Alena Svitáková

Genetic parameters of longevity for improving profitability of beef cattle

The objective of this study was to estimate genetic parameters for longevity and assess the suitability of using these selection criteria to improve the genetic merit of the beef cattle population of the Czech Republic. The performance record database, which contains records of 363,000 beef cattle animals of 19 breeds and their crosses, was used. The populations of Charolais and Aberdeen Angus were large enough that the genetic parameter estimations and all analyses were done for these breeds separately. Two similar approaches of longevity definition based on probabilities were considered as follows: productive longevity (PL), which is the number of calvings at target ages of 78, 90, 150, and 160 mo, and longevity (L), which is based on the probabilities of cow reappearance in the next parity. A multibreed single-trait animal model for L and a multitrait animal model for combinations of 78/150 and 90/160 mo for PL were used. Specific combinations of months were established based on the analysis and represented the critical culling rates in the studied population. The high genetic correlations (0.88-0.95) of the combination 90/160 suggested that the PL at 160 mo of age can be predicted on the basis of the value at 90 mo, which will make earlier selection possible. Combination 78/150 is less efficient in the Czech population of beef cattle due to the lower correlations (0.79-0.93) between traits. The estimated heritabilities were low for both traits (below 0.14), but the additive genetic variance was sufficient for identifying animals with high genetic merit.

Comparison of models to estimate genetic parameters for scores of competitive sport horse events in the Czech Republic

The objective of the present study was to estimate genetic parameters and predict breeding values of sport horses in the Czech Republic using animal model variations. The data set for the evaluation was com - posed of edited records of show jumping competitions in the Czech Republic in years 1991-2013. Input data were not normally distributed; hence Blom transformation was used for the variable filtration. The Gibbs sampling algorithm was used for the genetic parameters estimation. Two models were examined. The first was a random regression model including the effect of a horses experience in competition (expressed as the length of the horses sporting career in days), fixed effects of sex, age, and event, and random effects of rider, permanent environment, and animal. The second model was a multi-trait model with fixed effects for sex, age, and event and random effects for rider, permanent environment, and animal. In this latter case, horse performance was classified as three traits. The first trait was jumping results from obstacle heights of 90-110 cm, the second of 120-135 cm, and the third of 140-155 cm. In the random regression model, heritability estimates ranged from 0.01 to 0.11; whereas in the multi-trait model, heritabilities were 0.07, 0.11, and 0.14 for the first, second, and third trait, respectively. Results indicate that both models could be used to predict breeding values of sport horses in the Czech Republic. The multi-trait model revealed that heritability estimates increased with the increasing height of obstacle. In the random regression model, breeding values differed according to a horses experience in competition, allowing adjustment of the breeding value for the environmental effect of a past experience.

Variance components, heritability estimates, and breeding values for performance test traits in Old Kladruber horses

The Old Kladruber horse is an important Czech genetic resource. In the current study, two categories of traits were evaluated – the first, a numerical score for Type and Gender Expression and the second, 11 traits describing performance divided into four categories: (1) Rideability (Overall Impression, Rideability), (2) Gaits (Walk, Trot, Canter), (3) Carriage Drivability (Dressage Test, Obstacle Driving Test, Marathon Test), and (4) Reliability in Tug (First Tug, Second Tug, Third Tug). The original data set contained records from 700 individuals from the period 1995–2014, each horse having 3–5 performance evaluations for the suite of traits. Our objective was to identify a suitable model for the estimation of genetic parameters and prediction of breeding values. Only one model was examined for the Type and Gender Expression trait, whereas three models were compared for the analysis of each performance trait. Criteria for choosing the most appropriate model were minimal values for the deviance information criterion (DIC) statistics, low ratios of residual variance to phenotypic variance, and maximal heritability estimates. The heritability estimate for Type and Gender Expression was 0.18. For the performance traits, the model with the fewest sources of variation (model 1) was more appropriate than two alternatives with more sources of variation. Heritability estimates from this model ranged from 0.08 to 0.40, while estimates for various performance traits from the other models were in the range 0.08–0.24. Low heritabilities for several of the performance traits suggested that selection for their genetic improvement would likely be unsuccessful. In order to maintain genetic variability, inbreeding, and fitness in the Old Kladruber population we suggest to use breeding value estimation using the heritabilities and the method presented in this paper.

Effect of the FGF2 SNP11646 on milk production and fertility traits of Holstein cattle

Th e objective of this study was to estimate the eff ect of a single-nucleotide polymorphism (SNP11646) in the FGF2 (Fibroblast Growth Factor 2) gene on the deregressed proof of breeding values (DRP) of Holstein sires (n = 149) for milk traits (milk yield, fat yield and percentage, and protein yield and percentage) and fertility (relative breeding value for own fertility – conception rate of heifers, cows, all females inseminated by the sperm of the sire; relative breeding value for conception rate of daughters – heifers, cows, all females). Th e diff erences between genotypes for milk performance were not signifi cant. Th e lowest DRP for milk performance were found for AA sires. For fertility, sires with this genotype had the best values both for the maternal genetic eff ect (conception rate of the daughters) and for the direct genetic eff ect (fertility of the sire). For conception rate of the daughters, in some cases, the diff erences reached the threshold of signifi cance. Th us, the results indicate coincidently with other studies the potential opposing eff ects on milk performance and fertility. FGF2 SNP11646 is still of interest for future cattle breeding studies.