Research data show that the somatic cell count increases during the transition period when dairy cows are transferred from barns to pastures (month of May) and during the transition period when dairy cows are transferred from pasture to barn (month of October). During these period’s feedstuff composition changes, as does the temperature, microclimate parameters, which also have an influence on cows with Sub-clinical mastitis. Somatic cell counts are lowest in 1st lactation cows. 1st lactation cow somatic cell count in milk was 440,000 ± 66,400 cells/ml (2004) and 326,000 ± 55,500 cells/ ml (2005). Later lactation’s cow somatic cell counts in milk is higher, however the highest cow somatic cell count in milk is in 5th and upward lactations. Reproduction is usually evaluated during the span of the service period, taking into account the animal’s age at 1st parturition, its fertilisation index, timeframe between parturitions, and duration of pregnancy. These are important herd reproduction traits. Due to disorders in reproduction functions, costs of fertilisation increase and economic losses are sustained (Borman, 2006). The cow’s age at 1st parturition affects the heifer’s rate of maturity which also depends on the husbandry conditions and breed. During 2003 – 2004, the average age of 1st parturition Lithuanian Black/White breed cows was 26.7 - 32.6 months (Republic of Lithuania, Ministry of Agriculture, 2005). An early 1st parturition age (up to 23 months) is followed by a... [to full text]