Heritability Estimates For Growth Traits Research Articles

Heritability Estimates for Growth Traits and Correlation Analysis between Weight and Metamorphosis Rate in the Bullfrog Rana (Aquarana) catesbeiana

Metamorphosis is a crucial process in the life cycle of Rana (Aquarana) catesbeiana. R. catesbeiana tadpoles, in their short larval period, possess a high survival rate and also a highly competitive ability in the amphibious stage. In actual seed production, the economic traits of larval period and metamorphosis rate are used as quantifiable indicators of quality for individuals and populations, respectively. However, studies of these economic traits in larval cultivation and production are still lacking. In this study, we constructed 40 full-sib families of R. catesbeiana and measured the weight and metamorphosis rate of tadpoles at different developmental stages. Subsequently, we calculated the phenotypic and genetic association between weight and metamorphosis rate in tadpoles and assessed the heritability of these two traits. The heritabilities of weight at three developmental stages were all higher than 0.40 and decreased with advancement of the developmental stage; the heritability of the metamorphosis rate was 0.18 ± 0.20, a moderate level. Correlation analysis of weight and metamorphosis rate at each developmental stage in each tadpole family showed that weight at stages 25-I, 25-II, and 25-III was significantly correlated at the phenotypic level but non-significantly at the genetic level. The metamorphosis rate was only moderately associated with stage 25-III weight (0.38, p < 0.05). The results of this study confirm the importance and transportability of tadpole weight in actual seed production and provide basic data and a potentially optimized direction for the selective breeding of high-metamorphosis-rate bullfrogs.

A meta-analysis of genetic parameter estimates for growth traits in fat-tailed sheep

This study aimed at using a random-effects model of meta-analysis to compile the estimates of direct heritability, maternal heritability, the ratio of the permanent environmental variance to phenotypic variance, the correlation between direct and maternal genetic effects for growth traits (body weights, average daily gains, and Kleiber ratios), and also genetic correlations among these traits in fat-tailed sheep. A total of 458 direct heritability estimates, 260 maternal heritability estimates, 217 estimates of the ratio of the permanent environmental variance to phenotypic variance, 144 estimates of the correlation between direct and maternal genetic effects, and 349 genetic correlations from articles which were published between 1978 and 2021 were used in the meta-analysis. Chi-square (Q) test was performed to measure heterogeneity and the I2 statistic was determined. The average direct heritability estimates for the studied traits were low to moderate and ranged from 0.108 (for Kleiber ratio from three to six-months of age (KR3–6)) to 0.258 (for Kleiber ratio from birth to six-months of age (KR0–6)). The average maternal heritability estimates for growth traits were low and varied from 0.056 (for KR3–6) to 0.142 (for birth weight (BW)). The average correlation estimates between direct and maternal genetic effects for growth traits were negative and varied from −0.826 (for KR3–6) to −0.039 (for three-months weight (3 MW)). The genetic correlation estimates between BW and other traits were low to moderate and ranged from 0.089 (between BW-KR0–3) to 0.472 (between BW-3 MW). Also, the genetic correlation estimate between 3 MW and average daily gain from three to six-months of age (ADG3–6) was low (0.187) and not significant, but genetic correlation estimates between 3 MW and other traits were moderate to high and varied from 0.637 to 0.853 (P < 0.05). The meta-analysis showed that growth traits in fat-tailed sheep were under low to moderate genetic control. The average genetic parameter estimates obtained in this study could be utilized in the genetic selection plans for fat-tailed sheep, especially when there is limited access to accurate phenotypic records or genetic parameter estimates for the studied traits.

