimated by generalized least-squares. A model including direct and indirect genetic effects fit more closely to the data in both R and C lines. Overdominance of induced mutations did not seem to be present. Ancestral irradiation increased maternal additive genetic variances of body weights and gains but not direct genetic variances. Theoretically, due to a negative direct-maternal genetic correlation, within full-sib family selection would be ineffective in increasing body weight at six weeks in both R and C lines. However, progress from mass selection would be expected to be faster in the R lines.

Inheritance of Body Weight in Japanese Quail

Two generations of Japanese quail were weighed in order to estimate genetic parameters of body weight throughout the growth phase of the life cycle. Sexual dimorphism became evident at the age of sexual maturity. This was due to an acceleration of weight gains by females just prior to laying their first egg. Body weight at 1 day of age reflected a large maternal influence which rapidly declined with age. Unrealistic estimates of the heritability of female body weight were obtained at the time of sexual maturity. At other ages heritability estimates of body weight were generally moderate to high. All phenotypic correlations between weights at various ages were positive, with the magnitude generally decreasing as the interval between weighings increased. Genotypic correlations were larger and followed the same general trends as phenotypic correlations with certain exception, namely when one of the ages was day 1 and when the ages involved maturity of females.