Maternal Genetic Components Research Articles

Genetic parameters for direct and maternal genetic components of calving ease in Korean Holstein Cattle using animal models.

We investigated genetic parameters of calving ease (CE) using several animal models in Korean Holstein and searched for suitable models for routine evaluation of CE. Two phenotypic datasets of CE on first-parity Korean Holstein calves were prepared. DS5 and DS10 included at least 5 and 10 CE records per herd-year level and comprised 117,921 and 80,389 observations, respectively. The CE phenotypes ranged from 1 to 4, from a normal to extreme difficulty calving scale. The CE was defined as a trait of the calf. The BLUPF90+ software was used for (co)variances estimation through four animal models with a maternal effect (M1 to M4), where all models included effects of a fixed calf-sex, a fixed dam calving age (covariate), and one or more fixed contemporary group (CG) terms. The CG effects were different across models- a herd-year-season (M1, HYS), a herd-year and year-season (M2, HY+YS), a herd-year and season (M3, HY+S), and a herd and year-season (M4, H+YS). Direct heritability (h2) estimates of CE ranged from 0.005 to 0.234 across models and datasets. Maternal h2 values were low (0.001 to 0.090). Genetic correlations between direct and maternal effects were strongly negative to lowly positive (-0.814 to 0.078), further emphasizing its importance in CE evaluation models. These genetic parameter estimates also indicate slower future selection progress of CE in Korean Holsteins. The M1 fitted many levels with fewer observations per level deriving unreliable parameters, and the M4 did not account for confounded herd and animal structures. The M2 and M3 were deemed more realistic for implementation, and they were better able to account for data structure issues (incompleteness and confounding) than other models. As the pioneering study to employ animal models in Korean Holstein CE evaluation, our findings hold significant potential for this breed's future and routine evaluation development.

Estimation of direct and maternal genetic effects and annotation of potential candidate genes for weight and meat quality traits in a genotyped outdoor dual-purpose cattle breed.

With regard to potential applications of genomic selection in small numbered breeds, we evaluated genomic models and focused on potential candidate gene annotations for weight and meat quality traits in the local Rotes Höhenvieh (RHV) breed. Traits included 6,003 birth weights (BWT), 5,719 200 d-weights (200dw), 4,594 365 d-weights (365dw), and 547 records for intramuscular fat content (IMF). A total of 581,304 SNP from 370 genotyped cattle with phenotypic records were included in genomic analyses. Model evaluations focused on single- and multiple-trait models with direct and with direct and maternal genetic effects. Genetic relationship matrices were based on pedigree (A-matrix), SNP markers (G-matrix), or both (H-matrix). Genome-wide association studies (GWASs) were carried out using linear mixed models to identify potential candidate genes for the traits of interest. De-regressed proofs (DRP) for direct and maternal genetic components were used as pseudo-phenotypes in the GWAS. Accuracies of direct breeding values were higher from models based on G or on H compared to A. Highest accuracies (> 0.89) were obtained for IMF with multiple-trait models using the G-matrix. Direct heritabilities with maternal genetic effects ranged from 0.62 to 0.66 for BWT, from 0.45 to 0.55 for 200dW, from 0.40 to 0.44 for 365dW, and from 0.48 to 0.75 for IMF. Maternal heritabilities for BWT, 200dW, and 365dW were in a narrow range from 0.21 to 0.24, 0.24 to 0.27, and 0.21 to 0.25, respectively, and from 0.25 to 0.65 for IMF. Direct genetic correlations among body weight traits were positive and favorable, and very similar from different models but showed a stronger variation with 0.31 (A), −0.13 (G), and 0.45 (H) between BWT and IMF. In gene annotations, we identified 6, 3, 1, and 6 potential candidate genes for direct genetic effect on BWT, 200dW, 365dW, and IMF traits, respectively. Regarding maternal genetic effects, four (SHROOM3, ZNF609, PECAM1, and TEX2) and two (TMEM182 and SEC11A) genes were detected as potential candidate genes for BWT and 365dW, respectively. Potential candidate genes for maternal effect on IMF were GRHL2, FGA, FGB, and CTNNA3. As the most important finding from a practical breeding perspective, a small number of genotyped RHV cattle enabled accurate breeding values for high heritability IMF.

Direct and maternal genetic components for body weight traits in Markhoz goat.

