Direct Additive Effects Research Articles

The comparison of the selected morphometric traits in three medium-sized rabbit breeds

The comparison of the selected morphometric traits in three medium-sized rabbit breeds

Single-step genome-wide association for longitudinal traits of Canadian Ayrshire, Holstein, and Jersey dairy cattle

Estimating single nucleotide polymorphism (SNP) effects over time is essential to identify and validate candidate genes (or quantitative trait loci) associated with time-dependent variation of economically important traits and to better understand the underlying mechanisms of lactation biology. Therefore, in this study, we aimed to estimate time-dependent effects of SNP and identifying candidate genes associated with milk (MY), fat (FY), and protein (PY) yields, and somatic cell score (SCS) in the first 3 lactations of Canadian Ayrshire, Holstein, and Jersey breeds, as well as suggest their potential pattern of phenotypic effect over time. Random regression coefficients for the additive direct genetic effect were estimated for each animal using single-step genomic BLUP, based on 2 random regression models: one considering MY, FY, and PY in the first 3 lactations and the other considering SCS in the first 3 lactations. Thereafter, SNP solutions were obtained for random regression coefficients, which were used to estimate the SNP effects over time (from 5 to 305 d in lactation). The top 1% of SNP that showed a high magnitude of SNP effect in at least 1 d in lactation were selected as relevant SNP for further analyses of candidate genes, and clustered according to the trajectory of their SNP effects over time. The majority of SNP selected for MY, FY, and PY increased the magnitude of their effects over time, for all breeds. In contrast, for SCS, most selected SNP decreased the magnitude of their effects over time, especially for the Holstein and Jersey breeds. In general, we identified a different set of candidate genes for each breed, and similar genes were found across different lactations for the same trait in the same breed. For some of the candidate genes, the suggested pattern of phenotypic effect changed among lactations. Among the lactations, candidate genes (and their suggested phenotypic effect over time) identified for the second and third lactations were more similar to each other than for the first lactation. Well-known candidate genes with major effects on milk production traits presented different suggested patterns of phenotypic effect across breeds, traits, and lactations in which they were identified. The candidate genes identified in this study can be used as target genes in studies of gene expression.

Estimation of Variance Components for Birth and Weaning Weights in Holstein-Friesian Calves by using WOMBAT software

The aim of this study was to determine the variance components for birth and weaning weights in Holstein calves. In this purpose, a total of 675 calf birth weight and 295 weaning weight records of Holstein calves raised at Kuzucu Dairy Cattle Farm in Eregli, Konya Province were used for estimation of phenotypic and genetic parameters for calf birth weight and weaning weight. Phenotypic and genetic parameters were estimated by WOMBAT program using a Single Trait Animal Model (STAM). The model constitutes of additive direct effect, maternal genetic effect (only for Model II) and errors as random effects, birth type, sex of calf, season of birth, year of birth and age of dam as fixed effects. Least square mean of calf birth weight was determined as 34.992 ± 0.572 kg. The direct heritability (h a 2 ) of calf birth weight was calculated as 0.180±0.109 in Model I and the direct heritability (h a 2 ) and maternal heritability (h m 2 ) of calf birth weight were calculated as 0.154±0.096 and 0.141±0.106 in Model II, respectively. The effect of calving season, birth type, sex and age of dam on birth weight of calf were significant (P 0.05). As for calf weaning weight, least square mean was determined as 74.250 ± 1.775 kg. For calf weaning weight, the direct heritability (h a 2 ) in Model I was calculated as 0.104± 0.126 and the direct heritability (h a 2 ) and maternal heritability (h m 2 ) in Model II were calculated as 0.104± 0.127 and 0.00002±0.341, respectively. The effect of calving year (P 0.05) Furtermore, estimated breeding values (EBVs) estimated by BLUP (Best Linear Unbiased Prediction) for calves, sires and dams were found to be in general with the range of -3.245 to 2.577, -2.607 to 2.631 and -1.714 to 1.747 for birth weight and -2.969 to 2.274, -2.650 to 2.376 and -1.456 to 1.301 for weaning weight, respectively.

