1/2006 - Potravinárstvo

Potravinárstvo
positive significant correlation has been detected between fats-solids (r = 0.96), fats-SCC (r = 0.88), proteins-solids (r =
0.67), solids-SCC (r = 0.82), REN-urea (r = 0.76), high negative correlation between solids-urea (r = -0.75), SCC-urea (r = -
0.77) at the beginning of lactation. Moreover, high positive significant correlations has been found between fats-solids (r =
0.99), fats-urea (r = 0.96), fats-REN (r = 0.82), proteins-SCC (r = 0.99), solids-urea (r = 0.92), solids–REN (r = 0.75), urea-
REN (r = 0.95), and high negative correlation between proteins-lactose (r = -0.87) and SCC-lactose (r = -0.84) in the middle
lactation. In conclusion, we found some positive and negative high and middle significant correlations between parameters
of milk at the beginning of lactation and in the middle of lactation.
Keywords: biochemical parameter; metabolic disorder; milk quality; correlation
INTRODUCTION
Quality of cow milk and its composition is influenced by
several factors. One of the important exogenous factors is
nutrition of dairy cows. According to many authors (Kirst
and Jakobi, 2002; Kirchnerová, 2002; Kološta, 2001;
Kováčik, 1999), exactly nutrition can influence the
production and quality of milk. It is known that qualitative
nutrition is necessary for maintenance of adequate
performance in high-yielding dairy cows rearing. As it was
published, some deficiencies in nutrition and inadequate
technological facilities may lead to depression in milk
production (Kirchnerová, 2002; Hanuš et al., 2002;
Kováčik, 1999). Deficiencies in dairy cows nutrition have
effect on many biochemical and physiological processes.
Disturbed relationship between metabolic capacity of
animals dedicated to production and metabolic disorders
can appear as a consequence of nutrition insufficiency
(Kováčik, 1999). However, from the economic point of
view the most serious disorder of high – yielding dairy
cows presents acid-base unbalance related to energy
metabolism (Kirst and Jakobi, 2002).
The objective of this study was to evaluate selected
biochemical parameters, their correlations and to examine
the influence of metabolic disorders of dairy cows on
composition and quality of milk.
MATERIAL AND METHODS
Ten dairy cows from selected agricultural farm – Ostrov
near Piešťany were divided into three groups: group I: 3-4
weeks after calving (the beginning of lactation), group II:
3-4 months after calving (the middle of lactation). Samples
of milk were cooled down until 6 °C was reached. Milk
samples were collected by hand milking in early. Samples
were kept at the same temperature during the
determination of milk quality parameters: Determination
of milk fat, proteins and lactose conten (ISO 9622:1999,
infrared analyzer Milkoscan FT 120 fi FOSS Electric )
Somatic Cell Counts (Fossomatic device), urea
(photocolorimetric device with Ehrlich's reagent, 530 nm
wavelength), rennetability (time the precipitation of milk
at 35 ° C after the addition of rennet Fromase220 TL fi
GIST – BROCADES), freezing point (cryoskopic
thermistor device Cryostar fi. Funke Gerber, ISO
5764:2002 Milk – Determination of freezing point).
Significant differences between groups of dairy cows were
evaluated by t – test with using programme SAS.
Differences between the groups at p