Genetic and non-genetic parameter estimates for growth traits and Kleiber ratios in Dorper × indigenous sheep

Genetic improvement programme will only be successful when accompanied by a good understanding of the influence of different environmental factors, knowledge of the genetic parameters and the genetic relationships between the traits of interest. This study aimed to evaluate the influence of non-genetic factors on growth traits and Kleiber ratios and to estimate genetic parameters for early growth traits in Dorper × indigenous crossbred sheep. The effects of fixed factors were analysed by the general linear model procedure of statistical analysis system, while the genetic parameters were estimated using a WOMBAT computer program fitted animal model. The overall least-square mean for birth weight (BRW), weaning weight (3MW), six-month weight, nine-month weight, and yearling weight were 3.03 ± 0.02, 14.5 ± 0.18, 20.4 ± 0.26, 24.8 ± 0.31, and 28.3 ± 0.40 kg, respectively. The overall least-square mean for Kleiber ratio from birth to weaning (KR1), weaning to six months, six to nine months and nine months to yearling age were 16.8 ± 0.10, 6.41 ± 0.17, 4.55 ± 0.21 and 3.38 ± 0.20 g/kg of metabolic weight, respectively. The inclusion of maternal genetic effect had a significant influence on BRW, and it explains 20% of the phenotypic variation. The total heritability estimates for BRW, 3MW, birth to weaning average daily weight gain and KR1 were 0.10, 0.14, 0.16 and 0.12, respectively. The phenotypic correlation varied from −0.11 ± 0.05 to 0.98 ± 0.02, whereas the direct genetic correlation ranged from −0.32 ± 0.40 to 0.98 ± 0.17. The mean inbreeding coefficient was 0.105% with an annual rate of 0.02%. The heritability estimates for growth traits and Kleiber ratio suggest that slow genetic progress would be expected from the selection. However, the integration of selection with crossbreeding programme can enhance genetic gain. Therefore, selection should be conducted based on breeding values estimated from multiple information sources to increase the selection response.

English

The objective of this study is to estimate variance-covariance components and genetic parameters for growth traits in Tswana cattle. Genetic analyses for average daily gain (ADGs) and growth traits were conducted using 7223 records of animals which were born between 1996 and 2013 from 1662 dams and 188 sires in 54 contemporary groups. Both univariate and bivariate animal models were used. Heritability estimates for growth traits ranged from 0.12&plusmn;0.03 for BWT to 0.45&plusmn;0.03 for EWT while those obtained for ADGs were 0.24&plusmn;0.03 and 0.31&plusmn;0.04 for ADG1 and ADG2, respectively. Permanent maternal environmental effects were significant for WWT and ADG1. Substantial maternal genetic effects were observed in BWT, WWT and ADG1. Genetic correlations among growth traits and ADGs ranged from 0.19&plusmn;0.07 between BWT and ADG1 to 0.99&plusmn;0.02 between WWT and ADG1. Phenotypic correlations among growth traits and ADGs ranged from 0.19&plusmn;0.01 between BWT and ADG1 to 0.94&plusmn;0.01 between WWT and ADG1. The two selected lines significantly improved annual genetic gain for all the growth traits and ADG1. Genetic gain for EWT was optimally enhanced in S2 than in S1. The control line exhibited significant annual genetic gain in WWT which was not anticipated and perhaps attributed to asymmetry of selection response. Substantial genetic variations were observed in all growth traits and ADGs suggesting that growth improvement can be attained through selection for growth rate. High genetic correlations between growth traits and ADGs indicated that selection for one of these traits may result in indirect correlated response on the other traits. Key words: Bivariate analysis, genetic correlations, heritability, indigenous cattle, maternal effects, genetic variation.

Meta-analysis of genetic parameters for traits of economic importance for beef cattle in the tropics