CROSSBREEDING EFFECTS AND POLYMORPHIC ASSOCIATIONS OF GENOTYPES OF GH GENE WITH GROWTH TRAITS IN RABBITS

A simple crossbreeding experiment between two new synthetic rabbit lines (APRI and Moshtohor) was conducted to estimate the crossbreeding effects (direct additive, maternal additive and heterosis) on post-weaning body weights (BW) at 4, 6, 8, 10 and 12 weeks of age and daily weight gains (DG) during the intervals from 4 to 6, 6 to 8, 8 to 10 and 10 to 12 weeks, and to detect the polymorphic associations of the genotypes of GH gene with post-weaning body weight and daily gain traits. Four genetic groups of APRI (A-line), Moshtohor (M-line) and their simple F1 cross (½A½M) in addition to V-line rabbits (as a reference population) were used in this study.PCR-RFLP technique was applied using BstUI restriction enzyme SNP for genotyping the growth hormone gene (GH) (TT, TC and CC) genotypes. Heritabilities estimated by VCE program for body weights and daily weight gains were mostly low or moderate and ranging from 0.05 to 0.18. The percentages of direct additive effects on body weights were significantly (P<0.01) in favour of Moshtohor line by 2.7, 4.3, 1.4, 2.6 and 2.9 % at 4, 6, 8, 10 and 12 weeks and by 8.7, 15.9 and 18.6 % in daily weight gains at DG4-6, DG6-8 and DG8-10, respectively. The percentages of maternal effects on body weights at 4, 6, 8, 10 and 12 weeks were also significantly in favour of Moshtohor line by 2.8, 5.4, 3.5, 3.5 and 3.1%, respectively and ranged from 1.8 to 15% for daily weight gains in weight. The percentages of direct heterosis were significantly positive by 3.1, 8.1, 8.2, 5.2 and 3.8 % for body weights at 4, 6, 8, 10 and 12 weeks and by 13.0, 7.8 and 9.6% for daily weight gains at DG6-8, DG8-10 and DG10-12, respectively. The associations of the genotypes of GH gene were polymorphic and had significant effects on most growth traits (P<0.05). There were significant differences (P<0.05) between the generalized least square means of the different genotypes (TT, CC and TC) of GH gene for body weights at 4, 6, 8, 10 and 12 weeks of age in V-line, M-line, A-line and ½A½M cross rabbits. The TC genotype was positively associated with an increase in body weights of V-line, M-line and A-line rabbits, while the TT genotype indicated an increase in body weights of ½A½M rabbits. The significant associations between GH gene and growth traits confirmed that this gene could be a candidate gene and may be used in Marker-assisted selection (MAS) to improve growth performance in rabbits.Conclusively, GH gene could be used as a candidate gene in genetic improvement programs to improve growth performance in rabbits.

Understanding the porous aggregates carrier effect on reducing autogenous shrinkage of Ultra-High Performance Concrete (UHPC) based on response surface method

In this study, the porous aggregates carrier effect on reducing autogenous shrinkage and optimizing microstructure of Ultra-High Performance Concrete (UHPC) is investigated, including experimental study and mechanism analysis. Based on the modified dense particle packing model (Andreasen & Andersen model), the UHPC skeleton is designed. Then, the shrinkage reducing admixture (SRA) is absorbed by porous aggregates (PA), and the pretreated PA is used to replace the fine aggregates in UHPC. After that, a series of experiments are executed for the developed UHPC, including flowability, setting times, mechanical properties, autogenous shrinkage and microstructure development. Accordingly, based on the obtained experimental results, the Response Surface Methods (RSM) is utilized to get the optimized PA content and SRA solution concentration. The obtained results show that PA acting as carrier is beneficial to reduce the adverse effect of direct addition of SRA. Moreover, when the added PA content is 25% and the SRA solution concentration is 70%, the developed UHPC has advanced properties. Therefore, on the basis of on the method proposed in this study, it is possible to effectively reduce the UHPC autogenous shrinkage without sacrificing its fresh behavior, mechanical properties and dense microstructure.

Employees’ performance in a Mexican government agency depends on satisfaction with feedback

LKnowledge on the impact of feedback orientation measures and the effect of satisfaction with feedback on performance is scarce. Therefore, the aims of this study were: to identify the influences of feedback utility, accountability, self-efficacy and social awareness on satisfaction with feedback; and to define the effect of satisfaction with feedback on performance through regression analyses for the case of employees of a Mexican government agency. Then, two questionnaires were designed and applied. The first one considered the feedback orientation scale and 76 employees. The second questionnaire involved measures of in-role behavior and five managers. Almost 87% of the employees’ satisfaction with feedback variation is explained by the direct additive effects of utility, accountability, self-efficacy, and social awareness. The employees’ performance variation depends on satisfaction with feedback.

