Abstract
The aim of this study was to attempt at providing a complete picture of dynamics of selected biochemical blood parameters (parathyroid hormone, Calcium, Phosphorus, Sodium, Potassium, Chlorine and ionized calcium) around calving period in high producing dairy cattle (Holstein breed), giving new and useful information about the guidelines for the management strategies during different physiological phases. Seven pregnant Holstein cows were blocked by parity and fellow during the peri-parturient, calving and post-parturient period. Jugular blood samples were taken 8-15 days prior to expected calving, at calving and in day seven post-calving to estimate serum concentrations of Parathyroid Hormone (PTH), Calcium (Ca), Sodium (Na), Potassium (K), Chlorine (Cl) and ionized Calcium (i Ca). Results indicated that the level of PTH at calving time and in seven days post calving was significantly higher (p<0.05) than those in pre-partum and this is vice versa for blood calcium and ionized calcium. However, the levels of Na and Cl in pre-partum were significantly higher (p<0.05) than those at calving and post-partum. Other mineral levels were not significantly change over time of study. The present study indicates that serum PTH and some electrolytes could be severely altered in dairy around the time of calving.
Highlights
The most critical time in the life of a dairy cow is the days around parturition
The obtained results confirm the opinion of Mayer et al (1969) and Goff (2000) who observed that a decrease in serum calcium concentration in all examined cows occurs during the calving period which is closely related to the rise in Parathyroid Hormone (PTH) level and simultaneously delayed return of the calcium value to normal levels paralleled to the drop in the concentration of this hormone
Serum PTH increases near calving, activating bone resorption and renal tubular re-absorption to increase blood Ca (Goff, 2000)
Summary
The most critical time in the life of a dairy cow is the days around parturition. Parathyroid hormone is a single-chain polypeptide made up of 84 amino acids secreted by the chief cells in parathyroid gland. It augments the absorption of calcium from the intestines and simultaneously conditions its re-absorption from the skeleton (Horst et al, 1994, 1997). PTH is the principal hormone involved in the fine regulation of Ca homeostasis. The hypercalcemic biological action of PTH is by direct influence on target cells in bones (osteoclasts and osteocytes) and kidney (proximal and distal tubules) and by indirect action on the duodenum
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
