Impact of automatic milking system (AMS) on milk yield and some milk characteristics.

The trial was carried out in the experimental free stall barn “V. Tadini” equipped with an auto tandem (4+4) milking parlour and, since March 2004, with a single box automatic milking system (Galaxy, Milkline). Two similar herds were constituted and milked with milking parlour (MP) or with automatic milking system (AMS). The cows of the two herds were fed the same diet distributed using TMR technique, once a day (at 07:00). The cows in MP were milked twice daily (at 03:00 and at 15:00). After AMS installation the AMS herd was constituted of 20 mid-lactating cows, moved from the MP herd. In the next months other cows were introduced in the AMS herd, reaching a numerousness of 26 cows. In the AMS area forced cow traffic was applied. During the trial, started one month before and ended four months after AMS installation, individual milk yield was daily recorded and bulk milk of the two herds was sampled fortnightly and analysed for fat, protein, lactose and somatic cell count (SCC). Data on cow traffic in the AMS were obtained from the recorded visits in the milking unit. Milking frequency in AMS, excluding the first 3 weeks after AMS installation, averaged 2.61±0.78 milkings/day. Milk yield decreased, according to the advancing in the lactation phase, in both herds and the extent of the reduction was slightly lower in the AMS herd. Slight differences were observed in fat content of bulk milk with a reduction of the values in both herds in springtime. On average the values were 3.70±0.15% in AMS and 3.77±0.06% in MP, with a higher variability in AMS herd. Protein content was 3.37±0.05% in AMS and 3.33±0.17% in MP and the values observed in each herd during the trial have shown a similar pattern. Lactose content of bulk milk decreased, during the trial, in a lesser extent in AMS.Milk SCC were, on average, 5.58±0.16 log10(n/mcl) in AMS and 5.60±0.07 log10(n/mcl) in MP and a very close pattern during the trial was observed in the two herds. In conclusions our data show that the introduction of the AMS increases slightly milk yield with minor influence on milk composition and without effect on somatic cell count.