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1.
(Co)variance components, direct and maternal breed additive, dominance, and epistatic loss effects on preweaning weight gain of beef cattle were estimated. Data were from 478,466 animals in Ontario, Canada, from 1986 to 1999, including records of both purebred and crossbred animals from Angus, Blonde d'Aquitaine, Charolais, Gelbvieh, Hereford, Limousin, Maine-Anjou, Salers, Shorthorn, and Simmental breeds. The genetic model included fixed direct and maternal breed additive, dominance, and epistatic loss effects, fixed environmental effects of age of the calf, contemporary group, and age of the dam x sex of the calf, random additive direct and maternal genetic effects, and random maternal permanent environment effects. Estimates of direct and maternal additive genetic, maternal permanent environmental and residual variances, expressed as proportions of the phenotypic variance, were 0.32, 0.20, 0.12, and 0.52, respectively. Correlation between direct and maternal additive genetic effects was -0.63. Breed ranking was similar to previous studies, but estimates showed large SE. The favorable effects of direct and maternal dominance (P < 0.05) on preweaning gain were equivalent to 1.3 and 2.3% of the phenotypic mean of purebred calves, respectively. The same features for direct and maternal epistatic loss effects were -2.2% (P < 0.05) and -0.1% (P > 0.05). The large SE of breed effects were likely due to multicollinearity among predictor variables and deficiencies in the dataset to separate direct and maternal effects and may result in a less reliable ranking of the animals for across breed comparisons. Further research to identify the causes of the instability of estimates of breed additive, dominance, and epistatic loss genetic effects, and application of alternative statistical methods is recommended.  相似文献   

2.
The aim of this study was to estimate direct and maternal genetic parameters for calving difficulty score, stillbirth, and birth weight at first and later parities for Charolais and Hereford cattle in Sweden. Calving traits have long been recorded for pure-bred beef cattle in Sweden, but only birth weight has been used in the selection in order to avoid calving difficulties. Linear animal model analyses included records on birth weight for 60,309 Charolais and 30,789 Hereford calves born from 1980 to 1999, and calving traits for 74,538 Charolais and 37,077 Hereford calves born from 1980 to 2001. The frequencies of difficult calvings and stillbirths were approximately 6% at first and 1 to 2% at later parities for both breeds. Fewer than half the stillborn calves were born from difficult calvings. Heritabilities estimated for birth weight in different univariate and bivariate analyses for Charolais and Hereford calves born at first and later parities ranged from 0.44 to 0.51 for direct effects and 0.06 to 0.15 for maternal effects. Heritabilities on the observable scale for calving difficulty score of Charolais and Hereford, scored in three classes, ranged from 0.11 to 0.16 for direct and 0.07 to 0.12 for maternal effects at first parity, and lower at later parities. All estimated heritabilities for stillbirth were very low (0.002 to 0.016 on the observable scale). Direct-maternal genetic correlations were negative, with few exceptions. Genetic correlations between the traits and between parities within traits were generally moderate to high and positive. Calving difficulty score should be included in the genetic evaluation of beef breeds in Sweden, whereas progeny groups in Swedish beef populations are too small for stillbirth to be considered directly.  相似文献   

3.
Data spanning 1980 to 1993 from a multibreed beef herd including primarily eight breeds (Angus, Charolais, Gelbvieh, Hereford, Maine-Anjou, Pinzgauer, Simmental, and Tarentaise) were used to obtain 2,207 records on 200-d weaning gain (WG) and 1,826 records on 200-d milk yield (MY), obtained by machine milking after oxytocin injection. Estimates of (co)variances for the two traits (WG and MY) were obtained with REML with breed of calf, breed of cow, and heterotic effects modeled for the two traits. Animal effects of calf (CalfWG, CalfMY) and cow (CowWG, CowMY) contributions to each trait were modeled including 2,926 animals. The permanent environmental effect of the cow was modeled for MY, with 693 levels. Estimates of breed differences were generally similar to literature estimates. Simmental, Charolais, and Maine-Anjou were highest for CalfWG, and Tarentaise, Simmental, Gelbvieh, and Maine-Anjou were highest for CowMY. Heterosis was estimated at 8.00, 2.58, 4.05, and 5.50% of the mean for CalfWG, CowWG, CalfMY, and CowMy, respectively. Variance attributable to repeated records on CowMy represented 9% of phenotypic variance. Heritabilities estimated were .22 and .24 for CalfWG and CowWG and .04 and .35 for CalfMY and CowMY. Genetic correlations estimated between CalfWG and CowWG and between CalfMY and CowMY were -.35 and -.64, respectively. A genetic correlation between CowWG and CowMY of .76 indicates that maternal weaning gain evaluations are a good predictor of a cow's potential for milk yield.  相似文献   

