Dairy Sheep Symposium - the Department of Animal Sciences ...

IS MACHINE STRIPPING NECESSARY FOR EAST FRIESIAN DAIRY EWES?
Brett C. McKusick 1 , David L. Thomas 1 , and Yves M. Berger 2
1 Department of Animal Sciences and 2 Spooner Agricultural Research Station,
University of Wisconsin
Madison, Wisconsin
Abstract
Due to the large cisternal storage capacity and non-vertical teat placement in most dairy
ewes, machine stripping is commonly performed to remove milk not obtained by the machine.
However, stripping requires individual manual intervention, lengthens the milking routine, and
could inadvertently lead to overmilking of other ewes in the parlor. The objective of the present
experiment was to estimate the effect of omission of machine stripping on milk production and
parlor throughput. Forty-eight multiparous East Friesian-crossbred ewes, which had been machine
milked and stripped twice daily from d 0 to 79 of lactation, were blocked on percentage of
stripped milk (relative to total milk: ≤ 15% or > 15%), and randomly assigned to two stripping
treatments: normal stripping (S, n = 24), or no stripping (NS, n = 24) for the remainder of lactation.
NS ewes yielded 14% less (105.6 ± 4.8 vs. 122.7 ± 4.8 kg, respectively) commercial milk
during the experiment, but had similar lactation length, milk composition, and somatic cell count
compared to S ewes. Block × treatment interaction was non-significant for all traits. Average
machine milk yield (amount of milk obtained without manual intervention) was greater for NS
ewes compared to S ewes (0.68 ± 0.02 vs. 0.63 ± 0.02 kg/milking, respectively), but the difference
was not statistically significant. Average machine-on time for S ewes was longer than for
NS ewes (89.1 ± 2.4 vs. 78.7 ± 2.4 s, respectively) because of stripping, which may have resulted
in overmilking of many ewes in the S group. These results collectively suggest that residual milk
left in the udder as a result of omission of machine stripping does not negatively influence
lactation length or milk quality. Moreover, overmilking is avoided and parlor throughput is
improved when machine stripping is not practiced. The loss in milk yield can be compensated
for by the addition of more ewes to the milking flock.
Introduction
One of the most important goals of mechanized milking is to obtain the maximum amount of
milk that is rich in total solids, in the shortest amount of time without manual intervention. Therefore,
the use of machine and/or hand stripping is not common in dairy cattle, nor is it practiced in
dairy ewes in the Roquefort region of France with the Lacaune, where the greatest percentage of
dairy ewes are machine milked in the world (Barillet and Bocquier, 1993). Conversely, at present,
machine stripping still remains part of the normal milking routine for most sheep dairies in the
United States and Canada, where primarily the East Friesian and its crossbreeds are being milked.
The North American dairy sheep industry is in its infancy, and as a result, adequate research on
simplification of the milking routine and its economic ramifications has not yet been undertaken.
Cisternal storage volume in dairy ewes is large, comprising between 40 and 60% of the total
milk volume after a normal 12 h milking interval (Marnet and McKusick, 2001). While this can
be of benefit to milk secretion because the concentration of feedback inhibitors of lactation
stored within the alveoli is reduced (Davis et al., 1998), larger cisterns are correlated with higher