Mastitis, Udder Health in AMS Herds
Mastitis is one of the most economically important diseases on dairy farms. Most of the cost associated with mastitis is hidden in lower milk production, which is difficult to quantify on an individual farm. Research has shown that as the linear score (LS) increases by one, the somatic cell count (SCC) doubles and milk production decreases by 0.7 kg/cow/day. At LS = four (200,000 SCC), the estimated milk loss is 1.4 kg/cow/day. Mastitis is a serious and costly disease and measures taken to reduce the incidence in a herd will be well rewarded.
Mastitis in AMS herds
Early studies of automatic milking systems (AMS) reported between 2001 and 2006, compared AMS with conventional milking systems (CMS). Observations before and after the installation of an AMS to show that udder health deteriorated with the introduction of AMS. Researchers found higher numbers of new infections and higher mean SCC (Hovinen & Pyoraia, 2011). However, more recent studies with newer generation AMS, as well as improved barn design and management optimized for robot milking, showed no change in udder health and teat end condition, while in some cases, the introduction of AMS actually improved teat end condition (Jacobs & Siegford, 2012).
A study on 12 US farms over 3 years showed that SCC and bacterial counts declined the longer the farms milked cows on an AMS (Jacobs & Siegford, 2012). Some studies compared AMS to CMS on the same farm with similar environment and management showed no difference in udder health outcomes (Hovinen & Pyoraia, 2011). The often-contradictory results from various studies on AMS herds indicate that differences in environment, management and other farm level variables may be more important in determining the production, health and efficiency of AMS herds than the specific milking system (Jacobs & Siegford, 2012).
Factors related to udder health in AMS milking
There are significant differences in the management of udder health when comparing AMS to CMS. Cow movement, feeding systems and detection methods change when milking with an AMS. Milking frequency, milking interval, procedures for teat cleaning and teat dipping are all different compared to CMS. There is no longer visual oversight for ensuring adequately cleaned teats and clinical mastitis detection (Hovinen & Pyoraia, 2011). The mastitis detection methods have improved considerably in recent years and as robot milking systems are upgraded, udder health benefits.
Of the several aspects that may impact mastitis on an AMS system (cow and udder cleanliness and milk leakage for example) we’ll make a brief reference to failed or incomplete milkings. The normally accepted benchmark for failed milkings is five cows/robot/day although some authors use 5% as a benchmark. Ideally, a farm should have no failed milkings since these present a challenge in robot milking. This is because failed milkings expose cows to higher risk of infection if they go and lie down soon after being rejected. The teat canal is likely to still be open, the udder relatively full and these cows will often leak. Open teat canals expose those quarters to bacterial infection from the environment. In failed milking, the teats are not sprayed, significantly increasing the risk of infection. Keeping the number of failed milkings in check is an important management aspect of an AMS operation.