Previous genetic and economic evaluation of beef cattle breeding programmes have used genetic and phenotypic parameter estimates obtained in different studies. Such parameters are heterogeneous because they are obtained from different locations, using different sample sizes and estimation methods. The consequence of using such parameters is underestimation or overestimation of potential genetic gains, leading to wrong investment decisions. The objective of the current study was to estimate consensus genetic and phenotypic parameter estimates for beef cattle in the tropics. Meta-analysis of productive, reproductive, adaptation and disease resistance traits was done to obtain weighted traits means, heritabilities, and genetic and phenotypic correlations. Estimates from 208 means, 119 direct and 50 maternal heritability, 42 direct genetic and maternal genetic correlations, 136 genetic and 93 genetic and phenotypic correlations, respectively, were used. A random effect model was used to include the variances within and between studies. Unweighted average direct heritability estimates ranged from 0.26 to 0.32, 0.08 to 0.40, 0.14 to 0.34, 0.18 to 0.67 and 0.30 to 0.35 for growth, reproduction, disease resistance, adaptation and carcass traits, respectively. Weighted heritability estimates for birth weight, weaning weight and yearling weight ranged from 0.18 to 0.26, while those for reproduction traits ranged from 0.02 to 0.09. Weighted maternal heritability estimates for growth traits ranged from 0.07 to 0.11. Carcass, disease resistance and adaptation traits were the least studied despite their great economic importance to beef production in the tropics. Direct maternal heritability estimates for birth, weaning and yearling weights were 0.26, 0.24 and 0.18, while the corresponding maternal heritability estimates were 0.07, 0.11 and 0.08, respectively. Genetic and phenotypic correlations for body weights ranged from 0.43 to 0.88 and 0.32 to 0.80, respectively. Yearling weight and final weight had the highest genetic correlation (0.88). The genetic correlations between body weights and growth rates were moderate to high (0.37 to 0.79). Weaning weight was negatively correlated with post-weaning daily gain (-0.12). Disease resistance traits had low to negative genetic correlations with body weight and growth rate traits (-0.06 to 0.01). Some traits reviewed in the current study were not given a lot of attention, and therefore more focus is required on disease resistance, adaptation and carcass traits. In spite of these limitations, the weighted parameter estimates reported here can be used to add value to beef cattle improvement programmes in the tropics.

Genotype by environment interactions for inner shell color and growth traits in the purple freshwater pearl mussel, Hyriopsis cumingii, reared with different water depths and mud substrates

A breeding selection program for improving inner shell color and growth was developed for Hyriopsis cumingii, to enhance purple pearl production. In freshwater pearl culture, adjusting culture water depth and mud substrate supply are routinely carried out to improve pearl quality. To improve selection decisions in different conditions, we estimated heritabilities and genotype by environment (G × E) interactions on inner shell color and growth traits in 1571 17-month-old animals from 8 half sib family of purple selective strain of H. cumingii reared in different water depths (WD1, 32 cm; WD2, 48 cm) and mud substrates (MS, mussel pond mud substrate; SS, shrimp pond mud substrate) were analyzed. With the same mud substrate, H. cumingii reared at WD1 showed increased performance in shell color and growth. Heritability estimates for growth traits (shell length, shell height, shell width, body weight and shell weight) were higher at WD1 and higher at WD2 for inner shell color parameters (L, a, band dE⁎) when rearing in MS, while showed opposite pattern in SS. At the same water depth, H. cumingii reared with MS showed better performance in shell color and growth traits. Heritability estimates for growth traits were higher in SS and higher in MS for inner shell color parameters when rearing at WD1, while showed opposite pattern at WD2. Heritability estimates for L, a and all growth traits were moderate and high (h2 > 0.15), while were low for b and dE⁎ (h2 < 0.15). Genetic correlations for inner shell color parameters and growth traits within the four conditions were less than 0.8, except that some combinations of depth and mud substrate with over 0.9 for shell growth traits and shell color traits showed significant G × E correlations. The rank of individuals with comprehensive breeding value was different in four conditions, and the percentage of individual family sources shared in some pair conditions were small, which indicated re-ranking during selective breeding program. This study provides guidelines for a selective breeding strategy for improving inner shell color and growth in H. cumingii when mussels are reared under different conditions

Genetic parameters for growth and survival traits in a base population of Pacific white shrimp (Litopenaeus vannamei) developed from domesticated strains in China

