Ensiling characteristics of wet distillers grains mixed with soybean hulls and evaluation of the feeding value for growing Holstein heifers1

Abstract

Two experiments were conducted to evaluate the fermentation characteristics of ensiled wet corn distillers grains with solubles (WDG) alone or mixed with soybean hulls (SH) and the ability of the mixture to maintain growth performance in dairy heifers. The first experiment was an ensiling study using laboratory silos. Ensiled blends were 100% WDG, 85% WDG with 15% SH, and 70% WDG with 30% SH on an as-fed basis. Silos were opened for analysis on d 0, 3, 7, and 21. The pH was less in the 100% WDG compared with other treatments (P < 0.01), but all treatments had a pH near 4. Lactic acid concentration was greater in 100% WDG compared with the blends of WDG and SH (P < 0.01). Acetic acid was not found in 100% WDG and increased over time in the 2 blends (P < 0.01). Other differences between blends, such as DM, CP, ammonia N, fiber, and fat, were reflective of the different concentrations of WDG and SH in the blends. In the second experiment, the 70% WDG and 30% SH (as-fed) blend was ensiled in a silo bag and then evaluated as a feed for growing dairy heifer diets. Twenty-four heifers were used in a randomized complete block design and assigned to be fed 1 of 3 diets: 1) control, 2) low inclusion of WDGSH, and 3) a high inclusion of WDGSH. All treatment diets consisted of 50% brome grass hay on a DM basis. The control diet had 50% of the diet (DM basis) as a grain mix, which was composed of corn, soybean meal, and minerals. The low WDGSH diet contained 24.4% of the blend and 25.6% grain mix. The high WDGSH diet contained 48.7% of the blend and 1.3% mineral mix. Average daily gain and most of the body growth measures were similar among treatments. However, DMI decreased linearly (P < 0.01) as the WDGSH blends were fed, resulting in improved (P = 0.02) G:F. Results from these experiments indicated that WDG can be effectively ensiled with SH and sustain adequate growth rate when fed to growing dairy heifers.