1. The development of computer tools in animal science is specific due to biological background of livestock production where many exceptions are found during production process. It is hard to foresee all particularities in advance when new tools are designed, since they appear daily, especially with development of technologies. Internationally supported and synchronized development of information systems (ISs) in livestock production, based on open source development, resulted in the procedure which allows rapid creation of the IS for individual and specific tasks. All ISs constitute of mandatory tables, relations, and attributes. They have prepared scheme of different tables, relations and attributes which are used frequently. Database model is flexible and enables adding of specific items. Harmonized structure makes feasible upgrade by creation common or similar applications, like tools for analysis of population structure, data preparation for genetic evaluation, estimation of dispersion parameters or other statistical analyses; calculation of coancestry or inbreeding coefficients; analysis of production efficiency etc. 2. The statistical package VCE-5 represents one of the most used programs for analysis of dispersion parameters for selected samples. The VCE-5 is used for education, research, and development in animal breeding all over the world (more than 1000 sites). Beside all options of previous version, new modules for random-regression models for longitudinal measurements, as well as non-additive genetic effects in purebred and crossbred populations are developed. Additionally, it enables research of heterogeneity of (co)variances and includes elements for Bayesian approach. The package is developed in cooperation with strong international cooperation. This statistical tool enables geneticists and animal breeders research of (co)variance structure for many different situations in livestock breeding as well as in genetic diversity preservation. 3. Both research fields mentioned above are used for development of statistical models for genetic evaluation. In small ruminants, test-day model for test-day measurements was developed, which is now in use in Slovenia and Slovak Republic. Model was upgraded for growth in cattle and pigs where changes of breeding values and other random effects were modelled by random regression. The IS in such cases serves for data preparation only. Together with Croatian colleagues the IS for Croatian National Pig Breeding Scheme was established and data quality was analyzed. Statistical models for genetic evaluation of field test data and litter size in pigs were developed and validated. Random regression was used for modelling the litter size over parities. 4. Comprehensive scope dealt with slaughter traits and quality of animal products. Effects of genotype, growth, housing and feeding on physical, chemical, and sensoric traits of beef and poultry meat was studied. In poultry, free range rearing was compared with intensive indoor housing for presence of selenium and arsenic as well as for fat acids composition in eggs and meat. The double-regression approach was applied for calculation of prediction equation for lean meat percentage in pigs on slaughter line. Method was suitable for instrumental method (optical probe), but it failed for simple two-point caliper method. Regression equations were developed for determination of correction factors for calculation of daily milk yields and milk components from half-day milk samples (morning or evening milking).