The aim of the study was to estimate the (co)variance components and genetic trends of direct and maternal genetic effects in Markhoz goat using random regression (RR) models. A total of 16,283 body weight trait records from birth to 400 days of age were obtained from 3476 Markhoz kids. Kids were from 223 bucks and 1217 does raised in the Markhoz goat breeding station in Sanandaj, Iran. The fixed effects were gender, year of birth (1992-2014), age of dam (2 to 7 years old), and type of birth (single or twin). RR models based on Legendre polynomials of age at weight recording included direct and maternal genetic and permanent environmental effects. Heterogeneous residual variances were considered along age of recording. According to the Akaike information criterion (AIC), the Bayesian information criterion (BIC) and the likelihood ratio test (LRT), adding covariance between direct and maternal genetic effects, resulted in significant improvement in the level of fit. After examining models with different order of fits, the most suitable model consisted of the fourth-order polynomial for direct genetic effect and the third-order polynomial for maternal genetic, individual permanent environmental, and maternal permanent environmental effects. The direct heritabilities ranged from 0.21 at birth to 0.55 at 400 days of age. The largest (0.25) and the lowest (0.17) maternal heritabilities were estimated at birth and 60 days of age, respectively. Generally, negative direct-maternal genetic correlations were estimated between different ages, which might cause fluctuations of direct-maternal genetic trends along the years. It was concluded that selection at 100 days of age could reduce the impact of the antagonist relationship between maternal and direct genetic effects.

17 Investigating pig survival in different productive stages using genomic models

Abstract Pig survival is an economically important trait with animal welfare implications. Although survival is highly affected by the environment, previous studies reported genetic variability of this trait, indicating the opportunity for improvement through selection. Genomic information is currently included in the major commercial pig breeding programs, which can be incorporated by single-step genomic BLUP (ssGBLUP). The objectives of this study were to: 1) estimate (co)variance components for farrowing, lactation, nursery, and finishing survival; and 2) compare the individual breeding value accuracies obtained using traditional pedigree-based BLUP (BLUP) and ssGBLUP methods. Individual survival records were collected for a crossbred pig population, and two-trait threshold models, which included maternal effects, were used for (co)variance components estimation. Direct and maternal breeding values were estimated using BLUP and ssGBLUP methods, and individual accuracies were obtained based on posterior standard deviation. Heritabilities for the four survival phases were low, ranging from 0.04 to 0.12. Pre-weaning survival was controlled by dam and piglet additive gene effects. The additive direct and maternal components were equally important at farrowing, whereas the piglet’s own genetic merit was the most expressive during lactation. Common environment estimates were higher than maternal genetic effects, indicating early life experiences related to the sow, but independent of the maternal genetic component. Nursery and finishing survival showed the same or higher heritabilities compared to pre-weaning stages. The genetic correlation between the pre-weaning phases was high (0.68), whereas the correlation between the post-weaning measurements was moderate (0.42). The incorporation of genomic information through ssGBLUP increased the individual accuracy, on average, from 0.36 to 0.41 for direct and from 0.29 to 0.37 for maternal effects compared to BLUP. Although the heritabilities for survival in different productive stages are low, genetic gains can be obtained, given that breeding values benefit from the inclusion of genomic information.

193-OR: Physiology-Informed Type 2 Diabetes Genetic Clusters and Gestational Diabetes

