Authors: F. Neijenhuis, J. Eric Hillerton
As part of the EU project on Automatic Milking (AM) a study was carried out in the Netherlands, United Kingdom and Denmark on “Health of dairy cows milked by an automatic milking system”. The major part of this project was a study of 15 farms in each country. A separate experiment was conducted to determine the effects of milking intervals on the short-term effects of teat condition. Milking with shorter intervals leaves less time for teat tissue to recover and may lead to incomplete recovery of teats. This could lead to an accumulation of teat trauma. It suggests that a measurable risk may occur when using an AM system, if milking intervals are short.
An experiment was undertaken on the impact on teat condition when milking with short milking intervals as can be found with automatic milking. A Latin-square designed experiment in a conventional milking parlour used 12 cows which were allocated randomly for a period of 4 days, being milked every 4, 8, or 12 hours. The cows were housed in a free-stall barn and milked on one side of a 2 x 5 side-open milking parlour with whole udder cluster take off. After two days habituation, milk flow profiles were collected on the third day. At morning and evening milking on the fourth day, the two right teats were examined with ultrasound just before and just after milking to measure differences in teat dimensions. Milk samples were taken to determine milk composition.
Statistical analyses using random regression showed that milk yield increased 16% per day when milking frequency was greater than two times a day. First parity cows produced significantly less milk then older cows when milked twice a day. The overall increase in milk yield per day when cows were milked more than twice a day was only found for first parity cows. Milking four times a day, with whole udder take-off, doubled the machine-on time. The efficiency of milk harvesting decreased with increasing milking frequency.
Shorter milking intervals resulted in less increase in teat wall
thickness, less reduction in teat cistern width and less shortening in
teat canal length in response to milking. However, the teats milked
following short intervals had thicker teat walls, narrower teat cisterns
and longer teat canals before milking. These differences between the
treatments in teat dimensions disappeared after milking. This indicates
either that short milking intervals are insufficient to allow recovery of
teat tissue between milkings or are a result of less filling of the teat
cistern with milk. Furthermore, in this experiment whole udder take-off
was practised, most of the AM systems use quarter take off. This may
reduce the effects on teat condition because of a shorter low flow period
for individual quarters at the end of milking. In this experiment front
teats had a larger increase in overall teat width because of milking than
rear teats. The low flow period in front quarters will be longer than in
rear quarters with whole udder take-off. The cause and effect of changes
in teat dimensions after milking still require further investigation.
Milk composition, milk fat, protein, lactose and cell count, at different
milking intervals was not different.
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© Animal Sciences Group -
Wageningen UR. Last update:
20-02-2008 10:03. |
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