Contents of protein, glucose and lipid in the milk of breeding mares in the course of lactation

Milk samples were collected from 44 mares of different races (trotters, war mblooded horses, Quarter horses and heavy breed) during a lactation period of 90 days. The content of the following components was analysed during the lactation period: total protein, glucose, triglycerides, cholesterol in ad dition the total lipids and free fatty acids. Apart from that an explorativ e data analysis was performed to find out whether there was an influence of different races, fertility, date of foaling, age or number of previous lac tations on the milk components or if these components are correlated. Summarizing the following results were achieved: The mean content of total protein was 6,65 +/- 4,32 g/dl on the first day o f lactation and decreased until the 90(th) day p.p. to reach an average of 1,67 +/- 0,32 g/dl. Age, date of foaling and fertility related to lactation stage were statistically significant factors influencing the total protein content. Glucose was lowest on the first day p.p. (x(g) = 6,67 x 1,48(+/-1 ) mg/dl), increased during the first week of lactation up to 14 mg/dl and d ecreased slightly to a level of 10-11 mg/dl until the 90th day p.p. Date of foaling, number of previous lactations and fertility related to stage of l actation were statistically significant influencing factors. The mean trigl yceride content was lowest on the first day p.p. (x(g) = 1529,33 +/- 1,79(/-1) mg/dl) and fluctuated about 2000 mg/dl during the course of lactation. The influence of race and date of foaling related to stage of lactation tu rned out to be statistically significant. The mean content of total lipids was 2,03 +/- 0,61%. There was a high correlation between total lipids and t riglycerides. The correlation coefficients ranged from 0,84 to 0,97. The mean content of free fatty acids was 1,88 +/- 0,92 mmol/l. During lacta tion free fatty acids increased mainly in the first week from 0,355 +/- 0,2 71 to 1,870 +/- 0,961 mmol/l. This course was statistically highly signific ant. Cholesterol values were highest on the first day p.p. (x(g) = 16,05 x 3,95(+/-1) mg/dl) and decreased rapidly throughout 90 days of lactation (x, = 1,19 x 2,95(+/-1) mg/dl). The influence of fertility related to stage of lactation and date of foaling were statistically significant. Throughout lactation a positive correlation could be observed between total protein and cholesterol and a negative between glucose and triglycerides.