Maternal Additive Genetic Effects Research Articles

Early growth performance in the Murciano-Granadina goats: insights from genetic and phenotypic analyses

Abstract This study investigates the genetic and phenotypic aspects of early growth performance in the Murciano-Granadina goat breed, using data collected between 2016 and 2022 from a private dairy farm in Ghale-Ganj city, located in the southern area of Kerman province, Iran. Pedigree and data information were collected on several early body weight traits, including birth weight (BW), weaning weight (WW), average daily gain (ADG), Kleiber ratio (KR) and growth efficiency from birth to weaning (GE). Nine univariate animal models included direct additive genetic effects and different combinations of maternal effects were compared by using Akaike information criterion (AIC). Among the tested models, the best genetic analysis model for BW, included direct additive, maternal additive, maternal permanent and maternal temporary environmental effects. The best model for ADG, KR and GE included direct additive, maternal permanent and litter effects. For WW, the best model was determined to be one that included direct additive and maternal additive genetic effects. The estimated direct heritabilities were low values of 0.04, 0.07, 0.08, 0.05 and 0.07 for BW, ADG, KR, GE and WW, respectively. The estimates of genetic correlations among the studied traits were positive and low to high in magnitude which ranged from 0.11 for BW-KR to 0.91 for BW-GE. The phenotypic correlations ranged from 0.03 for KR-WW to 0.87 for ADG-KR. The positive correlations observed among the studied growth traits of the Murciano-Granadina goat breed indicate no negative genetic or phenotypic changes associated with selection for these traits.

78 Estimates of genetic parameters for weight, wool, and carcass traits of Rambouillet sheep

Abstract The Rambouillet sheep breed is the foundation to most western range sheep in the U.S. Through the National Sheep Improvement Program (NSIP), Rambouillet breeders seek to improve economically relevant traits. However, the parameters used in the NSIP genetic evaluation were last estimated two decades ago. Our aim was to re-estimate genetic parameters for body weight (BW), carcass, and wool traits. Data were provided by NSIP, which included BW at birth (BWT; n = 28,817), weaning [WWT; n = 5,633; age: 68 (SD 16) day], early post-weaning [PWTE; n = 23,303; 128 (SD 22) d], late post-weaning [PWTL; n = 7,689; 201 (SD 45) d] and as yearlings [YWT; n = 5,830; 375 (SD 33) d]. Yearling ultrasound scans of 12th rib backfat depth (YCF; n = 2,447) and eye muscle depth (YEMD; n = 2,457) were also available. Yearling wool traits were fiber curvature (YFC; n = 6,009), fiber diameter (YFD; n = 9,880), fiber diameter coefficient of variation (YFDCV; n = 8,803), greasy fleece weight (YGFW; n = 11,859) and staple length (YSL; n = 11,270). The pedigree consisted of 36,297 individuals. Animals with phenotypic records were progeny of 333 sires and 1,727 dams. A succession of univariate animal models was fitted. The most comprehensive model included direct and maternal additive genetic effects, their genetic covariance, and maternal permanent environmental and residual effects. Phenotypes were pre-adjusted for birth-rearing type category and, as covariates, dam age and age at recording. Contemporary group—a concatenation of flock, year, season, management group, sex, and, excluding BWT, recording date—was the only fixed effect fitted in the model. Model selection was based on the log-likelihood ratio test, and Akaike and Bayesian information criteria. The data structure, namely dams and their daughters and granddaughters contributing data, allowed reliable testing of the maternal effect terms. The direct-maternal genetic covariance did not explain variation for any trait (P > 0.18). The most parsimonious model for BW traits included direct and maternal additive genetic, and maternal permanent environmental, effects. For carcass and wool traits, only direct additive genetic effects were included in the final model. Such was unsurprising, as maternal effects often diminish as animals age. For the final models fitted (Table 1), direct heritabilities (± SE) for body weights ranged from 0.14 ± 0.01 (BWT) to 0.38 ± 0.04 (PWTL); the maternal heritabilities ranged from 0.04 ± 0.02 (PWTL; YWT) to 0.13 ± 0.01 (BWT). For carcass traits, direct heritabilities were 0.13 ± 0.04 (YCF) and 0.31 ± 0.05 (YEMD). For wool traits, they ranged from 0.37 ± 0.02 (YSL) to 0.58 ± 0.02 (YFD). These re-estimated parameter values are consistent with those used by NSIP, with the exception of PWTL (greater) and YSL (lower). With genomic data accumulating in Rambouillet, further refinements in parameter estimation are planned.