Background: We previously described physiology-informed genetically-anchored type 2 diabetes (T2D) clusters based on associations between glycemic traits and T2D-associated variants discovered in prior GWAS. Cluster polygenic scores (PSs) delineate T2D subtypes with distinct features (e.g., reduced beta-cell function, obesity, lipodystrophy-like). These PSs have not been tested for association with gestational diabetes (GDM). Methods: We tested for associations between PSs (beta-cell, proinsulin, lipodystrophy, obesity, liver/lipid) and traits at 24-30 weeks gestation in the Gen3G cohort (N=582, 97% white non-Hispanic) with linear regression (β=change per 1 SD increase in PS). In 3 cohorts [Gen3G, HAPO (N=1369, 100% white non-Hispanic) MGH2(N=621, 62% white non-Hispanic)], we tested for associations between PSs and GDM using logistic regression and conducted fixed effects meta-analyses. Results: The beta-cell PS was associated with higher 1-hr OGTT glucose (β=4.5 mg/dl, P<0.001) and lower insulin secretory response (β=-45.7 Stumvoll 1st phase index, P=0.02). The obesity PS was associated with higher BMI (β=0.5 kg/m2, P=0.03) and HbA1c (β=0.03%, P=0.02). The lipodystrophy PS was associated with higher 1-hr OGTT glucose (β=2.6 mg/dl, P=0.03), higher fasting triglycerides (TGs) (β=6 mg/dl, P=0.01), and lower insulin sensitivity (β=-0.6 Matsuda index, P=0.005). The liver/lipid PS was associated with lower fasting TGs (β=-11 mg/dl, P<0.001). In 3-cohort meta-analyses (297 cases), only the beta-cell PS was associated with GDM (OR 1.19, P=0.009). There was heterogeneity across cohorts for the liver/lipid PS-GDM association. No PS was associated with birth weight. Adjustment for maternal age and genetic principal components did not alter results. Conclusion: Clusters of T2D-associated genetic variants derived based on physiology outside of pregnancy are associated with expected traits in pregnancy. A cluster representing reduced beta-cell function is associated with GDM. Disclosure C.E. Powe: None. M. Udler: None. S. Hsu: None. A. Kuang: None. C. Allard: None. A. Manning: None. L. Bouchard: None. P. Perron: None. J.C. Florez: Advisory Panel; Self; Doris Duke Charitable Foundation. Other Relationship; Self; Novo Nordisk Inc., Park Street School. W. Lowe: None. D. Scholtens: None. M. Hivert: None. Funding American Diabetes Association (1-15-ACE-26 to M-F.H.); National Institutes of Health (K23DK113218); Robert Wood Johnson Foundation; Harold Amos Medical Faculty Development Award (72456)

Genetic parameters of pre-weaning weights in crossbred piglets using multi-trait animal model.

Variances and genetic parameters (heritability and correlation) were estimated for pre-weaning weights from birth to 6weeks of age at weekly intervals in crossbred (Landrace X Desi) pigs. Data were analysed using multi-trait animal model incorporating dam's age (covariable), parity of sow, sex of piglet, season of birth and year of birth as fixed effects and direct additive genetic, maternal genetic and permanent litter as random effects. The estimates of direct additive genetic and maternal genetic heritability were 0.18 ± 0.04 and 0.14 ± 0.04; 0.73 ± 0.06 and 0.62 ± 0.06; 0.64 ± 0.06 and 0.37 ± 0.05; 0.42 ± 0.05 and 0.30 ± 0.05; 0.37 ± 0.04 and 0.33 ± 0.05; 0.43 ± 0.04 and 0.34 ± 0.06 and 0.47 ± 0.04 and 0.36 ± 0.05 for birth weight and subsequent weights at weekly intervals up to 6weeks, respectively. The permanent litter effect ranged from 0.02 ± 0.01 (birth weight) to 0.11 ± 0.04 (weight at first week). The estimates of correlation between direct additive genetic component and maternal genetic component (i.e. ram) were moderate to high but all negative. ram ranged from - 0.79 ± 0.15 (weight at first week) to - 0.49 ± 0.26 (birth weight). The direct additive genetic and maternal genetic correlations between birth weight and weaning weight were 0.59 ± 0.04 and 0.62 ± 0.13, respectively, which revealed sufficient scope for selection based on birth weight itself. Early weights were found to be highly heritable with due influence of maternal and permanent litter effects, and thus, appropriate selection interventions may be aimed at this stage for favourable changes at subsequent ages.

Heritability estimation and genetic correlations for mature weight, visual scores, and growth traits in Nellore cattle

