Factors affecting the cholesterol content of milk of cows fed conserved feeds in a TMR system throughout the year
2010
Nina Strzałkowska | Artur Jóźwik | Emilia Bagnicka | Józef Krzyżewski | Ross G. Cooper | Jarosław Olav Horbańczuk
The aim of this study was to evaluate changes in the cholesterol content in the milk of high yielding cows fed a uniform diet composed of conserved feeds over the whole year. The investigationswere conducted on 124 Polish Holstein-Friesian cows, selected fromherd yielding 8457 kg milk with 4,58 % and 3,56 % of fat and protein content, respectively. The cows were maintained in a loose barn and fed ad libitum with TMR (total mixed ration) throughout the year. The diets consisted of corn silage and grass silage (at 50:50 ration on dry matter basis) and concentrates with mineral-vitaminmixture additives. Samples of milk were collected individually from each cow at monthly intervals during the whole year. The cholesterol content in milk (mg/dL) and in milk fat (mg/g) was related to the stage of lactation, season of the year, somatic cell count and fat content, but was not affected by the parity. The cholesterol content in daily milk yield (mg/cow/day) depended also on parity. Even though the cows were fed a uniform diet throughout the year according to the TMR system the cholesterol content in milk differed among seasons.
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