Abstract
Blood samples were taken weekly from 3 weeks pre-partum to 10 weeks post-partum period of lactation from 9 dairy cows, to study the physiological changes in plasma constituents in relation to parturition and lactation. Plasma glucose, free fatty acid (FFA), triglyceride, phospholipid, cholesterol, calcium (Ca), inorganic phosphorus (i-P), magnesium (Mg), sodium (Na), potassium (K) and chloride (Cl) levels and alkaline phosphatase (Al-P) activity were estimated. The following findings were obtained. 1) At parturition, plasma glucose level was higher than any other stages. 2) Plasma FFA level during the first few weeks post-partum was higher than dry period, thereafter, it decreased progressively. Parturition brought about a temporary decrease in plasma triglyceride level. Plasma phospholipid and cholesterol levels increased progressively after parturition till 10 weeks of lactation. The ratio of esterified cholesterol decreased slightly immediately after parturition. 3) Plasma Ca and i-P levels decreased after parturition, particularly abrupt decreases were observed at parturition. There is a transient fall in Mg level at 1-2 weeks after parturition. During the lactation period, plasma Na and Cl levels were slightly lower than dry period. Plasma K level increased at parturition, thereafter, it declined to less than pre-partum levels. 4) Plasma Al-P activity decreased at the first few weeks post-partum, then increased progressively. The changes in plasma glucose, lipids, Ca and i-P levels accompanying with parturition in the present experiment were well agree with those reported by previous workers. And it was clarified that plasma Na, K and Cl levels and Al-P activity may change in relation to parturition and lactation in dairy cows.
