New research published in the January Journal of Dairy Science takes a look at how exposure to grain or hay at an early age impacts feeding behavior post-weaning.
University of Guelph researchers randomly assigned eight Holstein bull calves at birth to a feed exposure treatment of concentrate or grass/alfalfa hay. Both feeds were offered ad libitum.
After weaning, calves were fed a mixed ration containing 60 percent concentrate and 40 percent grass/alfalfa hay for nine weeks.
Calves exposed to concentrate tended to have greater dry matter intake both before and after weaning than calves exposed to hay. Weights were similar during the milk-feeding stage, but calves exposed to concentrate had greater weights overall in the post-weaning stage.
Initially after weaning, calves sorted for familiar feed; calves previously exposed to concentrate sorted for short particles, which were primarily concentrate, whereas calves previously exposed to hay did not. Calves previously exposed to hay tended to sort for long particles, which were solely hay, whereas calves previously exposed to concentrate sorted against them.
The sorting observed for short particles was associated with consuming a diet with a greater concentration of protein, non-fiber carbohydrates, and metabolizable energy, whereas sorting for long particles was associated with consuming a diet with a greater concentration of neutral detergent fiber.
After four weeks of exposure to the mixed ration, sorting was similar between treatments, with calves in both treatment groups sorting for short and against long particles and consuming a diet with a similar concentration of nutrients and energy.
Researchers concluded that feed familiarity affected initial diet selection post weaning, but may not have a lasting effect, with all calves developing similar feed-sorting patterns.
Source: Journal of Dairy Science