Animal (2013), 7:1, pp 11–21 & The Animal Consortium 2012 animal doi:10.1017/S1751731112001322

Correlations of unfavorable movement characteristics in foals and mares with routinely assessed conformation and performance traits

- A.-C. Becker1, K. F. Stock1,2 and O. Distl1

1Institute for Animal Breeding and Genetics, University of Veterinary Medicine Hannover, Buenteweg 17p, 30559 Hanover, Germany; 2Vereinigte Informationssysteme Tierhaltung w.V., Heideweg 1, 27283 Verden, Germany

(Received 22 November 2011; Accepted 19 March 2012; First published online 6 July 2012)

New movement traits reflecting unfavorable movement characteristics were defined on the basis of detailed movement evaluations (DME) of warmblood foals and mares performed in connection with regular breeding events of the Oldenburg breeding societies in 2009 and 2010. DME information was available for 3374 foals and 2844 mares and used for correlation analyses with conformation information on 1987 mares from studbook inspections (SBI) in 2009 and performance information on 2758 mares from mare performance tests (MPT) in 2000 to 2008. Analyses of variance revealed few significant differences between scores for SBI and MPT traits in mares without and with indications of imbalance (IMB) in general or specific findings like irregular tail tone or posture (TTP). SBI scores for general impression and development were significantly lower and MPT scores for trot under rider tended to be higher in IMB-positive mares. Genetic parameters were estimated in linear animal models with residual maximum likelihood. Additive genetic correlations and Pearson correlation coefficients between univariately predicted breeding values indicated unfavorable genetic correlations of IMB and TTP with dressage-related conformation and performance traits. For SBI and MPT traits, we found similarities between the correlation patterns for DME traits in foals and mares. The results implied that breeding of dressage may benefit from revision of current movement evaluation and consideration of specific movement characteristics.

Keywords: indications of imbalance, mare performance test, studbook inspection, genetic correlation

Implications the discipline of riding sport, body control and balanced movement under the rider represent basic requirements for To be successful in riding sport of any discipline, horses have to successful performances, justifying that movement traits be able to move in balance under the rider. Gaits are therefore are integral parts of the routine evaluations for breeding routinely evaluated for breeding purposes. However, the tradi- purposes. For mares intended for breeding use, studbook tionally used subjective scoring system does not allow any inspections (SBI) including evaluations of movement at hand inferences on certain movement characteristics. Information are obligatory. Performance tests of mares including movement from detailed movement evaluations (DME) of foals and mares evaluations under rider are voluntarily, so the proportion of was used to define new movement traits and perform corre- performance-tested broodmares is usually below 50%. Never- lation analyses with routinely assessed conformation and per- theless, moderately high heritabilities and significant positive formance traits. Positive genetic correlations with findings genetic correlations with sport performances make perfor- indicating impaired balance in movement imply that horse mance test data a valuable source of information for routine breeding may benefit from extending DME and using more genetic evaluations of riding horses. In contrast, conformation specific information on gaits. information is available for significantly larger proportions of horses, including foals, but the way and extent of use of Introduction conformation data varies between breeding organizations. In Warmblood breeding primarily aims at producing riding Germany, traits from SBI and foal registrations are not included horses, which are highly competitive in sport. Regardless of in the national genetic evaluation for riding horses. Regardless of the evaluation circumstances, the currently used definitions - E-mail: [email protected] of conformation and performance traits are often very general

11 Becker, Stock and Distl and due to the common subjective scoring system do not allow had shown that specific findings could be grouped by the any statements on specific movement characteristics. Although affected structures or parts of the body and information from the benefits of refined trait definitions and descriptive eva- the two groups of judges, SJ and RJ, could be jointly used. luations have been stressed (Rustin et al., 2009), there are This resulted in a set of three composite traits and one still very few warmblood breeding organizations that have summary trait per age group: irregular tail tone and/or posture accordingly revised their routine scoring systems. (TTP; lower than normal tone of tail muscles and/or any Lacking specificity of gait scoring for breeding purposes deviation from normal straight tail carriage), irregular motion may relate to the fact that certain unfavorable movement pattern in hind legs (HM), irregularity in general motion pattern characteristics that are long known still occur. Hereditary (GM) and IMB (any irregularities of movement, i.e. TTP, HM, influences on impaired coordination in equines have been GM and/or pace in foals, TTP, HM and/or GM in mares). The suggested as early as in the first half of the 20th century prevalences of the binary traits were 3.97% for TTP, 2.31% for (Dimock and Errington, 1939; Dimock, 1950). In a recent study, HM, 1.13% for GM and 6.22% for IMB in the foals, and 4.89% indications of imbalance (IMB) were found in almost equal for TTP, 1.37% for HM, 0.08% for GM and 5.49% for IMB in the proportions of warmblood foals and presumptive warmblood mares. Heritability estimates of 0.08 6 0.03 in the foals and broodmares, and genetic analyses implied relevant genetic 0.04 6 0.02 in the mares were found for TTP, and heritability determination and opportunities to select against unfavorable estimates of 0.12 6 0.04 in the foals and 0.05 6 0.02 in the movement characteristics and forbetterbalanceinmovement mares were found for IMB by Becker et al. (2011b). in juvenile and adult horses (Becker et al., 2011b). However, recommending extension of detailed movement evaluations Conformation and performance data (DME) and introduction of new traits into existing breeding Results of conformation evaluations were available for 1987 programs requires knowledge of correlations with the routinely mares presented for studbook entry of one of the Oldenburg assessed traits: unnecessary increase of the number of traits to breeding societies in 2009. The SBI had either taken place in be recorded can be avoided (closely correlated traits), and connection with mare shows or during on-farm visits or foal interferences of concurrent breeding progress (unfavorable registrations. The age at SBI ranged from 2.6 to 23.2 years, correlations) can be taken into account. with a mean age of 7.03 6 4.64 years. The mares were pre- The aim of this study was to investigate the correlations sented standing and moving in walk and trot while led by a between the new movement traits assessed during DME of handler. Scores on a subjective scale from 1 to 10 were given by warmblood foals and mares and the standard conformation the judges of the breeding societies for conformation of head and performance traits routinely assessed during SBI and (Head), neck (Neck), -bearing area (Sad), front limbs mare performance tests (MPT) in the field. (FLimb), hind limbs (HLimb), frame (Frame), type (Type), general impression and development (Dev), walk (Walk), impetus and elasticity (ImpEl) and correctness of gaits (CorrG). In addition, a Material and methods score for body conformation (Body) was derived from the scores DME for Head, Neck, Sad, FLimb, HLimb and Frame, and a total score Information on DME was available for 3374 foals and 2844 was then calculated from scores for Body, Type, Dev, Walk, mares presented for regular breeding events of the Old- ImpEl and CorrG. enburg breeding societies in 2009 and 2010. During foal Results of MPT were available for 2758 mares that had registrations, foals and mares were evaluated by a special participated in 1-day field tests of mares organized by the judge focusing on unfavorable characteristics of movement Oldenburg society from 2000 to 2008. The (SJ; foals and mares) and by the regular judges of the mean age at MPT was 3.38 6 0.61 years, with a proportion breeding societies (RJ). Additional movement data of mares of 97% of 3- and 4-year-old mares. Subjective scores on a were collected during regular mare shows and few on-farm scale from 1 to 10 with intervals of 0.5 were given for the SBI of mares, with the same constellations of judges (SJ, RJ). following traits: Walk during free movement (Walk F), Walk All mares were evaluated in hand, that is, led by a handler, under rider (Walk R), Trot during free movement (Trot F), Trot in walk and trot, and the foals were evaluated moving freely under rider (Trot R), Canter during free movement (Canter F), alongside their dams. The mean age at DME was 2.3 months Canter under rider (Canter R), Rideability and Free jumping in the foals (range: 14 days to 7 months of age; 64% younger (Jumping). Rideability scores were given by test riders, whereas than 3 months of age) and 9.2 years in the mares (range: 3 the judges of the breeding societies were responsible for and 24 years of age; 27% up to 5 years old). DME of foals scoring of gaits and jumping. In addition, the balanced mean of were performed in 97 events, including 8 events with more gait scores achieved without rider and under the own rider than 100 evaluated foals (on average 34.79 6 41.39 eval- was calculated for each of the gaits: Walk F 1 R, Trot F 1 Rand uated foals per event). DME of mares were performed in Canter F 1 R. These summary gait scores were the only infor- 62 events (33 foal registrations, 29 mare shows), including mation on gaits available for the 979 mares tested in 2000 to 6 events with more than 100 evaluated mares (on average 2002. Scoring of walk during free movement was not continued 45.87 6 45.83 evaluated mares per event). after2005,soinformationonWalkFandWalkF1 Rwas The descriptive notes of the judges served as the basis for available only for the 896 mares tested in 2003 to 2005. Further defining movement traits. Previous analyses of the DME data details can be found in Becker et al. (2011a).