UTILIZAÇÃO DE MODELOS DE REGRESSÃO ALEATÓRIA PARA OBTENÇÃO DE PARÂMETROS GENÉTICOS DE BOVINOS DA RAÇA TABAPUÃ

Resumo Este trabalho utilizou 28.643 registros de pesos, do nascimento aos 660 dias de idade, de 6.471 animais da raça Tabapuã para estimar componentes de variância, covariância e parâmetros genéticos, utilizando o modelo de regressão aleatória. Foi utilizado algoritmo de busca AIREML através do método da máxima verossimilhança restrita pelo programa computacional DFREML. Os modelos incluíram: como aleatórios, os efeitos genético aditivo direto, materno, de ambiente permanente de animal e materno; como fixos, os efeitos de grupo de contemporâneos; como covariáveis, a idade do animal à pesagem e a idade da vaca ao parto. As estimativas de variância genética aditiva direta obtidas aumentaram com a idade. As estimativas de herdabilidade para o efeito aditivo direto mostram o decréscimo da herdabilidade do nascimento até a desmama, enquanto as estimativas de herdabilidade materna apresentaram aumento do nascimento até a desmama, decrescendo nas idades seguintes. As correlações genéticas diretas variaram de moderadas a altas, diminuindo suas magnitudes à medida que aumentou a distância entre as idades dos animais. O modelo de regressão aleatória utilizado mostrou-se adequado para descrever as mudanças nas variâncias dos pesos de bovinos da raça Tabapuã do estado da Bahia.

Longitudinal analysis of weight showed little relationship with age at puberty in gilts.

Continued selection for increased gilt body weight could negatively impact selection for age at puberty (AP) in gilts. The purpose of this study was to compare the genetic potential for growth to that for reducing age of puberty in swine. Females utilized (n = 1,079) were produced over a 6-yr period from a population developed to determine the impact of energy restrictions and genetic influences on sow development and longevity. From 120 to 235 d of age, BW was collected every 14 d and attainment of puberty tested. Age at puberty was defined as the first observed standing estrus in the presence of a mature boar. All females were genotyped with the Porcine SNP60K BeadChip and genotypes were used to construct a genomic relationship matrix. Univariate (AP), repeatability (BW), and random regression (BW; RR) models were fitted. Univariate analysis included the fixed effects of contemporary group (CG) and age at first boar exposure, and random direct additive and common litter effects. Repeatability analysis included the fixed effects of CG and random effects of direct additive, common litter, and permanent environmental (PE) effects. Random regression analysis included fixed effects of CG, and random direct additive, common litter, and PE effects. Proportion of phenotypic variation due to direct additive and common litter variance for AP were 0.33 and 0.06, respectively. Proportion of phenotypic variation due to direct additive, common litter, and PE variance estimated from the repeatability model for BW were 0.26, 0.11, and 0.40, respectively. Proportion of phenotypic variation due to direct additive, common litter, and PE variance estimated from the RR for BW ranged from (mean) 0.19 to 0.30 (0.27), 0.08 to 0.31 (0.19), and 0.42 to 0.62 (0.50), respectively. Direct additive correlations between test days for BW from RR ranged from 0.30 to 0.99. Rank correlations between estimated breeding values (EBV) for AP and BW from the RR were near zero across all age points ranging from -0.03 to 0.09. Rank correlations were higher (0.63) when BW was considered at the age at which puberty was reached. Correlations between AP and BW EBV from the repeatability model were low (-0.11). Growth appears to be less related to AP than previously reported, suggesting the need to either directly measure AP or investigate alternative indicator traits. Selecting gilts with most desirable BW EBV alone would not result in improvement in AP, at least in the current population.

