Growth performance and total-tract nutrient digestion for Holstein heifers limit fed diets high in distillers grains with different forage particle sizes

Abstract

ABSTRACT This study evaluated dairy heifer growth performance and total-tract nutrient digestion when fed diets high in distillers dried grains with solubles with different forage particle sizes. An 8-wk randomized complete block design study was conducted using 22 Holstein heifers (123 ± 32 d of age; BW 140 ± 23.5 kg). Treatments were 15% chopped (CHOP) or 15% pelleted (PELL) alfalfa hay on a DM basis. Both diets also contained 30% distillers dried grains with solubles, 53.8% corn silage, and 1.25% mineral mix and were limit fed for DMI at 2.3% of BW. Growth measurements were taken every 2 wk, and jugular blood samples were taken every 4 wk. During wk 8, rumen samples were taken on 2 d via esophageal tubing to evaluate fermentation, and fecal grab samples were collected at 8 times over 3 d and composited by heifer to determine total-tract nutrient digestion. Heifer DMI increased with CHOP, and BW and ADG were similar between treatments. Feed efficiency was less in the CHOP-fed heifers. Frame measurements were similar, with the exceptions of paunch girth, heart girth, and hip width, which were greater for CHOP. The CHOP-fed heifers had less BCS than PELL. Rumen fermentation characteristics were similar; however, rumen pH was greater for PELL. Serum glucose and plasma cholesterol were similar between treatments, but plasma urea nitrogen tended to be greater in heifers fed CHOP. Total-tract digestibility of nutrients was similar between treatments. Results indicate that forage particle size minimally affects utilization of distillers dried grains with solubles by heifers.