12 Correlation analyses of new movement traits

Of the 2844 mares with DME information, 605 mares to the model fit statistics of the procedures MIXED and were included in the SBI data (age at DME of 5.87 6 4.25 GLIMMIX of SAS: years) and 471 mares were included in the MPT data. yimnpst ¼ m þ b1 AGED Mi þ JUDGEm þ BMONn Statistical analyses þ eventDp þ as þ eimnpst ðDMEfoalsÞ To investigate the influence of unfavorable movement characteristics as reflected by the new movement traits from yjmopst ¼ m þ b2 AGED Jj þ JUDGEm þ ETYPEo DME on the standard SBI and MPT traits, multiple analyses þ eventDp þ as þ e ðDMEmaresÞ of variance were performed using the procedure MIXED of jmopst SAS (Statistical Analysis System, version 9.2, 2011). All new y ¼ m þ AGES þ BMON þ eventS movement traits (n 5 4; TTP, HM, GM, IMB in mares) and the knqst k n q directly scored conformation and performance traits, that is, þ as þ eknqst ðSBIÞ 11 SBI traits (Walk, ImpEl, CorrG, Head, Neck, Sad, FLimb, HLimb, Frame, Type and Dev) and eight MPT traits (Walk F, ylnrst ¼ m þ AGEMl þ BMONn þ eventMr Walk R, Trot F, Trot R, Canter F, Canter R, Rideability and þ a þ e ðMPTÞ Jumping) were included. Because of the low numbers of s lnrst HM-positive and GM-positive mares with MPT information, where y is the affection status for the respective DME trait only results for IMB and TTP will be presented from the yt or SBI score or MPT score of the sth horse, m the model multiple analyses of variance. constant, AGED_M (AGED_J ) the linear regression on the In each of the analyses, the standard trait from SBI or MPT i j ith DME age in months (jth DME age in years) with regres- was considered as dependent variable, and the new move- sion factors b (b ), AGES the fixed effect of the kth class of ment trait from DME was considered as independent vari- 1 2 k SBI age in years (k 5 1to2;<3 years of age, .3 years of able. To correct for environmental influences, the models age), AGEM the fixed effect of the lth class of MPT age in further included season of birth and age as fixed effects and l years (l 5 1to2;<3 years of age, .3 years of age), JUDGE evaluation event as random effect: m the fixed effects of the mth combination of DME judges (m 5 1 to 3; SJ only, RJ only, SJ 1 RJ), BMONn the fixed yijklm ¼ m þ DMEi þ AGEj þ BMONk þ eventl þ eijklm effects of the nth class of birth month (n 5 1 to 4; February to March, April, May, June to January), ETYPEo the fixed where yijklm is the SBI score (MPT score) of the individual effect of the oth DME type of mares (o 5 1 to 2; foal regis- horse, m the model constant, DMEi the affection status for tration, mare show), eventDp the random effect of the pth the respective DME trait, that is, IMB, TTP, HM or GM (i 5 1 DME event (p 5 1 to 125; individual combinations of date to 2; not affected, affected), AGEj the fixed effect of jth class and place of DME), eventSq the random effect of the qth SBI of evaluation age in years (j 5 1to2;<3 years of age, .3 event (q 5 1 to 341; individual combinations of date and years of age), BMONk the fixed effects of the kth class of place of SBI), eventMr the random effect of the rth MPT birth month (k 5 1 to 4; February to March, April, May, June event (r 5 1 to 37; individual combinations of date and place to January), eventl the random effect of the lth evaluation of MPT), as the random additive genetic effects of the sth event (lSBI 5 1 to 341, lMPT 5 1 to 37; individual combina- animal (s 5 1 to 44 158) and eyt the random residual. tions of date and place of SBI or MPT evaluation) and eijklm Variance components were estimated univariately and the random residual. multivariately in linear animal models with residual maximum likelihood (REML) using VCE software, version 603 (Variance Estimations of genetic parameters Component Estimation). Univariate genetic analyses of all traits Genetic analyses included four traits from DME (IMB in foals, (n 5 18: 4 DME, 6 SBI and 8 MPT traits) were followed by TTP in foals, IMB in mares, TTP in mares), six locomotion- bivariate analyses of one DME trait and one SBI or MPT trait related traits from SBI (Walk, CorrG, ImpEl, FLimb, HLimb each. Accordingly, additive genetic correlation estimates were and Frame) and eight traits from MPT (Walk F, Walk R, Trot F, obtained through 24 DME–SBI and 32 DME–MPT analyses. Trot R, Canter F, Canter R, Rideability and Jumping). GM and Variance estimates were used to predict breeding values HM were not considered because of their low prevalences (BV) in univariate linear animal models by best linear that were previously found to interfere with reliable esti- unbiased prediction (BLUP) with PEST (Prediction Estimation; mations of (co)variance components (Becker et al., 2011b). Groeneveld, 1990). Pearson correlation coefficients and Pedigree information on all horses was made available by Spearman rank correlations were determined between the the breeding society through the German unified animal own- univariately predicted BV using the procedure CORR of ership database (Vereinigte Informationssysteme Tierhaltung SAS. For the correlation analyses, two groups of sires were w.V., Verden). For all horses with phenotype data (DME, SBI considered: the first group (S1) included all 1086 sires with or MPT), information on four ancestral generations was offspring in the DME data. These sires had on average 5.7 considered, resulting in a relationship matrix with a total of offspring with DME (3.1 foals, 2.6 mares), 1.3 offspring with 44158 horses. The following models were chosen according SBI and 2.3 offspring with MPT; the second group (S2)