4.
The objective of this study was to estimate genetic correlations between calving difficulty score and carcass traits in Charolais and Hereford cattle, treating first and later parity calvings as different traits. Genetic correlations between birth weight and carcass traits were also estimated. Field data on 59,182 Charolais and 27,051 Hereford calvings, and carcass traits of 5,260 Charolais and 1,232 Hereford bulls, were used in bivariate linear animal model analyses. Estimated heritabilities were moderate to high (0.22 to 0.50) for direct effects on birth weight, carcass weight, and (S)EUROP (European Community scale for carcass classification) grades for carcass fleshiness and fatness. Heritabilities of 0.07 to 0.18 were estimated for maternal effect on birth weight, and for direct and maternal effects on calving difficulty score at first parity. Lower heritabilities (0.01 to 0.05) were estimated for calving difficulty score at later parities. Carcass weight was positively genetically correlated (0.11 to 0.53) with both direct and maternal effects on birth weight and with direct effects on calving difficulty score. Carcass weight was, however, weakly or negatively (-0.70 to 0.07) correlated with maternal calving difficulty score. Higher carcass fatness grade was genetically associated with lower birth weight, and in most cases, also with less difficult calving. Genetic correlations with carcass fleshiness grade were highly variable. Moderately unfavorable correlations between carcass fleshiness grade and maternal calving difficulty score at first parity were estimated for both Charolais (0.42) and Hereford (0.54). This study found certain antagonistic genetic relationships between calving performance and carcass traits for both Charolais and Hereford cattle. Both direct and maternal calving performance, as well as carcass traits, should be included in the breeding goal and selected for in beef breeds.  相似文献   

5.
Birth weights (BW) and weaning weights (WW) of 4,423 non-creep-fed Hereford calves were used to estimate direct and maternal sources of variation and maternal phenotypic effects (fm). Seventeen different (co)variances among relatives were estimated through Henderson's Method III and restricted estimated maximum likelihood procedures. Direct and maternal (co)variances and fm were evaluated by multiple regression procedures. Estimates of h2 for BW and WW were .28 and .28 respectively, by the paternal half-sib procedure and .45 and .88, respectively, based on full-sibs. Repeatability estimates were .21 for BW and .30 for WW. Heritabilities based on regression of offspring on dam and offspring on sire were .45 and .21 for BW and .28 and .06 for WW, respectively. Negative correlations were found between solutions for additive genetic direct and additive maternal effects (rG). Estimates of rG ranged from -.86 to -1.05 for BW and from -.57 to -.79 for WW. Estimates of heritability for direct effects (h2o), for maternal effects (h2m) and for total additive genetic effects (h2T) were .16 to .27, .18 to .63 and -.02 to .05 for BW and .26 to .32, .27 to .67 and .10 to .20 for WW. Dominance affected both direct and maternal effects for BW and WW. Values of -.15 (BW) and -.25 (WW) were found for fm (path coefficient between the maternal phenotypes of dam and daughter). These results indicated that selection response would be decreased due to the negative genetic correlation between direct and maternal effects.  相似文献   

