Effects of Different Levels of Dry-Rolled Corn or Barley on the Utilization of Medium Quality Meadow Hay with Steers and Performance with Heifers

Abstract

In Trial 1, five Angus-Gelbvieh crossbred steers (BW = 295 ± 3kg) fitted with rumen cannulas were used in a 5 × 5 Latin square design to determine intake and digestibility of medium-quality native grass hay (9.5% CP) when supplemented with 0.25% BW dry-rolled corn (low corn; LC), 0.50% BW dry-rolled corn (high corn; HC), 0.25% BW dry-rolled barley (low barley; LB), 0.50% dry-rolled barley (high barley; HB), or when receiving no supplement (NS). Forage DMI decreased with increasing level of corn (P<0.001) and with increasing level of barley (P=0.018) in the supplement (2.27, 2.06, 1.76, 2.11, and 1.95 ± 0.08% BW for NS, LC, HC< LB, and HB, respectively). Organic matter, NDF, and ADF digestibility were not altered (P<0.53) by supplemental treatment. Ruminal fluid pH was significantly changed by supplementation, but pH remained well above 6.2. In Trial 2, 40 weaned, Angus × Gelbvieh heifers (BW = 302 ± 8kg) were used to evaluate measure weight gain of animals fed diets similar to Trial 1. Supplemental treatments were NS, 0.68kg of rolled corn (LC), 1.36kg of rolled corn (HC), 0.68kg of rolled barley (LB); and 1.36kg of rolled barley (HB). Weight gain during the 77-d period was greater (P= 0.002) for all heifers receiving supplements (35, 48, 47, 45, and 55 ± 3kg for NS, LC, HC, LB, and HB, respectively). Both corn and barley supplementation had a linear effect (P<0.04) on weight gains. Neither condition score (5.1, 5.2, 5.2, 5.4, and 5.4 for NS, LC, HC, LB, and HB, respectively) nor condition score change was affected (P<0.37) by treatment. Supplementation with either corn or barley had a quadratic effect on forage and total DMI. These data suggest that with a medium quality meadow hay, either corn or barley can be fed up to 0.5% of BW without affecting total DMI or dietary DM and fiber digestibility, although supplements did decrease forage DMI.