The influence of stage of lactation and lactation number on the freezing point of milk
1997
Michalcova, A.
The effects of lactation stage and number on the freezing point of milk were studied. 237 milk samples were taken from 14 Slovakian Spotted dairy cows, of which 8 were on the 1st and 6 on the 3rd lactation, and from 12 Holstein-Friesian dairy cows, of which 7 were on the 2nd and 5 on the 5th lactation, between January-November 1995. With both cow breeds, the freezing point of milk nonsignificantly fluctuated during lactation and increased moderately at the end of lactation (+ 0.003 deg C). Nonsignificant changes in the freezing point of milk during lactation were influenced mostly by statistically nonsignificant differences in milk composition. However, the freezing point of milk decreased with the increasing number of lactations (-0.002 deg C) in both breeds. It was found that the freezing point depression was affected by significant differences in lactose (- 0.21% and 0.15%, respectively) and in chloride (+ 7.02 mg 100 g * (-1) and 15.15 mg 100 g * (-1), respectively) among lactations
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