Genome-Wide Association Study of Maternal Genetic Effects on Intramuscular Fat and Fatty Acid Composition in Rabbits.

Maternal genetic effects (MGE) could affect meat quality traits such as intramuscular fat (IMF) and its fatty acid composition. However, it has been scarcely studied, especially in rabbits. The objectives of the present study were, first, to assess the importance of MGE on intramuscular fat and fatty acid composition by applying a Bayesian maternal animal model in two rabbit lines divergently selected for IMF. The second objective was to identify genomic regions and candidate genes of MGE that are associated with the traits of these offspring, using Bayesian methods in a Genome Wide Association Study (GWAS). Quantitative analyses were performed using data from 1982 rabbits, and 349 animals from the 9th generation and 76 dams of the 8th generation with 88,512 SNPs were used for the GWAS. The studied traits were IMF, saturated fatty acids (total SFA, C14:0; myristic acid, C16:0; palmitic acid and C18:0; stearic acid), monounsaturated fatty acids (total MUFA, C16:1n-7; palmitoleic acid and C18:1n-9; oleic acid), polyunsaturated fatty acids (total PUFA, C18:2n-6; linoleic acid, C18:3n-3; α-linolenic acid and C20:4n-6; arachidonic acid), MUFA/SFA and PUFA/SFA. The proportion of phenotypic variance explained by the maternal genetic effect ranged from 8 to 22% for IMF, depending on the model. For fatty acid composition, the proportion of phenotypic variance explained by maternal genetic effects varied from 10% (C18:0) to 46% (MUFA) in a model including both direct and additive maternal genetic effects, together with the common litter effect as a random variable. In particular, there were significant direct maternal genetic correlations for C16:0, C18:1n9, C18:2n6, SFA, MUFA, and PUFA with values ranging from -0.53 to -0.89. Relevant associated genomic regions were located on the rabbit chromosomes (OCU) OCU1, OCU5 and OCU19 containing some relevant candidates (TANC2, ACE, MAP3K3, TEX2, PRKCA, SH3GL2, CNTLN, RPGRIP1L and FTO) related to lipid metabolism, binding, and obesity. These regions explained about 1.2 to 13.9% of the total genomic variance of the traits studied. Our results showed an important maternal genetic effect on IMF and its fatty acid composition in rabbits and identified promising candidate genes associated with these traits.

Estimation of nonadditive and additive genetic effects on growth traits of Horro cattle.

The estimation of nonadditive genetic effects plays a significant role in the accuracy of estimated breeding values for growth traits. Data for estimation of individual and maternal heterosis of crossbreed cattle in Ethiopia are limited to research institutions and universities. This paper aimed to estimate the crossbreeding effects for growth traits of Holstein Friesian × Horro and Jersey × Horro crossbreds in Ethiopia. The data included pedigree and weight data of animals born between 1980 and 2008. Heritability of growth traits was estimated using restricted maximum likelihood (ASREML). However, the additive genetic, maternal, and heterosis effects for growth traits of crossbred animals were estimated using the crossbreeding effects (CBE3) package by fitting Kinghorn's Model one. The direct and maternal heritability estimates for 1-year weight with the model that included the direct maternal covariance were 0.77 ± 0.12 and 0.26 ± 0.09, respectively. Individual heteroses estimated for Holstein Friesian × Horro and Jersey × Horro were significantly high and positive for 1-year weight (21.6 ± 6.7 and 26.0 ± 3.9kg), preweaning average daily gain (27.4 ± 26 and 28.9 ± 15g), and postweaning average daily gain (68.8 ± 16.6 and 61.8 ± 9.9g), respectively. The maternal additive genetic effect for growth traits was mostly positive; therefore, it may be preferable to use crossbred cows from purebred dams instead of crossbred cows from crossbred dams. The significantly higher heterosis and additive genetic parameters in Holstein Friesian × Horro crossbreds indicated that these crossbreds may be preferable to Jersey × Horro crossbreds in areas occupied by Horro cattle.

Estimation of genetic parameters for important traits using a multi-trait model in late-feathering Qingyuan partridge hens in China.