ABSTRACT This study was intended to estimate the genetic associations between growth traits and visual scores with possible changes in mature weight (MW) in 397,900 Nellore animals. A bi-character analysis was performed to estimate the (co)variances and genetic parameters for MW, which comprises the following traits: conformation, finishing precocity, musculature at weaning (WC, WP, and WM) and yearling (YC, YP, and YM), birth weight (BW), weight from birth to weaning (WG), weight from weaning to yearling (YG), and final index (FIND). The observed mean MW was 417.6±56.2 kg, and the direct genetic effect mean estimated heritability (h2a1) of MW was 0.45. Overall, the BW was 31.0±3.7 kg, and the estimated h² was 0.34. The heritability estimate of the maternal additive genetic component (h2m2) of BW was 0.07. We calculated the mean WG to be 144.1±26.3 and estimated the h2a2 as 0.18 and h2m2 as 0.07. The value for h2a YG (0.17) and YW (0.26) were also estimated. The heritability of the weaning WC (0.17), WP (0.19), and WM (0.17) and yearling YC (0.25), YP (0.27), and YM (0.25) were estimated using visual scores. The h2m values for weaning WC, WP, and WM (0.06) with visual scores were estimated. The genetic correlations between body weight (BoW) at YC and WC (0.62) were considered moderately high and positive. In addition, YP (0.18), YM (0.15), WP (0.13), and WM (0.14) were considered moderately low compared with MW. The genetic correlation between BW and FIND (0.38) was considered positive and moderate. The heritability estimation indicates that growth traits, visual scores, and weight of adult cows could be changed by selection. Cows that presented the highest h2a values for live weight responded rapidly to selection based on growth characteristics, visual scores, and FIND and might result in increased final MW.

Study of Genetic Diversity and Population Structure of the Yak (Bos grunniens) in the Sayan-Altai Region

The paper reports the first study of genetic diversity of the domestic yak in the Sayan-Altai region of Russia (Altai and Tuva) and Mongolia (Khuvsgul and Gobi) on the basis of the polymorphism analysis of the mtDNA D-loop hypervariable region. It has been demonstrated that, among all the studied populations, Tuva yaks are characterized by the highest haplotype diversity. Four new haplotypes, A4, A13, D9, and E3, have been described for the first time. The analysis of the contribution of maternal genetic component to the yak intrabreed and interbreed mtDNA diversity revealed two large clades. For the first time, comparative analysis of genetic structure of the Russian yak populations was carried out using 15 microsatellite loci. Low genetic difference between the populations was revealed, which may apparently be accounted for by the specific features of farm breeding, in particular, by animal exchange between the adjacent territories of the Sayan-Altai region.

The milk yield of dams and its relation to direct and maternal genetic components of weaning weight in beef cattle

Cow milk yield is a critical component for the growth of the calves in the preweaning period. The genetic correlation between direct weaning weight and milk yield traits may cause a decrease in the maternal ability of cows when they are selected for the direct weaning weight of the calf. The objective of this study was to analyse the genetic and environmental components of some traits of interest in beef cattle breeds managed in mountain conditions by analysing the actual cumulative milk yield at 150 days obtained by milking (MY150) and the weight at birth (BW), at 90 days (W90), at weaning (W150), and mature weight (MW). Genetic evaluations were conducted using field data from 2679 calves born from 553 dams of Parda de Montaña beef cattle breed. The variances, genetic (both direct and maternal) and phenotypic, were estimated by a multi-trait animal model. Milk yield was correlated with maternal components of calf weight at 90 days and 150 days (genetic correlations of 0.59 and 0.48, respectively) and also correlated with a direct genetic component of W90 and W150 (genetic correlations of 0.58 and 0.54, respectively). The maternal heritability values for W90 and W150 were 0.023 (0.005) and 0.009 (0.004), respectively. The estimates of the direct-maternal genetic correlation for W90 and W150 were − 0.13 (0.11) and − 0.34 (0.16), respectively. Environmental effects, especially the sex of calf and dam parity for direct genetic effects and energy level of cow and body condition at calving for maternal effects, should be included in the evaluation models to obtain a proper estimation of genetic parameters for beef cattle evaluation. Genetic milk yield explains half the variation of maternal effects for W90 and W150. The prediction of milk yield will be better using maternal effects at 90 days than at 150 days. The combined index (maternal and direct) for the trait weight at 150 days yielded the highest economic response increasing the direct effect indirectly without decreasing the maternal effect at 150 days.

Genetic parameters of calving ease using sire-maternal grandsire model in Korean Holsteins.