13 Becker, Stock and Distl included only sires with offspring in the DME and SBI data Table 1 Means, s.d. and ranges of scores for conformation and per- (157 sires with on average 20.4 offspring with DME and 6.5 formance traits from SBI in 2009 and MPT in 2000 to 2008 offspring with SBI) or DME and MPT data (155 sires with on Trait group Trait n Mean 6 s.d. Range average 18.3 offspring with DME and 14.6 offspring with MPT) that had at least five offspring in one of the two trait Conformation (SBI) Walk 1987 6.60 6 0.67 5.00 to 9.00 groups. Because Spearman rank correlations differed by CorrG 1987 6.22 6 0.67 3.00 to 8.00 maximally 60.06 from the Pearson correlations, only Pearson ImpEl 1987 6.58 6 0.74 5.00 to 9.00 correlation coefficients will be presented. Head 1987 6.99 6 0.78 5.00 to 9.00 To facilitate interpretation of BV distributions, relative Neck 1987 6.55 6 0.70 4.00 to 9.00 breeding values (RBV) were subsequently derived from the Sad 1987 6.57 6 0.60 5.00 to 8.00 univariately predicted BV by standardizing to a mean of 100 FLimb 1987 5.64 6 0.75 3.00 to 8.00 HLimb 1987 5.65 6 0.69 3.00 to 8.00 and a standard deviation (s.d.) of 20, such that RBV .100 Frame 1987 6.52 6 0.72 4.00 to 9.00 indicated higher and RBV ,100 indicated lower probability of Type 1987 6.87 6 0.74 5.00 to 9.00 an animal to pass favorable genetic disposition (no unfavor- Dev 1987 6.59 6 0.63 5.00 to 9.00 able movement characteristics; higher SBI or MPT scores) for Performance (MPT) Walk F 896 7.23 6 0.57 5.50 to 9.00 the respective trait to its offspring. Sires with offspring among Walk R 1779 7.24 6 0.64 5.00 to 10.00 the foals and the mares with DME (n 5 138), among the mares Trot F 1779 7.39 6 0.60 5.50 to 9.50 with SBI (n 5 867) and among the mares with MPT (n 5 458) Trot R 1779 7.11 6 0.69 5.00 to 10.00 served as reference for the respective group of traits. Joint Canter F 1779 7.24 6 0.54 5.00 to 9.00 distributions of RBV were then analyzed in the 1086 sires with Canter R 1779 7.34 6 0.61 5.00 to 9.50 offspring (foals and/or mares) in the DME data. RBV for the SBI Rideability 2749 7.38 6 0.67 5.00 to 9.50 and the MPT traits were compared between groups of sires Jumping 2749 7.13 6 0.82 4.50 to 10.00 with RBV for DME traits more than half a s.d. below the mean s.d. 5 standard deviations; SBI 5 studbook inspections; MPT 5 mare (,90; n 5 203 to 244), within one s.d. around the mean (90 to performance tests; CorrG 5 correctness of gaits, ImpEl 5 impetus and elasticity, FLimb (HLimb) 5 front (hind) limb conformation; Walk F (Trot F, 110; n 5 579 to 602) and more than half a s.d. above the Canter F) 5 Walk (Trot, Canter) during free movement; Walk R (Trot R, Canter mean (.110; n 5 248 to 297). R) 5 Walk (Trot, Canter) under rider.

Results movement characteristics are given in Table 3. LSM were Means, s.d., minima and maxima for SBI and MPT traits are mostly very similar in the unaffected mares than in the mares given in Table 1. Mean scores ranged between 5.64 and 6.99 affected with IMB or TTP. However, for only three of the eight in SBI and 7.11 and 7.39 in MPT, with s.d. of 0.60 to 0.78 for MPT traits, LSM were higher in the unaffected than in the the SBI traits and 0.54 to 0.69 for all MPT traits except affected mares. Scores for Trot R tended to be higher in the Jumping (s.d. of 0.82). For none of the conformation and IMB-positive mares (P 5 0.06), and results were similar, but performance traits the full scale of scores was used, with less clear for TTP (P 5 0.11). The same pattern of on average differences between minimum and maximum scores of higher MPT scores in the affected mares was found for Trot F between 3.5 and 5.5. and Canter F (P 5 0.11 to 0.16). The results of analyses of variance with comparison of SBI Genetic analyses revealed low to moderate heritability results between mares without and with unfavorable move- estimates for the SBI traits, with h2 5 0.05 to 0.10 for ment characteristics are given in Table 2. When compared with CorrG, FLimb, HLimb and Frame, h2 5 0.26 for Walk and the unaffected mares, mares affected with HM or GM had h2 5 0.33 for ImpEl (standard errors of 0.03 to 0.06). lower least square means (LSM) for all SBI traits. Mares Moderate heritabilities of h2 5 0.21 for Rideability, affected with TTP or IMB had lower LSM for all SBI traits except h2 5 0.35 to 0.50 for the gait traits (Walk F, Walk R, Trot Head, Neck and Sad. However, differences were in many cases F, Trot R, Canter F, Canter R) and h2 5 0.56 for Jumping not significant, particularly for IMB and TTP. LSM for FLimb and (standard errors of 0.04 to 0.10) were estimated for the Dev were significantly lower in the IMB-positive than in the MPT traits. Heritability estimates for the SBI and MPT IMB-negative mares (P 5 0.01 to 0.02). In the TTP-affected traits from univariate analyses and bivariate analyses with mares, scores for FLimb were on average significantly lower DME traits were very similar, with differences of ,0.01 for (P 5 0.02) and scores for Dev tended to be lower than in the all traits except Walk F (univariate h2 of 0.45 6 0.10 v. unaffected mares (P 5 0.10). Mares affected with HM or GM mean h2 from bivariate analyses of 0.43 6 0.08). had on average received significantly lower scores for Walk, Additive genetic and phenotypic correlations between SBI ImpEl and Dev (P , 0.05); results were similar, but less clear and DME traits and between MPT and DME traits are given for HLimb (P , 0.10). No significant differences were found in Table 4. The additive genetic correlation estimates regarding any of the DME traits for the SBI traits CorrG and obtained for IMB in foals, IMB in mares, TTP in foals and TTP Frame (P 5 0.24 to 0.84). in mares ranged mostly between 20.1 and 0.9, but were in The results of analyses of variance with comparison of many cases associated with high standard errors. In the foal MPT results between mares without and with unfavorable data, positive additive genetic correlations of 0.3 to 0.9 were

