Effects of automatic milking system on teat tissues, intramammary infections and somatic cell counts

To assess the impact of automatic milking systems (AMS) on the different aspects of milk production a research project involving both commercial and experimental dairy farms with different AMS and different management was started. This paper reports the results of a follow-up study on primiparous cows focused on assessing some markers to be used to monitor udder and teat health. Heifers were included after calving and sampled for at least 12 months. Quarter milk samples and teat measurements were taken to assess: intramammary infection (IMI) frequencies, somatic cell counts (SCC), teat thickness changes, teat skin and apex conditions. The study included 28 cows in herd A and 27 in herd B for a total number of 2344 samples. Overall, teat apex and skin conditions were maintained along the lactation. Teat skin conditions tended to decrease because of the accumulated number of milkings while lactation proceeded, but at a largely acceptable level in both herds. Teat apex conditions showed a decrease. Teat thickness changes displayed different patterns in the two herds, probably because of the different type of AMS, but in both cases a trend to decrease in thickness could be observed. The application of AMS in herd B, free from contagious pathogens, did not influence the frequency of IMI and the SCC. In herd A, characterized by the presence of Staphylococcus aureus IMI, the frequency of IMI showed a progressive increase, very likely as a consequence of the spread of infections during milking. Teat skin had no association with the frequency of IMI. Teat thickness changes outside values considered as physiological proved to be associated with decreased conditions in the teat apex score in herd A, but not in herd B. However, a decrease in teat apex score proved to be associated with an increase in IMI frequency in both herds. The results of this field trial confirm that AMS have no negative impact on IMI incidence, SCC and teat tissue conditions when the initial cow health status and overall herd management are good. In the presence of contagious pathogens, and when cows have more than 300 days in milk (DIM) the frequency of negative outcomes significantly increases and the proper control measures should be taken.