Differences between primiparous and multiparous cows in voluntary milking frequency in an automatic milking system

摘要

A total of four feeding experiments were designed to study the response of dairy cows to two different milking systems: a conventional auto-tandem milking parlor, and an automatic milking system (AMS, milking robot). The results were analyzed independent of the different feeding factors, because they were the same for all animals in both milking systems. The results, separately analyzed for first-lactating and multiparous cows, can be summarized as follows: First-lactating cows visited the automatic milking system more often (2.6 up to 3.5 times per day) than multiparous cows (2.5 up to 2.9 times per day), but the increased milking frequency did not positively affect milk yield. Although multiparous cows had a substantially higher FCM-yield (29.4 kg/day on average) than heifers (26.0 kg/day on average), they only went to the automatic milking system on average 2.6 times per day. The amount of time needed for first-lactating and multiparous cows to get used to the automatic milking system did not show a difference. They learned to visit the automatic milking system voluntarily after one week. During the course of lactation, differences in milking frequency were detected between first-lactating and multiparous cows. The milking frequency of multiparous cows was observed to be almost constant during the entire lactation, on average 2.5 times per day. However, first-lactating cows increase the milking frequency from the beginning (2.3 times per day) to the end of lactation (2.9 times per day), when the lactation is divided into three periods of 100 days each. The automatic milking system affects uncorrected milk yield positively. The increase of milk yield amounted up to 5.7% for primiparous cows in contrast to the multiparous cows with an increase of milk yield up to 3.1%. But all these differences proved not to be significant. The FCM-yield for primiparous cows (25.8 kg/day and 26.0 kg/day) and for multiparous cows (30.3 kg/day and 29.4 kg/day) were lower than the uncorrected milk yield, because the milk fat content was significantly lower for cows milked in the AMS (4.03% in the AMS compared to 4.36% in the milking parlor). But there were no differences in the FCM-yield and the milk fat content between first-lactating and multiparous cows.