Analysis of the milk yield and milking frequency of Polish Black-and-White Holstein-Friesian cows housed in a barn with an automatic milking system (AMS)

The aim of the study was to analyse milk yield and the frequency of use of a milking robot by Polish HolsteinFriesian cows. The study was carried out on a farm where a double-stall Astronaut milking robot from Lely was installed in a free-stall slatted-floor barn for 120 cows. The material for the study was obtained from the herd management system and comprised 850 milking records. Daily milk yield (in kg), number of milking sessions per day, and average milk yield per milking were analysed. The experimental factors were lactation number (primiparous and multiparous cows), daily milk yield (≤15 kg, 15.1–25.0 and >25.0 kg) and stage of lactation (≤100 days, 101– –200 days and >200 days). The cows in the herd were found to use the milking robot with an average frequency of 2.49 times a day. No significant differences were noted in daily yield or frequency of milking between primiparous and older cows. They also did not differ significantly in terms of milk yield per milking. The level of daily yield influenced the milking frequency. Use of the milking robot was most frequent among primiparous and multiparous cows with daily yield of more than 25.0 kg of milk (2.82 and 2.67 times per day, respectively). In the case of both primiparous and multiparous cows, an increase in daily milking frequency was accompanied by an increase in the amount of milk obtained per milking. In the group of primiparous cows, the daily milking frequency increased in the three successive stages of lactation. Increased milking frequency was also found to be linked to a decrease in the amount of milk obtained in one milking. In the multiparous cows, the daily milk yield and quantity of milk per milking decreased systematically in successive stages of lactation, while the daily milking frequency varied irregularly.