14 Correlation analyses of new movement traits

Table 2 Results of multiple analyses of variance for conformation traits from SBI of warmblood mares that underwent DME (n 5 605), with error probabilities (P), LSM and 95% CI for unfavorable movement characteristics SBI trait DME trait Unaffected mares LSM (95% CI) Affected mares LSM (95% CI) FP

Walk IMB 6.664 (6.576 to 6.751) 6.579 (6.413 to 6.746) 1.00 0.318 TTP 6.664 (6.592 to 6.735) 6.677 (6.516 to 6.838) 0.02 0.588 HM 6.658 (6.563 to 6.753) 6.080 (5.804 to 6.355) 18.17 ,0.001 GM 6.661 (6.573 to 6.750) 6.016 (5.677 to 6.355) 14.36 ,0.001 CorrG IMB 6.276 (6.165 to 6.387) 6.206 (6.029 to 6.382) 0.84 0.360 TTP 6.276 (6.165 to 6.387) 6.197 (6.014 to 6.379) 0.98 0.323 HM 6.273 (6.163 to 6.383) 6.127 (5.865 to 6.390) 1.39 0.239 GM 6.271 (6.161 to 6.381) 6.186 (5.867 to 6.506) 0.30 0.583 ImpEl IMB 6.624 (6.502 to 6.746) 6.532 (6.331 to 6.733) 1.03 0.309 TTP 6.621 (6.500 to 6.742) 6.578 (6.370 to 6.786) 0.21 0.647 HM 6.620 (6.498 to 6.742) 6.260 (5.955 to 6.565) 6.17 0.013 GM 6.619 (6.497 to 6.741) 6.146 (5.775 to 6.518) 6.82 0.009 Head IMB 6.972 (6.849 to 7.094) 6.975 (6.783 to 7.167) 0.00 0.966 TTP 6.969 (6.847 to 7.091) 7.017 (6.819 to 7.214) 0.31 0.578 HM 6.973 (6.851 to 7.095) 6.876 (6.592 to 7.159) 0.54 0.464 GM 6.973 (6.851 to 7.095) 6.834 (6.490 to 7.179) 0.70 0.404 Neck IMB 6.626 (6.500 to 6.753) 6.515 (6.320 to 6.710) 1.81 0.179 TTP 6.624 (6.498 to 6.750) 6.539 (6.338 to 6.740) 0.97 0.325 HM 6.620 (6.495 to 6.745) 6.481 (6.195 to 6.768) 1.08 0.300 GM 6.622 (6.497 to 6.747) 6.188 (5.842 to 6.534) 6.83 0.009 Sad IMB 6.504 (6.423 to 6.585) 6.619 (6.473 to 6.766) 2.64 0.105 TTP 6.503 (6.422 to 6.584) 6.626 (6.472 to 6.779) 2.70 0.101 HM 6.511 (6.430 to 6.593) 6.589 (6.354 to 6.824) 0.45 0.501 GM 6.512 (6.430 to 6.595) 6.482 (6.191 to 6.772) 0.04 0.832 FLimb IMB 5.470 (5.341 to 5.599) 5.222 (5.016 to 5.427) 7.65 0.006 TTP 5.466 (5.337 to 5.595) 5.242 (5.028 to 5.455) 5.69 0.017 HM 5.451 (5.322 to 5.580) 5.299 (4.990 to 5.608) 1.09 0.297 GM 5.451 (5.322 to 5.580) 5.216 (4.840 to 5.592) 1.67 0.197 HLimb IMB 5.560 (5.474 to 5.646) 5.448 (5.287 to 5.609) 1.93 0.165 TTP 5.558 (5.473 to 5.643) 5.457 (5.289 to 5.625) 1.44 0.231 HM 5.553 (5.470 to 5.637) 5.332 (5.071 to 5.593) 2.86 0.091 GM 5.551 (5.466 to 5.637) 5.148 (4.822 to 5.473) 6.11 0.014 Frame IMB 6.388 (6.264 to 6.511) 6.323 (6.138 to 6.509) 0.69 0.406 TTP 6.387 (6.263 to 6.510) 6.329 (6.137 to 6.520) 0.52 0.471 HM 6.384 (6.262 to 6.507) 6.272 (6.002 to 6.542) 0.82 0.367 GM 6.383 (6.260 to 6.506) 6.352 (6.026 to 6.679) 0.04 0.844 Type IMB 6.860 (6.732 to 6.988) 6.767 (6.572 to 6.963) 1.26 0.261 TTP 6.858 (6.730 to 6.986) 6.791 (6.589 to 6.993) 0.60 0.439 HM 6.856 (6.729 to 6.983) 6.654 (6.368 to 6.941) 2.31 0.130 GM 6.854 (6.727 to 6.981) 6.747 (6.401 to 7.094) 0.41 0.520 Dev IMB 6.564 (6.462 to 6.667) 6.392 (6.223 to 6.560) 5.37 0.021 TTP 6.560 (6.458 to 6.663) 6.431 (6.257 to 6.605) 2.72 0.100 HM 6.558 (6.457 to 6.659) 6.124 (5.872 to 6.376) 13.08 ,0.001 GM 6.556 (6.455 to 6.657) 6.027 (5.719 to 6.335) 12.46 ,0.001

Results with error probabilities of P , 0.1 are given in bold print. SBI 5 studbook inspections; DME 5 detailed movement evaluations; LSM 5 least square mean estimates; CI 5 confidence intervals; IMB 5 indications of imbalance; TTP 5 irregular tail tone and/or posture; HM 5 irregular motion pattern in hind legs; GM 5 irregularity in general motion pattern; CorrG 5 correctness of gaits; ImpEl 5 impetus and elasticity; FLimb (HLimb) 5 front (hind) limb conformation. found for FLimb, HLimb and Frame. In the mare data, addi- traits with SBI and MPT traits were low, ranging in the foal tive genetic correlations were higher, and rg 5 1.0 was found data from 20.01 to 0.05 for SBI and from 20.03 to 0.04 for for four of the six SBI traits (CorrG, ImpEl, FLimb and HLimb) MPT and in the mare data from 20.05 to 20.02 for SBI and and for four of the eight MPT traits (Walk R, Trot R, Canter R from 20.09 to 0.11 for MPT. and Rideability). Indications for negative genetic correlations Pearson correlation coefficients between univariately with IMB and TTP in foals and mares were found for only one predicted BV for DME, SBI and MPT traits are given in of the MPT traits (Jumping). Phenotypic correlations of DME Table 5. Consistent results were obtained for the two groups

15 Becker, Stock and Distl

Table 3 Results of multiple variance analyses for performance traits from MPT of warmblood mares that underwent DME (n 5 471), with error probabilities (P), LSM estimates and 95% CI for unfavorable movement characteristics MPT trait DME trait Unaffected mares LSM (95% CI) Affected mares LSM (95% CI) FP

