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1.
SUMMARY Heart scores derived from the ECG's recorded from sires, dams and progeny have been used to determine the heritability of heart size in Thoroughbred and Standard-bred horses. Regression of progeny on male parents gave an average heritability of about 0.4. The heart scores of progeny reflected the heart scores of dams more closely than those of sires. Although this result raises questions which cannot be answered completely from the data available, the heritability estimate of 0.4 should enable breeders to improve heart size by simple selection of breeding stock on heart score. The greater influence of dams on heart score could involve sex differences, maternal environmental factors and possibly sex-linkage. In addition, in the population studied there was unequal selection of sires and dams. Critical selection of mares seems to offer the largest potential for improvement in the future, but this will be inhibited by practical restraints on the culling of the brood mare population.  相似文献   

2.
Data on Charolais-sired calves in 31 commercial herds were analyzed to evaluate progeny performance relative to sire expected progeny differences (EPD). The traits analyzed were BW at birth (BBW; n = 3554) and at weaning (WBW; n = 3604) of crossbred progeny from nationally evaluated sires. Sire BBW EPD and WBW EPD were evaluated as predictors of performance in these commercial herds. Published sire BBW EPD and WBW EPD were averaged and weighted on the numeric accuracy published for each EPD. The average weighted sire BBW EPD was 0.4 kg, and the WBW EPD was 7.0 kg with an average accuracy of 0.79 and 0.75, respectively. Random regression coefficients were estimated for progeny BBW on sire EPD of 1.03 ± 0.09 kg/kg of BBW EPD, and for progeny WBW, 0.66 ± 0.11 kg/kg of WBW EPD. Correlations for sire effect solutions in commercial herds with published sire BBW and WBW EPD were 0.59 and 0.39, respectively. Sire BBW EPD and WBW EPD were favorably related to actual progeny performance. Therefore, selection based on sire EPD should result in change of crossbred progeny performance. This further validates use of EPD as a selection tool for BBW and WBW in commercial herds. However, WBW response was less than expected, possibly a result of management practices in commercial herds compared with seedstock herds.  相似文献   

3.
Direct and maternal (co)variance components and genetic parameters were estimated for growth and reproductive traits in the Kenya Boran cattle fitting univariate animal models. Data consisted of records on 4502 animals from 81 sires and 1010 dams collected between 1989 and 2004. The average number of progeny per sire was 56. Direct heritability estimates for growth traits were 0.34, 0.12, 0.19, 0.08 and 0.14 for birth weight (BW), weaning weight (WW), 12-month weight (12W), 18-month weight (18W) and 24-month weight (24W), respectively. Maternal heritability increased from 0.14 at weaning to 0.34 at 12 months of age but reduced to 0.11 at 24 months of age. The maternal permanent environmental effect contributed 16%, 4% and 10% of the total phenotypic variance for WW, 12W and 18W, respectively. Direct-maternal genetic correlations were negative ranging from −0.14 to −0.58. The heritability estimates for reproductive traits were 0.04, 0.00, 0.15, 0.00 and 0.00 for age at first calving (AFC), calving interval in the first, second, and third parity, and pooled calving interval. Selection for growth traits should be practiced with caution since this may lead to a reduction in reproduction efficiency, and direct selection for reproductive traits may be hampered by their low heritability.  相似文献   

4.
Heritability of hip dysplasia was estimated to be about 0.4 to 0.5 when based on the radiographic evaluations of the hip joints of 2,404 German Shepherd Dogs born at The Armed Forces Dog Training Center in Sweden. The material included all dogs in 401 litters born at the Center from 1965 through 1973 that reached the age of 15 months. To be expected with such high heritability, frequency of hip dysplasia in the offspring was shown to be affected by the hip joint status of sire and dam as well as by the hip joint status of their parents and littermates. Even matings between sires with normal hip joints and dams with only slight dysplasia resulted in significantly higher frequency of hip dysplasia in the offspring, when compared with the frequency if both sires and dams had normal hip joints. Frequency of hip dysplasia in the progeny of sires with normal hip joints varied greatly. Since 1973, selection of the breeding stock has been based on hip joint status (phenotype) of the breeding animals and of their relatives as well as on what had become known about frequency of hip dysplasia in the litters already born (progeny testing). In this way, frequency of hip dysplasia in 347 dogs born at the Center during 1975 was lowered to 28%. This figure should be compared with the figure of 50%, which represents the frequency of hip dysplasia in the kennel up to 1970, when selection was not as strict as could be expected in a well-controlled kennel.  相似文献   

