Anna Näsholm

Genetic parameters for traits at performance test of stallions and correlations with traits at progeny tests in Swedish warmblood horses.

Abstract Genetic parameters for traits evaluated in the Swedish stallion performance test (SPT) and correlations between stallion performance test traits and 4-year-old offspring results from field tests were estimated. Heritability coefficients were on average 0.40 for individual gaits under rider and 0.23–0.47 for jumping traits at SPTs. Repeatabilities between tests at 6-month intervals were 0.75–0.77 for gaits and 0.38–0.58 for jumping traits. The genetic correlation between the gaits ranged from 0.30 to 0.71. Positive genetic correlations were found between gaits under rider and jumping traits (0.14–0.54), thus breeding for both characteristics is facilitated. Free jumping results were highly correlated (0.93) to results in jumping under rider, and because of their higher heritability the former are very suitable for selection purposes. Genetic correlation estimates between a trait in SPT and the same trait at 4-year-old offspring field test were unity for gaits under rider and jumping. The genetic correlations between gaits and jumping at the two different tests were 0.26–0.35. It was concluded that the field tests are well suited for early progeny testing of the stallions, and will improve the accuracy in selection of stallions for performance traits.

Genetic variation in competition traits at different ages and time periods and correlations with traits at field tests of 4-year-old Swedish Warmblood horses.

For many years, the breeding value estimation for Swedish riding horses has been based on results from Riding Horse Quality Tests (RHQTs) of 4-year-olds only. Traits tested are conformation, gaits and jumping ability. An integrated index including competition results is under development to both get as reliable proofs as possible and increases the credibility of the indexes among breeders, trainers and riders. The objectives of this study were to investigate the suitability of competition data for use in genetic evaluations of horses and to examine how well young horse performance agrees with performance later in life. Competition results in dressage and show jumping for almost 40 000 horses from the beginning of the 1960s until 2006 were available. For RHQT data of 14 000 horses judged between 1988 and 2007 were used. Genetic parameters were estimated for accumulated competition results defined for different age groups (4 to 6 years of age, 4 to 9 years of age and lifetime), and for different birth year groups. Genetic correlations were estimated between results at RHQT and competitions with a multi-trait animal model. Heritabilities were higher for show jumping than dressage and increased with increasing age of the horse and amount of information. For dressage, heritabilities increased from 0.11 for the youngest group to 0.16 for lifetime results. For show jumping corresponding values increased from 0.24 to 0.28. Genetic correlations between competition results for the different age groups were highly positive (0.84 to 1.00), as were those between jumping traits at RHQT and competition results in show jumping (0.87 to 0.89). For dressage-related traits as 4-year-old and dressage competition results the estimated genetic correlations were between 0.47 and 0.77. We suggest that lifetime results from competitions should be integrated into the genetic evaluation system. However, genetic parameters showed that traits had changed during the over 35-year period covered due to the development of the sport, which needs to be considered in future genetic evaluations.

Genetic parameters for traits evaluated at field tests of 3- and 4-year-old Swedish Warmblood horses.

There are two types of 1-day field tests available for young Swedish Warmblood sport horses; one test for 3-year olds and one more advanced test for 4-year olds. Conformation, gaits and jumping ability are evaluated at both tests. Studies on various genetic parameters were based on about 20 000 tested horses. The data for 4-year olds consisted of 30 years of testing. The aims of the study were to estimate genetic parameters for results from different time periods, and to estimate heritabilities for, and genetic correlations between, traits scored in the two tests. The judgement of traits was shown to have been changed during the 30 years of testing, resulting in changes in higher heritabilities in, and stronger genetic correlations between, later time periods. In the first time period, records showed higher residual and lower genetic variances than in the subsequent time periods. Genetic correlations between traits recorded in the first and last time period deviated considerably from unity. Further studies are needed to investigate how to treat data from the early period in genetic evaluations. Heritabilities were moderate to high for conformation traits (0.24 to 0.58) at both types of tests, except for correctness of legs (0.08). The heritabilities for gait traits were also moderate to high (0.37 to 0.53). For jumping traits, the heritabilities ranged between 0.17 and 0.33. The highly positive genetic correlations (0.82 to 0.99) between corresponding traits tested at the simpler test for 3-year olds and at the ridden test of 4-year olds implied that it would be desirable to include the test results of 3-year olds into the genetic evaluation as breeding values for Swedish Warmbloods for many years has only been based on results from 4-year olds.