6.
Variances and covariances for birth weight, gain from birth to weaning (ADG), and 205-d weight were obtained from a sire-dam model and a sire-maternal grandsire model for a herd of Angus and a herd of Hereford cattle. Estimates of direct additive genetic variance (sigma 2A), maternal additive genetic variance (sigma 2M), covariance between direct and maternal additive genetic effects (sigma AM), permanent environmental variance (sigma 2PE), and residual variance (sigma 2e) were obtained both with and without the inverse of the numerator relationship matrix (A-1) included. Estimates of heritability for direct genetic effects (h2A), maternal genetic effects (h2M), and the correlation between direct and maternal effects (rAM) for birth weight were .37, .18, and -.01 in Angus and .53, .23, and -.19 in Herefords, respectively, for the analyses without A-1. For the analyses with A-1, estimates of h2A, h2M, and rAM were .42, .22, and -.12 for Angus and .58, .22, and -.13 for Herefords, respectively. Estimates of h2A, h2M, and rAM for ADG were .43, .15, and -.44 in Angus and .52, .38, and -.03 in Herefords, respectively, without A-1. With A-1, estimates of h2A, h2M, and rAM were .57, .15, and -.32 for Angus and .58, .39, and -.05 for Herefords, respectively. Estimates of h2A, h2M, and rAM for 205-d weight were .49, .15, and -.46 for Angus and .58, .43, and -.06 for Herefords, respectively, without A-1. With A-1, estimates of h2A, h2M, and rAM were .63, .16, and -.36 for Angus and .66, .43, and -.08 for Herefords, respectively. Estimates of h2A were higher with A-1 than without A-1, but estimates of h2M were similar. Using variances and covariances obtained from analyses including A-1 generally gave higher estimates of direct breeding values than using variances and covariances obtained from analyses not including A-1. Both Pearson product-moment and Spearman rank correlations were high (.99) between estimates of breeding values from the two analyses, although some changes in rank did occur.  相似文献   

7.
The objective of this study was to quantify the effect of inbreeding on carcass quality, growth rate, live conformation measures, and calving performance in purebred populations of Charolais, Limousin, Simmental, Hereford, and Angus beef cattle using data from Irish commercial and pedigree herds. Variables analyzed are reflective of commercial farming practices. Inbreeding was included in a linear mixed model as either a class variable or a linear continuous variable. Nonlinear effects were nonsignificant across all traits. Inbred animals had decreased carcass weight and less carcass fat. The effects of inbreeding were more pronounced in the British beef breeds. Effects for carcass weight ranged from -0.87 kg (Charolais) to -1.90 kg (Hereford) per 1% increase in inbreeding. Inbred Charolais and Hereford animals were younger at slaughter by 3 and 5 d, respectively, per percentage of increase in inbreeding, whereas the effect of inbreeding on age at slaughter differed significantly with animal sex in the Limousin and Angus breeds. Inbred Limousin and Angus heifers were younger at slaughter by 5 and 7 d, respectively, per percentage of increase in inbreeding. Continental animals were more affected by inbreeding for live muscling and skeletal conformational measurements than the British breeds; inbred animals were smaller and narrower with poorer developed muscle. Calf inbreeding significantly affected perinatal mortality in Charolais, Simmental, and Hereford animals. The effects were dependent upon dam parity and calf sex; however, where significant, the association was always unfavorable. Dam inbreeding significantly affected perinatal mortality in Limousin and Hereford animals. Effects differed by parity in Limousins. Inbred first-parity Angus dams had a greater incidence of dystocia. Although the effects of inbreeding were some-times significant, they were small and are unlikely to make a large financial effect on commercial beef production in Ireland.  相似文献   

