摘要：Milkability traits have an increasing importance in modern cattle production, although they are the secondary selective trait. The machine milking of cows has indicated that there is no complete alignment between the machine and the animals, what lead to increasing duration of milking and disturbances in health of udder. Because of that, the aim of this study was to investigate the influence of the ordinal number of lactation and stage of lactation on milkability traits (amount of milk per milking (KMM), maximum milk flow rate (MPM), average milk flow rate (PPM), duration of the start of milk flow (tS500), duration of the ascending phase of milking (tUFM), duration of the plateau phase of milking (tPFM), duration of the descending phase of milking (tSFM), duration of the main phase of milking (tGFM)), and recommend the same for the selection work. The study was done on 322 Holstein cows in the period from the first to third lactation, arranged in three stages of lactation (the first of the 50-90 day, the second stage of the 91-135 day and a third of 136-180 day of lactation). The results showed that the ordinal number of lactation had a highly statistically significant influence (P<0.01) on KMM and MPM, and on the PPM and tGFM (P<0.05). Statistically significant influence of the stage of lactation on the KMM was recorded in the first and second lactation (P<0.05) respectively in the third lactation (P<0.01). Was recorded a significant positive influence of KMM (P<0.05) on the MPM, tPFM, tSFM and tGFM (r = from 0.22 to 0.52). The negative correlation of the MPM (P<0.05) was recorded with some parts of the milking phase duration (r = -0.14 to -0.47). The results indicate that there are opportunities for selection work to improve milkability traits, which can have a positive impact on the economy of expenditure of time during milking, and indirectly improve the health of the udder.
关键词：milkability; lactation; stage of lactation; Holstein