5.
Data pertaining to a closed White Leghorn flock maintained at the Punjab Agricultural University were used for estimating genetic and phenotypic parameters for age at first egg and 70‐d egg production and also to evaluate the expected response to different methods of selection. Records of 2377 pullets, a progeny of 1001 dams and 155 sires over a period of two years, were used. The birds in this flock attained sexual maturity on an average at the age of 176.6 d and produced on an average 33.6 eggs in first 70 d of egg production.

Heritability for age at first egg and 70‐d egg production was obtained from different observational components. Age at first egg was found to have a medium heritability, the estimates being 0.370 ±0.003, 0.080 ±0.016 and 0.224 + 0.040 from sire, dam and full sib components, respectively. The heritabilities for 70‐d egg production were low. The estimates were 0.132±0.004, 0.214±0.011 and 0.173±0.06 from sire, dam and full sib components, respectively. Phenotypic, genetic and environmental correlations were also obtained from analysis of variance and covariance. These two traits were found to be highly genetically negatively associated (—0.554 ±0.007). Phenotypic and environmental correlations between these two traits were also found to be negative and very low.

An index incorporating age at first egg and 70‐d egg production with 1.5 times negative weightage to the former was found to be two times more effective in reducing the age at first egg and 2–3 times more effective in increasing the 70‐d egg production as compared to direct selection for the two traits individually.  相似文献   


6.
The earnings obtained by horses in obstacle jumping in France in 1972 and in 3-day events from 1971 to 1973 are analyzed in order to estimate the genetic parameters for several measures of competitive performance. With the aim of obtaining variables for classical statistical calculation, the earnings of each horse per year and average earning per start were computed using logarithmic transformation.In obstacle jumping, least squares analysis of variance on the transformed variables and a stock of 5 279 winners show that sex plays no role, whereas age is highly significant (maximum between 8 and 10 years). The data for age have been corrected. The 3 766 winners (offspring of 329 sires from three different areas) are then analyzed using an hierarchal analysis of variance. It is shown that area has an effect (0.5% of the variance); this is, however, slight as compared to sire effect (4.5% of the variance), which value gives heritability estimations ranging between 0.17 and 0.19.In the 3-day events, effects of age (constant improvements with time), sex (superiority of whole “males” and “geldings”) and year of performance are determined on 2 941 annual records using the same methods; the data for these are corrected. The hierarchal an area effect and gives heritability estimations ranging between 0.14 and 0.26.A classification of stallions according to genetic value in the two competitions is proposed. Although based on selected offspring (choice of horses participating in shows), this classification seems to be better than the usual prize lists established on total earnings of the progeny.  相似文献   

7.
Genotype x environment interaction (G x E) is increasingly important, because breeding programs tend to be more internationally oriented. The aim of this theoretical study was to investigate the effects of G x E on genetic gain in sib-testing and progeny-testing schemes. Loss of genetic gain due to G x E was predicted for different values of heritability, number of progeny per dam, number of progeny per sire, proportion of selected sires, and population size in the selection environment. Two environments were considered: a selection environment (SLE) and a production environment (PDE). The breeding goal was only for performance in PDE. A pseudo-BLUP selection index was used to predict genetic gain. Recording of half-sibs or progeny in PDE limited the loss in genetic gain in PDE due to G x E between SLE and PDE. Progeny-testing schemes had less loss in genetic gain than sib-testing schemes. Higher heritability increased the loss in genetic gain, whereas increasing the number of progeny per sire in PDE decreased the loss in genetic gain. The number of progeny per sire required to minimize loss in genetic gain due to G x E was greater for sib-testing schemes than for progeny-testing schemes. More progeny per dam slightly increased the loss in genetic gain. Genetic gains for sex-limited and carcass traits were less affected by G x E than traits measured on both sexes. Loss in genetic gain was due to decreased accuracy of selection in most situations, but it was due to decreased selection intensity in situations with small population size and a low proportion of selected sires. It was concluded that recording performance of relatives in PDE minimizes loss in genetic gain due to G x E, and that progeny-testing schemes rather than sib-testing schemes are preferable in situations with low to moderate heritability (h(2) 相似文献   