IMPROVING GROWTH TRAITS AND ESTIMATING HETEROSIS, ADDITIVE AND MATERNAL EFFECTS A CROSS DIALLEL MATING AMONG THREE LINES SELECTED HEAVIEST BODY WEIGHT UNDER HEAT CONDITION

A crossbreeding experiment was executed between three breeds were selected three generation for heavy body weight under high temperature condition Sinai (SI) and Rhode Island Red (RI) and Fayoumi breeds. 900 crossing meals from each genotype were recorded singular body weight and body weight gain at hatch, 4, 8 and 12 weeks of age. crosses SI XRI and reciprocal RI x Si significant heaver body weight and body weight gain compared than other crosses and pure breed. On the other hand body weight and body weight gain were significant heaver for pure line Sinai or Rod iland read and crosses SI x F, F x RI, Fx SI and RI xF compared to Fayoumi pure line. Heterosis was positive significant on body weight at hatch, 4,8 and 12 weeks of ages. As the same trend results of body weight gain but, negative significant at the intervals from 4wks to 8wks only. It could be observed that the hybrid vigor of body weight was significant positive effect for crosses SI X RI and reciprocal crosses RI XSI and RI XF ones.While, the hybrid vigor of body weight gain was significant positive effect for all diallel crossing except F X RI crosses. the direct additive effects were negative for line Fayoumi both body weight and weight gain taits at diferent age of these study. But these reciprocal effect were significant positive for Sinai and Rodiland red lines both body weight and body weight gain. These resuls shown that the croses RI XSI beter than SI X RI for both body weight and body weight gain. Maternal effect of body weight and body weight gain were significant positive effect at hatcher , for FF and SI SI. While, it was significant negative effect for RIRI. On the other hand, were significant positive for body weight at hatcher and 4 weeks of age only. While, maternal effect was significan positive at the intervals 0-4weeks only. The last shown that the maternal effect had a play essential role on body weght and body weight gain.Recommended used crosses Sinai and rod Iland red to produce commercial meat strains in hot climated countery.

Modelling non-additive genetic effects using ridge regression for an Angus–Nellore crossbred population

Data from 294045 records from a crossbred Angus × Nellore population were used to estimate fixed genetic effects (both additive and non-additive) and to test different non-additive models using ridge regression. The traits studied included weaning gain (WG), postweaning gain (PG), phenotypic scores for weaning (WC) and postweaning (PC) conformation, weaning (WP) and postweaning (PP) precocity, weaning (WM) and postweaning (PM) muscling and scrotal circumference (SC). All models were compared using the likelihood-ratio test. The model including all fixed genetic effects (breed additive and complementarity, heterosis and epistatic loss non-additive effects, both direct and maternal) was the best option to analyse this crossbred population. For the complete model, all effects were statistically significant (P &amp;lt; 0.01) for weaning traits, except the direct breed additive effects for WP and WM; direct complementarity effect for WP, WM, PP and PM and maternal epistatic loss for PG. Direct breed additive effect was positive for weaning traits and negative for postweaning. Maternal breed additive effect was negative for SC and WP. Direct complementarity and heterosis were positive for all traits and maternal complementarity and heterosis were also positive for all traits, except for PG. Direct and maternal epistatic loss effects were negative for all traits. We conclude that the fixed genetic effects are mostly significant. Thus, it is important to include them in the model when evaluating crossbred animals, and the model that included breed additive effects, complementarity, heterosis and epistatic loss differed significantly from all reduced models, allowing to infer that it was the best model. The model with only breed additive and heterosis was parsimonious and could be used when the structure or amount of data does not allow the use of complete model.

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.

Association of MSTN gene polymorphism (C354T) with performance traits in raccoon dogs

The aim of the study was to identify polymorphisms within nuclear DNA genes and determine their association with the performance traits of farmed raccoon dogs. The study involved 354 animals and their breeding documentation data. Myostatin (MSTN), insulin-like growth factor 1 (IGF1), and growth hormone (GHR) genes were amplified, sequenced, and subjected to bioinformatics and statistical analysis. Estimation of variance components was performed with the residual maximum likelihood (REML) method, and best linear unbiased prediction (BLUP) of the breeding values was carried out. The predictors of the traits of direct additive, maternal additive, and random-specific maternal environmental effects were analysed. Within the nucleotide sequences of the analysed genes, one silent single nucleotide polymorphism (SNP) was identified in exon 1 of the MSTN gene. The analysis of the variance of the fixed-specific maternal environmental effect revealed statistically significant differences in the body weight among raccoon dogs with alternative polymorphisms. The mean effects of the estimators of polymorphism addition and dominance measured by MSTN gene regression had mostly a significant impact on the level of the traits estimated in animals. There was statistically significant association of the polymorphism in the MSTN gene with the body weight in raccoon dogs, which validates selection thereof as a candidate gene for this economically most important performance trait of raccoon dogs.

