11 1RYHPEHU 2020, Brno, Czech Republic

Evaluating and comparing descendants of from the Dark Ronald line in Czech breeding according to basic body measurements

Zuzana Kubikova, Iva Jiskrova, Barbora Kubistova Department of Animal Breeding Mendel University in Brno Zemedelska 1, 613 00 Brno CZECH REPUBLIC [email protected]

Abstract: The aim of this study was to evaluate the influence of the Dark Ronald line in the breeding of the Czech Warmblood. To evaluate the importance of the line, the offspring of stallions authorized to act as stud in the breeding of the Czech Warmblood were used. The values of the basic body measurements of their offspring (SHW, THW, ChC and CBC) were used to evaluate the quality of the stallions. A total of 6 breeding stallions were compared: two representatives of the Holsteiner (2765 CASSILIUS, 2666 PORTER), one Russian Holsteiner (2782 BALLAST), one Slovak Warmblood (794 CORSÁR), one Dutch Warmblood (2745 OSCAR) and one representative of the Zweibrücker breed (662 CARBIDO). The group for comparison consisted of 284 offspring of the Czech Warmblood breed from these sires. Evaluation by the GLM model detected statistically significant differences between the basic body measurements of the individual groups of offspring. The influence of the dams on the basic body measurements of offspring was taken into account by a graphical comparison of the massiveness and boniness indices. It was found that the stallion 2782 BALLAST significantly affects the massiveness of his offspring, but the dam has a greater influence on boniness than the sire. Furthermore, it was found that mares are statistically significantly more massive than stallions, but that they have a smaller cannon bone circumference. It was found that the progeny of 2666 PORTER is the most balanced, while in other stallions it is highly variable, and the greatest, statistically significant influence of the sire can be observed in the stallion 2782 BALLAST. Key Words: stallion, offspring, line, Czech Warmblood

INTRODUCTION The main trend in contemporary is the production of high-quality athletes capable of the best possible performance. Breeders One of the main assessment criteria in horse breeding is sporting performance, and individual breeders’ associations try to respond to this demand in their breeding programmes (Czech Warmblood Horse Association 2017). The right choice of horses for breeding is therefore extremely important. Cross-breeding is used to correct the traits of certain breeds. This phenomenon can be seen relatively frequently in warmblood breeding, since the use of English stud horses to increase constitutional hardness is common. Unfortunately, however, this refinement also entails a negative aspect: the lightening of the frame, which is definitely not desirable for a (Dušek 2011). Sobotková and Oravcová (2014) state that the Czech Warmblood should be a noble, sound and easy-to-ride horse which is suitable for all FEI equestrian disciplines due to its character, temperament, stride and elastic movement and good health. At the same time, however, it should be suitable for recreational and carriage riding. An adult Czech Warmblood horse has a medium build with good lines, a solid foundation and no apparent defects or diseases of a genetic nature. The breed standard gives the range for stick height at withers as 161−167 cm for mares and 162−170 cm for stallions (Czech Warmblood Horse Breeders Association 2017). According to Dušek (2011), the variability of conformation in the Czech Warmblood has been affected by the relatively short period of improvement and the use of a large number of breeds. The aim of the current breeders’ association

116 11 1RYHPEHU 2020, Brno, Czech Republic should therefore be to place greater emphasis on the conformation of breeding stock. Individuals for breeding should be free of exterior defects, have a strong constitution and be in good health. Saastamoinen and Barrey (2000) say that the conformation plays an important role in the breeding programme of Horse Breeders Association to achieve better soundness and locomotion and thus, in practical selection, individuals with serious weaknesses and conformational defects should be culled. Dark Ronald was an English Thoroughbred stallion who was sold to the German stud in 1913 (Eurodressage 2020). Peters (2005) reports that Dark Ronald was a good racer but had far greater significance as a stud horse. Although he only physically stood in England and Germany, his influence has been global and he has influenced the breeding of many warmblood breeds. Dark Ronald was sired by Ronald and was the founder of one of the two Thoroughbred lines which have long dominated warmblood breeding in Germany. His Thoroughbred sons Son-in-Law and Dark Legend went on to play an important role in the pedigrees of showjumpers throughout Europe and North America (Birdsall 2017). According to Peters (2005), Dark Ronald had good conformation and a powerful frame, was well-muscled and was fairly low at the withers, which became typical of this line.