8.
A check on the linearity of offspring-parent regression was made using data on 6-week body weight from unselected random bred mice. The study comprised 1099 offspring (family mean)-parent pairs spanning 20 generations from which regression and heritability estimates were obtained based on regression on one parent, mid-parent or simultaneously on both parents. Investigation of linear and nonlinear relationships showed that the offspring-sire regressions were significantly, but not greatly, nonlinear, whereas the regression of offspring on dams did not depart significantly from linearity. No significant contribution from cross-products of sire and dam coefficients was found. The data were close to normally distributed, and for this trait errors in prediction of selection response would generally be small if nonlinearity were ignored.  相似文献   

9.
The objective of this project was to determine the genetic control of conception rate, or pregnancy percentage in Angus beef heifers. Producers from 6 herds in 5 states provided 3,144 heifer records that included breeding dates, breeding contemporary groups, service sires, and pregnancy check information. Two hundred fourteen sires of the heifers were represented; with 104 sires having less than 5 progeny, and 14 sires having greater than 50 progeny. These data were combined with performance and pedigree information, including actual and adjusted birth weights, weaning weights, and yearling weights, from the American Angus Association database. Heifer pregnancy rate varied from 75 to 95% between herds, and from 65 to 100% between sires, with an overall pregnancy rate of 93%, measured as the percentage of heifers pregnant at pregnancy check after the breeding season. Pregnancy was analyzed as a threshold trait with an underlying continuous distribution. A generalized linear animal model, using a relationship matrix, was fitted. This model included the fixed effects of contemporary group, age of dam, and first AI service sire, and the covariates of heifer age at the beginning of breeding, adjusted birth weight, adjusted weaning weight, and adjusted yearling weight. The relationship matrix included 4 generations of pedigree. The heritability of pregnancy and first-service conception rates on the underlying scale was 0.13 +/- 0.07 and 0.03 +/- 0.03, respectively. Estimated breeding values for pregnancy rate on the observed scale ranged from -0.02 to 0.05 for sires of heifers. Including growth traits with pregnancy rate as 2-trait analyses did not change the heritability of pregnancy rate. As expected for a reproductive trait, the heritability of pregnancy rate was low. Because of its low heritability, genetic improvement in fertility by selection on heifer pregnancy rate would be expected to be slow.  相似文献   

10.
The objective of this study was to determine the relationship between individual sire estimated breeding values (EBV) for litters/sow/year (LSY) and sire progeny means for farrowing rate (FR), removal parity and lifetime born alive (LTBA). Genetic parameters and breeding values were estimated using ASREML. The heritability estimate for LSY was 0.11. When all sires with 10 or more daughters with records were included in the analysis, Spearman rank correlations between the sire's LSY EBV and the sires' daughter means for FR, removal parity and LTBA were 0.49, 0.23 and 0.25 (p < 0.01). The sire EBV for LSY was favourably correlated with sires' daughter means for all three traits. This provides evidence that selecting sires with high EBV for LSY could improve herd FR, removal parity and LTBA. By including LSY as part of the selection criterion, the LTBA may be indirectly improved. The positive genetic correlation between LTBA and LSY may be a result of the improved longevity of sows with greater LSY compared with sows with lower LSY. The relationships between LSY and FR, removal parity and LTBA are strongly supported by the correlations between the sire progeny means for each trait and the sire LSY EBV.  相似文献   

