EN
Despite many genetic and environmental factors, the level of physical activity may be a very good indicator of the physiological (e.g. estrus, approaching parturition) or health status of cows. The aim of this study was to analyse the 24-hour walking activity of lactating cows as related to the milk yielded in particular milkings over two stages of lactation. Used were 41 cows in early lactation (group G1) and 54 cows in late lactation undergoing a gradual decline in milk production (group G2). Activity of animals was measured with activity meters and expressed in Alpro units (AU), version 6.5 by DeLaval. The cows were kept in a loose system in one common building and milked three times a day in a milking parlour. Two hours before morning and evening milking the G2 cows occurred more active than cows G1 (43 and 45 vs. 26 and 31 AU, respectively). From morning to noon milking the G1 cows showed significantly lower activity (33 AU) than G2 cows (40 AU). The highest positive significant correlation coefficients (r) were estimated for G1 cows between milk yield at noon and mean 24-hour activity, mean activity between morning and noon milking, and mean activity associated with partial mixed rations (PMR) intake between evening milking and first (morning) PMR feeding (r = 0.47-0.48). The r coefficients between investigated indicators were generally lower in G2 than in G1 cows.