Innovative Technology and Sustainable Development of Organic - 1.

3.2.9 Milk Quality Aspects
Indicators selected to assess milk quality aspects related directly to the AMS technique (Meijering et
al., 2004) or to grazing (Elgersma et al., 2004; Ellis et al., 2006). The concentration of free fatty acids
(FFA) in milk is assumed to be influenced by milking frequency, milk flow per milking, storage time,
pumping and mixing (especially of milk that is not cooled), and diet composition (Rasmussen et al.,
2006). Large amounts of saturated lipids in the diet can result in large fat globules in the milk, which
are susceptible to lipolysis and cause the breakdown of protected fat to free fatty acids. The FFA
concentration in milk, measured in acid degree value (ADV in milli equivalents per litre [meq/l] of
milk), was therefore chosen as an indicator for milk quality. Data on FFA concentration in milk was
acquired from a milk composition survey financed by the Danish Dairy Board (Rasmussen et al.,
2006).
Furthermore, insufficient hygiene using AMS might result in contamination by spores of
Clostridium tyrobutyricum. This bacterium can cause cheese to explode because of a fermentation
process producing hydrogen and carbon dioxide. Spores are resistant to pasteurization and contaminate
milk through contaminated roughage silage causing spores in manure, which in addition can infect
teats. When washing of the udder is neglected before the milking process, this can cause high spore
concentrations in the milk. The number of spores per litre of milk, therefore, was taken as an indicator
of milk quality.
Somatic cell count (SCC) indicates mastitis problems, as well as possible stress and is therefore
used as an indicator in this study. Mastitis can be provoked by stress or neglected surveillance, which
have both been suggested as possible problems with AMS use (Meijering et al., 2004). SCC counts
leucocytes and cows’ own udder cells, which are in emulsion with the milk. The amount is correlated
with infection (clinical and sub clinical) of the udder, which is usually mastitis. Both milk delivered
and milk directly sampled from the cows was analyzed.
3.2.10 Statistical Analysis
Quantified SI of both farm groups were tested for normality, using the Anderson-Darling test, which is
suitable for small sample sizes (n ≤ 25) (Anderson and Darling, 1952). Subsequently, SI were analyzed
by single-factor ANOVA testing the variance and probability for significant differences. Standard
deviations were computed for each set of data registered for each SI. Only differences with a P value of