11.
A breeding program has been established in 2008 to improve productivity of Horro chicken, an indigenous population in the western highlands of Ethiopia. The pedigree descended from 26 sires and 260 dams. Body weights were measured every 2 weeks from hatch to 8 weeks then every 4 weeks for the next 8 weeks. Egg production was recorded to 44 weeks of age for one generation. Genetic parameters were estimated using animal model fitted with common environmental effects for growth traits and ignoring common environment for egg production traits. Direct heritabilities ranged from low (0.15 ± 0.08), for body weight at 6 weeks, to moderate (0.40 ± 0.23), for hatch weight. Heritabilities of common environmental effects on growth were high at hatch (0.39 ± 0.10) and remained low afterwards. Age at first egg showed a very low heritability (0.06 ± 0.15). Heritabilities of egg numbers in the first, second, third, and fourth months of laying were 0.32 (±0.13), 0.20 (±0.16), 0.56 (±0.15), and 0.25 (±0.14), respectively. Heritabilities of cumulative of monthly records of egg numbers were from 0.24 ± 0.16 (for the first 2 months, EP12) to 0.35 ± 0.16 (over the 6 months, EP16). Body weight at 16 weeks of age (BW16) has a strong genetic correlation with the cumulative of monthly records: 0.92 (with EP12), 0.69 (with EP36), and 0.73 (with EP16). Besides their strong association, BW16 and EP16 showed higher heritability, relative to their respective trait categories. These two traits seemed to have common genes and utilizing them as selection traits would be expected to improve both egg production and growth performance of local chicken. However, the standard errors of estimates in this study were mostly high indicating that the estimates have low precision. Parameter estimations based on more data are needed before applying the current results in breeding programs.  相似文献   

12.
Data were obtained at Whatawhata on the growth of goats to the yearling stage and on their cashmere production as hoggets. There were 884 animals recorded from the 1985 to 1989 birth years, comprising the progeny of 60 sires. Records from kid shearings were also obtained in the last two years. Mixed-model restricted maximum likelihood (REML) models were fitted. Heritabilities from yearling fleece records were 0.42±0.13 for fleece weight, 0.57±0.15 for yield, 0.62±0.15 for down weight, 0.35±0.12 for guard hair weight, 0.99±0.19 for down fibre diameter and 0.57±0.15 for mean down length; corresponding values from kid fleeces (23 sires only) were smaller in most cases than from yearlings, being respectively 0.14±0.06, 0.19±0.07, 0.20±0.07, 0.04±0.04, 0.19±0.07 and 0.87±0.29. The phenotypic and genotypic correlations between down weight and fibre diameter in yearlings were 0.50±0.03 and 0.81±0.08 respectively, representing an unfavourable relationship when selecting for heavier but finer down. The genetic correlations of yearling weight with down weight and down fibre diameter were slightly negative (−0.34 and −0.25), but the estimates were non-significant.  相似文献   

13.
Records on crossbred calves from the eight crosses between Angus (A) and Hereford (H) cows, and A, H, Jersey, Simmental and Brahman sires, and raised in two pasture programs were used to assess sire × pasture interactions on preweaning traits. There were 518–734 calves from 252–318 dams and 122–166 sires in the data set; numbers vary by traits. Sires, AI or natural service, constituted a representative sample of the breeds. Pasture programs differed principally in the winter period (tall fescue hay vs. corn silage). Heritabilities across and within pastures were: 0.28±0.19 and 0.28 ± 0.19 for birth weight (BW ); 0.08 ± 0.58 and 0.58 ± 0.19 for weaning weight (WW); 0.30 ± 0.41 and 0.71 ± 0.19 for weight adjusted to 205 days (W205); 0.00 ± 0.00 and 0.36 ± 0.15 for daily gain (DG); 0.61 ±0.35 and 0.94±0.25 for frame score (FRAM); 0.14±0.38 and 0.53±0.22 for muscle score (MUSC); and 0.00±0.00 and 0.14±0.21 for conformation score (CONF), respectively. Correlations between progenies of the same sire in different pasture programs are: 1.00±0.00 for BW; 0.13±0.99 for WW; 0.42±0.58 for W205; 0.00±0.00 for DG; 0.65±0.34 for FRAM; 0.27±0.71 for MUSC; and 0.00±0.00 for CONF. Except for birth weight, estimates (although imprecise) suggest that changes in the ranking of sires should be expected to occur between the two environments, possibly in part from incomplete adjustment for changes in season of calving between pasture environments for calves sired by the same sire.  相似文献   