Walk F (n 5 157) IMB 7.214 (7.076 to 7.353) 6.992 (6.450 to 7.535) 0.66 0.418 TTP 7.211 (7.073 to 7.348) 7.104 (6.501 to 7.708) 0.12 0.728 Walk R (n 5 339) IMB 7.297 (7.197 to 7.396) 7.357 (6.892 to 7.822) 0.07 0.798 TTP 7.296 (7.197 to 7.396) 7.388 (6.892 to 7.884) 0.13 0.716 Trot F (n 5 339) IMB 7.237 (7.059 to 7.414) 7.544 (7.134 to 7.954) 2.48 0.116 TTP 7.235 (7.057 to 7.413) 7.571 (7.136 to 8.006) 2.58 0.110 Trot R (n 5 339) IMB 7.104 (6.964 to 7.243) 7.571 (7.086 to 8.056) 3.70 0.055 TTP 7.106 (6.967 to 7.246) 7.520 (7.003 to 8.038) 2.53 0.113 Canter F (n 5 339) IMB 7.082 (6.900 to 7.265) 7.328 (6.948 to 7.709) 1.95 0.164 TTP 7.080 (6.897 to 7.263) 7.385 (6.982 to 7.787) 2.59 0.108 Canter R (n 5 339) IMB 7.241 (7.064 to 7.419) 7.452 (7.006 to 7.899) 0.96 0.329 TTP 7.241 (7.063 to 7.419) 7.469 (6.995 to 7.943) 0.98 0.324 Rideability (n 5 471) IMB 7.250 (7.107 to 7.393) 7.191 (6.789 to 7.592) 0.09 0.763 TTP 7.251 (7.108 to 7.394) 7.164 (6.745 to 7.584) 0.17 0.676 Jumping (n 5 471) IMB 7.143 (7.006 to 7.280) 7.019 (6.526 to 7.511) 0.25 0.614 TTP 7.143 (7.006 to 7.281) 7.012 (6.497 to 7.527) 0.26 0.613

MPT 5 mare performance tests; DME 5 detailed movement evaluations; LSM 5 least square mean; CI 5 confidence intervals; IMB 5 indications of imbalance; TTP 5 irregular tail tone and/or posture; Walk F (Trot F, Canter F) 5 Walk (Trot, Canter) during free movement; Walk R (Trot R, Canter R) 5 Walk (Trot, Canter) under rider.

Table 4 Additive genetic correlations (rg) with their standard errors (SErg) and phenotypic correlations (rp) from bivariate genetic analyses of conformation and performance traits from regular SBI and MPT and unfavorable movement characteristics from DME of foals and mares

SBI or MPT trait DME trait Foals, rg 6 SErg (rp) Mares, rg 6 SErg (rp)

Walk IMB 0.004 6 0.185 (0.001) 0.449 6 0.450 (20.050) TTP 20.127 6 0.312 (20.010) 0.575 6 0.828 (20.024) CorrG IMB 0.091 6 0.336 (0.009) 0.491 6 0.429 (20.030) TTP 20.168 6 0.161 (20.008) 1.000 6 0.021 (20.029) ImpEl IMB 0.000 6 0.082 (0.000) 1.000 6 0.012 (20.032) TTP 0.062 6 0.163 (0.006) 1.000 6 0.005 (20.016) FLimb IMB 0.412 6 0.407 (0.024) 1.000 6 0.018 (20.045) TTP 0.860 6 0.531 (0.031) 1.000 6 0.001 (20.035) HLimb IMB 0.386 6 0.111 (0.025) 0.670 6 0.726 (20.034) TTP 0.622 6 0.532 (0.024) 1.000 6 0.008 (20.031) Frame IMB 0.603 6 0.240 (0.051) 0.161 6 0.301 (20.032) TTP 0.262 6 0.488 (0.012) 0.376 6 0.883 (20.028) Walk F IMB 0.252 6 0.267 (0.044) 0.605 6 0.752 (20.086) TTP 0.110 6 0.411 (0.011) 0.849 6 1.046 (20.058) Walk R IMB 0.104 6 0.053 (0.016) 1.000 6 0.020 (0.018) TTP 0.285 6 0.311 (0.026) 1.000 6 0.003 (0.025) Trot F IMB 20.139 6 0.221 (20.026) 0.743 6 0.555 (0.108) TTP 20.025 6 0.312 (20.003) 0.796 6 0.842 (0.087) Trot R IMB 20.045 6 0.217 (20.007) 0.819 6 0.636 (0.107) TTP 0.058 6 0.319 (0.006) 1.000 6 0.047 (0.082) Canter F IMB 20.081 6 0.218 (20.013) 0.430 6 0.350 (0.089) TTP 20.097 6 0.323 (20.009) 0.469 6 0.424 (0.087) Canter R IMB 20.077 6 0.214 (20.012) 1.000 6 0.028 (0.040) TTP 0.094 6 0.310 (0.009) 1.000 6 0.005 (0.039) Rideability IMB 20.082 6 0.177 (20.010) 0.929 6 0.348 (0.011) TTP 20.026 6 0.086 (20.002) 1.000 6 0.063 (20.003) Jumping IMB 20.131 6 0.059 (20.026) 20.859 6 0.786 (0.027) TTP 0.037 6 0.202 (0.004) 21.000 6 0.008 (0.024)

SBI 5 studbook inspections; MPT 5 mare performance tests; DME 5 detailed movement evaluations; IMB 5 Indications of imbalance; TTP 5 Irregular tail tone and/or posture; CorrG 5 correctness of gaits; ImpEl 5 impetus and elasticity; FLimb (HLimb) 5 front (hind) limb conformation; Walk F (Trot F, Canter F) 5 Walk (Trot, Canter) during free movement; Walk R (Trot R, Canter R) 5 Walk (Trot, Canter) under rider.

16 Correlation analyses of new movement traits

Table 5 Pearson correlation coefficients between univariately predicted breeding values for conformation and performance traits from regular SBI and MPT and unfavorable movement characteristics from DME of foals and mares in sires with offspring in DME (S1, n 5 1086), and sires with offspring in DME and SBI (DME and MPT) and at least five offspring in one of the two trait groups (S2, n 5 157 for SBI, n 5 155 for MPT) Foals Mares

SBI or MPT trait DME trait S1 S2 S1 S2

Walk IMB 0.074 0.092** 0.266*** 0.258*** TTP 0.085 0.089** 0.293*** 0.288*** CorrG IMB 0.019 0.002 0.230** 0.207*** TTP 20.047 20.028 0.230** 0.218*** ImpEl IMB 0.069 0.073* 0.413*** 0.336*** TTP 0.045 0.041 0.426*** 0.342*** FLimb IMB 0.223** 0.106*** 0.238** 0.241*** TTP 0.263*** 0.151*** 0.239** 0.239*** HLimb IMB 0.131 0.101*** 0.210** 0.216*** TTP 0.168* 0.140*** 0.197* 0.223*** Frame IMB 0.239** 0.155*** 0.242** 0.219*** TTP 0.096 0.0571 0.231** 0.204*** Walk F IMB 0.1521 0.113*** 0.222** 0.293*** TTP 0.093 0.065* 0.266*** 0.344*** Walk R IMB 0.121 0.063* 0.325*** 0.371*** TTP 0.131 0.111*** 0.348*** 0.394*** Trot F IMB 0.123 0.065* 0.330*** 0.227*** TTP 0.065 0.043 0.302*** 0.214*** Trot R IMB 0.1351 0.069* 0.268*** 0.333*** TTP 0.075 0.091** 0.281*** 0.362*** Canter F IMB 20.061 20.042 0.207** 0.145*** TTP 20.1511 20.076* 0.202* 0.158*** Canter R IMB 20.017 20.073* 0.296*** 0.249*** TTP 20.044 20.0551 0.279*** 0.267*** Rideability IMB 0.128 0.142*** 0.347*** 0.354*** TTP 0.085 0.121*** 0.333*** 0.348*** Jumping IMB 20.243** 20.204*** 20.249** 20.368*** TTP 20.173* 20.150*** 20.268*** 20.405***

