Annual, career or single race records for breeding value estimation in race horses

The racing careers of 2, 3, 4, and 5-year-old Thoroughbreds and French trotters born in France between 1995 and 1999 were analysed. The horses were evaluated on a set of traits, with particular attention to annual or career earnings and number of starts.

As expected, the distributions of earnings corrected for year, age and sex are very skew and thus inappropriate for breeding value estimations. However, Log transformation results in near normal distributions more suitable for this purpose.

Another problem of annual or career earnings required a more complex approach. As most horses did not win any money in France (67% of the trotters and 41% of the Thoroughbreds), it is difficult to correctly evaluate these horses. On the other hand, a linear adjustment of the Log of earnings by the Log of the number of starts (exponential adjustment of the earning index) leads to regression coefficients close to 1. It justified the use of the Log of earnings per start and explained its higher heritability in literature. A quadratic adjustment of the Log of earnings by the Log of the number of starts (sigmoid adjustment of the earning index) improves the adjustment for the Thoroughbred only and should be implemented for these horses.

The probability of a horse to be placed according to the number of starts was also studied. It is shown that the observed percentage of non-placed horses p_s according to the number of starts, s, is in all cases inferior to the expected percentage (p_s < p₁^s). Therefore, races of the same horse cannot be considered as independent events. The percentage of horses placed and the mean earnings for each age can be combined in order to estimate the economical weights for each age class. Economical weights for the French trotter were 0.00, 0.21, 0.40, and 0.39 for 2, 3, 4, and 5-year olds respectively. They were 0.11, 0.45, 0.26 and 0.18 respectively for Thoroughbreds of the same age categories. The current tendency to move from annual or career criteria towards criteria at the race level is discussed. However, the question on how to evaluate the important proportion of horses born that never appeared in a race still remains open and should focus future research.     

Animal model estimation of non-additive genetic parameters in dairy cattle, and their effect on heritability estimation and breeding value prediction

SUMMARY: First lactation production records of pedigree Holstein-Friesian cows in the UK were analysed by an animal model, in order to estimate effects of heterosis and recombination loss between North American Holstein and European Friesian cattle and the influence of these effects on breeding value prediction. Coefficients of heterosis and recombination loss were fitted in the animal model as covariables and unknown parents were assigned to a varying number of genetic groups. The estimates of heterosis effects were 104 kg, 4.3 kg and 2.9 kg for milk, fat and protein yield, respectively, while the corresponding coefficients for recombination loss were -135 kg, -2.6 kg and -3.7 kg respectively. Neither the sire component of variance nor the heritability estimates were appreciably affected by the inclusion of heterosis and recombination loss in the model. Including both these effects in the breeding value estimation increased the predicted sire proof for fat plus protein of a typical F1 Holstein × Friesian sire by 3 kg. ZUSAMMENFASSUNG: Tiermodellsch?tzungen nicht-additiv genetischer Parameter bei Milchrindern und ihre Auswirkung auf Heritabilit?tssch?tzung und Zuchtwertvoraussage Laktationsleistungen von Herdbuch Holstein-Friesen Kühen im UK wurden mittels eines Tiermodells analysiert zur Sch?tzung der Wirkungen von Heterosis und Rekombinationsverlust zwischen nordamerikanischen Holstein und europ?ischen Schwarzbunten und Einflu? dieser Wirkungen auf Zuchtwahlvorhersagen. Koeffizienten für Heterosis und für Rekombinationsverlust wurden im Tiermodell als Co-Variable berücksichtigt und unbekannte Eltern einer unterschiedlichen Zahl genetischer Gruppen zugeordnet. Sch?tzungen der Heterosiswirkungen waren 104 kg, 4,3 kg und 2,1 kg für Milch-, Fett- Proteinmengen, w?hrend die diesbezüglichen Koeffizienten für Rekombinationsverlust -135, -2,6 und -3,7 kg waren. Weder die Vatervarianzkomponente noch Heritabilit?tswerte wurden durch Berücksichtigung von Heterosis und Rekombinationsverluste im Modell tangiert. Berücksichtigung beider Wirkungen in der Zuchtwertsch?tzung erh?hte den gesch?tzten Vaterzuchtwert für Fett + Protein eines typischen F1 Holstein-Friesen-Stieres um 3kg.     