8.
Estimates of direct and maternal genetic parameters in beef cattle were obtained with a random regression model with a linear spline function (SFM) and were compared with those obtained by a multitrait model (MTM). Weight data of 18,900 Gelbvieh calves were used, of which 100, 75, and 17% had birth (BWT), weaning (WWT), and yearling (YWT) weights, respectively. The MTM analysis was conducted with a three-trait maternal animal model. The MTM included an overall linear partial fixed regression on age at recording for WWT and YWT, and direct-maternal genetic and maternal permanent environmental effects. The SFM included the same effects as MTM, plus a direct permanent environmental effect and heterogeneous residual variance. Three knots, or breakpoints, were set to 1, 205, and 365 d. (Co)variance components in both models were estimated with a Bayesian implementation via Gibbs sampling using flat priors. Because BWT had no variability of age at recording, there was good agreement between corresponding components of variance estimated from both models. For WWT and YWT, with the exception of the sum of direct permanent environmental and residual variances, there was a general tendency for SFM estimates of variances to be lower than MTM estimates. Direct and maternal heritability estimates with SFM tended to be lower than those estimated with MTM. For example, the direct heritability for YWT was 0.59 with MTM, and 0.48 with SFM. Estimated genetic correlations for direct and maternal effects with SFM were less negative than those with MTM. For example, the direct-maternal correlation for WWT was -0.43 with MTM and -0.33 with SFM. Estimates with SFM may be superior to MTM due to better modeling of age in both fixed and random effects.  相似文献   

9.
Genetic parameters for a random regression model of growth in Gelbvieh beef cattle were constructed using existing estimates. Information for variances along ages was provided by parameters used for routine Gelbvieh multiple-trait evaluation, and information on correlations among different ages was provided by random regression model estimates from literature studies involving Nellore cattle. Both sources of information were combined into multiple-trait estimates; corrected for continuity, smoothness, and general agreement with literature estimates; and extrapolated to 730 d. Covariance functions using standardized Legendre polynomials were fit for the following effects: additive genetic (direct and maternal), and animal and maternal permanent environment. Residual variances at different ages were fitted using linear splines with three knots. Fit was by least squares. The order of polynomials was varied from third to sixth. Increasing the fit beyond cubic provided small improvements in R2 and increased the number of small eigenvalues of covariance matrices, especially for the additive effect. Parameters for a random regression model in beef cattle can be constructed with negligible artifacts from literature estimates. Formulas can easily be modified for other types of polynomials and splines.  相似文献   

10.
Estimates of genetic parameters resulting from various analytical models for birth weight (BWT, n = 4,155), 205-d weight (WWT, n = 3,884), and 365-d weight (YWT, n = 3,476) were compared. Data consisted of records for Line 1 Hereford cattle selected for postweaning growth from 1934 to 1989 at ARS-USDA, Miles City, MT. Twelve models were compared. Model 1 included fixed effects of year, sex, age of dam; covariates for birth day and inbreeding coefficients of animal and of dam; and random animal genetic and residual effects. Model 2 was the same as Model 1 but ignored inbreeding coefficients. Model 3 was the same as Model 1 and included random maternal genetic effects with covariance between direct and maternal genetic effects, and maternal permanent environmental effects. Model 4 was the same as Model 3 but ignored inbreeding. Model 5 was the same as Model 1 but with a random sire effect instead of animal genetic effect. Model 6 was the same as Model 5 but ignored inbreeding. Model 7 was a sire model that considered relationships among males. Model 8 was a sire model, assuming sires to be unrelated, but with dam effects as uncorrelated random effects to account for maternal effects. Model 9 was a sire and dam model but with relationships to account for direct and maternal genetic effects; dams also were included as uncorrelated random effects to account for maternal permanent environmental effects. Model 10 was a sire model with maternal grandsire and dam effects all as uncorrelated random effects. Model 11 was a sire and maternal grandsire model, with dams as uncorrelated random effects but with sires and maternal grandsires assumed to be related using male relationships. Model 12 was the same as Model 11 but with all pedigree relationships from the full animal model for sires and maternal grandsires. Rankings on predictions of breeding values were the same regardless of whether inbreeding coefficients for animal and dam were included in the models. Heritability estimates were similar regardless of whether inbreeding effects were in the model. Models 3 and 9 best fit the data for estimation of variances and covariances for direct, maternal genetic, and permanent environmental effects. Other models resulted in changes in ranking for predicted breeding values and for estimates of direct and maternal heritability. Heritability estimates of direct effects were smallest with sire and sire-maternal grandsire models.  相似文献   

