Milk composition and properties were studied in 20 goats of the White
Polled Short-wooled breed in the first lactation from the 6th to 255th
day in nine time intervals. Goat milk samples were examined for somat
ic cell counts (Fossomatic and mastitis N-test) and the following prop
erties were investigated at the same time: basic milk components (fat,
crude protein, lactose, ash), N-matters (true proteins, casein, whey
proteins, nonprotein nitrogen, urea, ammonia), minerals (Ca, Mg, total
P, inorg. P, Na, K, Cl), physical and chemical properties (titratable
acidity, pH, buffering capacity, electrical conductivity) and renneta
bility and alcoholic stability as processing properties. Correlation a
nalysis was used to assess the relations of milk composition and prope
rties to somatic cell (SC) counts. The results were grouped according
to SC counts into classes of 250,000 SC per 1 ml milk, means and varia
bility of all values concerned were calculated for every class and sig
nificance of differences in the means between the classes was tested.
SC differential counts were determined after staining microscopic prep
arations by Giemsa method. The assessment involved 146 milk samples in
total from animals in which the occurrence of acute mastitis was not
demonstrated. SC counts varied in a wide range of 78,000 to 4,520,000
SC per 1 mi milk with an average value of 860,947 (Tab. I). A mastitis
N-test used for rapid diagnosis of secretory disorders in dairy cows
was verified at the same time. A statistically highly significant corr
elation (r = 0.56(++)) was found out between SC counts and N-test valu
es (Tab. II). Samples with low N-test values exhibited high SC counts
and vice versa. No relationship was demonstrated between the lactation
pattern and SC counts. Increased SC counts were occasionally observed
in the 3rd to 4th month of lactation, which could be partly due to tr
ansition to machine milking. Tab. III shows the values of correlation
coefficients for relations between SC counts and the characteristics u
nder study. The classes from which the average values against the prec
eding class are significantly different can be seen for the milk compo
nents and properties in Tab. IV. A decrease in potassium content (r =
-0.17(+)) and in a K/Na ratio (r = -0.15(+)) was recorded for SC count
s higher than 0.5. 10(6) per 1 ml goat milk. With SC counts higher tha
n 0.75.10(6) lactose content is decreasing (r = -0.31(++)), the ratio
chlorides/lactose - chlorine-sugar number is increasing (r = 0.16(+)),
whey protein content is rising (r = 0.17(+)) and there are significan
t variations in casein, sodium and chloride contents. With SC counts h
igher than 1.10(6) there is a statistically significant decrease in go
at milk titratable acidity (r = -0.13(+)) and alcohol number and signi
ficant variations in milk pH value and buffering capacity. SC counts e
xceeding the limit 1.25.10(6) result in significant variations of aver
age values in a majority of other N-matters under observation, in an i
ncrease in ash content (r = 0.30(++)), in a decrease in inorganic phos
phorus content (r = -0.42(++)) and its percentage in total phosphorus
content (r = -0.38(++)), in prolonged time of milk rennet clotting (r
= 0.42(++)) and in variations of specific weight. Total phosphorus con
tent in milk is significantly decreasing (I = -0.15(+)) with SC counts
higher than 1.5.10(6) per 1 ml milk. Average values in the establishe
d classes are significantly different from the preceding classes for f
at, ammonia nitrogen, milk conductivity (r = -0.13(+)), calcium (r = -
0. 21(+)) and magnesium only when SC counts are higher than 1.75 and/o
r 2.0.10(6) per 1 ml milk. To determine the percent representation of
the SC groups in goat milk. differential SC counts were informatively
determined in 16 milk samples at various stages of lactation and with
SC counts ranging from 123,000 to 4.52.10(6) per 1 ml, out of which 10
samples bad SC counts maximally up to 1.10(6) per 1 ml milk. Polymorp
honuclears showed the highest percent representation from 40 to 70% wi
th peak in the 3rd to the 4th month of lactation. Macrophage counts ra
nged between 10 and 20% without any apparent relation to lactation sta
ge. Lymphocyte counts were highest at the beginning of the period of o
bservation (about 20%) and they were slightly decreasing to 5 to 7% un
til the end of lactation. The representation of epithelial cells range
d from about 10 to 15% at the beginning of lactation, showing a clear
drop until the 2nd month of lactation, followed by a moderate increase
to 15% since then until the end of the period of observation. It was
not possible to assess the relationship between the representation of
the SC groups and total SC counts due to a small number of randomly se
lected samples. Nevertheless, some statistically highly significant re
lations between somatic cell counts and milk composition could be dete
rmined. The results document that with SC counts higher than 1.10(6) p
er 1 ml milk significant variations in values of many basic components
and properties of milk can occur in individual goat milk samples, the
re are variations in the averages in the particular classes or the var
iability of the average is increasing. Therefore we believe that hygie
nic requirements for goat milk to be processed should comprise the est
ablishment of a limit value of SC counts amounting to 1.10(6) per 1 ml
for milk from individual animals and to 750,000 SC per 1 ml for bulk
goat milk.