Simulation of genetic control of reproduction in beef cows. III. Within-herd breeding value estimation with known breeding dates

Procedures for breeding value estimation for reproductive traits with known breeding dates were developed and tested using results of a computer simulation model of genetic control of bovine reproduction. The model generated realized reproductive outputs as a function of underlying genetic variation in two independent traits: conception rate (CR), which was indicative of the ability to conceive given estrus, and PPI, the postpartum interval from calving to first estrus. Two scenarios were considered. In the first, all cows were assumed to be cycling at the start of breeding and to be bred artificially. For this scenario, breeding values for CR could be estimated from information on observed breeding and calving dates by using a categorical trait, multi-stage selection model. Breeding value estimation for PPI, however, required actual measurement of PPI because if PPI and CR are genetically independent and if all cows are cycling at the beginning of breeding, subsequent breeding and calving dates are independent of PPI. The second scenario recognized that not all females would be cycling at the start of breeding. For this scenario, the categorical trait, multi-stage selection model could still be applied for breeding value estimation for CR, but accumulation of data across years was complicated by a need to consider the lifetime reproductive pattern of the individual rather than just the sum of each year's performances. Breeding value estimates for PPI could be obtained from observed breeding and calving dates for this scenario, but required consideration of the distributional properties of PPI.     

Selection practices and genetic and phenotypic trends estimated from Nebraska SPF swine field records

Records collected during 1971 through 1979 from 101,606 pigs raised in 18 herds that were members of the Nebraska SPF Swine Accrediting Association were evaluated for phenotypic trends and predicted and observed genetic trends. Traits considered were backfat at 100 kg (BF) and weight at 140 d of age (WT). Phenotypic change on average was beneficial for BF (-.05 mm/yr) but undesirable for WT (-.2 kg/yr). However, the average observed genetic trend was nil for BF and .6 kg/yr for WT. An average, predicted response based on observed selection differentials and estimates of within herd-sex genetic parameters was in good agreement with observed response for BF, but was three times higher for WT.     

Use of marker haplotypes to refine covariances among relatives for breeding value estimation

Markers flanking DNA regions, where quantitative trait loci (QTL) have been previously spotted, can be used to trace the common inheritance of major genes for a better definition of covariances among animals. A practical approach to the use of marker data to refine the additive relationship matrix used in the traditional best linear unbiased prediction (BLUP) methodology is presented. The technique allows the number of the mixed model equations to be kept to an animal level, blending polygenic pedigree data with marker haplotype information. The advantage of this marker-assisted selection (MAS) approach over BLUP selection has been assessed through a stochastic simulation. A finite locus model with 32 independent biallelic loci was generated with normally distributed allelic effects. The heritability of the trait, measured on both sexes and on females only, was set to 0.2 and 0.5. Five-allelic markers 2, 10 and 20 cM apart, bracketed the QTL with the largest effect on the trait, accounting for 17% of the genetic variance. The bracketed QTL had two or eight alleles and its position was undefined within the bracket. Results show a moderate 2% advantage of MAS over BLUP in terms of higher genetic response when trait was recorded on both sexes and heritability was 0.2. The benefit is in the short term, but it lasts longer with polyallelic QTL. When the trait was recorded on females only, MAS produced only a small and insignificant genetic gain, but reduced the overall inbreeding in the population. MAS was also inefficient when heritability was 0.5.     

Simulation of genetic control of reproduction in beef cows. IV. Within-herd breeding value estimation with pasture mating

Procedures for breeding value estimation for reproductive traits under pasture mating conditions were developed and tested using a computer simulation model of genetic control of bovine reproduction. The model generated annual calving rates (BCR) (0 or 1) and calving dates (CD) for each cow as a function of underlying genetic variation in two independent traits: single-service conception rate, which was indicative of the ability to conceive when estrus occurs, and postpartum interval (PPI) from calving to first estrus. Observed values for BCR and CD were shown to be complex, nonlinear functions of breeding values for ability to conceive (CRG) and for postpartum interval (PPIG) and of the previous CD. Effects of CRG on BCR and CD were small at high values of CRG, but these effects increased as CRG declined. Effects of PPIG on BCR and CD were small for cows that previously calved within the first 21 d of the calving season, but these effects increased for cows that calved after d 21. Previous CD had substantial nongenetic carryover effects on both BCR and CD. Unbiased estimates of CRG and PPIG could not be derived in the absence of breeding information. However, CD were reasonably highly correlated with breeding values for ability to conceive, provided information on open cows was included in the evaluation. Calving dates were only weakly associated with breeding values for PPI, in part because of the relatively short mean PPI (70 d) that was simulated.     