Qingyuan partridge chicken is one of the most well-known Chinese indigenous yellow broilers. In breeding programmes, five traits are usually selected when the chickens are 105 days old, namely body weight (BW), comb height (CH), shank length (SL), shank girth (SG) and feather maturity (FM). The objective of this study was to estimate the genetic parameters of these five traits, especially direct additive genetic correlations, to lay the foundation for balanced selection of Qingyuan partridge chickens. Approximately 9600 records were used for estimation. Variance components for these five traits were estimated using three multi-trait models incorporating different effects via Gibbs sampling. Based on model 1 in which the random effects included direct additive genetic effects and residuals, the estimated direct heritabilities for BW, CH, SL, SG and FM were 0.29 ± 0.04, 0.53 ± 0.04, 0.47 ± 0.04, 0.43 ± 0.05 and 0.18 ± 0.03, respectively. The direct genetic correlations ranged from -0.08 to 0.46. When additionally considering maternal additive genetic effects (model 2), the estimates of direct heritabilities and absolute values of direct additive genetic correlations were smaller. The heritabilities were 0.14 ± 0.04, 0.40 ± 0.02, 0.34 ± 0.05, 0.27 ± 0.05 and 0.12 ± 0.03 for BW, CH, SL, SG and FM, respectively. The direct additive genetic correlations ranged from -0.33 to 0.36. More specifically, the direct additive genetic correlations between BW and CH, SL, SG and FM were 0.19 ± 0.13, 0.15 ± 0.15, 0.36 ± 0.15 and - 0.33 ± 0.21, respectively. The genetic correlations of FM with SL, SG and CH were - 0.15 ± 0.15, -0.08 ± 0.17 and 0.18 ± 0.15, respectively. The direct genetic correlations between CH and SG and SL were - 0.02 ± 0.11 and - 0.20 ± 0.11, respectively, and that between SL and SG was 0.19 ± 0.11. The total heritabilities and maternal additive genetic correlations ranged from 0.16 to 0.44 and from -0.13 to 0.61, respectively. The third model also included the maternal permanent environmental effect for BW. The estimates of direct heritability, direct additive genetic correlation, total heritability and maternal additive genetic correlation were only slightly different from those based on the second model. Therefore, the maternal additive genetic effect has a large effect on the estimation of genetic parameters, and it is better to consider this effect in the genetic evaluation of these five traits. Relatively high direct and maternal additive genetic correlations for most trait pairs suggested that it is better to jointly evaluate these five traits in breeding programmes.

Genetic analysis of growth efficiency-related traits in Mazandaran native chickens

The aim of this study was to investigate the genetic and phenotypic aspects of growth efficiency-related traits in Mazandaran native chickens. For this purpose, phenotypic and pedigree data of 21 generations were obtained from Mazandaran native chicken breeding center. Studied traits included Kleiber ratio (KR), relative growth rate (RGR) and growth efficiency (EF) at different growth phases from hatch to 8 weeks of age (1-8), hatch to 12 weeks of age (1-12), 8 weeks to 12 weeks of age (8-12), hatch to sex maturity (1-SM), 8 weeks of age to sex maturity (8-SM) and 12 weeks of age to sex maturity (12-SM). Genetic parameters and (Co) variance components were estimated by Restricted Maximum Likelihood (REML) procedure under six different univariate animal models using WOMBAT software with and without considering the maternal effects. Based on the results of the best model, determined by the Akaike Information Criterion (AIC), the estimates of direct heritability ranged from 0.05 (EF8-12) to 0.32 (EF12-SM) for growth efficiency, from 0.06 (KR8-12) to 0.37 (KR8 -SM) for Kleiber ratios and from 0.06 (RGR8-12) to 0.16 (RGR1-12) for relative growth rates. Maternal heritability ranged from 0.03 (EF8-12, EF1-8) to 0.08 (EF1-SM) for growth efficiency, from 0.006 (KR8-12) to 0.097 (KR1-SM) for Kleiber ratios and form 0.03 (RGR8-12) to 0.14 (RGR1-12) for relative growth rates. Negative genetic correlations between direct and maternal additive genetic effects were estimated for all studied traits. In conclusion, significant maternal effects indicated that these effects should be considered in genetic evaluation of traits.

Evaluation of Genetic Parameters of Growth of Pelibuey and Blackbelly Sheep through Pedigree in Mexico.