14.
Inheritance and determinants of pulmonary oedema in swedish hunting dogs   总被引：1，自引：0，他引：1  
By using information derived from questionnaires sent to registered owners of drever dams and sires in Sweden with offspring born in 1992 and/or 1994, two groups of offspring were identified: one with one parent said to have had breathing difficulties after hunting, and another with both parents unaffected. Questionnaires were sent to the owners of these offspring, and multiple logistic regression was used to analyse the offspring data, with the status of their sire and dam with respect to breathing difficulties after hunting included as covariates. For the outcome 'breathing difficulties after hunting' in the 266 offspring, the odds ratio (OR) was 4.4 (95 per cent confidence interval [CI] 1.8 to 10.8) if the dam was affected and 3-9 (95 per cent CI 1.2 to 11.1) if the sire was affected. The OR for male offspring was 2.4 (95 per cent CI 1.1 to 5.7). The heritability of the condition was estimated to be 0.34 from the dogs born in 1992, and 0.28 from the dogs born in 1994.  相似文献   

15.
Hip dysplasia (malformation of the coxofemoral joint) in dogs is a major health problem for which the British Veterinary Association (BVA) had set up a control scheme in 1965. Based on scoring nine components of the radiographs of both the left and right joints, the degree of hip joint malformation is now quantified by an overall hip score (a measure of the condition of the hip joint). The hip scores of 1258 flat-coated retrievers and 1566 Newfoundlands (registered with The Kennel Club in the United Kingdom) were analysed after merging with Kennel Club pedigree data for 19036 flat-coated retrievers registered by 1995 and 14336 Newfoundlands registered by 1997. The merged data included the animal's identity, date of birth, sex and hip scores and also similar records for the dog's relatives including the hip score if the relative had been tested. In recent years, breeding has been increasingly from tested parents. There has been some reduction in offspring hip scores - presumably because breeders avoided breeding from males with very high scores. However, a much greater reduction in offspring hip score would be achieved by stricter science-based selection of potential sires and dams. Regression modelling quantified the positive relationship between offspring and parental hip scores. The genetic heritability of hip scores was large and significant in both breeds (particularly from dams). The breeders in UK tended to use healthy sires for breeding but they have taken less care in selecting dams. Our regression models emphasise the need for both sires and dams, particularly dams, to be healthy with very small hip scores.  相似文献   

16.
Genetic and phenotypic variation in sources of preweaning lamb mortality   总被引：1，自引：0，他引：1  
Information on causes of mortality to 8 wk weaning for 16,881 lambs of 10 line-breed groups by 594 sires born over a 5-yr period was analyzed by least squares procedures to estimate sire variance and covariance components within line and year-season. Heritability estimates were approximately 5% for total mortality in the binomial scale and near 10% when converted to a normal scale. Average heritability estimates in the binomial and normal scale were, respectively, 4 and 12% for perinatal and 3 and 7% for postnatal mortality. The heritability estimates for respiratory problems were inconsistent; binomial-scale estimates ranged from 0 to 7% in different populations. Regression adjustment for effects of variation in litter size and birth weight caused only minor changes in the heritability estimates. Comparison of covariances among half-sibs vs full-sibs indicated very large maternal effects on perinatal mortality but smaller and less consistent effects on sources of postnatal mortality. Phenotypic correlations among sources of mortality indicated a 26% greater influence of postnatal than perinatal mortality on variation in total mortality, but both the genetic and phenotypic correlations between those two components were slightly negative. These results suggest that the use of family and progeny test selection for transmitted effects on both perinatal and postnatal lamb viability should be effective.  相似文献   

17.
Weaning weight records of 44,357 Australian Angus calves produced by 1,020 sires in 90 herds were used to evaluate the importance of sire x herd interactions. Models fitted fixed effects of contemporary group (herd-year-date of weighing subclass), sex, calf age, and dam age and random effects of sire or of sire and sire x herd interaction using REML. Effects of standardizing the data, including sire relationships and including dam maternal breeding values (MBV) as a covariate were also investigated. Sire x herd interactions were found (P less than .05) in all cases and, in the most complete model, accounted for 3.3% of phenotypic variance. Across-herd heritabilities ranged from .19 to .28. Differential nonrandom mating among herds seemed to occur in the data. Significant sire x herd effects were observed for dam MBV, and adjustment for dam MBV yielded the smallest estimates of interaction variance and across-herd heritability. If sire x herd interactions were due only to genotype x environment interaction, within-herd heritabilities would range from .33 to .49. These estimates are larger than previously reported estimates. Thus, unreported environmental effects common to progeny of individual sires may also be involved in the observed interaction but could not be disentangled from true genotype x environment interaction effects using these data. Results of these analyses suggest that some accommodation of sire x herd interaction effects on weaning weight may be needed in beef cattle genetic evaluations, but a compelling case for development of herd-specific breeding value prediction cannot be made.  相似文献   

