Growth factors are thought to play a decisive role
in the course of
inflammatory processes. The aim of the present study was
to characterize a potential
interrelationship between the concentrations of
insulin-like growth factor-1 (IGF-1),
basic fibroblast growth factor (bFGF) and somatic cell
count (SCC) in normal milk,
and to investigate the presence of these growth factors
in mammary secretions of
cows suffering from clinical and subclinical mastitis.
Quarter secretions of cows with
spontaneous acute clinical mastitis and of cows with
subclinical mastitis were
analysed radioimmunologically for their concentrations of
IGF-1 and bFGF. During
two relocation trials with normally lactating Brown
Swiss cows, dramatic changes in
milk somatic cell count were obtained following a short-term
change (5 d) of location
and housing system. The animals were relocated from
their familiar loose housing
system with concrete slatted floor to a separate stanchion
barn with long stalls and
straw bedding, and vice versa. The concentration
profile of IGF-1, but not of bFGF,
corresponded well with SCC during the relocation trials,
the positive correlation
between the characteristics being highly significant, as
determined by regression
analysis (r=0·60; P<0·001).
The results provide evidence that significant changes
in SCC and growth factor content may be caused by
environmental factors other
than infection. The concentrations of both IGF-1 and bFGF
were greatly elevated in
secretions of quarters affected by acute clinical
mastitis compared with the
corresponding clinically healthy quarters. Subclinically
affected quarters with high
SCC, as compared with non-affected quarters with low SCC,
also had elevated milk
IGF-1, but unchanged bFGF. Measuring of growth factor
profiles in milk may have
value in the near future in monitoring the state of udder
health in addition to SCC.