Simple SummaryThe importance of sheep production in Mexico has been increasing in recent years. Animal performance can be improved through continuous selection and cumulative genetic management. Studies on non-genetic factors that influence the growth characteristics of sheep, due to their positive genetic correlation with other live weights, can present data of great interest to small producers with limited resources. In the present study, genealogical and functional information from the historical archive of the Mexican Association of Sheep Breeders (AMCO) was used. The objective was to estimate the heritability and genetic correlations of the growth of ewes born and weaned at different times of the same year from different herds with pedigree registration. The expected results could be incorporated into genetic selection programs with a favorable impact on the local economy of small sheep producers in Mexico.Birth weight (BW) and weaning weight (WW) data from Pelibuey and Blackbelly lambs belonging to the Asociación Mexicana de Criadores de Ovinos (AMCO) were used with the objective of estimating genetic parameters (heritability and genetic correlations) and analyzing the growth characteristics of ewes born and weaned at different times of the same year from different herds with pedigree registration. In the case of Pelibuey lambs, the animal model included the weaning weight at 75 days of age, considering the direct additive genetic effect, maternal additive genetic effect, covariance between direct and maternal effects, as well as the permanent environmental effect of the mother. The direct estimators of heritability for Pelibuey were BW = 0.01 ± 0.021 and WW = 0.31 ± 0.074 and for Blackbelly they were BW = 0.05 ± 0.042 and WW = 0.41 ± 0.146. In the case of the maternal heritability estimators in Pelibuey they were BW = 0.02 ± 0.040 and WW = 0.21 ± 0.121 and for Blackbelly they were BW = 0.12 ± 0.054 and WW = 0.28 ± 0.121. The magnitude of the estimates of genetic correlations between direct and maternal effects for adjusted weaning weight at 75 days of age indicate that genetic progress may be slow in a breeding program. However, these selection results could be included in the short term in the breeding programs for the Pelibuey and Blackbelly breeds in Mexico, for livestock development in low-income rural areas.

The estimation of (co)variance components and genetic parameters for growth and wool traits in Harnali sheep

The present study was undertaken to estimate (co)variance components and genetic parameters of important growth and wool traits in Harnali sheep using data records of 1862 lambs born to 144 sires and 591 dams for the period from 1998 to 2018. Six univariate animal models including or ignoring maternal genetic and permanent environmental effects were fitted to birth weight (BWT), weaning weight (WWT), 6 months weight (6WT), 12 months weight (YWT), first clip greasy fleece weight (FGFW) and annual greasy fleece weight (AGFW) and further compared using likelihood ratio test. It was observed that the model including direct additive genetic and maternal additive genetic effect without taking covariance between them into account was the most suitable for BWT and WWT. For remaining traits, only direct additive genetic effect model was found to be most appropriate. The estimates of heritability under the best model for BWT, WWT, 6WT, YWT, FGFW and AGFW were 0.23, 0.10, 0.18, 0.11, 0.08 and 0.31, respectively. The maternal influence accounted for 8 % of variation for BWT and WWT which indicated importance of maternal effect during preweaning period. The genetic and phenotypic correlations of 6WT with other traits were positive and ranged medium to moderate. Therefore, it was concluded that medium genetic variability of 6WT and its potential ability for improving other traits should be exploited to achieve genetic improvement in Harnali sheep.

Evaluation of animal models for genetic analysis of growth performance in Landlly pigs

Selection of the most appropriate animal model for the estimation of genetic parameters for body weight was carried out using restricted maximum likelihood (REML) procedure at birth and thereafter at 3, 6, and 8 weeks of age in Landlly pigs. Six different models were fitted for each trait; by inclusion or exclusion of maternal additive genetic effect, maternal permanent environmental effect, and covariance between direct and maternal additive genetic effects. Records on 1968 piglets, born in 4 parities of 131 gilts/sows, sired by 68 boars during a period of 5 years from 2014 to 2018 were used. In order to determine the most appropriate model, Log likelihood values, log the likelihood ratio test and Akaike's information criterion were used. A model including direct additive genetic and maternal permanent environmental effects fitted best to data for birth weight. The best model explaining W3, W6, and W8 included direct additive genetic, maternal genetic and maternal permanent environmental effect with direct and maternal genetic covariance. Total heritability estimates for the body weights were low to moderate across best models.

Random regression models for the evaluation of the growth of goats of the Anglonubian breed

ABSTRACT A total of 6593 weight records collected from 796 male and female Anglo-Nubian goats aged up to 130 days, offspring from 29 sires and 225 dams, were used to compare models and estimate genetic parameters throughout the growth curve by applying random regression models. Direct and maternal additive genetic effects and direct and maternal permanent environmental effects were included as random in the models. The contemporary groups were included as fixed effects and goat age at kidding was included as a covariable (linear and quadratic). The choice of the best model was based on the AIC, BIC and AICc criteria. Variance estimates of the four random effects increased as the animals aged. Direct heritability (h2) rose from 0.13 to 0.40 with age, whereas maternal heritability showed a low value. Genetic correlations of weight between closer ages were high. The most suitable random regression model to compare the fitting of random effects was that which employed the Legendre polynomials of quadratic order with homogeneous variance (3333-1).