11.
The effects of heterosis for gestation length, dystocia, calf survival, birth weight, 200-d weight, and ADG from birth to weaning were evaluated in F1, F2, and combined F3 and F4 generations in three composite populations. Breed effects were evaluated for the nine parental breeds (Red Poll, Hereford, Angus, Limousin, Braunvieh, Pinzgauer, Gelbvieh, Simmental, and Charolais) that contributed to the three composite populations. Breed effects were significant for all traits evaluated except survival at birth. The large differences among breeds in additive direct and additive maternal genetic effects offer a great opportunity to use the genetic differences among breeds to achieve and maintain optimum additive genetic (breed) composition to match genetic resources to a wide range of production-marketing ecosystems. There was no heterosis for gestation length. Mean heterosis for dystocia was significant estimated in F1 but not in F2 or in the combined F3 and F4 generations. Mean heterosis was not significant in any generation for survival at birth, to 72 h, and to weaning for the F1 generation; mean heterosis was significant for survival to weaning for the F2 generation and approached significance (P = .06) for the combined F3 and F4 generations. Mean heterosis over all composite populations and heterosis for each composite population were significant in all generations for weight at birth and at 200 d and for ADG from birth to weaning. Retained heterosis was not less than expected from retained heterozygosity in composite populations for the traits evaluated. These results suggest that heterosis for these traits likely is due to dominance effects and, thus, can be attributed to the recovery of accumulated inbreeding depression in the parental breeds.  相似文献   

12.
Direct and maternal additive effects and heterosis were estimated using data from straightbred Angus, Brahman, Charolais, Hereford, and four generations of rotational crosses among these breeds. Traits of interest were birth weight, Julian day of birth, average daily gain from birth to weaning, 205-d weight, and weaning weight per cow exposed. Complete data were available on 3,445 calves produced from 4,733 matings. Discrete generations of 4-yr duration were produced from 1970 through 1988. Brahman was included in each rotational crossbreeding system. Genetic effects were estimated by regression. Direct and maternal additive effects of Brahman, Charolais, and Hereford were estimated as deviations from Angus. Direct and maternal heterosis effects were assumed proportional to expected heterozygosity. The Brahman direct additive effect resulted in later-born calves (P < 0.01). Brahman, Charolais, and Hereford direct additive effects increased birth weight, and the Brahman maternal additive effect decreased birth weight compared with Angus (P < 0.05). Charolais direct and maternal additive effects were greater than Angus for average daily gain and 205-d weight (P < 0.01). The Hereford maternal additive effects on average daily gain and 205-d weight were less than those of the other breeds (P < 0.01). Breed combinations including Brahman had greater direct heterosis for birth weight, average daily gain, and 205-d weight than other combinations (P < 0.01). Angus, Charolais, and Hereford direct additive effects on weaning weight per cow exposed were greater than Brahman (P < 0.05). Predicted average daily gain, 205-d weight, and weaning weight per cow exposed were, on average, greater in four-breed rotation systems than in three- and two-breed systems. Among two-breed rotation systems, predicted average daily gain and 205-d weaning weight were greatest for Charolais-Brahman and least for Angus-Hereford. Calves from the Angus-Charolais-Hereford system weighed less at weaning than any other three-breed combination. However, weaning weight per cow exposed from the Angus-Charolais-Hereford system was greatest among three-breed systems. Within three- and four-breed rotation systems, ranges in predicted birth and weaning weights among generations varied by up to 10.0 and 25.2 kg, respectively. The choice of breeds affects performance, and the sequence of their use may affect intergenerational variation in performance.  相似文献   