A base population containing broad genetic variation provides a fundamental resource for a successful genetic improvement program. Here, we assess quantitative data on growth traits taken from the base population of Pacific white shrimp. Body weight was scored at two ages (BW1 and BW2) from 2752 and 2452 individuals, representing 89 full-sib families. Estimated heritabilities (h2 ± SE) for BW1, BW2 and survival (S) were 0.52 ± 0.09, 0.44 ± 0.07, and 0.01 ± 0.02, respectively. The genetic correlation between growth traits (BW1 and BW2) was 0.95, a result significantly different from zero. Genetic correlations between survival and body weight were low however, 0.26 (S vs BW1) and 0.18 (S vs BW2), respectively. The SA_1 strain from South Asia showed the best performance for both growth rate and survival in the test tank systems. High heritability estimates for growth traits confirm that a substantial component of additive genetic variance is available for growth in our L. vannamei culture line families in China prior to imposing genetic selection to improve relative productivity.

Genetic parameters and genotype-environment interaction for growth traits of North African catfish, Clarias gariepinus (Burchell, 1822)

Aquaculture of North African catfish, Clarias gariepinus (Burchell, 1822) (Cg) has been widely practiced with global production sharply increasing by almost three folds in the past decade (FAO, 2018). Despite its advantageous growth rate and disease resistance, the genetic potential has not been fully exploited. Therefore, this research was conducted to estimate genetic parameters of growth traits of Cg in Thailand and to estimate the interaction of genetics and environment when it is cultured in different pond-types. Three genetically distinct stocks of Cg were crossed following a factorial mating design (a male mated with 2–3 females, each from different strains) which resulted in a total of 90 full-sib and 29 half-sib families. The fry were separately reared in two replicate hapas until 98 days after hatching (DAH) and were then tagged using elastomers and communally reared in two environments, namely earthen ponds and circular polyethylene (PE) tanks, each with two replicates. Body measurements were made when the fish reached market size (BW~300 g, 138 DAH) and genetic analyses were performed using an animal model. The results showed significant differences in body size and growth rate among families. Heritability estimates for the growth traits (body weight, BW; total length, TL; and standard length, STL) were high (0.49–0.51) at 98 DAH, while heritability for condition factor (K) was 0.06 ± 0.01. At 138 DAH, the heritability estimates for growth traits were slightly lower than at 98 DAH. Heritability (h2) estimated for the two environments were equal for body length, and slightly different for BW (PE-tanks: h2BW = 0.35 ± 0.07; h2TL = 0.34 ± 0.07, h2STL = 0.29 ± 0.07; earthen ponds: h2BW = 0.25 ± 0.06; h2TL = 0.34 ± 0.07, and h2STL = 0.29 ± 0.07). Heritability for K was higher in the PE-tanks (h2K = 0.31 ± 0.07) than in the earthen ponds (h2K = 0.11 ± 0.04). Genetic correlation of the same traits between the two environments was high for all traits and hence suggested no G × E interaction for growth traits in Cg. The results suggested that selective breeding of this population would give substantial selection response, and the improved strain derived from the PE-tank environment would perform similarly in earthen ponds.

Genetic parameters estimates for growth performance traits at harvest in Japanese flounder (Paralichthys olivaceus)

Despite Japanese flounder (Paralichthys olivaceus) is of importance in aquaculture of Northeast Asia, selective breeding programs for growth performance traits remain limited. The aim of this study was to estimate parameters of growth performance traits in this species. The heritabilities, genetic and phenotypic correlations, and breeding values were estimated for body weight (BW), total length (TL), condition factor (K), and average daily gain (ADG). The genetic analyses were performed on a total number of 186 full-sib families (108 sires and 146dams, 16,807 individuals with integrated pedigree information) from 4 year-classes based on three mixed animal models with tank and year-class as fixed effects, mean family trait values at tagging as a covariate, and additive genetic effect as a random effect using the restricted maximum likelihood method. For all growth traits the maternal and sir-dam interaction effects in proportion to phenotypic variance were very low (0.00–0.05). The heritability estimates for growth traits ranged from 0.12 to 0.39, which is in a low to moderate level. These results indicated that there is a considerable additive genetic variation in growth traits, and the ongoing selective breeding project will produce considerable genetic improvement in growth traits of Japanese flounder. The genetic and phenotypic correlations among BW, TL and ADG were high and positive (0.87–0.94, P < .001). However, the correlations between K and other three traits were low to moderate (−0.10–0.58, P < .001). These data indicate that these traits (except K) could be selected and enhanced simultaneously and also imply that direct selection of TL, which is an easily measurable trait, will be more favorable than selection on BW and ADG. The estimated breeding values of parents and individuals and the average family breeding values for 4 traits were obtained. In summary, all the findings in this study will be of significance to optimize the flounder selective breeding program. Statement of relevanceThis paper offers guidelines to select breeding strategy in Japanese flounder.