Genetic parameters for growth and cow productivity traits in Angus, Hereford and crossbred cattle

Reproductive and growth performance are major factors affecting the efficiency of beef production. The objectives of this study were to estimate genetic parameters for five cow fertility and productivity traits (pre-weaning average daily gain (PWG), weaning-to-first calving average daily gain (WFCG), age at first calving (AFC), cow weight at weaning (CWW) and cow average annual productivity (CAAP) in an experimental herd of Angus, Hereford, and reciprocal Hereford-Angus crossbred cattle. (Co)variance components were estimated by Bayesian inference using ten bivariate animal models representing all possible pairwise combinations of the five traits. Fixed environmental effects were contemporary group (all traits), class of age of dam at calving (PWG only), age of heifer at first calving (WFCG only), and cow age at weaning, age of calf at weaning and sex of calf (CWW only). Fixed genetic effects for all traits were breed group of cow and heterosis of the cow as a function of expected heterozygosity. Random effects were direct additive genetic (PWGd and WFCGd; d = direct), maternal additive genetic effects (PWGm and WFCGm; m = maternal), maternal permanent environmental effect (PWG only), direct permanent environmental effect (CWW only), and residual (all traits). Direct heritability estimates ± standard deviations for PWG and WFCG were 0.15 ± 0.04 and 0.44 ± 0.18, respectively. Heritability for maternal additive genetic effects was lower for WFCG (0.08 ± 0.05) than for PWG (0.17 ± 0.13). Direct-maternal genetic correlations were -0.38 ± 0.35 for WFCG and -0.26 ± 0.17 for PWG. Heritabilities were low for AFC (0.08 ± 0.05) and CAAP (0.17 ± 0.06). Conversely, CWW had high heritability (0.64 ± 0.13) and repeatability estimates (0.74 ± 0.03). AFC showed a high positive genetic correlation with PWGd (0.98 ± 0.01) and a negative correlation with PWGm (-0.51 ± 0.13). CWW was positively and highly associated genetically with PWGd and WFCGd, while genetic correlations were moderate and positive between CAAP and CWW (0.46 ± 0.13) and high and positive between CAAP and PWGm (0.93 ± 0.03). The estimated genetic variation for CAAP makes it a good selection objective. However, unrestricted selection for CAAP could increase mature weight. Thus, monitoring female mature weight under grazing conditions is essential to avoid large and heavy replacement cows with high nutritional requirements. Therefore, beef selection programs in Argentina should be aimed at increasing CAAP while maintaining mature weight, by imposing restrictions on CWW or other traits measured earlier in life. Outcomes of this study will contribute to the development of optimized bioeconomic models for commercial beef cattle herds under the extensive production conditions in Argentina.

Genetic analysis of live weight of local kids to promote genetic evaluations in the arid areas of Tunisia.

Goat meat production, a widely extended activity in the more arid areas of Tunisia, relies on local breeds. These breeds are well adapted to produce under harsh conditions but have a very small size and low productivity. The aim of this study was to establish the basis for future genetic evaluations to improve growth potential of this local stock. A total of 13,095 body weights and pedigree of 945 kids in the caprine herd of the Arid Areas Institute of Médenine were used. Random regression (RR) and multiple trait (MT) models were analyzed and compared. All models included effects of age and weight of dam, age, sex and type of birth of the kid, and year × month of recording, plus random direct and maternal additive genetic and permanent environmental effects. RR and MT models behave similarly, with RR showing slightly better goodness of fit. Heritability estimates for direct (ranging from 0.15 to 0.4) and maternal (0.05 to 0.3) effects showed that efficient selection for weight is feasible in this population. Estimated correlations between ages were high (> 0.8) for direct effects across all ages and low (down to 0.2) for weights taken at distant ages for maternal effects. Estimated genetic correlations between direct and maternal components revealed an antagonistic relationship, especially at early ages. Recording of at least one weight in the first month of age of the kids to evaluate the maternal capacity and a later weight to evaluate direct effects on weight is recommended for genetic evaluations under field conditions.

