Gestation length is dependent on many factors. The default setting for gestation in BoviSync is based on published research.* Breed, parity, month due, sex, twin status, and conception sire (GL PTA) all are factors that BoviSync takes into account to calculate gestation. Using the predicted due date improves the accuracy of management decisions over DCC alone. Closeup moves based on a single DCC may shortchange the time in the closeup pen for animals that are likely to calve earlier. By using the default due date for dry and closeup management it is possible to actually simplify protocols. 

If a producer really wants to dial in dry and closeup protocols, a due date that reflects the likelihood of freshening is preferable to separate lists of protocols by DCC.

To utilize the default due date, set the "Herd Settings" in Setup to blank or by breed. Any integer (like a value for DCC) recorded in "Gestation Length" will become the value of the gestation length for animals in the herd. 

*2009 H.D.Norman J.R.Wright M.T.Kuhn S.M.Hubbard J.B.Cole P.M.VanRaden

*CDCB Gestation Length, 8 August 2017