ObjectiveCalving ease (CE) is a complex reproductive trait of economic importance in dairy cattle. This study was aimed to investigate the genetic merits of CE for Holsteins in Korea.MethodsA total of 297,614 field records of CE, from 2000 to 2015, from first parity Holstein heifers were recorded initially. After necessary data pruning such as age at first calving (18 to 42 mo), gestation length, and presence of sire information, final datasets for CE consisted of 147,526 and 132,080 records for service sire calving ease (SCE) and daughter calving ease (DCE) evaluations, respectively. The CE categories were ordered and scores ranged from CE1 to CE5 (CE1, easy; CE2, slight assistance; CE3, moderate assistance; CE4, difficult calving; CE5, extreme difficulty calving). A linear transformation of CE score was obtained on each category using Snell procedure, and a scaling factor was applied to attain the spread between 0 (CE5) and 100% (CE1). A sire-maternal grandsire model analysis was performed using ASREML 3.0 software package.ResultsThe estimated direct heritability (h2) from SCE and DCE evaluations were 0.11±0.01 and 0.08±0.01, respectively. Maternal h2 estimates were 0.05±0.02 and 0.04±0.01 from SCE and DCE approaches, respectively. Estimates of genetic correlations between direct and maternal genetic components were −0.68±0.09 (SCE) and −0.71±0.09 (DCE). The average direct genetic effect increased over time, whereas average maternal effect was low and consistent. The estimated direct predicted transmitting ability (PTA) was desirable and increasing over time, but the maternal PTA was undesirable and decreasing.ConclusionThe evidence on sufficient genetic variances in this study could reflect a possible selection improvement over time regarding ease of calving. It is expected that the estimated genetic parameters could be a valuable resource to formulate sire selection and breeding plans which would be directed towards the reduction of calving difficulty in Korean Holsteins.

Genetic parameters for lameness, mastitis and dagginess in a multi-breed sheep population

The objective of the present study was to quantify the extent of genetic variation in three health-related traits namely dagginess, lameness and mastitis, in an Irish sheep population. Each of the health traits investigated pose substantial welfare implications as well as considerable economic costs to producers. Data were also available on four body-related traits, namely body condition score (BCS), live weight, muscle depth and fat depth. Animals were categorised as lambs (<365 days old) or ewes (⩾365 days old) and were analysed both separately and combined. After edits, 39 315 records from 264 flocks between the years 2009 and 2015 inclusive were analysed. Variance components were estimated using animal linear mixed models. Fixed effects included contemporary group, represented as a three-way interaction between flock, date of inspection and animal type (i.e. lamb, yearling ewe (i.e. females ⩾365 days but <730 days old that have not yet had a recorded lambing) or ewe), animal breed proportion, coefficients of heterosis and recombination, animal gender (lambs only), animal parity (ewes only; lambs were assigned a separate ‘parity’) and the difference in age of the animal from the median of the respective parity/age group. An additive genetic effect and residual effect were both fitted as random terms with maternal genetic and non-genetic components also considered for traits of the lambs. The direct heritability of dagginess was similar across age groups (0.14 to 0.15), whereas the direct heritability of lameness ranged from 0.06 (ewes) to 0.12 (lambs). The direct heritability of mastitis was 0.04. For dagginess, 13% of the phenotypic variation was explained by dam litter, whereas the maternal heritability of dagginess was 0.05. The genetic correlation between ewe and lamb dagginess was 0.38; the correlation between ewe and lamb lameness was close to zero but was associated with a large standard error. Direct genetic correlations were evident between dagginess and BCS in ewes and between lameness and BCS in lambs. The present study has demonstrated that ample genetic variation exists for all three health traits investigated indicating that genetic improvement is indeed possible.

Genetic parameter estimates for prenatal and postnatal mortality in Nellore cattle.

The aim of this study was to estimate genetic parameters for prenatal (PRE) and postnatal (POS) mortality in Nellore cattle. A total of 13141 (PRE) and 17818 (POS) records from Nellore females were used. PRE and POS were recorded using binary scale scores: a score of '1' was given to calves that were born alive (PRE) and those that were alive at weaning (POS), and a score of '0' was given to calves that were not alive at or around birth (PRE), as well as to those weighed at birth but not at weaning (POS). The relationship matrix included 698 sires, 107 paternal grandsires and 69 maternal grandsires. Data were analysed using Bayesian inference and a sire-maternal grandsire threshold model, including contemporary groups as random effects, and the classes of dam age at the beginning of mating season (for PRE), and dam age at calving and birthweight (linear covariable) (for POS), as fixed effects. For both traits, the covariance between direct and maternal effects (rD,M ) was estimated (rD,M ≠ 0) or fixed at zero (rD,M =0). PRE and POS rates were 3.00 and 4.04%, respectively. Estimates of direct and maternal heritability were 0.07 and 0.17, respectively, for PRE, and 0.02 and 0.07, respectively, for POS, assuming rD,M =0. For rD,M ≠0, these estimates were 0.07 and 0.12, respectively, for PRE, and 0.03 and 0.07, respectively, for POS. The correlation estimates between direct and maternal effects were -0.71 (PRE) and -0.33 (POS). PRE and POS show low genetic variability, indicating that these traits probably suffer major environmental influences. Additionally, our study shows that the maternal genetic component affects preweaning calf mortality twice as much (or more) as the direct genetic component. A large number of offspring per sire is necessary in progeny tests to genetically decrease calf mortality.

