When cows are not willing to go back to the bunk and eat, the extra nutrients must be mobilized from body tissue reserves. The time between parturition and first ovulation has been reported to be a function of energy balance. If time to first ovulation is extended it could delay the time to potential rebreeding. Excess body condition loss will decrease conception rates. For every full body condition score difference between calving and breeding, conception rate will decrease about 15 percent.
Adequate lighting is necessary to identify correctly cows that are in estrus.
Heat detection inaccuracies and improper timing of insemination can decrease conception rates considerably. During periods of environmental stress, cows may not express estrus. Therefore, the ventilation system must be capable of maintaining a nonstressful environment for cows. Inadequate ventilation can also cause reduced feed intakes leading to increased body tissue reserve mobilization and subsequently reduced conception rates. A cow will not express estrus when she is sick.