MATERIAL AND METHODS The underlying database was created from data provided on the website of the Association of Czech Warmblood Breeders. Six stud horses classified within the Dark Ronald line were selected and the relevant data on the stud horses and their offspring were collected. The database contains a total of 284 descendants, with the following data being recorded for each of them: name, year of birth, year of measuring, sex, sire’s data, and body measurements: stick height at withers (SHW), tape height at withers (THW), chest circumference (ChC) and cannon bone circumference (CBC). The database of descendants was created in the programme Microsoft Office Excel 2010. The data acquired were then statistically processed using the GLM linear model in the statistical programme Statistica. Each stud horse was assigned an internal identification number from 1 to 6 solely for the purposes of statistical processing. The effect of the sire, year of birth and sex on the values of the basic body measurements was observed. It was also necessary to separate sex numerically into groups 1 (stallions and geldings) and 2 (mares). In addition, hippometric indices were calculated: a massiveness index and a boniness index for offspring, sires and dams. The indices were subsequently graphically processed, compared and evaluated. Distribution of stud horses 1) 2765 CASSILIUS 2) 2782 BALLAST 3) 662 CARBIDO 4) 794 CORSÁR 5) 2666 PORTER 6) 2745 OSCAR Model equation: yijk = μ + pi + qj + rk +eijk where: yijk is the observed effect (SHW, THW, ChC and CBC) μ is the total average of the set pi is the fixed effect of the i-th group of sires (i = 1,…, 6) qj is the fixed effect of the j-th year of birth (j = 1,…, 20) rk is the fixed effect of the k-th sex (k = 1,2) eijk is the random effect Based on the results of the general linear model, the differences between values were established by subsequent testing using the Scheffe method. The test was conducted at a significance level of P ≤ 0.01.

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Hippometric indices Formula for the massiveness index: * 100 ChC SWH Formula for the boniness index: * 100 CBC SWH RESULTS AND DISCUSSION Table 1 Results of statistical significance of variance analysis by GLM Body Sire Year of birth Sex measurement SHW - * - ChC ** - ** CBC - - * Evaluation by the GLM model in Table 1 revealed high statistical significance of the observed effects of sire and sex for the basic body measurement of chest circumference. Another two statistically significant effects were noted with tape height at withers and cannon bone circumference. A highly significant influence of the sire could only be proven statistically in the case of chest circumference. This confirms that the transfer of sires’ phenotypic traits to offspring exhibits a degree of heritability, but according to these results it primarily affects massiveness. The effect of the year of birth emerged as statistically significant for the attribute SHW. This result can be explained by the fact that more descendants with an above-average stick height at withers were born in one of the year groups. The highly significant statistical result for the effect of sex on chest circumference can be rated very positively since the conformation of stallions and mares should be different. When assessing the influence of sex on cannon bone circumference, a statistically significant effect was recorded. Cannon bone circumference is an important breed attribute subject to Czech Warmblood standards. That is why the assessment and observation of this measurement is extremely important, as it indicates the strength of the skeleton, which is highly desirable. At present it is essential that stud horses with the ability to pass on a powerful frame to their offspring are included in breeding, as the influence of a wide range of different breeds in Czech Warmblood breeding has resulted in it becoming lighter, which is definitely undesirable for the breed. It can therefore be said that the importance of observing this attribute has been confirmed and statistically proven. Results of effect of sires on chest circumference Table 2 Results of comparison of stud horses according to offspring ChC by Scheffe testing No. of Average Name 662 Carbido 2666 Porter 2745 Oscar offspring ChC 2765 Cassilius 53 191.02 cm - - - 2782 Ballast 72 195.08 cm * * * 662 Carbido 50 190.44 cm - - - 794 Corsár 37 190.95 cm - - - 2666 Porter 50 189.58 cm - - - 2745 Oscar 22 188.68 cm - - - The evaluation by Scheffe subsequent testing in Table 2 showed that offspring by the stud horse 2782 Ballast have a statistically significantly higher chest circumference than offspring by the stallions 662 Carbido, 2666 Porter and 2745 Oscar. According to the average values, it can be stated that the group of offspring by 2782 Ballast achieves the highest value from the whole assessed set, with a difference of 6.4 cm compared to the group by 2745 Oscar, which has the lowest average group value. At the same time, the group by 2782 Ballast greatly surpasses the group of offspring with the second highest average value, that of 2765 Cassilius, the difference being 4.06 cm. Based on these results, it can be stated that offspring by the stud horse 2782 Ballast exhibit statistically significant massiveness, which is rated very positively. Furthermore, it was found that 86%