Genetic analyses of field-recorded growth and carcass traits for Swedish beef cattle

Abstract To investigate the possibility of using carcass data from commercial slaughterhouses for the genetic evaluation of beef cattle, genetic parameters for carcass traits and their correlations with field-recorded growth traits were estimated. The data comprised information on carcass weight (CWT), carcass fleshiness (FLESH) and carcass fatness grade (FAT) according to the (S)EUROP scale for 5870, 1509 and 1119 young bulls of the Charolais, Hereford and Simmental breeds, respectively. In addition, information on field-recorded pre-weaning gain (WG) and post-weaning gain (PWG) was available for more than 23 200 and 15 700 bulls, respectively. The breeds were analysed separately using BLUP animal models. The results showed that it is feasible to include field-recorded carcass traits in the genetic evaluation. The estimated direct heritabilities of FLESH, FAT, CWT, WG and PWG were in the ranges 0.21–0.39, 0.23–0.45, 0.42–0.70, 0.31–0.41 and 0.29–0.42, respectively. The genetic correlations differed between breeds, though for all breeds studied the genetic correlations with pre-weaning gain were weaker for FAT and FLESH than for CWT. The effect of selection on pre-weaning gain appeared to be stronger for CWT than for the other traits.

Genetic parameters for carcass cut weight in Irish beef cattle.

The objective of this study was to estimate genetic parameters for the weights of different wholesale cuts, using an experimental and a commercial data set. The experimental and commercial data sets included 413 and 635 crossbred Belgian Blue, Charolais, Limousin, Angus, Holstein, and Simmental animals, respectively. Univariate analyses using a mixed linear animal model with relationships were undertaken to estimate the heritability of cold carcass weight, carcass conformation and fat, and the cut weights, whereas a series of bivariate analyses was used to estimate the phenotypic and genetic correlations between carcass weight, carcass conformation, carcass fat, and the major primal cuts. Heritability estimates for cold carcass weight in both data sets were moderate (>0.48), whereas heritability estimates for carcass conformation and fat grading were greater in the commercial data set (>0.63) than in the experimental study (>0.33). Across both data sets, heritability estimates for wholesale cut weight in the forequarter varied from 0.03 to 0.79, whereas heritability estimates of carcass cut weight in the hindquarter varied from 0.14 to 0.86. Heritability estimates for cut weights expressed as a proportion of the entire carcass weight varied from 0.04 to 0.91. Genetic correlations were strong among the different carcass cut weights within the experimental and the commercial studies. Genetic correlations between the weights of selected carcass cuts and carcass weight were moderate to high (minimum 0.45; maximum 0.88) in both data sets. Positive genetic correlations were observed in the commercial data set between the different wholesale cut weights and carcass conformation, whereas these were positive and negative in the experimental data set. Selection for increased carcass weight will, on average, increase the weight of each cut. However, the genetic correlations were less than unity, suggesting a benefit of more direct selection on high value cuts.

Influence of sex on genetic expressions and variance of 4-month weight of Swedish lambs

Abstract Influence of sex on 4-month weight was studied on lambs in the Swedish Sheep Recording Scheme (SSRS). Correlations between genetic expressions in the sexes were of interest and 4-month weight was analysed as a different trait in female and male lambs. Data included two sets of breeds, the so-called white breeds (Swedish landrace breeds, Texel, Dorset, Oxford down, Suffolk, East Friesian milk sheep, and Swedish crossbred; (23,985 observations) and the Gotland breed (35,891 observations)). Phenotypic variances were lower for females than for males. Estimates of direct heritabilities (0.14–0.24) were higher, whereas maternal heritabilities (0.07–0.18) were lower for females. Negative genetic correlations between direct and maternal effects (−0.45 to −0.19) were more pronounced for males. The results indicate heterogeneity of both genetic and environmental variances by sex. Interactions between sex and lamb age on weight were also shown. Genetic correlations between direct effects on the female and male traits, respectively, and the corresponding correlations between maternal effects were high (0.89–0.99). It is concluded that the observed heterogeneity in variance due to sex could be accounted for in the genetic evaluations by treating 4-month weight as a different trait in female and male lambs.

Associations of health status and conformation with longevity and lifetime competition performance in young Swedish Warmblood riding horses: 8,238 cases (1983-2005).

