Body Composition, Cattle - metabolism, Milk - chemistry, Parturition, Body Weight, Growth Hormone - blood, Blood Glucose - analysis, 3-Hydroxybutyric Acid - blood, Postpartum Period, Insulin-Like Growth Factor I - analysis, Pregnancy, Calcium - blood, Animals, Leptin - blood, Animal Nutritional Physiological Phenomena, Fatty Acids, Nonesterified - blood, Fem...