118 11 1RYHPEHU 2020, Brno, Czech Republic of the descendants of the stud horse 2782 Ballast had their measurements taken at the age of three, when they were entered in the stud book, as did 86% of the offspring by 2745 Oscar. With the stud horse 2666 Porter, as many as 90% of offspring were measured at three years old, and with offspring by 662 Carbido the figure was 74%. It can therefore be said that the age of measuring did not substantially affect the values of chest circumference in the observed set. Table 3 Results of comparison of effect of stud horses according to massiveness indices of sire, offspring and dams No. of % of offspring % of offspring % of dams greater Name offspring greater than sire greater than dams than sire 2765 Cassilius 53 45 39.6 64 2782 Ballast 72 33 54 27.7 662 Carbido 50 49 43 60.7 794 Corsár 37 72.9 48 86 2666 Porter 50 74 20 98 2745 Oscar 22 18 27 31 As is shown by Table 3 above, according to a comparison of the massiveness indices of the sires, offspring and dams, the sires have an influence on the massiveness of offspring only in the groups by 2782 Ballast and 2745 Oscar. The massiveness of the other groups is influenced more by the dams than the sires. It can therefore be said that the stud horse 2782 Ballast greatly influences the ChC measurement and related massiveness of his offspring. If we take into account the fact that offspring by 2745 Oscar have a statistically significantly smaller ChC than offspring by 2748 Ballast and at the same time this group achieves the smallest average values of all the groups, it is thus apparent that the dams mated with the stallion 2745 Oscar were of a lighter frame and less massive. Results of effect of sex on chest and cannon bone circumference Table 4 Results of comparison of sex by offspring ChC according to Scheffe testing Sex Number Average ChC Stallions Mares 270 192 cm ** Stallions 14 186 cm Table 4 shows that the mares have a statistically highly significantly larger chest circumference than the stallions. This can be regarded as desirable since the body of mares should in general be more capacious for breeding purposes. Baban et al. (2009) assert that a larger chest circumference together with a larger cannon bone circumference positively affects the length and speed of the stride. This is desirable in sport horses and, as Rustin et al. (2009) state, conformation and gaits are among the most important criteria for selecting horses for breeding. When comparing the average values of stallions with the obtained results of a study of stallions of Polish (Pietrzak et al. 2016), it was found that Czech warmbloods have an average of 4.49 cm smaller chest circumference. Table 5 Results of comparison of sex according to offspring CBC by Scheffe testing Sex Number Average CBC Mares Mares 270 20.65 cm Stallions 14 21.22 cm * From Table 5 it is clear that mares have a statistically significantly smaller cannon bone circumference than stallions. This can be rated very positively as stallions should have a more powerful conformation than mares and therefore the cannon bone circumference should also be larger. The average values can be regarded as very good since in both groups of sexes they meet the breed standard for the Czech Warmblood, which according to Czech Warmblood Horse Breeders Association (2017) is 19.5−22 for mares and 21−22.5 for stallions. Novotná et al. (2017) mention that there is a moderately high phenotypic correlation between refinement and cannon bone circumference.

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This is also confirmed by these results, as the more refined and lighter mares have a smaller cannon bone circumference than stallions, which should have clear secondary sex characteristics including a larger cannon bone circumference. In comparison with the stallions of the Polish Warmblood (Pietrzak et al. 2016), the stallions in the monitored group have a cannon bone circumference 0.21 cm smaller on average. Table 6 Results of comparison of effect of stud horses according to boniness indices of sire, offspring and dams % of offspring % of offspring % of dams greater Name No. of offspring greater than sire greater than dams than sire 2765 Cassilius 53 20.7 28 37.7 2782 Ballast 72 2.7 48.6 11 662 Carbido 50 18 70 12 794 Corsár 37 2.7 16 37.8 2666 Porter 50 52 30 72 2745 Oscar 22 77 50 81.8 When the boniness indices of sires, offspring and dams in Table 6 were compared, it was found that the stud horse 662 Carbido had the greatest influence on the boniness of his offspring. A total of 70% of offspring by this stallion achieve a greater boniness index than their dams and 18% even surpass the sires; with these offspring, the influence of the dam can be seen in three cases out of nine where the dams surpass the sires. Another stud horse that substantially influences the boniness of his offspring is 2782 Ballast. In this case we can see that 48.6% of the descendants have a greater boniness index than the dams, and only 11% of the dams have a greater index than the sire. At the other end of the scale, the stallions 2666 Porter and 2745 Oscar have the smallest influence on the boniness of their offspring. In the case of offspring by 2666 Porter, 72% of the dams and 52% of the descendants have a greater index than the sire, and 30% of the offspring even surpassed their dams. With the group by 2745 Oscar, the effect of the sire on the boniness index is even smaller. Nearly 82% of the dams and 77% of the descendants have a greater index than the sire, and as many as 50% of the offspring surpassed their dams. According to Černohorská et al. (2013), the influence of the sire line on the conformation of offspring has not been proven in rearing facilities for testing young horses. However, according to these results, it can be said that within the Dark Ronald line the stud horse 2782 Ballast has a statistically significant effect on the chest circumference, massiveness and boniness of his offspring in comparison with the other stud horses from the line.