Genetic parameters for ewe reproductive performance and peri-parturient fecal egg counts and their genetic relationships with lamb body weights and fecal egg counts in Katahdin sheep.

This study estimated genetic parameters for ewe reproductive traits [number of lambs born (NLB) and weaned (NLW) per ewe lambing] and fecal egg counts (FEC) during the peri-parturient rise (PPR) for use in genetic evaluation of Katahdin sheep. Data included NLB and NLW for 23,060 lambings by 9,295 Katahdin ewes, 1,230 PPR at lambing (PPR0) for 750 ewes, 1,070 PPR at approximately 30 d postpartum (PPR30) for 611 ewes, BW at birth, weaning, and (or) post-weaning for 12,869 lambs, and FEC at weaning and (or) post-weaning for 4,676 lambs. Direct additive, permanent environmental, and residual (co)variances were estimated in univariate and bivariate animal models. Fixed effects included effects of ewe management group and ewe age for all traits, and, for PPR, a continuous effect of days between lambing and measurement. Effects of litter size on PPR0 and number of lambs suckled on PPR30 were included in univariate models but excluded from bivariate models for PPR and NLB or NLW. Heritability estimates in univariate models for NLB, NLW, PPR0, and PPR30 were 0.09 ± 0.01, 0.06 ± 0.01, 0.35 ± 0.06, and 0.24 ± 0.07, respectively. Estimates of permanent environmental variance as a proportion of total phenotypic variance were 0.02 ± 0.01 for NLB, 0.03 ± 0.01 for NLW, 0.05 ± 0.06 for PPR0, and 0.13 ± 0.07 for PPR30. Direct additive, phenotypic, permanent environmental, and residual correlations between NLB and NLW were 0.88 ± 0.03, 0.74 ± 0.004, 0.54 ± 0.15, 0.74 ± 0.003, respectively; corresponding correlations between PPR0 and PPR30 were 0.96 ± 0.07, 0.46 ± 0.03, 0.98 ± 0.50, 0.18 ± 0.05, respectively. The additive genetic correlation (rd) between ewe reproductive traits and PPR ranged from 0.12 to 0.18. Estimates of rd between lamb BW and subsequent ewe NLB and NLW ranged from 0.07 to 0.20, and those between PPR and lamb BW ranged from -0.03 to 0.29. The rd between ewe reproductive traits and lamb FEC ranged from 0.27 to 0.40, and those between PPR and lamb FEC ranged from 0.56 to 0.77. Correlations between maternal additive effects on BW and direct additive effects on PPR were low (-0.08 to 0.10), and those between maternal additive effects on BW and direct additive effects on ewe reproductive traits were variable (-0.36 to 0.11). We conclude that FEC in growing lambs and peri-parturient ewes are controlled by similar genes and that modest, but manageable, genetic antagonisms may exist between FEC and ewe productivity.

Parâmetros e tendências genéticas para peso ao sobreano de animais Nelore criados no estado do Paraná, Brasil

Objetivou-se avaliar os efeitos de meio e estimar os parâmetros e tendência genética para peso aos 365 e 550 dias de animais da raça Nelore criados no estado do Paraná. Utilizou-se do método dos quadrados mínimos, incluindo os efeitos fixos de ano, mês de nascimento, sexo e a co-variável idade da vaca ao parto (linear e quadrática). Os parâmetros genéticos foram estimados utilizando-se um modelo animal que continha os efeitos aleatórios genéticos direto e materno, de ambiente permanente e o erro; além do efeito fixo de grupo contemporâneo e da co-variável idade da vaca ao parto. A tendência genética foi obtida por meio de análise de regressão linear do valor genético do animal sobre o ano de nascimento. As herdabilidades diretas foram 0,24±0,03 e 0,35±0,05; as herdabilidades maternas foram 0,08±0,03 e 0,03±0,04, para peso aos 365 e 550 dias, respectivamente. As tendências genéticas direta e materna foram 0,506 kg/ano e -0,184 kg/ano para P365; e 0,712 kg/ano e 0,187 kg/ano para P550. Os resultados indicam a existência de variabilidade genética o que possibilitam ganhos através de seleção.