SBI 5 studbook inspections; MPT 5 mare performance tests; DME 5 detailed movement evaluations; IMB 5 indications of imbalance; TTP 5 Irregular tail tone and/or posture; CorrG 5 correctness of gaits; ImpEl 5 impetus and elasticity; FLimb (HLimb) 5 front (hind) limb conformation; Walk F (Trot F, Canter F) 5 Walk (Trot, Canter) during free movement; Walk R (Trot R, Canter R) 5 Walk (Trot, Canter) under rider. Levels of significance: ***P , 0.001, **P , 0.01, *P , 0.05, 1P , 0.10. of sires, with BV correlations 20.24 to 0.26 (S1) and 20.20 and Rideability (P , 0.01), and sires with RBV .110 for TTP in to 0.16 (S2) in the foal data and 20.27 to 0.43 (S1) and foals had .5 points lower mean RBV for Walk, FLimb, HLimb, 20.41 to 0.39 (S2) in the mare data. Although BV correla- Walk R, Trot R and Rideability (P , 0.01). In the sires with RBV tions were generally lower for IMB and TTP in foals than for .110 for IMB and TTP in mares, mean RBV for SBI traits ranged IMB and TTP in mares, very similar correlation coefficients between 93.2 and 98.7 and mean RBV for MPT traits ranged were determined for FLimb (IMB and TTP in S1, r 5 0.22 to between 89.0 and 114.1. When compared with the sires with 0.26), Frame (IMB in S1, r 5 0.24) and Jumping (IMB and RBV ,90 for IMB and TTP in mares, their mean RBV for TTP in S1, r 520.17 to 20.27). Significantly, positive BV Jumping were by 19.8 to 23.7 points higher (P , 0.001). How- correlations of r . 0.3 with IMB and TTP in mares were ever, their mean RBV for all SBI traits and all MPT traits except found for ImpEl, Walk F, Walk R, Trot F, Trot R and Rideability. Jumping were by 7.6 to 22.8 points lower (P , 0.01). Mean RBV for SBI and MPT traits by classes of RBV for DME traits in the 1086 sires with offspring in the DME data are given Discussion in Table 6. In the sires with RBV .110 for IMB and TTP in foals mean RBV for SBI traits ranged between 96.9 and 102.9 and Data for this study originated from DME of warmblood foals mean RBV for MPT traits ranged between 92.2 and 110.3. When and mares, SBI and MPT. DME and SBI data were collected in compared with the sires with RBV ,90 for IMB and TTP in foals, two subsequent years, 2009 and 2010, under stable evaluation their mean RBV for Canter R and Jumping were by 3.7 to 10.8 conditions and by the same teams of judges, resulting in com- points higher (P , 0.01). However, sires with RBV .110 for IMB pleteDMEinformationon3374foalsand2844maresand in foals had .5 points lower mean RBV for Walk, Frame, Walk F complete SBI information on 1987 mares. In contrast, the MPT

17 Becker, Stock and Distl

Table 6 Means of RBV for conformation and performance traits from SBI and MPT by classes of RBV for unfavorable movement characteristics in 1086 sires with offspring among the foals (n 5 3724) and mares (n 5 2844) with DME Foals Mares

SBI or MPT trait DME trait ,90 90 to 110 .110 ,90 90 to 110 .110

Walk IMB 102.97a 101.34a 96.95b 112.05a 100.41b 94.63c TTP 103.98a 100.97ab 98.27b 112.89a 100.84b 94.09c CorrG IMB 102.12a 100.93a 102.89a 109.49a 101.15b 96.23c TTP 100.34a 101.37a 102.76a 110.26a 101.33b 96.22c ImpEl IMB 105.06a 101.04b 100.33b 115.99a 100.55b 94.74c TTP 102.83a 101.59a 100.91a 118.59a 100.27b 95.76c FLimb IMB 102.32a 100.28ab 97.59b 109.42a 100.25b 93.20c TTP 105.35a 99.85b 97.30b 108.57a 100.77b 93.33c HLimb IMB 101.82a 101.99a 97.29b 110.06a 100.46b 97.54c TTP 105.21a 101.41b 96.87c 109.38a 101.40b 95.79c Frame IMB 108.24a 100.11b 99.83b 113.57a 99.83b 98.63b TTP 103.93a 101.12a 101.21a 113.31a 100.20b 98.72b Walk F IMB 99.17a 100.21a 93.35b 107.48a 99.19b 91.90c TTP 97.65ab 100.26a 94.66ab 110.55a 99.14b 91.45c Walk R IMB 98.35a 100.20a 95.00b 109.04a 99.46b 90.14c TTP 100.49a 99.84a 94.37b 110.37a 99.83b 89.61c Trot F IMB 102.28a 100.70ab 98.23b 109.91a 99.37b 98.14b TTP 100.96a 101.06a 98.32a 112.32a 98.70b 99.82b Trot R IMB 100.63a 100.27a 97.64a 109.91a 100.15b 91.53c TTP 101.93a 100.22a 96.83b 113.09a 100.17b 90.98c Canter F IMB 100.88a 100.34a 102.57a 107.87a 99.41b 100.24b TTP 99.27a 100.60ab 102.93b 110.02a 98.73b 101.80c Canter R IMB 99.16a 99.88a 104.31b 109.99a 99.29b 97.03b TTP 98.98a 100.19ab 102.70b 112.81a 98.73a 98.19b Rideability IMB 99.83a 98.90a 92.21b 107.74a 98.55b 88.96c TTP 99.60a 98.85a 93.18b 110.06a 98.45b 89.41c Jumping IMB 99.50a 98.64a 110.33b 93.44a 98.52b 113.25c TTP 101.23a 98.34b 109.78c 90.43a 98.33b 114.11c

