The optimal level of factors for high daily milk yield in automatic milking system

Abstract

Optimising daily milk yield in automatic milking systems (AMS) became one of the basic issues raised by many farmers. The aim of this study was to determine the best combination of factors and their levels suggested by the decision tree for high daily milk yield per AMS in dairy cattle herds. The study involved 4854 Polish Holstein-Friesian cows milked in 20 barns with Lely AMS. Statistical analysis was performed using two methods: multifactorial analysis of variance and classification tree technique. Milk yield, number of cows, free robot time, milking speed, and cow treatment time (i.e. cleaning of teats before and after milking) were the significant determinants of total milk yield for all cows per milking robot and were most frequently used to construct the decision tree. The tree shows that the highest total milk yield per robot was observed for the group of cows that produced more than 30 kg of milk per day, with a milking speed of over 2.40 kg/min. and during robot days in which free time did not exceed 10% of the day. In AMS dairy herds, efforts should be made to select animals that transmit high milk yield and high milking speed while shortening free robot time and increasing daily milk yield per robot. Also, attention should be given to the percentage of box time spent on preparing the cow for milking and after milking because prolongation of this variable has a negative effect on daily milk yield per AMS.