Reduced-rank estimation of genetic parameters for egg production traits and cluster analyses with predicted breeding values

The aims of this study were to compare the suitability of the multi-trait (MUT) model to estimate genetic parameters with that of 13 reduced-rank principal component models (PC1 to PC13), and then to explore the additive genetic patterns of the breeding values obtained from these using clustering analyses of egg production traits. A total of 1,212 records were used to estimate genetic parameters using the MUT and PC models. The PC4 model was the best representation of the data since it had a lower AIC value and was more parsimonious than the MUT model. The estimated heritability of the age at the first egg (AFE) trait from this model was 0.28?±?0.06, and the estimated genetic correlation between AFE and total egg production (TP) was ?0.52?±?0.23. Potentially animals from cluster 2 are more likely to be in the selected group to help improve the egg production.     

狗牙根品种(系)表型及分子遗传变异研究

狗牙根系世界著名多年生禾本科暖季型草坪草,广泛用于不同用途草坪建植.本研究对国内审定的5个狗牙根品种,1个新品系及1个国外引进品种进行表型性状和分子遗传的比较研究,以进一步明确我国狗牙根品种资源的利用特性和遗传基础.结果表明,1)供试狗牙根品种(系)'02011'在试验区域的成坪速度为53 d,绿期为269 d,高于国内审定品种;2)反映株高,匍匐茎,旗叶,花序等特性的9个表型性状在品种间差异均达极显著水平(P<0.01);3)各品种(系)在匍匐茎表面颜色,花序抽出度,叶片上表面颜色,生长习性,生殖枝表面花青甙显色,外颖颖壳,颖尖花青甙显色等植物新品种测试性状上表现出不同程度的群体差异;4)SRAP与SSR分子标记各18对引物分别扩增出167和316条谱带,多态性比例分别为87.51%和70.13%,来自相同地域的供试狗牙根品种具有较近的遗传相似度.     

The value of genetic information in selecting dairy replacements

The objective of this study was to empirically determine the economic value of genetic information in the selection of dairy replacements, and assess whether this value was sufficient to prompt producers to select replacements on this basis. The data set consisted of 1982 Michigan Holstein replacements in 115 herds. Each herd had a minimum of 10 replacements that were born in the last 6 months of 1992 and calved within the last 6 months of 1994. The data for each replacement included the estimated breeding value (EBV) for milk at the beginning and end of the rearing period, and the estimated lifetime profit corrected for the opportunity cost of postponed replacement (ELPCOC). The replacement selection decision for a profit-maximizing dairy producer selecting 70 or 80% of the replacements was modeled. We modeled three methods of selection: genetic, random and ex poste. Genetic selection was evaluated using the EBV milk available at the beginning or end of the rearing period. For each herd, the profit associated with each of the three methods of selection was simulated. The value of the genetic information and perfect information were the differences in herd profits of genetic selection and ex poste selection relative to random selection, respectively. The difference in value of the genetic information between the end of the rearing period and the beginning of the rearing period was the increase in value of the genetic information due to updating. The value of information was calculated as the average herd profit per replacement. The value of the genetic information ranged from 22 dollars/replacement to 30 dollars/replacement and was statistically greater than zero at a 95% confidence level. It is unclear whether this value is sufficient to prompt producers to select replacements on the basis of EBV milk as has been recommended. The negative value of EBV milk (from the end of the rearing period when selecting 80% of the replacements) for 32 herds was consistent with the noisiness of the genetic estimates as messages of ELPCOC. The increased value of the genetic information due to updating was approximately 5 dollars/replacement. This increased value is likely insufficient to warrant delaying replacement selection decisions solely to obtain the updated information. The value of EBV milk was approximately 4 dollars/replacement higher when selecting 70% of the replacements versus 80%. The genetic information captured between 15% (selecting 70% at the beginning of the rearing period) and 20% (selecting 80% at the end of the rearing period) of the value of perfect information.     