Genetic parameters for growth and survival traits in Litopenaeus vannamei at different ages

The aim of the current study was to estimate the genetic parameters for growth and survival tolerance traits in Litopenaeus vannamei at different ages (weeks 6, 10, 14, and 18). Sixty-five full-sib families (including 30 half-sib families) of L. vannamei, which were produced by 50 sires and 65 dams, were obtained by artificial insemination. There were a total of 6500 tagged shrimps representing 65 full-sib families evaluated for growth and survival traits in this study. The heritability estimates for growth traits were moderate to high (0.24 to 0.46), which suggested that selection for increasing growth traits were feasible, but the heritability of survival traits estimated on the observed scales were also low (0.01 to 0.06). The genetic correlations between growth traits (including body length and weight) within age were all positive and high, which ranged from 0.82 to 0.95 (P < 0.01). A significant correlation between growth traits showed that only selecting one growth trait for better growth and other correlated traits can be improved simultaneously. The genetic correlation between growth and survival traits within age were positive (0.02 to 0.05) at the early life stage and negative (−0.06 to −0.22) at later growth phase, which indicated that selecting for growth traits may not cause a positive correlated response in survival traits. Our results also showed that the uniformity ratio and correlation coefficient of families at adjacent growth stage increasing with age, which suggested that selection applied at early stage may result in only poor response and selection after week 14 can increase selection accuracy and accelerate the breeding process.

Genetic Parameters for Growth and Hypoxic Tolerance Traits in Pacific White Shrimp Litopenaeus vannamei at Different Ages

AbstractThe aim of the current study was to estimate the genetic parameters for growth and hypoxic tolerance traits in Pacific white shrimp Litopenaeus vannamei at 8 and 13 weeks of ages. Forty full‐sib families (including 28 half‐sib families) of L. vannamei, which were produced by 26 sires and 40 dams, were obtained by artificial insemination. There were a total of 3,200 tagged shrimps representing 40 full‐sib families evaluated for growth and hypoxic tolerance traits in this study (1,600 records were collected at weeks 8 and 13, respectively). The heritability estimates for growth traits were low to medium (0.11–0.23), and the heritability of hypoxic tolerance traits estimated on the observed scales was also low to medium (0.07–0.15), which suggested that selection for increasing growth and hypoxic tolerance traits was feasible. The genetic correlations between growth traits (including carapace length, abdominal segment length, body length, and body weight) within age were generally high, ranging from 0.84 ± 0.06 to 0.95 ± 0.02 (P &lt; 0.05). A significant correlation between growth traits showed that any growth traits can be replaced by other growth traits for indirect selection. The genetic correlation between growth traits and hypoxic tolerance traits within age was low but positive (0.24–0.29), which indicated that selecting for growth traits will cause a positive correlated response in hypoxic tolerance traits. Our results also showed that there was a relatively low genetic correlation between growth traits at different ages (0.18–0.25), which suggested that selection for growth traits in L. vannamei at an early age may not be optimal and should be undertaken at later stages of growth.

