Measurements of teat end expansion and contraction times from step changes in pressure suggest that teat ends require a minimal duration of liner closure for response. Effect of duration of liner closure per pulsation cycle on susceptibility of the udder to infection was tested. Four durations of liner closure (liner more than half closed) were applied: zero, .17, .34, and .51 s per pulsation cycle. For the latter three treatments, duration of the liner more than half open was .66 s per pulsation cycle, resulting in pulsation rates of 72.3, 60.0, and 51.3 pulsations per min. Four groups, each of 10 British Friesian cows, were in a 4-wk experiment. High bacterial exposure of all teats was ensured by dipping them before and after each milking in a suspension of Streptococcus agalactiae and Streptococcus dysgalactiae. Numbers of quarters becoming infected per treatment group were 20, 11, 4, and 5. This result represents both a significant inverse linear and quadratic relationship between proportion of quarters becoming infected and duration of liner closure. We conclude that a sufficient duration of liner closure, i.e., one-third of a second or more, per pulsation cycle contributes to reducing risk of new mammary gland infections.

The rectal temperatures of ten cows were measured each morning and their milk temperatures measured at each morning and afternoon milking for 40 days in order to study the value of these temperature measurements in determining the best time to inseminate, whether or not standing oestrus is exhibited. The best determination was based on the observation that a cow in oestrus had a milk temperature, taken at morning or afternoon milking, at least 0-1 °C higher than the corresponding temperature on any one of the previous 15 days. This method successfully detected 12 of 14 oestrous periods in the 10 cows (86%) and gave a false positive diagnosis on 6 days out of a total of 236 non-oestrous days (2-6 %).

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The Milk Marketing Board (MMB) specification for milk yield recording defines the acceptable limits of error for any recording equipment whether manual or automatic. This is that at any milking 95 per cent of the measurements must not deviate more than ± 5 per cent or 0.25 kg (whichever is the greater) from the true weight. Hence an error of ± 0.25 kg is allowable for yields below 5 kg and 5 per cent of yield for quantities greater than 5 kg.