OBJECTIVE To determine associations of health status and conformation with competition longevity and lifetime performance in young Swedish Warmblood riding horses. DESIGN Cohort study and genetic analysis. ANIMALS 8,238 horses. PROCEDURES Horses were examined for health, conformation, and performance from 1983 to 2005, when they were 4 to 5 years old, and competition results from 1983 to 2012 were evaluated. Associations between conformation, health, and talent scores of young horses and longevity (years in competition) and lifetime performance were analyzed. Odds ratios of competing later in life among horses with joint flexion test reactions were determined. Genetic correlations between young horse health, conformation, and talent scores and longevity and lifetime performance were determined. RESULTS Good overall 4- to 5-year-old health, conformation, and talent scores for performance were phenotypically and genetically associated with greater longevity and lifetime performance. Good health was genetically correlated (rg = 0.3) to longevity and lifetime performance. Among conformation traits, body type and movements in the trot were most strongly associated with future longevity; these were genetically correlated (rg = 0.2 to 0.3) to longevity and lifetime performance. Intermediate-sized horses were associated with highest longevity and lifetime performance. Positive flexion test results were associated with lower ORs (OR, 0.59 for moderate to severe and 0.76 for minor reactions) of competing later in life, compared with no reaction, and were associated with lower longevity (0.4 years). CONCLUSIONS AND CLINICAL RELEVANCE Horses with good health and conformation at a young age had better longevity in competitions than the mean. Positive correlations suggested that improvement of health and conformation of young horses will enhance their future athletic talent and performance.

Prevalence of clinical findings at examinations of young Swedish warmblood ridinghorses

BackgroundSoundness of an individual horse is important for animal welfare and ownereconomy. However, knowledge of health status in normal horse populations islimited due to lack of systematic health recordings. The aim of theinvestigation was to study the prevalence of veterinary clinical findings in4-5-year-old Swedish warmblood riding horses, and their influence on overallhealth scores, where associations to future longevity has beenindicated.ResultsThe prevalence of clinical findings in 8,281 horses examined during1983–2005 was studied according to a standardised protocol and relatedto overall health scores in linear statistical models. Effects of sex, age,examination event and changes over time were included. In total, 49% of thehorses had clinical findings of medical health (MED), 42% in hooves (HOOF)and 74% of palpatory orthopaedic health (PALP). However, only 6%, 3% and 24%had moderate or severe findings, of MED, HOOF and PALP, respectively.Flexion test reactions were reported in 21% of the horses (5%moderate/severe), heavily influencing the overall score (H2). One fifth ofthese horses also had findings of unprovoked lameness while 83% had PALPfindings (44% with moderate/severe findings). Acute clinical signs, i.e.heat or soreness, had a large influence on the H2 score but were rare,whereas more common clinical findings had smaller effects on overall health.Large variations in recorded health results were observed among events. Adecrease in findings has occurred since 1983, in particular for PALPfindings.ConclusionsResults of occurrence and relevance of evaluated clinical findings could beused for advice on preventive actions to keep horses sound, and possibly forbenchmarking, and genetic evaluation of health traits. The distinct effectof event on recorded clinical findings emphasises that further harmonisationof veterinary examinations are desirable.

Genetic analysis of post-weaning gain of Swedish beef cattle recorded under field conditions and at station performance testing

Abstract Field data comprising 74 581 records on post-weaning gain from the Swedish beef recording scheme were analysed together with station performance test results for 2117 bulls of the breeds Charolais, Hereford and Simmental. Single-trait and multiple-trait best linear unbiased prediction (BLUP) animal models were used. The breeds were analysed separately and male and female post-weaning gain were regarded as different traits. Estimated heritabilities for post-weaning gain under field conditions were 0.22–0.40 for males and 0.29–0.40 for females. For average daily gain of bull calves at station performance testing heritabilities were between 0.11 and 0.42. Genetic correlations with daily gain at the station testing for male and female post-weaning gain under field conditions were 0.90 and 0.80, respectively, for Charolais, 0.65 and 0.51 for Hereford, and 0.81 and 0.66 for Simmental. In conclusion, the BLUP animal model has proven to be very valuable for selection based on field data, while the added value of station performance testing is questioned.

Effects of long-time series of data on genetic evaluations for performance of Swedish Warmblood riding horses.

For Swedish Warmblood sport horses, breeding values (BVs) are predicted using a multiple-trait animal model with results from competitions and young horse performance tests. Data go back to the beginning of the 1970s, and earlier studies have indicated that some of the recorded traits have changed through the years. The objective of this study was to investigate the effects of including all performance data or excluding the older ones compared to a bivariate model (BM) considering performance traits in early and late periods as separate traits. The bivariate approach was assumed to give the most correct BVs for the actual breeding population. Competition results in dressage and show jumping for almost 40 000 horses until 2006 were available. For riding horse quality test (RHQT), data of 14 000 horses judged between 1973 and 2007 were used. Genetic correlations of 0.69 to 1.00 were estimated between traits recorded at different time periods (RHQT data) or different birth year groups (competition data). A cross-validation study and comparison of BVs using different sets of data showed that most accurate and similar results were obtained when BVs were predicted from either the BM or the univariate model including all data from the beginning of the recording. We recommend using all data and applying the univariate model to minimise the computational efforts for genetic evaluations and for provision of reliable BVs for as many horses as possible.