Inclusion of cytoplasmic lineage effect and direct-maternal genetic covariance for genetic evaluation of growth traits in Nellore cattle.

We evaluated the impact of cytoplasmic lineage effects (Lc) for growth traits on genetic evaluation, including the genetic covariance between direct and maternal effects (σam). Pedigree data from 496,190 Nellore animals and observations on birth weight (BW, N = 243,391), weaning weight (WW, N = 431,681), and post-weaning weight gain adjusted to 345 days (PWG, N = 172,131) were analyzed. Four univariate models were used to obtain estimates of (co)variance components using the restricted maximum likelihood method in the BLUPF90 program. Model 1 included Lc and σam. Model 2 included Lc and σam was set to zero. Model 3 did not include Lc. Model 4 did not include Lc and σam was set to zero. These models considered the effects of the Lc as random. Phenotypic variance obtained through cytoplasmic lineage effects was determined for all traits, ranging from 0.07 to 0.15, 0.15 to 0.03, and 0.05 to 0.03% for BW, WW, and PWG, respectively, for models 1 and 2. Correlations between direct and maternal genetic components were positive for WW and negative for BW and PWG. No differences were observed for genetic parameter estimates or animal ranking with the inclusion of σam. For BW, the likelihood ratio suggested that model 1 best fits the data, while model 4 was the most appropriate for WW and PWG. Thus, these models are recommended for genetic evaluations. Despite the low magnitude of cytoplasmic lineages, this effect could predict breeding value and improve the selection of animals for BW in this Nellore population.

Genetic Evaluation of Dual-Purpose Buffaloes (Bubalus bubalis) in Colombia Using Principal Component Analysis.

Genealogy and productive information of 48621 dual-purpose buffaloes born in Colombia between years 1996 and 2014 was used. The following traits were assessed using one-trait models: milk yield at 270 days (MY270), age at first calving (AFC), weaning weight (WW), and weights at the following ages: first year (W12), 18 months (W18), and 2 years (W24). Direct additive genetic and residual random effects were included in all the traits. Maternal permanent environmental and maternal additive genetic effects were included for WW and W12. The fixed effects were: contemporary group (for all traits), sex (for WW, W12, W18, and W24), parity (for WW, W12, and MY270). Age was included as covariate for WW, W12, W18 and W24. Principal component analysis (PCA) was conducted using the genetic values of 133 breeding males whose breeding-value reliability was higher than 50% for all the traits in order to define the number of principal components (PC) which would explain most of the variation. The highest heritabilities were for W18 and MY270, and the lowest for AFC; with 0.53, 0.23, and 0.17, respectively. The first three PCs represented 66% of the total variance. Correlation of the first PC with meat production traits was higher than 0.73, and it was -0.38 with AFC. Correlations of the second PC with maternal genetic component traits for WW and W12 were above 0.75. The third PC had 0.84 correlation with MY270. PCA is an alternative approach for analyzing traits in dual-purpose buffaloes and reduces the dimension of the traits.

Direct and maternal genetic components of variance for growth traits in Nilagiri and Sandyno Sheep of South India