Two mitochondrial genes are associated with performance traits in farmed raccoon dogs (Nyctereutes procyonoides)

The relationships between chosen mitochondrial genes polymorphisms and performance traits in raccoon dogs were determined. The study involved 354 farmed raccoon dogs. Blood collected from the animals was the analysed biological material. Mitochondrial DNA genes, i.e. MT-CO1 (mitochondrially encoded cytochrome c oxidase I), MT-CO2 (mitochondrially encoded cytochrome c oxidase II), and MT-CYB (mitochondrially encoded cytochrome b) were amplified using the polymerase chain reaction method. The amplicons obtained were sequenced and subjected to bioinformatics analysis. Based on the nucleotide sequences, three haplotypes for the MT-CO1 gene fragment and two haplotypes for the MT-CO2 gene fragment were identified. The sequence of the MT-CYB gene was monomorphic. Based on the haplotypes, five previously undescribed mitochondrial haplogroups were determined. Statistical analysis revealed significant differences between the values of three of the five investigated performance traits of raccoon dogs and the identified haplotypes and mitochondrial haplogroups, taking into account predictors of direct additive effects, additive maternal effects, and fixed specific maternal environmental effects. The new mitochondrial haplogroups identified in the farmed raccoon dog population may imply constant emergence of adaptive mutations that are conserved in subsequent generations. The results of the association study indicate a statistically significant association between haplotypes and mitochondrial haplogroups of farmed raccoon dogs and their body weight, body size, and colour type, which allows considering MT-CO1 and MT-CO2 genes as candidate genes encoding these traits in raccoon dogs. The results of the molecular analyses can be applied to improve the performance traits in farmed raccoon dogs.

Direct and maternal additive effects are not the main determinants of Iberian piglet perinatal mortality.

Data of 127,800 Iberian piglets were used to study genetic parameters of mortality at birth at the piglet level. These records proceed from three data sets: 4,987litter of 2,156 sows of a dam line, 2,768litter of 817 sows of a complete diallel cross between four Iberian strains and 7,153litter of 2,113 sows of the Torbiscal composite line. Perinatal mortality was considered as a binary trait, and Bayesian threshold animal models were fitted to separately analyse the three data sets. The posterior means of direct heritability were 0.010, 0.004 and 0.003, and those of maternal heritability were 0.034, 0.011 and 0.014 for dam line, diallel cross and Torbiscal line, respectively. Important effects of litter size and parity order were inferred in the three data sets, of within-breed cross-breeding parameters in the diallel cross and of sex and sow handling in the Torbiscal line Therefore, the inclusion of perinatal mortality in the objective of selection is questionable in this breed and strategies for reducing piglet mortality successful in other breeds should be considered.

Variance components for direct and maternal effects on body weights of Katahdin lambs.

The aim of this study was to estimate genetic parameters for BW in Katahdin lambs. Six animal models were used to study direct and maternal effects on birth weight (BWT), weaning weight (WWT), and postweaning weight (PWWT) using 41,066 BWT, 33,980 WWT, and 22,793 PWWT records collected over 17 yr in 100 flocks. Models included fixed effects of management group, dam age, type of birth (for BWT) or birth and rearing (for WWT and PWWT), and lamb age at weighing (fitted as a covariate for WWT and PWWT; all < 0.05). Variance components for random effects were estimated in sequentially more complex models and tested for significance with likelihood-ratio tests. A model that fitted only an additive animal effect overestimated additive variance for all BW, resulting in larger estimates of direct heritability than models that included maternal effects. Maternal effects explained variation ( < 0.05) in all BW. Heritability estimates for optimal models were 0.15 ± 0.01 for BWT, 0.18 ± 0.02 for WWT, and 0.20 ± 0.02 for PWWT. Estimates of maternal heritabilities were 0.14 for BWT, 0.10 for WWT, and 0.06 for PWWT, with SE = 0.01. Permanent environmental maternal effects explained 4 to 6% (±1%) of total phenotypic variances for these BW. Litter effects included temporary environmental effects common to littermates and a proportion of the dominance genetic variance and accounted for 16 to 19% (±1%) of phenotypic variance. Correlations between additive direct and maternal genetic effects were -0.14 for BWT, -0.23 for WWT, and -0.04 for PWWT but differed from 0 ( < 0.05) only for WWT. The total heritability predicted the total response in direct and maternal genetic effects from mass selection and was 0.23 for BWT, 0.20 for WWT, and 0.23 for PWWT. Direct and maternal additive, maternal permanent environmental, residual, and phenotypic correlations between BWT and WWT were 0.53 ± 0.05, 0.58 ± 0.06, 0.51 ± 0.06, 0.39 ± 0.01, and 0.44 ± 0.01, respectively; those between BWT and PWWT were 0.45 ± 0.06, 0.58 ± 0.08, 0.36 ± 0.08, 0.33 ± 0.01, and 0.37 ± 0.01 respectively; and those between WWT and PWWT were 0.85, 0.99, 0.92, 0.77, and 0.81, respectively, with SE ≤ 0.02. Therefore, both direct and maternal effects had an important impact on BW in Katahdin lambs. Models that included both additive and permanent environmental maternal effects as well as a temporary environmental litter effect should result in more accurate estimates of breeding values and better selection decisions.

