Distillers dried grains with solubles (DDGS) are fed to pigs as a source of energy and amino acids. In recent years, ethanol plants have begun recovering corn oil from DDGS to sell for biodiesel and other uses. Conventional corn DDGS contains 10-12 fat, compared with 5-9% fat in low oil DDGS. Previous research in our lab showed that amino acid digestibility was reduced in low oil DDGS compared with conventional DDGS, but that research used DDGS from only one supplier. An experiment was conducted to compare the digestibility of amino acids in low oil DDGS sourced from multiple different suppliers.

Experimental design

The experiment used seven sources of DDGS obtained from different suppliers, and these were labeled DDGS A through DDGS H. Diets containing each source of DDGS as the sole source of amino acids were formulated and fed to seven groups of growing barrows (average initial body weight: approximately 65 kg). A nitrogen-free diet was also fed to determine the basal endogenous losses of amino acids and protein.

Ileal digesta samples were collected, and the apparent ileal digestibility (AID) of crude protein and amino acids were calculated for the seven sources of DDGS. The AID of crude protein and amino acids were corrected for basal endogenous losses to determine the standardized ileal digestibility (SID) of these components.

Variability in SID of amino acids among different sources of DDGS

The concentrations of acid hydrolyzed ether extract (AEE) in the seven sources of DDGS ranged from 7.19% in DDGS G to 9.14% in DDGS B (Table 1). There was little variability in the concentrations of crude protein and amino acids among the seven sources.

The SID of crude protein did not differ among the DDGS sources. The SID of lysine ranged from 61.4% in DDGS D to 73.5% in DDGS B (Table 2) and differences among sources were observed (P < 0.05). The SID of most other amino acids also differed (P < 0.05) among sources. The average SID of all amino acids ranged from 78.8% in DDGS D to 88.1% in DDGS B. These differences are likely due to different methods of processing and fat extraction.

The average SID of most AA in the seven sources of DDGS was greater than what has been reported in the past for both low-oil and conventional DDGS. One reason for this observation may be that the concentration of lysine expressed as a percentage of crude protein was greater in all seven of the sources of DDGS used in this work, which indicates that these sources of DDGS were not heat damaged to the same degree as previous sources have been. This likely explains the greater SID of not only lysine but also other amino acids in the DDGS. As a consequence of this increased digestibility of amino acids, the seven sources of DDGS that were included in this work have greater protein value than sources used in previous research.

Key points

• The amount of fat removed from DDGS varies among suppliers.
• DDGS sourced from different suppliers varied little in crude protein and amino acid content.
• There is variability in SID of amino acids among different sources of DDGS, which may be due to different processing methods.
• The DDGS used in this experiment appears to be less heat damaged compared with DDGS used in previous experiments, which results in increased protein value.

Table 1. Analyzed nutrient composition of distillers’ dried grains with solubles (DDGS), as-fed basis

Table 2. Standardized ileal digestibility of crude protein and amino acids in distillers’ dried grains with solubles (DDGS)

^a-d Means within a row with different superscripts differ (P ≤ 0.05).

This report is based on unpublished research by Charmaine Espinosa and Hans H. Stein.