Congenital defects inheritance of AI boars: Genetic parameters and breeding value estimation procedures

Genetic and phenotypic parameters were estimated for the congenital defects atresia ani (AA), intersexuality (IS), cryptorchidism (CR) and scrotal hernia (SH) in Dutch Landrace (DL) and Dutch Yorkshire (DY) pigs, based on data collected in Herdbook defects inventarization during 1976–1984 in the progeny of 194 DL and 294 DY AI boars.Heritabilities were estimated using analysis of variance with correction for categorical data type, and using the proband method derived by Falconer. The results of both methods differed considerably. Using the ANOVA estimates for CR and SH, and the proband estimates for AA and IS, h_HS² ranged between 0.16 and 0.35, and h_FS² between 0.34 and 0.94, indicating large non-additive genetic and maternal effects. Genetic correlation coefficients, estimated by the proband method, generally differed significantly from zero.Frequency distributions of the percentage affected litters per sire were approximated with chi-square functions; for AA and IS, estimated df of these functions were <1, indicating little between-sires variation of this percentage. For CR and SH, estimated df ranged between 1.5 and 4.8, indicating a more quantitative inheritance pattern for these traits.Based on the assumption of a quantitative inheritance pattern for CR and SH, and an oligogeneous one for AA and IS, selection criteria for AI boars were derived following the usual selection index approach, giving higher weights to traits with larger h², larger economical value and taking into account the variation present in the population, as indicated by the chi-square functions.     

Genetic parameter estimation and implementation of the genetic evaluation for gaits in a breeding program for assisted-therapy in donkeys

Genetic analyses in donkeys are likely to face compromises in terms of sample size and population structure. This study aims at implementing a suitable model to estimate breeding values and genetic parameters for gaits in Andalusian donkeys. Empirical observation revealed that ambling donkeys (showing a slightly uneven, non-isochronous 1–2, 3–4 lateral sequence gait) did not walk (i.e. presented an isochronous, even 1-2-3-4 sequence gait) and vice versa. However, the two donkey groups could trot, equally. In this study, 2700 gait records were registered from 300 donkeys. The sample included 1350 gait records from 169 ambling/trotting donkeys and 1350 gait records from 131 walking/trotting donkeys. Fixed effects included year, season, sex, farm/owner, husbandry system, weather, ground type and appraisers. Weight and age were included as covariates. MTDFREML software was used to estimate (co)variance components, genetic parameters and predict breeding values and their accuracies in both sets, separately. Gaits’ heritability?±?SE estimates were 0.56?±?0.155, 0.53?±?0.317 and 0.67?±?0.166 for amble, walk and trot, respectively. Genetic correlations were 0.31?±?0.216, 0.42?±?0.115 and 0.28?±?0.178, for amble and walk, amble and trot and walk and trot, respectively. Not all gaits are suitable to treat every human sensomotor condition. We developed a locomotion selection index, assessing the relative loss/gain in index accuracy when each gait modality was excluded to develop different gait specific therapeutic lines to genetically select the best performing donkeys from each gait modality. Our results suggest that gait genetic lines could be developed and may be potential selection criteria to consider in assisted-therapy donkey breeding programs.     

Estimation of phenotypic and genetic parameters for weight gain and weight at fixed ages in the double-muscled Belgian Blue Beef breed using field records