13.
Data from a French experimental herd recorded between 1990 and 1997 were used to estimate genetic parameters for individual birth and weaning weight, as well as litter size of Large White pigs using restricted maximum likelihood (REML) methodology applied to a multivariate animal model. In addition to fixed effects the model included random common environment of litter, direct and maternal additive genetic effects. The data consisted of 1928 litters including individual weight observations from 18151 animals for birth weight and from 15360 animals for weaning weight with 5% of animals transferred to a nurse. Estimates of direct and maternal heritability and proportion of the common environmental variance for birth weight were 0.02, 0.21 and 0.11, respectively. The corresponding values for weaning weight were 0.08, 0.16 and 0.23 and for litter size 0.22, 0.02 and 0.06, respectively. The direct and the maternal genetic correlations between birth and weaning weight were positive (0.59 and 0.76). Weak positive (negative) genetic correlations between direct effects on weight traits and maternal effects on birth weight (weaning weight) were found. Negative correlations were found between direct genetic effect for litter size and maternal genetic effects on all three traits. The negative relationship between litter size and individual weight requires a combined selection for litter size and weight.  相似文献   

14.
Heterosis effects for birth weight, ADG from birth to weaning, 200-d weight, ADG from weaning to 368 d, 368-d weight, 368-d height, 368-d condition score, and 368-d muscling score (males only) were evaluated separately for each sex in F1, F2, and combined F3 and F4 generations in three composite beef cattle populations. Breed effects were evaluated for the nine parental breeds (i.e., Red Poll [R], Hereford [H], Angus [A], Limousin [L], Braunvieh [B], Pinzgauer [P], Gelbvieh [G], Simmental [S], and Charolais [C]) that contributed to the three composite populations (MARC I = 1/4 C, 1/4 B, 1/4 L, 1/8 H, 1/8 A; MARC II = 1/4 G, 1/4 S, 1/4 H, 1/4 A; and MARC III = 1/4 R, 1/4 P, 1/4 H, 1/4 A). Breed effects were significant for all traits evaluated. The large differences among breeds for growth and size traits in combined additive direct and additive maternal genetic effects (Gi + Gm) provide an opportunity to use genetic differences among breeds to achieve and maintain optimum additive genetic (breed) composition for growth and size traits to match cattle genetic resources to a wide range of production and marketing situations. Combined individual and maternal heterosis was significant in the F1, F2, and combined F3 and F4 generations for each composite population and for the mean of the three composite populations in both sexes for most of the traits evaluated. In both sexes, heterosis retained in combined F3 and F4 generations was greater (P less than .05) than expected based on retained heterozygosity for birth weight, ADG from weaning to 368 d, and for 368-d weight and did not differ (P greater than .05) from expectation for other traits. These results support the hypothesis that heterosis in cattle for traits related to growth and size is due to dominance effects of genes.  相似文献   

15.
Weaning weights from Gelbvieh (GV; n = 82,138) and Limousin (LM; n = 88,639) calves were used to estimate genetic and environmental variance components with models that included different values for the correlation (lambda) between permanent environmental effects of dams and their daughters. Each analysis included fixed discrete effects of contemporary group, sex of calf, age of dam at calving, and month of calving, a fixed continuous effect of age of calf, random direct and maternal additive genetic effects, permanent environmental effects due to dams, and residual effects. The REML procedure was employed with a "grid search," in which the likelihood was computed for a series of values for lambda. For both breeds, models that included a nonzero value for lambda fitted the data significantly better than the model that did not include lambda. The maximum restricted likelihood was obtained for lambda of approximately -0.2 for both breeds. Estimates of residual and direct genetic variances were similar for all values of lambda, including zero; however, estimates of maternal genetic variance and maternal heritability increased slightly, and maternal permanent environmental variance and the proportion of the maternal variance to the total (phenotypic) variance decreased slightly, when the correlated structure for permanent environmental effects was assumed. As the value of lambda became more negative, absolute values of the direct-maternal genetic covariance and direct-maternal correlation estimates were decreased. Pearson and rank correlations for direct genetic, maternal genetic, and maternal environmental effects estimated with and without lambda were very high (>0.99). These results indicated that the linear relationship between maternal permanent environmental effects of dams and their daughters for weaning weight is negative but low in both breeds. Considering this relationship in the operational model did not significantly affect estimated breeding values, and thus, it may not be important in genetic evaluations.  相似文献   

