Composicion fisico-quimica de leche de oveja Finnish Landrace x Romney Marsh.

Milk samples from ewe's Romney Marsh x Finnish Landrace crossbreed, were analyzed. The animals were subjected to intensive management, in both improved and regenerated grasslands, under rotational grazing. The aims of the present study were: a) To measure acidity, pH and freezing point of milk collected from two groups, both with ten ewes: (Group A) single birth ewes whose lambs were reared uniques. (Group B) double birth ewes which lambs were reared twins, b) To determine the behavior of the parameters during lactation. c) To establish the quantitative relationships between those parameters. The composition was determined according to the following methods: acidity, tritration; pH, potentiometer; freezing point, termistor; total solids, gravimetric method; lactose, cloramine T; milk fat, Gerber method; ashes, calcination; total protein, micro-Kjeldhal; casein, by difference between total protein and non-casein nitroge, determined by micro-Kjeldhal. The average values for group A were: acidity 25,3 deg D; pH 6,43; freezing point -0,587 deg C; total solids 20,29%; lactose 4,87%; milk fat 8,16%; ashes 0,93% total protein 5,98% and casein 4,64%. Group B showed the following average values: acidity 26,8 Deg D; pH 6,4; freezing point -0,581 deg C; total solids 20,97; lactose 4,69%; milk fats 8,8%; ashes 0,88%; total protein 6,15% and casein 4,97%. Once compared the results of the physico-chemical parameters, no significant differences were found, between both groups (p < 0.01) at the same time, no significant variations were found during the lactation, for none of the parameters under study. In general, the various chemical components of the milk showed a tendency to an initial decrease followed by an increase duly supported until the end of lactation, when decreased slightly. Lactose and ashes were the exception showing an opposed trend. As far as the physical parameters are concerned, they did not show an important variation, but rather, a stable tendency. For both ewe's groups, the relationship between the compositional parameters showed a positive correlation coefficient (r) being highly significant for: total solids and protein, total solids and casein, milk fat and ashes, milk fat and protein, milk fat and casein, ashes and casein and protein and casein. Lactose showed a negative relationship with other parameters, with the exception of acidity and pH. Excluding lactose, there is a high relationship between all the milk chemical components. There was not a significant relationship between the physical and compositional parameters.