CHEMICAL COMPOSITION AND SOMATIC CELL EVOLUTION DURING LACTATION IN ROMANIAN BLACK AND WHITE COWS
Keywords:
lactation curve, milk yield, chemical composition, somatic cell count, calving season, cows, Romanian Black and WhiteAbstract
The aim of the paper was to study the evolution of the chemical composition and
somatic cell count during lactation in Romanian Black and White cows and effect of
calving season on the shape of the lactation curve. Lactations form 125 multiparous
cows were studied. Milk yield and sampling were carried out using the official
performance control method A4. Milk was analyzed for composition in infrared
spectrometry and for SCC using a viscosimeter. Results were modeled using Wood’s
incomplete gamma function y=abx
e
(-cx), and season effect was assessed using
ANOVA/MANOVA. A discussion was carried out regarding the shape of the
lactation curves for milk yield, each milk component and SCC. The calving season
had a significant effect (p<0.005) on the shape of the lactation curve for milk yield,
milk chemical composition and milk somatic cell count. Summer calving cows had
flatter lactation curves for milk yield and composition compared to winter calving
cows. For somatic cell count spring calving cows had the flattest lactation curve
while autumn calving cows has the steepest lactation curve.
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