16.
Data from a French experimental herd recorded between 1990 and 1997 were used to estimate genetic parameters for individual birth and weaning weight, as well as litter size of Large White pigs using restricted maximum likelihood (REML) methodology applied to a multivariate animal model. In addition to fixed effects the model included random common environment of litter, direct and maternal additive genetic effects. The data consisted of 1928 litters including individual weight observations from 18 151 animals for birth weight and from 15 360 animals for weaning weight with 5% of animals transferred to a nurse. Estimates of direct and maternal heritability and proportion of the common environmental variance for birth weight were 0.02, 0.21 and 0.11, respectively. The corresponding values for weaning weight were 0.08, 0.16 and 0.23 and for litter size 0.22, 0.02 and 0.06, respectively. The direct and the maternal genetic correlations between birth and weaning weight were positive (0.59 and 0.76). Weak positive (negative) genetic correlations between direct effects on weight traits and maternal effects on birth weight (weaning weight) were found. Negative correlations were found between direct genetic effect for litter size and maternal genetic effects on all three traits. The negative relationship between litter size and individual weight requires a combined selection for litter size and weight.  相似文献   

17.
The aim of this paper was to estimate direct and maternal genetic parameters for calving ease (CE), birth weight (BrW), weaning weight (WW), and calving interval (CI) to assess the possibility of including this information in beef cattle improvement programs. Field data, including a total of 59,813 animals (1,390 sires and 1,147 maternal grand sires) from the Asturiana de los Valles beef cattle breed, were analyzed with a multivariate linear model. Estimates of heritability for direct genetic effects (CED, CID, BrWD, and WWD) were 0.191 +/- 0.019, 0.121 +/- 0.013, 0.390 +/- 0.030, and 0.453 +/- 0.035, respectively, whereas those for maternal genetic effects (CEM, BrWM, and WWM) were 0.140 +/- 0.015, 0.208 +/- 0.020, and 0.138 +/- 0.022, respectively. Genetic correlations between direct or maternal genetic effects across traits were, in general, positive and moderate to low. However, genetic correlation for the pair CED-BrWD was positive and high (0.604 +/- 0.064). Genetic correlations between the direct and maternal genetic effects within a trait were negative and moderate (-0.219 +/- 0.097 for CE, -0.337 +/- 0.080 for BrW, and -0.440 +/- 0.102 for WW). Genetic correlations for CED-BrWM and CED-WWM were -0.121 +/- 0.090 and -0.097 +/- 0.113, respectively. The genetic correlation for CEM-CID was unfavorable (0.485 +/- 0.078), and those for CEM-BrWD (-0.094 +/- 0.079) and CEM-WWD (-0.125 +/- 0.082) were low and negative. The genetic correlation between CID and WWM was favorable (-0.148 +/- 0.106). Overall, the data presented here support the hypothesis that maternal effects for CE and BrW are not the same and that the genetic relationships between CI and maternal effects for WW in beef cattle follow a similar pattern to that reported between CI and milk yield in dairy cattle. Moreover, the need to include direct and maternal breeding values in beef cattle selection programs is suggested.  相似文献   