RBV 5 relative breeding values; SBI 5 studbook inspections; MPT 5 mare performance tests; DME 5 detailed movement evaluations; IMB 5 indications of imbalance; TTP 5 irregular tail tone and/or posture; CorrG 5 correctness of gaits; ImpEl 5 impetus and elasticity; FLimb (HLimb) 5 front (hind) limb conformation; Walk F (Trot F, Canter F) 5 Walk (Trot, Canter) during free movement; Walk R (Trot R, Canter R) 5 Walk (Trot, Canter) under rider. Standardization of RBV for all traits such that larger RBV indicate favorable genetic dispositions; significant differences (P , 0.05) between mean RBV are indicated by different superscript letters. data were collected over a longer time period (2000 to 2008) in mares presented in the regular breeding events used for DME. which some minor changes of performance evaluations and Signs corresponding to TTP may occur as accompanying find- score documentation had been made. To avoid bias of corre- ings in horses with clinically manifest ataxia, for example, in the lation estimates caused by reference to genetically hetero- context of the Wobbler syndrome. In our study, we found other geneous traits (Becker et al., 2011a), only the traits with and more severe IMB (HM, GM) in about every fourth horse maximum and uniform specificity of recording were included with tail irregularities (TTP) and estimated significantly positive in this study. Accordingly, the numbers of informative mares genetic correlations between TTP, HM and GM in foals and differed between the MPT traits and ranged from 896 for Walk mares (Becker et al., 2011b). Therefore, only the comprehensive F over 1779 for the other gait traits (Walk R, Trot F, Trot R, DME trait, IMB and the most prevalent DME trait, TTP, were Canter F, Canter R) to 2749 for Rideability and Jumping. included in the extensive genetic correlation analyses with the Specific documentation of movement characteristics dur- standard traits from SBI and MPT. ing DME made it possible to distinguish not only between In the warmblood horse, subjective scoring on a scale horses without and with IMB, but also between horses from 1 to 10 has been and is still the most common method without and with certain kinds of imbalanced movement. of conformation and performance evaluation. Although Signs corresponding to HM and GM are considered indicative of slight differences in the trait definitions may exist between impaired balance and coordination of horses of different ages the breeding organizations, the standard set of traits eval- (Van Biervliet, 2007). However, the prevalences of these more uated in SBI and MPT has been unchanged in Germany for at severe IMB findings were very low in the warmblood foals and least two decades. In previous population, genetic studies on

18 Correlation analyses of new movement traits conformation and performance in the German warmblood, MPT. Given the focus of DME on the unfavorable movement Hanoverian SBI and MPT data from 1995 to 2004 had been characteristics, the genetic correlations with the standard SBI used (Stock and Distl, 2006 and 2007). Despite the much and MPT traits were supposed to indicate whether or not larger numbers of informative mares (20 768 mares with SBI, selection based on these standard traits is suitable to reduce or 10 935 mares with 1-day field test of MPT) and somewhat at least avoid increase of the prevalences of IMB. different score distributions (0.19 to 0.98 higher means of In the analyses of variance, for which mares with DME and SBI scores; 0.09 to 0.33 lower means of MPT scores for all SBI records (n 5 605) and mares with DME and MPT records gaits and rideability, 0.13 higher mean of MPT score for (n 5 471) were considered, we found significant differences in Jumping), the heritability estimates were very similar to scoring of the mares without and with IMB, using compre- those found in this study: the lowest heritabilities of about hensive and specific definitions of the DME traits (IMB v. TTP, 0.1 were found for FLimb, HLimb and CorrG (h2 5 0.09 to HM, GM). However, the most consistent results were obtained 0.12; Stock and Distl, 2006), whereas heritabilities for the for the SBI trait Dev, and only the mares with more severe signs other movement-related traits were in the order of 0.3 to 0.4 of impaired balance (HM, GM) were scored significantly worse (h2 5 0.25 to 0.39 for Walk and ImpEl from SBI and Walk R, in Walk and ImpEl. Absence of significant differences in the SBI Trot R, Canter R, Rideability and Jumping form MPT; Stock trait CorrG and in most of the MPT traits and the tendency to and Distl, 2006 and 2007). According to the literature, neither even higher scoring of IMB-positive mares in MPT trait Trot breed nor evaluation age seemed to have major influence R indicate that the current definitions of gait traits do not cope on the heritabilities of subjectively scored conformation and with all movement characteristics seen in the presented mares. performance traits: recent reports refer to the same traits Owing to the data structure, the time period between DME and asevaluatedinGermanSBIandMPT,analyzedinasampleof MPT was larger than between DME and SBI, and MPT partici- 783 3- to 4-year-old mares from the Hungarian pation preceded DME in all mares, and thus IMB may not have population (h2 5 0.2to0.5;Postaet al., 2010) and to more been visible at MPT in all mares that were later identified as generallydefinedconformationtraitsanalyzedin8391juvenile IMB positive (n 5 11). However, phenotype distributions with Finnhorses and Standardbreds (age range of 7 to 45 months, respect to DME and SBI are unlikely to be influenced by some h2 5 0.1 to 0.5; Schroderus and Ojala, 2010) and 3695 time gap, because mares were usually identified as IMB posi- warmblood foals (h2 5 0.45 to 0.49; Bhatnagar et al., 2011). tive (n 5 88) at the same events as they were scored for SBI. Furthermore, for Finnhorse and Standardbred trotters, it has Studies on the development of equine locomotion pattern been shown that subjectively scored conformation traits are with age have revealed that certain kinematic characteristics moderately heritable in foals (h2 5 0.1 to 0.5) and mares remain remarkably stable over time and that intralimb (h2 5 0.1 to 0.8) and additive genetic correlations of 0.6 to coordination pattern are already established at foal age 1.0 between analogous foal and mare traits imply benefits (Back et al., 1994). These findings are in line with the sig- from using foal data as an early source of information nificantly positive genetic correlations we had previously (Suontama et al., 2011). found between analogously defined DME traits in foals and The valuating scoring of vaguely defined traits and the mares (Becker et al., 2011b). DME information on foals and unsatisfactory use of the full score scales are well-known mares was therefore included in the genetic correlation problems in horse breeding, interfering with clear distinction analyses, with separate trait definition within age group. In between individuals with regard to conformation and per- the multivariate estimations of genetic parameters, the formance characteristics (Stock and Distl, 2006 and 2007; phenotypic correlations with SBI and MPT traits were much Bhatnagar et al., 2011). To better capture the variability in lower (20.03 to 10.05 for IMB and TTP in foals, 20.09 to the population, splitting up of the standard traits and 10.11 for IMB and TTP in mares) than the additive genetic descriptive scoring on linear scales have been recommended correlations (20.17 to 10.86 for IMB and TTP in foals, 21.00 and studied, but introduced by just very few horse breeding to 11.00 for IMB and TTP in mares). In this connection, it has to organizations yet: in 1989 in the Royal Warmblood Studbook be taken into account that compared with the standard SBI and of the Netherlands (KWPN; Koenen et al., 1995) and in 2003 MPT traits (observed score ranges from 3 to 10), the additive in the studbook of the Belgian warmblood horse (BWP; genetic variances of the binary coded, new movement traits Rustin et al., 2009). The additional efforts of refined evaluation from DME were very small, interfering with reliable estimation were justified by the expected increase of heritabilities and the of variance–covariance matrices (Becker et al., 2011b). improved information basis to make selection decisions. After To overcome the problem of low reliabilities of additive the first 5 years of linear scoring in the BWP, phenotype dis- genetic correlation estimates, univariately predicted BV were tributions implied the need for further consolidation of the used for further correlation analyses. Significantly, positive newly established system. However, mean heritability over 33 BV correlations were determined between IMB and TTP on linear type traits and gaits was 0.32 in a sample of 987 mares, the one hand and dressage-related standard traits from SBI with h2 5 0.15 to 0.55 for 27 type traits and h2 5 0.33 to 0.52 and MPT, particularly when referring to the DME traits in for six gait traits (Rustin et al., 2009). mares. After uniform standardization, analyses of RBV fur- In this study, we used DME to support rather than replace ther illustrated the unfavorable genetic correlations between the routine evaluations of foals and mares, and performed the DME traits and conformation and between DME traits correlation analyses combining information from DME, SBI and and dressage-related performance. Selection of dressage

