Authors: JOANNA BARLOWSKA, ROBERT PASTUSZKA, JOLANTA KRÓL, ANETA BRODZIAK, ANNA TETER, ZYGMUNT LITWINCZUK
Abstract: The objective of the research was to analyse the technological parameters of milk and assess the impact of selected factors, i.e. the genetic group of goats (improved goats?Saanen crosses vs various crossbreds of unknown genetic origin?breedless goats with different coat for which no breeding books were kept), production season (winter, spring/summer, and autumn), which was associated with the stage of lactation (1, 2, and 3), the region where the goats were raised (upland or mountainous areas) and daily yield (< 1.0, 1.0-2.0, or > 2.0 kg). A total of 480 milk samples were evaluated (203 milk samples from Saanen crosses and 277 from various crossbreds of unknown genetic origin). The milk was tested for proximate chemical composition, casein content, active and potential acidity, coagulation time, and heat stability. All factors analysed were found to significantly affect daily milk yield, potential acidity and composition (contents of fat, nonfat dry matter, total protein, and casein). Goat crossbreds of unknown genetic origin produced milk with better chemical composition, i.e. higher contents of fat, nonfat dry matter, total protein, and casein, and technological parameters? higher heat stability (despite lower daily yield) than Saanen crosses, especially in autumn (end of lactation). The region of production was also significant. Goats raised in mountainous areas produced milk with a more favourable chemical composition, i.e. higher content of dry matter and protein, including casein, but with lower heat stability, in most cases irrespective of the production season. As daily milk yield increased, there was a decrease in the content of fat and nonfat dry matter, including total protein and casein, as well as a reduction in the rennet clotting time. Analysed factors and their interactions play an important role in shaping the chemical composition of goat milk and determine its technological usefulness.
Keywords: Goat milk, chemical composition, technological parameters, casein, correlation
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