Breeding value evaluation of Simmental cows by lifetime productivity depending on age of retirement and origin

The purpose of research is to study the variability of genetic assessments of cows of different origins for traits of lifelong milk production when varying the age of retirement in the population of Simmental cattle in Russia. The analyzed database included breeding cows of the Simmental breed that were retired in the period 2001-2020; the total number of livestock was 47,868 head. Calculation of the breeding value of productive longevity was carried out using the BLUPF90 program based on the BLUP Animal Model methodology. The share of Simmental cows of foreign selection that were eliminated after the 1st and 2nd lactations was 61.2 %, and those lactating longer than 6 lactations was only 4.0 %, while cows of Russian selection were 12.3 % less eliminated during the first two lactation and are able to produce longer. Phenotypic values of lifetime productivity in Simmental cows for an equal number of lactations are significantly higher in animals of foreign selection: from 824 kg of milk when leaving after the 1st lactation to 4,210 kg when leaving after the 10th lactation, from 35.3 to 188.5 kg by lifetime amount of fat and from 27.3 to 190.9 kg by lifetime amount of protein, respectively. The maximum estimates of breeding value for the lifetime productivity of a cow of foreign selection reach +115.7 kg of milk fat and +91.3 kg of milk protein for a productive life by the 7th lactation.In cows of Russian selection, the predicted maximum breeding value estimates are achieved by the 9th lactation with indicators of +111.0 kg of milk fat and +88.4 kg of milk protein during the period of productive use. Lifetime milk productivity is significantly higher in Simmental cows of imported origin (by +824...+4210 kg), as well as estimates of breeding value (by +27.5...+35.9 kg), however, domestic Simmentals had a longer use period - on average for 2 lactations.