CONCLUSION The aim of this work was to evaluate the influence of the Dark Ronald line in the breeding of the Czech Warmblood. With THW, no statistical significance of the observed effects was found. In the case of the attribute SHW, the effect of the year of birth is significant. With the measurement ChC, a statistically highly significantly larger chest circumference was demonstrated in offspring by 2782 Ballast than in the offspring of the stallions 662 Carbido, 2666 Porter and 2745 Oscar. The hippometric indices of massiveness and boniness revealed that the massiveness of offspring is mainly influenced by 2782 Ballast and 2745 Oscar and the boniness by 2782 Ballast and 662 Carbido. With CBC the effect of sex is significant: it was found that stallions have larger CBC than mares, which is rated very positively with regard to secondary sex characteristics. According to the results obtained, it can be said that within Czech Warmblood breeding the greatest influence on the conformation of offspring from the Dark Ronald line comes from the stud horse 2782 Ballast. This stud horse has not played an active role in breeding since 2011; nevertheless, he has left behind many high-quality mares and stud horses which breeders should continue to include in breeding, making use of their genotypic traits, which are also very well reflected in the phenotype of conformation.

REFERENCES Baban, M. et al. 2009. Phenotypic Correlations of Stride Traits and Body Measurements in Lipizzaner Stallions and Mares. Journal of Equine Veterinary Science, 29(7): 513–518.

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Birdsall, P. 2017. Sire Lines Of International Jumpers The Dark Ronald Line. Sporthorse-data Passionate about Pedigrees [Online]. Available at: https://sporthorse-data.com/articles/2017/01/01/sire- lines-international-jumpers-dark-ronald-line. [2020-07-27]. Czech Warmblood Horse Breeders Association, 2017. Řád plemenné knihy ČT. Svaz chovatelů českého teplokrevníka [Online]. Available at: http://www.schct.cz/cz/svaz/rad-pk.html. [2020-07-27]. Černohorská, H. et al. 2013. Analysis of lines and breeds of sires in the breeding of the Czech warmblood horses based on grading their off spring in rearing facilities for testing young horses (RFT). Acta Universitatis Agriculturae et Silviculturae Mendelianae Brunensis, 61(6): 1605–1612. Dušek, J. et al. 2011. Česká teplokrevná plemena. In Chov koní. Praha: Nakladatelství Brázda, pp. 114–115. Eurodressage, 2020. Dark Ronald xx, Not Origin Horse for Warmblood Fragile Foal Syndrome (WFFS) [Online]. Available at: https://www.eurodressage.com/2020/07/07/dark-ronald-xx-not-origin-horse- warmblood-fragile-foal-syndrome-wffs. [2020-07-27]. Novotná, A. et al. 2017. Estimation of genetic parameters for linear type traits in the population of sport horses in the Czech Republic. Livestock Science, 202(8): 1–6. Peters, A. 2005. Dark Ronald. Thoroughbred Heritage [Online]. Available at: https:// www.tbheritage.com/Portraits/DarkRonald.html. [2020-07-27]. Pietrzak, S. et al. 2016. Effect of some factors on performance value assessment of stallions during performance tests. Annals of Animal Science, 16(4): 1175–1184. Rustin, M. et al. 2009. Multi‐trait animal model estimation of genetic parameters for linear type and gait traits in the Belgian warmblood horse. Journal of Animal Breeding and Genetics, 126(5): 378–386. Saastamoinen, M., Barrey, E. 2000. Conformation, locomotion and physiological traits. In The Genetics of the Horse. Wallingford, UK: CABI, pp. 439–472. Sobotková, E., Oravcová, I. 2014. Czech Warmblood. Horse Husbandry [Online]. Available at: https://web2.mendelu.cz/af_291_projekty2/vseo/stranka.php?kod=487. [2020-08-03].

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