Ah. Herlin et A. Christiansson, CHEESE-BLOWING ANAEROBIC SPORES IN BULK MILK FROM LOOSE-HOUSED AND TIED DAIRY-COWS, Milchwissenschaft, 48(12), 1993, pp. 686-690
Two management systems for dairy cows, tied and loose-housing with cub
icles, were compared in a longterm (2 years) experiment. During experi
mental periods in each year the numbers of cheese-destroying anaerobic
spores were determined by most probable number technique (MPN) and by
a filtration method followed by ELISA confirmation of Clostridium tyr
obutyricum, C. butyricum and C. sporogenes. Total counts and psychrotr
ophic bacteria were also analysed. Samples from bulk milk were taken e
very second day for 7 weeks in the first year and for 5 weeks in the s
econd year. Feeds, including grass and alfalfa silage, and pre-milking
routines were kept identical in the management systems. Total counts
in both systems were at a low level and differences were, on average,
less than a few thousand CFU per ml. In both years, more than twice th
e number of spores were found in the bulk milk from loose-housed cows
than from tied cows. The differences were significant when detected by
the ELISA method in both years, whereas in the first year the MPN met
hod did not give reliable results. There was a large difference betwee
n the two years in anaerobic spore level (tenfold more spores in the f
irst year than in the second), caused by differences in silage quality
. Although feeds, milking routines and animals were the same or unifor
m for the two management systems, differences between the systems were
distinctly reflected in the spore levels of the milk. The ELISA metho
d offers a more accurate tool of determining cheese-destroying anaerob
ic spores than MPN techniques. The unexpected lower values for tied co
ws could be explained by the more intensive care and working time used
on scraping, litter management and thorough cleaning of dirty teats t
han for the loose-housed cow. It may be concluded, from this and other
studies, that feed quality is of the greatest importance for the spor
e content in milk. The scraping, litter management and cleaning of the
teats are important factors that may eliminate a less optimal hygieni
c function of the environment of the cow.