The Nilagiri sheep is known for its prolificacy and adaptability to high altitudes of the Nilgiri hills. This breed was crossed with exotic sheep such as Rambouillet and Merino to develop a new synthetic sheep called Sandyno at Sheep Breeding Research Station, Sandynallah (Tamil Nadu). Both these breeds have been maintained as closed flocks in this station and growth data from 1992 to 2011 were utilized to estimate direct and maternal genetic (co)variance components for various growth traits viz., weight at birth (BW), 3 (3W), 6 (6W), 9 (9W), 12 (12W) and 18 (18W) months of age. An animal model including maternal effects was used to obtain restricted maximum likelihood estimates of (co)variances. The h2 values for BW, 3W, 6W, 9W, 12W and 18W were 0.140, 0.130, 0.074, 0.168, 0.129 and 0.166, respectively in Nilagiri sheep and 0.147, 0.114, 0.098, 0.141, 0.144 and 0.115 in Sandyno sheep. In Nilagiri sheep, maternal influence was significant (P<0.05) for BW, 3W, 6W and 9W and the maternal heritability values for the traits were 0.211, 0.050, 0.126 and 0.098, respectively. In Sandyno sheep, the maternal heritability values were significant (P<0.05) for BW, 3W, 6W, 9W and 18W with values of 0.285, 0.035, 0.054, 0.058 and 0.110, respectively. BW and 6W in Sandyno sheep were the only traits for which models with direct and maternal genetic correlation (σam) were significant (P<0.05). Genetic correlations among body weight traits were positive and moderate to high and ranged from 0.375 to 0.994 in Nilagiri and 0.553 to 0.952 in Sandyno sheep. Maternal effects were important with respect to growth traits in Nilagiri and Sandyno sheep. Moderate estimates of heritabilities and higher genetic correlations provide scope for further improvement in growth traits.

Males and females contribute unequally to offspring genetic diversity in the polygynandrous mating system of wild boar.

The maintenance of genetic diversity across generations depends on both the number of reproducing males and females. Variance in reproductive success, multiple paternity and litter size can all affect the relative contributions of male and female parents to genetic variation of progeny. The mating system of the wild boar (Sus scrofa) has been described as polygynous, although evidence of multiple paternity in litters has been found. Using 14 microsatellite markers, we evaluated the contribution of males and females to genetic variation in the next generation in independent wild boar populations from the Iberian Peninsula and Hungary. Genetic contributions of males and females were obtained by distinguishing the paternal and maternal genetic component inherited by the progeny. We found that the paternally inherited genetic component of progeny was more diverse than the maternally inherited component. Simulations showed that this finding might be due to a sampling bias. However, after controlling for the bias by fitting both the genetic diversity in the adult population and the number of reproductive individuals in the models, paternally inherited genotypes remained more diverse than those inherited maternally. Our results suggest new insights into how promiscuous mating systems can help maintain genetic variation.

Genetic parameters and non-genetic influences related to birth weight in farmed white-tailed deer

SUMMARYStudying and understanding the sources of variation in early life traits in farmed deer are fundamental for management and/or breeding purposes. Data from a captive white-tailed deer population were analysed to identify non-genetic and genetic factors affecting the birth weight (BW) of fawns. The year, type of birth and sex were included in a fixed linear model to examine their significance. All of the examined non-genetic factors had a highly significant effect on BW (P&lt;0·001). The examined years showed variation attributed to food availability affecting the gestational conditions of does. Male fawns were 193 g heavier than female fawns at birth (P&lt;0·001), and singleton births were associated with a higher BW (2·97±0·043 kg) compared with twin (−0·261 g) and triplet (−0·642 g) fawning (P&lt;0·001). The best-fitting animal model was selected by comparing reduced and complete models. Based on the selected animal model, which included direct genetic and common maternal effects, genetic components and parameters were estimated. The direct heritability was found to be 0·28±0·126, and a small but important contribution of common maternal environmental effects was identified (c2=0·15±0·062). The results support the importance of certain environmental factors affecting BW and indicate the relevance of direct genetic and maternal environmental influences to sustained genetic changes in BW and positively correlated traits in farmed white-tailed deer populations.

The genetics of cow growth and body composition at first calving in two tropical beef genotypes

