Somatic Cell Counts
When you switch on milking machines in your parlour, you could
also be switching on a factor contributing to elevated somatic cell
When looking at an overall strategy to reduce your herd's somatic
cell count [SCC], consider vibrations your cows feel from milking
machines. While it's just one of many factors influencing udder
health, Swiss researchers have found that reduced vibrations can
contribute to a lower SCC.
Previous research has shown that excessive noise during handling
increases heart rates and stress levels in beef cattle. This has
been accepted as the animals' natural fear response. Recently, scientists
have speculated about whether noise influences dairy cows, impacting
udder health, production and milk quality.
The Swiss researchers studied two types of sonic waves and their
effect on production and health of dairy herds in parlours. Structure-borne
waves are vibrations the cows feel from the milking machine. They
feel airborne waves from the actual noise generated by the milking
machine and associated equipment.
Bulk tank samples for the year before the study were averaged for
herd SCC and then measured for three months after milking systems
were modified to lower sonic wave amplitude, or size. The researchers
believed that the larger the sonic wave amplitude, the greater the
effect on cow health. They also considered several variables when
analysing the effect of vibration and noise on SCC but focused on
parlour style as having the most influence on these waves.
Different parlour styles were measured for the presence of these
two types of sonic waves, including herringbone, autotandem, side-by-side
and carousel, with herringbone parlours most common on Swiss dairy
farms. Regardless of parlour style, researchers observed a reduced
SCC on every farm in the study after milk equipment modifications.
However, the effect of vibrations, or structure-borne waves, proved
to influence SCCs more than noise, or airborne waves. Previous studies
had found no evidence that noise impacted cow health or production
but they observed only noise, not simultaneous vibrations. In the
Swiss study, parlour modifications reduced vibrations to a greater
degree than noise.
As the figure on page 38 shows, vibration reduction did correlate
with improved herd SCCs. The researchers believe a few factors could
The first was oxytocin response, which allows the udder to let
down milk. A cow releases this hormone at milking through physical
stimulation of the teats from cleaning before unit attachment and
by the milking machine. Increased vibration from the machine to
the cow may cause significant stress that could reduce oxytocin
levels and milk yields. This would have a domino effect, raising
the mastitis risk from residual milk in the udder and elevating
Another factor the researchers assessed was vacuum stability resulting
from the milking system modifications. A more stable vacuum reduces
milk droplet impact on the teat end, further reducing mastitis risk.
Management practices were also considered a factor that would impact
SCC before and after modifications. The study included different
management practices at all levels. It found that even with large
vibrations associated with poor management practices, it was difficult
to observe the vibration level without using measuring equipment.
The research-ers concluded that even the best management practices
might be unable to identify a vibration problem without proper measurement
of structure-borne waves.
While the Swiss study showed how vibrations can influence SCC,
you have to look at several factors when assessing an SCC reduction
strategy for your herd. At the individual cow level, mastitis history,
breed, yield and parity would have to be considered. Items such
as machine settings, environmental factors, and teat cleaning and
stimulation routines are also important to the big picture. And,
of course, management practices play a huge role in your herd's
overall health and production.
Before calling in your equipment dealer for a complete system overhaul,
evaluate your herd's performance and health. Make sure you keep
your milking system maintained and at the appropriate vacuum and
pulsator settings. If your herd SCC still needs improvement, have
your equipment dealer or udder health specialist assess your milking
system. See if you can make improvements to reduce the impact from
vibration as part of the SCC reduction strategy.
Gygax, L. and D. Nosal. "Contribution of Vibration and Noise
During Milking to the Somatic Cell Count of Milk", J. Dairy
This article first appeared in the Ruminations column of The Milk
Producer Magazine, September, 2006.