Effects of corn grinding and time of corn feeding on growth, starch utilization and digesta passage characteristics of growing steers fed hay-based diets

Two forms of corn, whole (WC) and ground (GC), were fed with hay (WH; 900) or 4 h after hay (AH; 1300) feeding to evaluate their effects on growth, starch utilization and digesta passage characteristics in growing steers. Twenty-four Angus steers with ad libitum access to fescue hay were individually limit-fed ground or whole corn (2.27 kg/d) in a 2 x 2 factorial arrangement of treatments: GC- WH, GC-AH, WC-WH and WC-AH. Average daily gain was improved with feeding GC (P less than .08), especially when fed at the same time as hay. Fecal starch (%) was less (P less than .001) for GC (7.07) than for WC (15.68). No difference was observed in rate of liquid or solid (hay) passage. Mean retention time (MRT) of whole corn (stained with neutral red and crystal violet) was decreased (P less than .07), and rate of corn passage tended to be faster for steers fed WC-AH than for those fed WC-WH. Although time of corn feeding had no effect on performance, steers fed WC-AH had more whole corn particles recovered from the feces and the MRT for whole corn particles was reduced, indicating that time of supplementation may affect passage characteristics. Altering time of supplement feeding may have applications in other feeding situations, such as with protein supplementation where ruminal escape would be advantageous.