Avantium to locate new plant-based monoethylene glycol plant in Delfzijl

The aim of this study was to investigate the genetic and phenotypic aspects of growth efficiency-related traits in Mazandaran native chickens. For this purpose, phenotypic and pedigree data of 21 generations were obtained from Mazandaran native chicken breeding center. Studied traits included Kleiber ratio (KR), relative growth rate (RGR) and growth efficiency (EF) at different growth phases from hatch to 8 weeks of age (1-8), hatch to 12 weeks of age (1-12), 8 weeks to 12 weeks of age (8-12), hatch to sex maturity (1-SM), 8 weeks of age to sex maturity (8-SM) and 12 weeks of age to sex maturity (12-SM). Genetic parameters and (Co) variance components were estimated by Restricted Maximum Likelihood (REML) procedure under six different univariate animal models using WOMBAT software with and without considering the maternal effects. Based on the results of the best model, determined by the Akaike Information Criterion (AIC), the estimates of direct heritability ranged from 0.05 (EF8-12) to 0.32 (EF12-SM) for growth efficiency, from 0.06 (KR8-12) to 0.37 (KR8 -SM) for Kleiber ratios and from 0.06 (RGR8-12) to 0.16 (RGR1-12) for relative growth rates. Maternal heritability ranged from 0.03 (EF8-12, EF1-8) to 0.08 (EF1-SM) for growth efficiency, from 0.006 (KR8-12) to 0.097 (KR1-SM) for Kleiber ratios and form 0.03 (RGR8-12) to 0.14 (RGR1-12) for relative growth rates. Negative genetic correlations between direct and maternal additive genetic effects were estimated for all studied traits. In conclusion, significant maternal effects indicated that these effects should be considered in genetic evaluation of traits.

Genetic appraisal of growth traits in Iranian native Ghezel sheep using random regression models

This research was carried out to estimate the genetic parameters of the body weight traits of the Ghezel sheep using three different random regression models. The used data were 39,288 test-day records collected from 13,378 animals at Ghezel Sheep Breeding Station in Miandoab, West Azerbaijan Province, Iran from 1994 to 2012. Fixed effects in models included type of birth (single, twin) and year of birth (1994-2012). The weight as a function of age in the days of weighting was considered as the fixed regression of orthogonal polynomial. The random effects of the basic model were direct genetic and direct permanent environment. Maternal genetic and maternal permanent environment effects were added to it respectively. In the basic model, increasing the order of fit for the fixed regression, direct genetic and direct permanent environment effects, increased the accuracy of the model. Adding the maternal permanent environmental effect to the model and increasing the order of fit increased the accuracy of the model. However, adding the maternal additive genetic effect to the model and increasing the order of fit for this effect, decreased the model accuracy. Direct heritability for birth weight and weight at 90, 180, 270, and 360 days of age were: 0.30, 0.22, 0.39, 0.38, and 0.55, respectively. These heritability estimates reduced after birth and reached the lowest amount for body weight at 20 days of age; however, after that, they increased as the age increased (this increase was not uniform and had some fluctuations). The direct additive genetic correlations between the traits of weight at 90 days of age and the weight at 180 days of age was the highest (0.955) and between the birth weight and 180 days of age was the lowest (0.072). These correlations between adjacent age groups were closer than the remote age groups. The value of the direct genetic, direct permanent environment, maternal permanent environment, and the phenotypic variances for birth weight was the lowest and increased by increasing of the age (maximum was for weight of 360th day of age).

Variance components due to direct and maternal effects for birth weight of Brown Swiss cattle

This study was conducted to estimate variance components and genetic parameters for birth weights of Brown Swiss calves. Experimental data were gathered from the records of a State Farm of Turkey (Konuklar) covering the years between 1995 and 2005. Random effects considered in this study included direct and maternal additive genetic effects, maternal permanent environmental effects with direct-maternal genetic covariance and random residual effects. AI-REML algorithm of WOMBAT software was used to estimate variance and covariance components, genetic parameters and breeding values. The general mean for birth weights of all calves was calculated as 38.12±0.006 kg. The least square for mean birth weights was calculated as 38.99±0.007 kg for male calves and as 37.26±0.008 for female calves. Direct heritability (hD2), maternal heritability (hM2), total heritability (hT2), rAM and cAM estimates were respectively calculated as 0.15, 0.10, 0.39, 0.96 and 0.13

Random regression models to explore genetic variation and genetic variability in the growth curve of Baluchi lambs

