Discipline: Veterinary Medicine
The changes in the serum concentrations of sodium, potassium, calcium, glucose, triglycerides, and total proteins of sexually mature female Philippine domestic chickens were determined at different stages in the reproductive cycle, namely pre-lay, laying, and brooding stages. Two groups of hens were used. The first group consisted of hens that were less than one year old and had undergone one brooding previously: these hens are referred to as young hens. The other group consisted of hens that were more than one year old that had completed at least three broodings. From hens belonging to “young” and “adult” groups, blood samples for biochemical analysis were collected at prelay, day 1 of laying, day 7 of laying, day 1 of brooding, day 11 of brooding, and day 21 of brooding. The results of blood test for sodium, potassium, calcium, glucose, and total protein were maintained throughout the stages of the reproductive cycles, while potassium concentrations were constantly lower during laying and brooding than during pre-laying stage. This might be attributed to the excretion of potassium in exchange for sodium that needed to be reabsorbed, and possibly to lack of dietary supplement of potassium. Increases in serum calcium and triglycerides corresponded to the increased demands for these nutrients during egg information, but were reduced again to pre-lay values during the brooding stage. These observations were associated with physiological events involved during egg formation and egg-laying.