Effects of control on the dynamics of an adjacent protected wolf population in interior Alaska

Effects of control on the dynamics of an adjacent protected wolf population in interior Alaska

Alternative approaches to evaluation of cow efficiency

The purpose of this study was to evaluate alternative expressions of genetic merit for cow efficiency. Weights of Pinzgauer cattle taken at birth, weaning, and maturity were extracted from the South African National Database. Average daily gain from birth to weaning (ADG) and cow weight (CWT) were analyzed with a multi-trait mixed model. The model included direct and maternal genetic effects, a permanent environmental effect attributable to dams on ADG, a direct genetic effect and a permanent environmental effect attributable to there being multiple observations from the same cow on CWT as random effects. Heritability estimates for direct and maternal additive effects on ADG were 0.27 ± 0.04 and 0.06 ± 0.02, respectively. The estimated heritability for CWT was 0.45 ± 0.06. Estimates of repeatability for ADG and CWT were 0.42 and 0.67, respectively. Estimated breeding values based on the preceding results and using the maternal genetic effect on ADG as a proxy for the direct genetic effect on milk production were combined in six indexes of cow efficiency. These indexes sought to increase output and decrease input simultaneously, to increase output holding input constantly, and to hold input constant while decreasing input. The diversity of emphasis applied across these indexes suggests the need for due diligence in developing breeding objectives for improvement of cow efficiency. Indexes that are consistent with the econometric definition of efficiency and seek to simultaneously increase output and reduce input are recommended. ______________________________________________________________________________________ Keywords : genetic parameters, multiple trait selection, Pinzgauer, selection index

Genetic evaluation of growth traits in Iranian Kordi Sheep using random regression model with homogeneous and heterogeneous residual variances

The purpose of this study was estimation of genetic parameter using random regression model (RRM) with various error variance in Iranian Kordi sheep. The data (consisting of 7875 weight records from birth to 360 days of age) were collected during the period 2000 to 2013 from the rearing and breeding station of Kordi sheep in Shirvan, Iran. The independent variables were Legendre polynomials (LP) of age at weighing and orders of fit from 2 to 5 were considered. Analyses were carried out fitting sets of random regression coefficients due to direct additive genetic, direct and maternal permanent environmental effects, with heterogeneous and homogeneous error variances. To compare the model were used different criteria such as LogL, AIC, BIC and LRT. The best fitting RRM among homogeneous error variance was the model with a LP of fourth order for fixed effect, fourth order for direct additive genetic and fifth order for direct and maternal permanent environmental effects (model 4455). Among the models with heterogeneous error variances different, model 7 (Heterogeneous error variances of 72 various classes), was selected as the best model. The variances increased along the trajectory from 3.75 to 12.81, 4.43 to 30.28 and 1.49 to 8.49; 0.25 to 27.94, 0.03 to 12.32 and 0.15 to 22.66 for direct additive genetic, direct and maternal permanent environmental effect by homogeneous and heterogeneous error variances, respectively. The direct heritability ranged from 0.15 to 0.41 and 0.11 to 0.56 by homogeneous and heterogeneous error variances, respectively. Genetic correlation between adjacent test days was more than between distant test days. This research has demonstrated the possibility of application of RRM with heterogeneous error variance for genetic evaluation of Iranian Kordi Sheep.