When should the cluster be detached for cows?

Faster milking. Early detachment reduces machine-on time. This may or may not result in milking more cows per hour depending on parlour size and milking routine. AMS benefit the most from a short machine-on time.

Calm cows. Several studies have observed calmer cows when detaching at a higher flow rate. First lactation cows seem to be more sensible to overmilking than older cows.

Improved teat condition. Front quarters have less milk and are in general milked out earlier than rear quarters. Overmilking results in more hyperkeratosis especially on front teats and may disturb blood flow in the teat especially in combination with a high milking vacuum.

Milk yield. Even high detachment levels do not decrease milk yield although strip yield may increase.

Historically, cows were considered milked out when the milk flow rate decreased to 200 g/min and most ACR's were set to this level. Sagi (1978) and Rasmussen (1993) concluded that the cluster can be detached at a flow rate of 400 g/min with no negative effect on the milk yield and the incidence or prevalence of clinical and subclinical mastitis. Milking time was also significantly shorter. Even higher thresholds may be used without loss of milk. Stewart et al. (2002) compared detachment thresholds of 0.50 with 0.64 kg/min in one herd and 0.73 with 0.82 kg/min in four herds. The higher thresholds increased milk flow, decreased machine-on time, increased milk yield in two herds and had no effect in the remaining three herds.

Although the machine-on time still decreased with even very high detachment thresholds these improvements did not affect parlour turns per hour positively (Stewart et al., 2002). Bandošová et al. (2003) observed a higher stripping yield of 2nd lactation and older cows with a peak flow <3.5 kg/min detaching at 540 g/min instead of at 300 g/min. However, milk yield was not affected. For New Zealand conditions clusters can be removed at a pre-set max machine-on time without loss of milk production (Jago et al., 2010). For cows milked twice a day, Magliaro and Kensinger (2005) experienced a 2.5% milk yield loss for detachment at 800 g/min.

High yielding dairy cows with large cisternal capacities are less susceptible for variations in milking interval and emptiness of the udder. Leaving some milk in the udder does not influence the effectiveness of the alveolar tissue of cows milked three times per day. Detach at 600-1000 g/min.

Cows milked twice a day seems to decrease milk yield when detaching at more than 600 g/min.

For single quarter detachment divide the above figures with 2.

Changes in mouthpiece vacuum level and fluctuations is a clear signal of milking on empty teats.

High milking vacuum and a short d-phase call for early detachment.