In the double‐muscled Belgian Blue beef (DM‐BBB) breed, selection focuses on muscular conformation and not on weight gain and higher weight. There are very few studies on growth in the DM‐BBB using field records. Therefore, farms have no available useful figures on weight at fixed ages and weight gain for the DM‐BBB. This study describes and evaluates live weights of DM‐BBB animals. All the data were gathered on farms in Belgium. It was found that a male DM‐BBB weighs an average of 51 kg at birth, 98 kg at 3 months, 242 kg at 7 months, 430 kg at 13 months and 627 kg at 20 months. Between the age of 7 and 20 months, weight gain is more than 1200 g a day. Females weigh 47 kg at birth, 96 kg at 3 months, 189 kg at 7 months and 332 kg at 13 months. For males, estimates of heritability for weights at 7, 13 and 20 months were between 0.21 and 0.36. The heritability for weight gain between 13 and 20 months was 0.13. This demonstrates that it is possible to select for higher weights and for increased growth between 13 and 20 months. Animals having high weights at a young age (7 and 13 months) tend to have also high weight at slaughtering age (20 months; r_g between 0.81 and 0.98), but no additional growth between 13 and 20 months (r_g between −0.09 and 0.00). High weight at 20 months is partially due to growth between 13 and 20 months (r_g = 0.49).     

Repeatability and phenotypic correlations for body weight and reproduction in commercial ostrich breeding pairs

1. Reproduction is an important aspect of ostrich farming, where income is mainly derived from hides and meat. No estimates of repeatability or phenotypic correlations for reproduction and body weight are currendy available for commercial ostriches.

2. Means, standard deviations, repeatability coefficients and phenotypic correlations for and among reproductive traits and body weight were computed for the average yearly production of 42 to 67 mixed age ostrich breeding pairs maintained on the Klein Karoo Agricultural Development Centre from 1990 to 1994. The among‐breeding‐pair variance component was used in the repeatability estimations, as the pairing off of the same male:female combinations repeatedly resulted in the confounding of these effects.

3. Phenotypic correlations of male body weight with egg production performance ( — 0.20) and female body weight with hatchability percentage ( — 0.16) were negative. Correlations of egg production performance with infertility (— 0.20) and hatchability (0.23) percentages were favourable.

4. The repeatability of annual adult body weight was 0.68 ± 0.05 in male ostriches and 0.61 ±0.05 in females.

5. Ostrich reproduction traits were extremely variable. An appreciable portion of this variation could be attributed to the repeatable nature of breeding pair performance from year to year. All the reproduction traits analysed were moderately repeatable, ranging from 0.38 ± 0.07 (hatchability percentage) to 0.51 ± 0.06 (percentage of embryonic deaths). Egg production performance during the first breeding season of 17 breeding pairs for which data were available predicted subsequent performance satisfactorily, suggesting that selection decisions can be made at quite an early age.     

评估育种值对遗传进展的重要性

正生猪生产与世界的变化保持一样的快速发展。发明于法国的批次管理系统,不是生猪生产变革的唯一变化。最近,法国公司已经开始在市场上出售无抗生素的鲜猪肉。这意味着,上游的生产条件必须极佳,以便能够从断奶到屠宰都不使用抗生素,同时能保持较高的生产水平。生产链中的所有环节正从这一改进中获胜。法国由于其猪种拥有出色的遗传潜力并伴有较高的生猪生产卫生水平实现了高生产性能而闻名于世界。未来几年的问题必须现在就做好准备。猪遗传     

Genetic and phenotypic parameters estimated from Nebraska specific-pathogen-free swine field records

Records collected during 1971 through 1979 from 101,606 hogs raised in 18 Nebraska Specific Pathogen Free herds were analyzed. Traits considered were backfat at 100 kg (BF), weight at 140 d of age (WT) and, in some analyses, number of live pigs/litter at birth (NBA). The phenotypic correlation of BF and WT, averaged across herds, was -.07. The correlations between BF and NBA and between WT and NBA were .04 and -.05, respectively. Average phenotypic standard deviations for BF, WT and NBA were 2.6 mm, 8.8 kg and 2.0 pigs. Estimates of the heritability of BF and WT were lower than most estimates reported from university research herds. Within breed, herd and sex estimates of heritability ranged from -.22 and .51 (unweighted mean = .16 +/- .025) for BF and ranged from -.28 to .49 (mean = .16 +/- .016) for WT. Estimates of the genetic correlation between BF and WT were extremely variable (mean = -.62 +/- 14.3, range = -9.42 to 1.30) among breed-herd-sex subclasses.     

布尔山羊及其种用价值

综合了国内外关于布尔山羊种质特性与利用方面的最新资料，并对该品种作了较全面的客观评价，以对各地引种和繁殖利用提供重要参考。