Effects on mastitis of overmilking in conjunction with pulsation failure

Abstract

Half-udder comparisons were made using 56 cows for 2 months, in an experiment involving high bacterial challenge, to assess the combined effects of 5 min overmilking and pulsation failure (resulting from the use of shortened teatcup liners) on teat condition and mastitis. Only three new infections were confirmed in over 12500 quarter milkings in quarters milked with control liners (of 148 mm effective length) indicating little or no effect of prolonged overmilking in these quarters. A 3 -5-fold increase in the new infection rate (NIR) based on bacteriological diagnosis alone (P < 0-01), or a 9-fold increase in NIR based on bacteriological diagnosis plus raised cell count and/or iV-acetyl-/?-D-glucosaminidase (P < 0-01), occurred in quarters milked with the same liners shortened to an effective length of 120-130 mm. The mean interval to infection or teat canal colonization (41 v. 60 milkings), and for a quarter infection to be confirmed by other diagnostic tests (45 v. 79 milkings) was significantly less in quarters overmilked with short liners. The results confirm that NIR increases whenever pulsation fails. Overmilking may increase NIR when it is associated with pulsation failure.Experiments in which apparently undesirable machine conditions have been imposed, in conjunction with overmilking, have shown little or no effect of overmilking on the rate of new infections or other indicators of mastitis. Overmilking at high vacuum levels (57-70 kPa) had no effect on new infections, clinical mastitis or udder irritation in heifers (Mochrie et al. 1953;Neave et al. 1962) or in previously uninfected cows (Olney & Mitchell, 1983). Natzke (1978) and Natzke et al. (1978) compared normal milking and overmilking with and without large vacuum fluctuations and concluded that if overmilking is associated with mastitis the effects appear to be small.Milking with short teatcup liners resulted in about twice the new infection rate (NIR) of quarters milked with liners of normal length, but the experimental differences were confined mainly to front quarters (Mein et al. 1983). Although many controlled experiments have failed to show that overmilking seriously affects mastitis (see reviews by Fell, 1964;Dodd & Neave, 1968;Natzke, 1978;Schultze, 1979), it was thought that this interaction in treatment response to pulsation failure between front and hind quarters could be associated with more overmilking on the front quarters. A further, short-term experiment was conducted to assess the combined effects of overmilking and pulsation failure (resulting from the use of shortened teatcup liners) on NIR.

Influence of static and dynamic teat characteristics and milking time on udder health in Norwegian Red Cattle

“…In conclusion, it was apparent that, with the exception of SCC, all the udder health parameters considered in this study showed a consistent pattern, which was largely in agreement with the findings of Mein et al (1983Mein et al ( , 1986. The deep penetration of the fore teats into the teatcup liner together with long milking times adversely affects the health of the fore quarters.…”

“…The correlation between teat end hardness score and teat penetration at end of milking for fore teats was highly significant implying that reduced, or total lack of, massage on the teat end at the end of milking increased the teat end hardness. These results are consistent with those of Mein et al (1983Mein et al ( , 1986. Hamann (1987) postulated that increasing hyperkeratosis and teat end stiffness (both closely related to teat end hardness) over a certain level gave rise to increasing infection risk.…”

“…The investigation also showed that the teat end height above the floor was negatively correlated with mean cell count for the previous year (P < OOOl), and with the prevalence of subclinical mastitis in rear quarters (P < 0-05). Mein et al (1983Mein et al ( , 1986 have shown that milking with short teatcups gave rise to a substantial increase in the incidence of mastitis. This was explained as being due to a lack of compressive load on the teat end in the massage phase.…”

Review: Milking machine settings, teat condition and milking efficiency in dairy cows

“…) finds that a combination of higher vacuum level and lower level of cluster detachment leads to a more prominent prolongation of the teat canal and widening of teat diameter. Conversely, almost no effect of prolonged milking in quarters was observed when using a liner that provided a massage on the whole teat (Mein et al, 1986). Another fact that should be considered is that overmilking is milk flow dependent.…”

Influence of switch level of automatic cluster removers on milking performance and udder health

“…Natzke (1978) concluded that if overmilking is associated with mastitis its effects appear to be small. A detrimental effect of overmilking on new infection rate has only been shown in conjunction with pulsation (Mein et al 1986). However, 0steras & Lund (1988 found a significantly higher frequency of Staphylococcus aureus mastitis in herds with highline milking practising > 1 min overmilking.…”