The genetics of cow growth and body composition traits, measured before first calving (pre-calving: in females before calving following their first 3-month annual mating period, at an average age of 34 months) and at the start of the subsequent mating period (Mating 2: on average 109 days later), were evaluated in 1016 Brahman (BRAH) and 1094 Tropical Composite (TCOMP) cows. Measurements analysed were liveweight, ultrasound-scanned measurements of P8 and 12/13th rib fat depth and eye muscle area, body condition score and hip height. Traits describing the change in these from pre-calving to Mating 2 were also included in the analysis. The maternal genetic component of weaning weight was estimated from weaning-weight records on these cows, their steer half-sibs and their progeny generated from up to six matings (n = 12 528). Within pregnant cows at pre-calving, BRAH were significantly lighter, leaner at the P8 site and taller than their TCOMP contemporaries, and these differences were also significant at Mating 2. There was a genetic basis for variation in growth and body composition traits measured at pre-calving and Mating 2 in BRAH (h2 = 0.27–0.67) and TCOMP (h2 = 0.25–0.87). Traits describing the change from pre- calving to Mating 2 were also moderately heritable for both genotypes (h2 = 0.17–0.54), except for change in hip height (h2 = 0.00 and 0.10 for BRAH and TCOMP, respectively). Genetic correlations between measurements of the same trait at pre-calving and Mating 2 were consistently positive and strong (rg = 0.75–0.98) and similar for both genotypes. In lactating cows, genetic correlations of growth and body composition traits with their change from pre-calving to Mating 2 showed that when animals had low levels of P8 and rib fat at Mating 2, change in eye muscle area was an important descriptor of genetic body condition score (rg = 0.63). This was supported by moderate genetic relationships, which suggested that lactating cows that were genetically predisposed to lose less eye muscle area were those that ended the period with higher P8 fat (rg = 0.66), rib fat (rg = 0.72) and body condition score (rg = 0.61). Change in liveweight, body condition score and, in particular, eye muscle area was significantly related to the maternal genetic component of weaning weight (rg = from –0.40 to –0.85) in both genotypes, suggesting that cows with higher genetic milk-production potential were those with the propensity for greater loss of these traits over the period from pre-calving to Mating 2. These results showed that for tropically adapted cows, the change in eye muscle area from pre-calving to Mating 2 was a more important descriptor of body condition at Mating 2 than was change in fat depth, and that higher genetic milk-production potential, measured as maternal weaning weight, was genetically related to higher mobilisation of muscle, and therefore body condition, over this period.

Bold colors in a cryptic lineage: do Eastern Indigo Snakes exhibit color dimorphism?

Many species exhibit variation in the color of their scales, feathers, or fur. Various forms of natural selection, such as mimicry, crypsis, and species recognition, as well as sexual selection, can influence the evolution of color. Eastern Indigo Snakes (Drymarchon couperi), a federally threatened species, have coloration on the sides of the head and the chin that can vary from black to red or cream. Despite significant conservations efforts for this species, little is known about its biology in the field. Past researchers have proposed that the color variation on the head and chin is associated with the sex of the individual. Alternatively, color might vary among individuals because it is controlled by genes that are under natural selection or neutral evolution. We tested these alternative hypotheses by examining whether coloration of the sublabial, submaxillary, and ventral scales of this species differed by sex or among clutches. We used color spectrometry to characterize important aspects of color in two ways: by examining overall color differences across the entire color spectrum and by comparing differences within the ultraviolet, yellow, and red colorbands. We found that Eastern Indigo Snakes do not exhibit sexual dichromatism, but their coloration does vary among clutches; therefore, the pattern of sexual selection leading to sexual dichromatism observed in many squamates does not appear to play a role in the evolution and maintenance of color variation in Eastern Indigo Snakes. We suggest that future studies should focus on determining whether color variation in these snakes is determined by maternal effects or genetic components and if color is influenced by natural selection or neutral evolutionary processes. Studying species that exhibit bright colors within lineages that are not known for such coloration will contribute greatly to our understanding of the evolutionary and ecological factors that drive these differences.

Estimates for the heritability of growth of Mytilus edulis

13 half-sib families and 39 full-sib families of Mytilus edulis were established with the balance nest design in which each male mated with three females and the artificial fertilization technique.The shell height and length of each family were measured in 2,3,5,6 months.The heritability of the growth was estimated using the full-sib families theories.The results show that the maternal genetic variance component estimates are all significantly greater than those of paternal ones of each growth trait(P0.05).The female genetic variance components have significant maternal effects(P0.05),suggesting that the large non-additive genetic effects could not be differentiated from the available data,so the heritability of paternal half-sib families estimates in the narrow sense were precise unbiased estimator.The shell height heritability of paternal half-sib families estimates are 0.29,0.85,0.84,0.87 respectively.The shell length heritability are 0.27,0.87,0.86,0.85 respectively,during 2,3,5,6 months.There were significant additive genetic variance of the growth and different heritability of shell height and shell length,indicating that there is a great potential genetic improvement for the growth of M.edulis using the selective breeding.