The aim was to apply Random Regression Model (RRM) to describe growth curve of Baluchi lambs. Data was retrieved from an experimental population of Baluchi sheep and consisted of body weight records from 50 to 400 days of age. Regressions for the direct and maternal random effects in the RRM were modeled using different combinations of legendre polynomials with orders from one (i.e., simple repeatability model, SRM) to four. Mean trends were also modeled through a quadratic regression on orthogonal polynomials of age. Homogeneity and heterogeneity of error variance were considered along growth trajectory. The Akaike's Information Criterion (AIC) and Bayesian Information Criterion (BIC) were computed to compare different models. According to AIC and BIC values, simple repeatability model was the worse model and resulted in greater estimates of error variance. A RRM with legendre polynomials of orders 4, 4, 4, and 4 for direct additive genetic, direct permanent environment, maternal additive genetic and maternal permanent environmental effects was selected as the parsimonious model. The AIC and BIC values significantly increased when maternal effects excluded from the parsimonious model. Direct heritability (h2) decreased from 0.32 at 50 days of age to 0.09 at 90 days of age and increased thereafter to a peak at 400 days of age (0.42). Direct permanent environmental effect (p2) was minimum at 50 days of age (0.20), increased gradually and reached the maximized value around 150 days of age (0.54) and decreased thereafter. Maternal heritability (m2) was close to zero at 50 days of age, but increased thereafter to a peak at 400 days of age (0.08). Maternal permanent environmental effect (c2) was 0.22 at 50 days of age, decreased sharply to 0.01 at 100 days of age when it fixed below 0.05 until end of trajectory. Measures of genetic and environmental variability (coefficient of variations: CVA, CVP, CVM and CVC) had the almost similar patterns with corresponding genetic and environmental parameters. Direct and maternal correlations were positively high between adjacent weighs but decreased with increasing number of days between records. In general, estimates of genetic parameters and coefficient of variations showed opportunity for genetic improvement in growth curve of Baluchi lambs.

Genetic and non-genetic factors influencing the live weight of artificially-reared lambs

The Spooner Agricultural Research Station (ARS) of the University of Wisconsin-Madison housed the only dairy sheep research flock in North America at the time of its closing in 2016. Multiple experiments conducted at the Spooner ARS determined that raising dairy lambs on milk replacer can be profitable and has since become a common practice in many U.S. dairy flocks. While the genetic basis of early growth traits in naturally-reared lambs has been extensively researched, little is known about the extent to which direct and maternal additive effects influence these traits in artificially-reared animals. The traits analyzed were birth weight (BW0) and 30 d adjusted weaning weight (BW30). Univariate models first determined the significant non-additive genetic effects on BW traits. Lacaune breed composition negatively affected (P < 0.01) both BW traits. Individual heterosis positively influenced (P ≤ 0.04) both BW traits, but only BW0 was positively influenced by maternal heterosis (P < 0.001). A bivariate model was used to estimate genetic and non-genetic relationships among BW0 and BW30. The estimated direct heritabilities of BW0 and BW30 were 0.27 ± 0.04 and 0.39 ± 0.05, respectively. The higher than generally reported heritability for BW30 was likely due to a decrease in environmental variation associated with artificial rearing. Lamb BW traits were estimated to be highly phenotypically (0.54 ± 0.02) and genetically (0.63 ± 0.07) correlated. Additive maternal genetic effects explained a substantial proportion of the phenotypic variation of BW0 (0.25 ± 0.02). Although only artificially-reared lambs were included in the analyses of BW30, additive maternal genetic effects were non-zero (0.13 ± 0.02). The sale of market lambs represents a significant source of revenue for U.S. dairy sheep producers, and knowledge of the factors affecting lamb performance has important economic implications.

The application of recursive multivariate model for genetic evaluation of early growth traits in Raeini Chasmere goat: A comparison with standard multivariate model

Data collected on 2638 kids originated from 1305 dams and 197 sires during 1979 to 2012 in Raeini Cashmere goat breeding station located in Baft, Kerman province, south-eastern part of Iran, on body weights of 2638 Raeini Cashmere kids at birth (BW), at weaning (WW) and at six-month age (6 MW) were used to adopt a fully recursive multivariate model considering causal effects from BW on WW and on 6 MW and from WW on 6 MW. The adopted recursive multivariate model (RMM) was compared with a standard multivariate mixed model (SMM), in which causal relationships were ignored, in terms of deviance information criterion (DIC), predictive ability and the estimates of genetic and phenotypic parameters. Preliminary analyses revealed that the importance of direct additive genetic, maternal permanent environmental and temporary environmental effects for genetic evaluation of all the studied traits. Maternal additive genetic effects were only influencing on BW. Model comparisons via DIC revealed the plausibility of RMM over SMM; DIC value obtained by fitting RMM (-15,218.76) was lower than that of obtained under SMM (21,654.92). For BW, lower mean square of error (MSE) and higher Pearson's correlation coefficient between the observed and predicted values (r(y,y^)) were obtained under SMM but in the case of WW and 6 MW lower MSE and higher r(y,y^) were obtained under RMM. The causal effects of BW on WW and on 6 MW and that of WW on 6 MW were 1.94 kg, 2.48 kg and 1.03 kg, respectively. The estimates of direct heritability, maternal heritability (for BW) and ratio of permanent and / or temporary environmental variances to phenotypic variance were not significantly affected by model fitted (SMM and RMM). Direct additive genetic correlations of BW-WW and BW-6 MW were not statistically significant under SMM (95% HPD interval included zero) but the corresponding estimates under RMM were significant (99% HPD interval did not include zero) values of 0.28 and 0.84, respectively; implying that genes associated with BW also increase WW and 6 MW in Raeini Cashmere goat. Direct genetic correlation estimate for WW-6 MW were 0.88 (under SMM) and 0.29 (under RMM). Generally, RMMs perform better than SMMs and may provide a better explanation to biological relationships among the studied traits.