Heritability Estimates for Growth Traits in the Nigerian Local Chicken

Heritability Estimates for Growth Traits in the Nigerian Local Chicken

Genetic parameter estimates for growth of grass carp, Ctenopharyngodon idella, at 10 and 18 months of age

The aim of this study was to estimate the growth trait parameters in grass carp, Ctenopharyngodon idella, which is one of the major freshwater aquaculture species in China. The heritability, genetic and phenotypic correlations were estimated for body weight, standard length, body height and body thickness measurements of 10 and 18month old fish. Analyses were performed on a total of 41 and 104 full-sib families of grass carp including 937 and 2454 individuals at 10 (first spring) and 18months (second winter) of age, respectively. The families were reconstructed using the molecular pedigree based on twelve microsatellite loci, and 97.6% of the offspring were unambiguously assigned to single parent pairs. Unbalanced contributions to progeny were found among families and parents (P<0.01). Variance components and genetic parameters were estimated using the restricted maximum-likelihood algorithm with animal models. For all growth traits across two stages of grass carp, the common environment/maternal effect in proportion to phenotypic variance was very low (0.00–0.06), and not significant (P>0.05). The heritability estimates for growth traits ranged from 0.24 to 0.38, and were significantly different from zero (P<0.01). These results indicated that the breeding population had considerable additive genetic variation in growth traits, and the ongoing selective breeding program should produce considerable genetic improvement in the growth traits of the grass carp. High genetic and phenotypic correlations were found among growth traits (0.81–0.99, P<0.01). These data indicate that selection for improved standard length will have a favorable effect on body weight in grass carp which is the key economic parameter for production yield. High and positive genetic correlations between growth traits at 10 and 18months of age were also detected in grass carp (0.87–0.95, P<0.01), which indicated that individuals with higher growth performance at 10months also grew to be better at 18months. The results showed that genetic differences in growth traits among grass carp progeny could be determined earlier by measuring indicator traits predictive of long-term genetically determined growth. Statement of relevanceOur article comply with the Policy Statement for submission of manuscripts to the Genetic Section.In this study, we aim to estimate the genetic parameters of growth traits in grass carp, Ctenopharyngodon idella, which is one of the major freshwater aquaculture species in China.The heritability, genetic, and phenotypic correlations were estimated for growth traits of grass carp at 10 and 18months. Our study is an essential report on the quantitative genetic analysis of growth traits in sub-adult grass carp.This paper has not been submitted to any other journal for publication. The authors can confirm that the study has no actual or potential conflicts of interest to report. All authors have read and agreed the contents of the manuscript and consent to its publication.

Genetic relationship between growth and carcass traits in Large White pigs

Genetic relationships between growth and carcass traits in South African Large White pigs were estimated. Genetic parameters for growth and carcass traits were generated using a maternal effects model in ASREML. Data analysed were on 13 703 pigs from 28 herds tested between 1990 and 2007, and 4 128 carcasses from 21 herds evaluated between 1993 and 2007. The traits included in the study were backfat thickness (BFAT), test period weight gain (TPG), lifetime weight gain (LTG), test period feed conversion ratio (FCR), age at slaughter (AGES), lean percentage (LEAN), drip-free lean percentage (DLEAN), drip loss percentage (DRIP), carcass length (CRLTH), dressing percentage (DRESS), eye muscle area (AREA) and carcass fat (CFAT). Heritability estimates for growth traits ranged from 0.24 ± 0.03 for FCR to 0.45 ± 0.04 for BFAT, while those for carcass traits ranged from 0.14 ± 0.06 for DRIP to 0.55 ± 0.0.08 for AREA. Maternal genetic effects were significant in most traits, and were negatively correlated with direct heritabilities. Genetic correlations among growth traits ranged from –0.14 ± 0.08 between BFAT and LTG to –0.99 ± 0.01 between TPG and FCR, and LTG and AGES. For carcass traits, genetic correlations ranged from –0.02 ± 0.20 between DRIP and CRLTH to 0.99 ± 0.01 between LEAN and DLEAN. There is substantial genetic variation in growth and carcass traits; hence faster genetic improvement may be achieved through selection. Growth performance and carcass characteristics can be improved through selection for reduced backfat thickness and increased daily weight gain. Keywords : Genetic selection, growth traits, carcass traits, correlations

Genetic parameters and efficiency of early selection for half rotation-aged growth and form traits in Pinus taeda in China

