Prime Archives in BiochemistryThe Occurrence of a Negative Energy Balance in Holstein-Friesian and Simmental Cows and Its Association with the Time of Resumption of Reproductive ActivityDownloadThe-Occurrence-of-a-Negative-Energy-Balance-in-Holstein-Friesian-and-Simmental-Cows-and-Its-Association-with-the-Time-of-Resumption-of-Reproductive-Activity