18.
The aim of this study was to estimate genetic parameters for BW of Angus cattle up to 5 yr of age and to discuss options for including mature weight (MW) in their genetic evaluation. Data were obtained from the American Angus Association. Only records from herds with at least 500 animals and with >10% of animals with BW at ≥ 2 yr of age were considered. Traits were weaning weight (WW, n = 81,525), yearling weight (YW, n = 62,721), and BW measured from 2 to 5 yr of age (MW2, n = 15,927; MW3, n = 12,404; MW4, n = 9,805; MW5, n = 7,546). Genetic parameters were estimated using an AIREML algorithm with a multiple-trait animal model. Fixed effects were contemporary group and departure of the actual age from standard age (205, 365, 730, 1,095, 1,460, and 1,825 d of age for WW, YW, MW2, MW3, MW4, and MW5, respectively). Random effects were animal direct additive genetic, maternal additive genetic, maternal permanent environment, and residual. Estimates of direct genetic variances (kg(2)) were 298 ± 71.8, 563 ± 15.1, 925 ± 52.1, 1,221 ± 65.8, 1,406 ± 80.4, and 1,402 ± 66.9; maternal genetic variances were 167 ± 4.8, 153 ± 6.1, 123 ± 9.1, 136 ± 12.25, 167 ± 18.0, and 110 ± 14.0; maternal permanent environment variances were 124 ± 2.9, 120 ± 4.3, 61 ± 7.5, 69 ± 11.9, 103 ± 15.9, and 134 ± 35.2; and residual variances were 258 ± 3.8, 608 ± 8.6, 829 ± 34.2, 1,016 ± 38.8, 1,017 ± 52.1, and 1,202 ± 63.22 for WW, YW, MW2, MW3, MW4, and MW5, respectively. The direct genetic correlation between WW and YW was 0.84 ± 0.14 and between WW and MW ranged from 0.66 ± 0.06 (WW and MW4) to 0.72 ± 0.11 (WW and MW2). Direct genetic correlations ranged from 0.77 ± 0.08 (YW and MW5) to 0.85 ± 0.07 (YW and MW2) between YW and MW, and they were ≥ 0.95 among MW2, MW3, MW4, and MW5. Maternal genetic correlations between WW and YW and MW ranged from 0.52 ± 0.05 (WW and MW4) to 0.95 ± 0.07 (WW and YW), and among MW they ranged from 0.54 ± 0.14 (MW4 and MW5) to 0.94 ± 0.07 (MW2 and MW3). Genetic correlations suggest that a genetic evaluation for MW may be MW2-based and that including BW from older ages could be accomplished by adjusting records to the scale of MW2.  相似文献   

19.
This study estimated genetic and phenotypic parameters and annual trends for growth and fertility traits of Charolais and Hereford cattle in Kenya. Traits considered were birth weight (BW, kg), pre-weaning average daily gain (ADG, kg/day) and weaning weight (WW, kg); calving interval (CI, days) and age at first calving (AFC, days). Direct heritability estimates for growth traits were 0.36 and 0.21; 0.25 and 0.10; 0.23 and 0.13 for BW, ADG and WW in Charolais and Hereford, respectively. Maternal heritability estimates were 0.11 and 0.01; 0.18 and 0.00; 0.17 and 0.17 for BW, ADG and WW in Charolais and Hereford, respectively. Direct-maternal genetic correlations ranged between −0.46 and 1.00; −0.51 and −1.00; −0.47 and −0.39 for BW, ADG and WW in Charolais and Hereford, respectively. Genetic correlations ranged from −0.99 to unity and −1.00 to unity for growth and fertility traits respectively. Prospects for improvement of growth and fertility traits exist.  相似文献   

20.
Variance and covariance components were estimated for weaning weight from Senepol field data for use in the reduced animal model for a maternally influenced trait. The 4,634 weaning records were used to evaluate 113 sires and 1,406 dams on the island of St. Croix. Estimates of direct additive genetic variance (sigma 2A), maternal additive genetic variance (sigma 2M), covariance between direct and maternal additive genetic effects (sigma AM), permanent maternal environmental variance (sigma 2PE), and residual variance (sigma 2 epsilon) were calculated by equating variances estimated from a sire-dam model and a sire-maternal grandsire model, with and without the inverse of the numerator relationship matrix (A-1), to their expectations. Estimates were sigma 2A, 139.05 and 138.14 kg2; sigma 2M, 307.04 and 288.90 kg2; sigma AM, -117.57 and -103.76 kg2; sigma 2PE, -258.35 and -243.40 kg2; and sigma 2 epsilon, 588.18 and 577.72 kg2 with and without A-1, respectively. Heritability estimates for direct additive (h2A) were .211 and .210 with and without A-1, respectively. Heritability estimates for maternal additive (h2M) were .47 and .44 with and without A-1, respectively. Correlations between direct and maternal (IAM) effects were -.57 and -.52 with and without A-1, respectively.  相似文献   

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