Linear conformation traits in Latvian Blue cows in relation to possession to gene pool and discarding

Latvian Blue (LZ) cows are kept for a variety of herd colours and because of national cow breed value. Resources of LZ cow breed remained low over the last decade. The aim of the study was to evaluate LZ cow breed linear conformation traits and analyse results in relation to their possession to the gene pool (GF) status and productive lifetime in 2017−2018. Information of the Agriculture Data Centre Republic of Latvia (LDC) and linear evaluation in vivo were used. The number of LZ cows registered in LDC in 2017−2018 was 1648 and only 339 cows were gene-pool animals (LZ GF), and 140 of LZ GF animals were culled because of different reasons in 2017−2018. There were registered 544 (190 primiparous of them) closed standard LZ cow lactations in 2009 and only 292 (64 primiparous of them) in 2018. The oldest LZ GF cow was 16.3 years old; 20% of LZ GF cows were more than 10 years old, and only 10% were younger than 5 years. The overall exterior rating was established more than 80 points for 64.4% of the evaluated LZ GF cows. Some LZ GF linear conformation traits did not change significantly (p is greater than 0.05) with age – exterior, milking properties and cow’s temperament. Udder parameters, rump and foot angle became worse with animals advancing in age and could be improved by breeding. No statistically significant differences (p is greater than 0.05) were established regarding all parameters of conformation traits among LZ and LZ GF dairy cows except a tendency of larger body depth in LZ GF (p=0.054). In conclusion, the linear conformation traits of LZ cows, despite the presence of genetic influence of other breeds, do not differ significantly from the gene pool animals. Rump angle, udder and teat qualities became worse with age in LZ and LZ GF cows. Legs and hoofs were stable parameters inherited by the LZ offspring.