Estimation of direct and maternal genetic parameters for individual birth weight, weaning weight, and probe weight in Yorkshire and Landrace pigs.

As a result of selecting for increased litter size, newborn piglets are being born lighter and have a lower chance of survival. Raising fewer pigs to market weight would have a negative impact on the industry and farmer profitability; thus, understanding the genetics of individual growth performance traits will determine whether these traits will play an important role in pig breeding schemes. This study aimed to estimate genetic parameters for individual birth weight (BW), weaning weight (WW), and probe weight (PW) in Canadian-purebred Yorkshire and Landrace pigs. PW is a live weight taken at the time of the ultrasound measurements, when pigs weigh about 100 kg. Data were collected from 2 large and related breeding herds from 2003 to 2015. Four linear animal models were used, which included the following: Model 1-direct additive genetic effect; Model 2-direct additive genetic and maternal genetic effect; Model 3-direct additive genetic and common litter effect; and Model 4-direct additive genetic, maternal genetic, and common litter effect. The model which included all 3 random effects (Model 4) was determined to be the best fit to the data. Low to moderate direct heritability estimates were observed as follows: 0.15 ± 0.03 for BW, 0.04 ± 0.01 for WW, and 0.33 ± 0.03 for PW for the Yorkshire breed; and 0.05 ± 0.01 for BW, 0.01 ± 0.01 for WW, and 0.27 ± 0.03 for PW in the Landrace breed. As expected, the direct heritability estimates increased with age as a result of decreased maternal influence on the trait. Bivariate animal models were also used to estimate genetic and environmental correlations between traits. Strong direct genetic correlations were observed between BW and WW in both breeds. Based on the estimates of genetic parameters, individual BW could be evaluated and considered in breeding programs aiming to increase BW and improve subsequent performance. Different selection emphasis could also be applied on direct and maternal additive genetic effects on BW to optimize the breeding programs and improve selection efficiency.

Statistical models for genetic evaluation of some first kidding and lifetime traits of the Egyptian Zaraibi goats

The aim of the present study was to define the best fitting model for genetic evaluation of the Egyptian Zaraibi goats using three statistical models. Models differed based on the inclusion or exclusion of maternal additive genetic effects and the direct-maternal genetic covariance (σam). The models used were; Model 1 (without maternal effects); Model 2 (with maternal effects where σam = 0) and Model 3 (as in Model 2, but σam ≠ 0). The evaluated traits were; litter size at birth (LSB, kid), litter size at weaning (LSW, kid), litter weight at birth (LWB, kg), litter weight at weaning (LWW, kg), first lactation milk yield (FLMY, kg), first lactation length (FLL, day), total milk yield in productive life (TMY, kg) and total lactation length in productive life (TLL, day). Data represented some first lactation and longevity traits. A total of 2270 first kidding records produced from 600 does that were sired by 95 bucks. Statistical analyses were done using VCE-6 software. Model selection was built on the value of Akaike information criterion (AIC). Direct heritabilities were higher than maternal heritabilities in all models, and varied between 0.09 to 0.21, 0.05 to 0.22, 0.11 to 0.24 and 0.05 to 0.20 for LSB, LSW, LWB and LWW, respectively. Direct heritability for yield and lifetime traits were low to moderate and varied from 0.16 to 0.18, 0.07 to 0.34, 0.15 to 0.16 and 0.08 to 0.18 for FLMY, FLL, TMY and TLL, respectively. Maternal heritabilities ranged from 0.02 to 0.30 from models 2 and 3. Direct-maternal genetic correlations were low to moderate, negative for most of studied traits and ranged from −0.01 to −0.38. The inclusion of both direct and maternal effects in addition to the covariances between them in statistical models is recommended for the best genetic improvement of Egyptian Zaraibi goats.