نوع مقاله : مقاله پژوهشی
نویسندگان
1 گروه علوم دامی، دانشکده کشاورزی، دانشگاه زنجان، زنجان. ایران.
2 گروه علوم دامی، دانشکده کشاورزی، دانشگاه زنجان، زنجان، ایران.
3 گروه علوم دامی، دانشکده کشاورزی، دانشگاه زنجان، زنجان. ایران
چکیده
کلیدواژه‌ها
موضوعات
عنوان مقاله [English]
نویسندگان [English]
Genetic evaluation of sport horses using various methods is commonly carried out in many countries, except for Iran. Accurate estimation of genetic parameters for functional traits in horses has always been a subject of interest among livestock breeders. The aim of this study was to investigate the genetic parameters of athletic performance traits in Iranian jumping horses. Traits include race completion time (RCT), rank at the end of the competition (REC), and number of errors in the competition (NEC). The study were conducted based on Equestrian Federation of Iran (FEI) athletic performance records of 1498 horses (10–23 years old). The genetic parameters were estimated by using Restricted Maximum Likelihood (REML) procedures and airemf90 software. The statistical model included fixed effects of birth year, sex, age, breed, height of obstacles, date/city, level of difficulty of the event and random effects of rider, permanent environment and an additive genetic effect. Heritability of RCT, REC and NEC traits were estimated 0.03, 0.11 and 0.09 and their repeatability were 0.16, 0.25 and 0.13, respectively. Genetic and phenotypic trends of RCT, REC and NEC traits were estimated -0.002, 0.0091, 0.0003 and -0.7057, 0.2575, -0.0807, respectively. According to this result, the performance traits are highly affected by environmental factors, especially the effect of the rider, but among the studied traits, selection based on rank traits can lead to more genetic progress. It can be concluded that we can apply these parameters to improve the genetic potential of show jumping performance records and design the appropriate breeding strategies for horse jumping population in Iran.
کلیدواژه‌ها [English]
Extended Abstract
Introduction
Genetic evaluation of sport horses using various methods is commonly carried out in many countries, except for Iran. Accurate estimation of genetic parameters of functional traits in horses has always been a subject of interest among livestock breeders. The aim of this study was to investigate the genetic parameters of athletic performance traits in Iranian sport horses. Traits include race completion time (RCT), rank at the end of the competition (REC), and a number of errors in the competition (NEC).
Materials and Methods
The study was conducted based on Equestrian Federation of Iran (FEI) athletic performance records of 1498 horses (10–23 years old). The statistical model included fixed effects of birth year, sex, age, breed, height of obstacles, date/city, level of difficulty of the event and random effects of rider, permanent environment and an additive genetic effect. Data were collected and adjusted using Excel software and R scripts. The quality controls were applied for performance records and horse with one records and races under 5 race horse for competition were excluded. CFC software was used to survey the structure of the pedigree. Fitting the appropriate model were applied by R software. Variance components and genetic parameters were estimated by the restricted maximum likelihood (REML) method for a single trait animal model using airemf90 software. Genetic trend is a compilation of average estimated breeding value (EBV) per generation and indicates the direction of genetic change across generations. It is often visualized in a curve and is useful to check whether there are exist the genetic progression or not due to a selection scecnario. The genetic trend in the racing traits were estimated by calculating the linear regression of average breeding values on birth years.
Results and discussion
Heritability of RCT, REC and NEC traits were 0.03, 0.11 and 0.09 and their repeatability were 0.16, 0.25 and 0.13, respectively. Genetic trends of RCT, REC and NEC traits were estimated -0.002, 0.0091, 0.0003 and phenotypic trends of RCT, REC and NEC traits were -0.7057, 0.2575, -0.0807, respectively. According to this result, sport performance traits are highly affected by environmental factors, especially by the effect of the rider, although, many environmental effects cannot be measured and included in the model. Among all traits, selection based on rank at the end of the competition (REC) can lead to more genetic gain. Differences between the results of this research compared to other researchers can be attributed to the data structure, pedigree, accuracy of the records, number of records, and applied statistical model.
Conclusion
Selection may be most efficient for the REC trait rather than other traits because of its estimated medium heritability. It is essential to estimate the breeding value of each animal to improve their genetic potential in competitions and appling in the Iranian sport horse breeding strategies. Despite the advances in the field of genetics and animal breeding genetic trend in sport horse performance is slow in Iran, It can be concluded that we can apply these parameters to improve the genetic potential of show jumping performance records and design the appropriate breeding strategies for horse jumping population in Iran.
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