AbstractGenetic parameters for height (H), diameter at breast height (DBH), stem straightness (STR), and under crown clear bole height (CH) of loblolly pine (Pinus taeda L.) were estimated for 255 families (209 open pollinated (OP) and 46 controlled pollinated (CP) families) using a family model and an individual tree model at age 1, 2, 3, 5, 11, and 15 years. Heritability estimates for growth traits of individual trees at age 11 years were the highest (0.17-0.78), and those at age 15 years were the lowest (0.05-0.74). Heritability estimates for DBH, STR, and CH were lower than those for H. Genetic correlations between H and DBH were generally strongly positive, attained a maximum values at age 2 to 3, and declined slightly thereafter. The genetic correlations between CH at age 11 and both H and DBH at different ages were moderate. Age-age genetic correlations for growth traits were moderate to high (0.56-0.91) at age 5 for half-rotation age (15 years), indicating the opportunity exists for early selection. Indirect selection from the age 5 to 11 years for H and DBH could be expected to produce gains of over 50% and 35% respectively, for these two ages, relative to direct selection at age 15. Efficiencies of early selection for H and DBH indicated that growth at maturity could be improved by early selection.

Genetic and phenotypic parameters and annual trends for growth and fertility traits of Charolais and Hereford beef cattle breeds in Kenya

This study estimated genetic and phenotypic parameters and annual trends for growth and fertility traits of Charolais and Hereford cattle in Kenya. Traits considered were birth weight (BW, kg), pre-weaning average daily gain (ADG, kg/day) and weaning weight (WW, kg); calving interval (CI, days) and age at first calving (AFC, days). Direct heritability estimates for growth traits were 0.36 and 0.21; 0.25 and 0.10; 0.23 and 0.13 for BW, ADG and WW in Charolais and Hereford, respectively. Maternal heritability estimates were 0.11 and 0.01; 0.18 and 0.00; 0.17 and 0.17 for BW, ADG and WW in Charolais and Hereford, respectively. Direct-maternal genetic correlations ranged between -0.46 and 1.00; -0.51 and -1.00; -0.47 and -0.39 for BW, ADG and WW in Charolais and Hereford, respectively. Genetic correlations ranged from -0.99 to unity and -1.00 to unity for growth and fertility traits respectively. Prospects for improvement of growth and fertility traits exist.

Direct and maternal (co)variance components and genetic parameters for growth and reproductive traits in the Boran cattle in Kenya

Direct and maternal (co)variance components and genetic parameters were estimated for growth and reproductive traits in the Kenya Boran cattle fitting univariate animal models. Data consisted of records on 4502 animals from 81 sires and 1010 dams collected between 1989 and 2004. The average number of progeny per sire was 56. Direct heritability estimates for growth traits were 0.34, 0.12, 0.19, 0.08 and 0.14 for birth weight (BW), weaning weight (WW), 12-month weight (12W), 18-month weight (18W) and 24-month weight (24W), respectively. Maternal heritability increased from 0.14 at weaning to 0.34 at 12 months of age but reduced to 0.11 at 24 months of age. The maternal permanent environmental effect contributed 16%, 4% and 10% of the total phenotypic variance for WW, 12W and 18W, respectively. Direct-maternal genetic correlations were negative ranging from -0.14 to -0.58. The heritability estimates for reproductive traits were 0.04, 0.00, 0.15, 0.00 and 0.00 for age at first calving (AFC), calving interval in the first, second, and third parity, and pooled calving interval. Selection for growth traits should be practiced with caution since this may lead to a reduction in reproduction efficiency, and direct selection for reproductive traits may be hampered by their low heritability.