19 Becker, Stock and Distl horses for better scores in SBI and MPT and without con- frame (facilitating swinging of the back) with a relatively short sideration of DME information will therefore bear the risk neck (facilitating elevation), may in connection with the apti- of increasing prevalences of IMB in future generations. tude to move with much expression overstrain the mechanisms According to our results, there is no such risk in the selection of coordination. In contrast, horses bred for show jumping of horses for better jumping performance: the BV correla- are less homogeneous with regard to conformation and move tions were significantly negative and the RBV distributions economically rather than expressively, particularly in trot. were parallel for the DME traits and the MPT trait Jumping. Accordingly, the probability to develop and show IMB may be Although this is the first study on genetic correlations with increasedinhorsesbredfordressage performance and may unfavorable movement characteristics considered indicative further increase with continuing selection with the focus on for impaired balance, the available literature on equine impressive movement. locomotion, conformation and performance provides data Given the positive genetic correlations we found between that agree with our results (Saastamoinen and Barrey, 2000). dressage and unfavorable movement characteristics, extension Selection for proportionate conformation without major of DME may be recommended to enable considering unfavor- conformational defects is being practiced with different inten- able movement characteristicswhenmakingbreedingdeci- sities and focuses in most horse populations, from racehorses sions. Warmblood riding horses showing IMB during free and trotters over draught horses to riding horses (Ducro et al., movement may not necessarily perform worse under rider than 2009a; Viklund et al., 2010). Biokinematics help to explain why unaffected horses at young age. However, long-term effects of certain conformational characteristics are more likely to be these conditions in warmblood riding horses are unknown so found in successful dressage horses than in the average far. DME data collected in foals and mares will provide a sui- population (Holmstro¨m et al., 1990 and 1995). Positive pheno- table basis for further correlation analyses between unfavorable typic and genetic correlations of frame, front and hind limb movement characteristics and performance on different levels conformation with dressage abilities have been reported and in different disciplines of sports. (Holmstro¨m et al., 1990 and 1995; Holmstro¨m and Philipsson, 1993; Ducro et al., 2009a and 2009b; Rustin et al., 2009), Acknowledgements whereas correlations between conformation and show jumping performance appeared to be less clear and partly opposite to The authors thank the Oldenburg horse breeding society for those found between conformation and dressage (Holmstro¨m substantial support and valuable discussions helping to improve et al., 1990; Ducro et al., 2009a and 2009b). For the DME traits the paper. reflecting unfavorable movement characteristics, we also obtained clearly different results for Jumping on the one hand References and dressage-related traits on the other hand. Negative genetic Back W, Barneveld A, Schamhardt HC, Bruin G and Hartman W 1994. Longitudinal correlations with Jumping indicated that IMB and TTP were less development of the kinematics of 4-, 10-, 18- and 26-month-old Dutch Warmblood likely to be transmitted by horses with high genetic potential for horses. Equine Veterinary Journal Supplements 26 (suppl. 38), 3–6. good jumping performance. The opposite was true for horses Becker A-C, Stock KF and Distl O 2011a. Genetic correlations between free movement and movement under rider in performance tests of German with high genetic potential for good dressage performance, warmblood horses. Livestock Science 142, 245–252. that is, high probability to receive above-average scores for Becker A-C, Stock KF and Distl O 2011b. Genetic analyses of movement traits FLimb, HLimb, Frame and gait traits in SBI and MPT. Obvious derived from detailed evaluations of warmblood foals and mares. Journal of differences between the relations of balance in movement with Animal Breeding and Genetics, doi:10.1111/j.1439-0388.2011.00980.x. dressage-related traits and with jumping-related traits have Bhatnagar AS, Lewis RM, Notter DR, Schacht C and Splan RK 2011. Genetic parameters of foal inspection scores for two North American sporthorse also been reported for the Dutch warmblood. On the basis of registries. Livestock Science 140, 88–94. first stallion inspections of the KWPN, balance was positively Van Biervliet J 2007. An evidence-based approach to clinical questions in the correlated with walk (rg 5 0.79) and trot (rg 5 0.88) during free practice of equine neurology. Veterinary Clinics of the North American Equine movement, but genetically uncorrelated with takeoff, technique Practitioners 23, 317–328. and power during free-jumping (r 520.02 to 20.09; Ducro Dimock W 1950. Wobbles, an hereditary disease in horses. Journal of Heredity g 41, 319–323. et al., 2007). Dimock W and Errington EJ 1939. Incoordination of , ‘‘Wobbles’’. Journal Significant phenotypic correlations exist between mor- of the American Veterinary Medical Association 95, 261–267. phometric and kinematic measures of the equine back, Ducro BJ, Koenen EPC, Van Tartwijk JMFM and Van Arendonk JAM 2007. indicating increase of lateral bending with increasing length Genetic relations of first stallion inspection traits with dressage and show- of the back, particularly in the thoracic part (Johnston et al., jumping performance in competition of Dutch Warmblood horses. Livestock Science 107, 81–85. 2002). Because of the fundamental role of the equine back Ducro BJ, Bovenhuis H and Back W 2009a. Heritability of foot conformation and for locomotion, any structural and functional changes in the its relationship to sports performance in a Dutch Warmblood horse population. back are likely to affect the general motion pattern of the Equine Veterinary Journal 41, 139–143. horse, including its coordination abilities (Van Weeren et al., Ducro BJ, Gorissen B, van Eldik P and Back W 2009b. Influence of foot 2010). The results of this study may be interpreted as a hint conformation on duration of competitive life in a Dutch Warmblood horse population. Equine Veterinary Journal 41, 144–148. towards some limit of balancing capacities, which may have Groeneveld E 1990. PEST User’s Manual. Institute for Animal Science and been reached in dressage horse breeding. Conformational Animal Husbandry, Federal Agricultural Research Centre (Bundesforschungsan- characteristics favorable for a dressage horse, like a rectangle stalt fu¨ r Landwirtschaft, FAL), Mariensee/Neustadt, Germany.

20 Correlation analyses of new movement traits

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