by Amanda Smith, Associate Editor, Hoard's Dairyman

It can be a struggle to keep calf pens stocked with dry bedding, especially when the weather isn't on our side, but recent work shows that it matters. Prior to the University of British Columbia's research, released in the June 2012 Journal of Dairy Science, there was little work evaluating the impact lying surface and dry matter had on calves' behavior.

While it was a small sample size, five 2-week-old Holstein calves were housed in pens bedded with sawdust of differing dry matters. One half of the pen was bedded with kiln-dried sawdust at 90 percent dry matter. The other half of the pen contained wet bedding with dry matter content set at 74, 59, 41 or 29 percent. High dry matter sawdust was also paired with bare concrete as a negative control.

Prior to the study, calves were kept in individual pens bedded with the 90 percent dry matter sawdust used through the rest of the experiment. As the study began, the wall between adjacent pens was removed, giving calves access to a double pen.

Calves were given three days to acclimate to a double pen that was bedded with 67.5 pounds of sawdust at 90 percent dry matter. Afterwards, one side of each pen was bedded with 33.75 pounds of sawdust with one of four levels of dry matter. All calves were exposed to the five treatments for 24 hours.

The time calves spent lying on the wet side dropped as bedding dry matter was reduced. At 74 percent dry matter calves spent approximately five hours per day lying on the wet sawdust and 12 hours on the dry side of the pen. On the wettest bedding, the time dropped to almost zero hours per day as calves stayed on the 90 percent dry matter sawdust. Additionally, calves never chose to lay on bare concrete. Calves spent several hours each day lying down on the 59 percent dry matter bedding.

One criticism of the study was the calves' familiarity with the high dry matter sawdust since it was always available. But, calves had been exposed to bedding of variable dry matters before the experiment began. Regardless, calves always preferred the drier surface to spend their 17 to 18 hours per day lying down.