Metanálise bayesiana de parâmetros genéticos para características de crescimento em bovinos de corte

Foi conduzida uma metanálise, sob enfoque bayesiano, em um conjunto de estimativas de herdabilidade, para características de crescimento em bovinos de corte de raças indianas, com 869 estimativas de herdabilidade de efeito direto, 186 estimativas de herdabilidade de efeito materno e 123 estimativas do coeficiente de correlação genética entre os efeitos direto e materno. A construção e o desenvolvimento de um modelo hierárquico possibilitam a obtenção de estimativas combinadas de herdabilidade para as características peso ao nascimento, peso ao desmame, peso aos 365 dias e peso aos 550 dias, cujos valores são, respectivamente: 0,31, 0,24, 0,28 e 0,33 para efeitos diretos; 0,09, 0,13, 0,12 e 0,05 para efeitos maternos; e -0,16, -0,16, -0,20 e -0,16 para as correlações entre esses efeitos. A metanálise conduzida sob enfoque bayesiano mostrou-se bastante adequada, uma vez que um modelo hierárquico considera as variâncias dentro e entre os estudos, e sua implementação e condução são facilitadas em virtude, principalmente, do avanço conseguido na área computacional.

Genetic Control of Growth Traits in Shortleaf Pine in Missouri

Abstract Genetic parameters for height (HT), diameter (diameter at breast height [dbh]), and volume for a shortleaf pine (Pinus echinata Mill.) population in Missouri were estimated from a single progeny test comprising 44 half-sibling families assessed at 3, 5, 7, 10, and 17 years. Individual tree heritability estimates for growth traits at age 10 years and younger were high (0.30–0.43), and those at age 17 years were low (0.11–0.24). Heritability estimates for dbh were lower than those for HT. Family mean heritability estimates were moderate to high (0.32–0.66). Genetic correlations were higher than their phenotypic counterparts for all growth traits. Age-age genetic correlations for growth traits were moderate to high (0.68–0.98), indicating opportunity for early selection. Genetic correlations between different growth traits were high (0.81–1.00). Indirect selection on age 5- or 7-year HTs may be expected to produce over 25% more volume at 17 years compared with direct selection for volume at age 17 years. Efficiencies of selection suggest that early HT is a better selection criterion for volume at older ages than dbh because of the high heritability at young ages and strong juvenile-mature genetic correlations. Genetic gain in an unrogued seed orchard was predicted to be 6.7 and 27.2% for 10- and 17-year volume, respectively. These results suggest that growth traits in shortleaf pine in Missouri have high genetic variation, and genetic improvement was effective. South. J. Appl. For. 29(4):200–204.

Genetic and environmental parameters for traits derived from the Brody growth curve and their relationships with weaning weight in Angus cattle.

Direct and maternal genetic and environmental variances and covariances were estimated for weaning weight and growth and maturing traits derived from the Brody growth curve. Data consisted of field records of weight measurements of 3,044 Angus cows and 29,943 weaning weight records of both sexes. Growth traits included weights and growth rates at 365 and 550 d, respectively. Maturing traits included the age of animals when they reached 65% of mature weight, relative growth rates, and degrees of maturity at 365 and 550 d. Variance and covariance components were estimated by REML from a set of two-trait animal models including weaning weight paired with a growth or maturing trait. Weaning and cow contemporary groups were defined as fixed effects. Random effects for weaning weight included direct genetic, maternal genetic, and permanent environmental effects. For growth and maturing traits, a random direct genetic effect was included in the model. Direct heritability estimates for growth traits ranged from .46 to .52 and for maturing traits from .31 to .34. Direct genetic correlations between weaning weight and weights and growth rates at 365 and 550 d ranged from .56 to .70. Correlations of maternal weaning genetic effects with direct genetic effects on weights at 365 and 550 d were positive, but those with growth rates were negative. Between weaning weight and degrees of maturity at both 365 and 550 d, direct genetic correlation estimates were .55 and maternal genetic correlations estimates were -.05, respectively. Direct genetic correlations of weaning weight with relative growth rates and age at 65% of mature weight ranged from .04 to .06, and maternal-direct genetic correlation estimates ranged from -.50 to -.56, respectively. These estimates indicate that higher genetic capacity for milk production was related to higher body mass and degrees of maturity between 365 and 550 d of age but was negatively related to absolute and relative growth rates in that life stage.