THE EFFECT OF TRANSITION PERIOD HEALTH ON REPRODUCTIVE PERFORMANCE IN DAIRY COWS

摘要

Essentially all dairy cattle experience a period of insulin resistance, reduced feed intake, negative energy balance, hypocalcemia, reduced immune function, and bacterial contamination of the uterus soon before, or in the weeks after calving. Half ofdairy cows have some form of metabolic or reproductive disorder in early lactation. High NEFA (> 0.4 mmol/L) in the last 10 days before expected calving is associated with increased risk of retained placenta, culling before 60 days in milk, and less milkproduction in the first 4 months of lactation. Subclinical ketosis (serum BHB > 1.2 mmol IL) in the first or second week after calving is associated with increased risk of metritis, endometritis, prolonged postpartum anovulation, and lower milk production in early lactation. Recent data also indicate that serum calcium < 2.2 mmol/L in the first week postpartum is associated with increased risk of DA, lower milk production in early lactation, and reduced probability of pregnancy at first insemination.There are few management practices or interventions that specifically prevent reproductive disease or support fertility. The general objective is to support innate immune function and so reduce the risk that the inevitable inflammation and bacterial contamination after calving progress to reproductive tract disease. Excessive negative energy balance and circulating free fatty acid concentrations, and excessive insulin resistance contribute to a state of metabolic inflammation that may actually impair neutrophil function. While there is a great deal still to be learned about the determinants of metabolic health and reproductive performance in dairy cattle, management practices generally recommended for peripartum dairy cows are likely to contribute to reducing the incidence of reproductive disease in the early postpartum period.