18.
Records for pigs included in an experiment on reciprocal recurrent selection conducted from 1956 through 1971 at the USDA Beltsville Agriculture Research Center were analyzed to obtain estimates of heritabilities and genetic correlations and to derive prediction equations for estimating weight of lean cuts (WTLC) and percentage of lean cuts of shrunk slaughter weight (LCPC). Lean cuts growth rate (LCGR) was then estimated as WTLC/age of pig at slaughter. The base population consisted of two unrelated crossbred strains. A total of 1,294 records of F1 and F2 crossbred pigs were analyzed with one barrow and one gilt from each litter. Estimates of heritabilities and genetic correlations were computed with sire components of variance and covariance from a nested analysis of variance with an assumed model of years, strain-lines within years, sire within strain-lines, dams within sires and residual. Degrees of freedom were 307 for sires in strain-lines, 270 for dams in sires and 646 for residual. Heritability (h2) estimates were .42 +/- .13, .41 +/- .13 and .27 +/- .18 for WTLC, LCPC and LCGR, respectively, and .71 +/- .16, .38 +/- .13, .31 +/- .13 and .25 +/- .15 for carcass length, average backfat thickness, longissimus muscle area and ADG in BW, respectively. These estimates were apparently the first published genetic estimates involving LCGR based on carcass data. It was recommended that prediction equations to estimate WTLC, LCPC and LCGR for use in swine testing programs be derived from current meat-type pigs.  相似文献   

19.
The occurrence of intervertebral disc calcification was investigated by conventional spinal radiography in eight families of wirehaired dachshunds, with each family comprising one sire, two dams and one litter from each dam. Each offspring was examined radiographically once at 24-35 months of age. The occurrence of disc calcification was rated according to four different scales. A strong correlation was found in the occurrence of disc calcification between offspring and mean parent (P < 0.001) and between offspring and dams (P < 0.005) on an either/or scale. Statistically significant estimates of heritability of 0.60 and 0.87 were found based on the offspring-sire relationship using the total score and three-class scale, respectively. Higher correlation estimates were found based on the dam-offspring relationship than based on the sire-offspring relationship, suggesting an effect of maternal environmental factors.  相似文献   

20.
(1) The study was conducted to estimate the heritability, genetic correlations and breeding values of laying hens based on individual records and group mean records. (2) Records of two pure lines from a commercial breeding programme of White Leghorns from three generations housed in single cages and in group cages were used. A total of 8483 and 8817 individual records of lines A and D, respectively, and a total of 1358 (line A) and 1161 (line D) group mean records were analysed. (3) An animal model using Restricted Maximum Likelihood (REML) was used to estimate variance components of individual records. Group mean records were analysed using the sire model, taking heterogeneity of error variance and correlated residual effects into account. Breeding values of sires were estimated based on the BLUP method using a multivariate sire model. Spearman Rank correlations were used to compare sire breeding values estimated from individual records and from group mean records. The traits studied were monthly egg production, cumulative production and egg weight. (4) Heritability estimates based on individual records were higher than from group mean records. Heritabilities for cumulative production records were higher than for monthly production, based on individual as well as group mean records. The estimates of genetic correlations between monthly egg production and cumulative production were moderate to high. Egg production and egg weight recorded individually were highly genetically correlated with those recorded on group means. Sire breeding values estimated from individual records showed high correlations with those from group mean records. (5) Differences in the ranking of sire breeding values estimated from individual vs group mean records were negligible, indicating that no genotype x environment interaction exists. Selection based on individual performance records of laying hens housed in single cages could give a good response on performance of laying hens housed in group cages. Cumulative egg production over periods 1 to 6 is the best trait for the selection programme.  相似文献   

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