August 06, 2013

Amino acid digestibility of heat damaged distillers dried grains with solubles fed to pigs

The production of corn distillers dried grains with solubles (DDGS) involves a drying step in which temperature may reach 500°C or greater. The application of heat and moisture to feedstuffs results in the Maillard reaction, which reduces the concentration and digestibility of amino acids. Lysine's chemical structure makes it particularly susceptible to the Maillard reaction. 

However, during the acid hydrolysis step of amino acid analysis, some lysine is recovered from Maillard products, but this lysine cannot be utilised by the animals, and thus, the amount of digestible lysine in a sample may be overestimated. Therefore, methods other than simple lysine analysis must be used when assessing feed that may be heat damaged.

An experiment was conducted to determine the effects of heat damage on the digestibility of crude protein and amino acids in corn DDGS fed to growing pigs. A second objective of the experiment was to develop regression equations to predict the concentration of standardised ileal digestible (SID) amino acids in DDGS.

Experimental design
Ten growing pigs with an average initial body weight of 53.5 kg were surgically equipped with a T-cannula in the distal ileum and fed one of five diets. Corn DDGS from a single source was separated into four batches; the first batch was not autoclaved, and the others were autoclaved at 130°C for 10, 20, or 30 minutes. The concentrations of acid detergent fiber (ADF), neutral detergent fiber (NDF), lignin, ash, reducing sugars, furosine, and acid detergent  insoluble nitrogen (ADIN), and the colors of the DDGS determined as  L* (lightness), a* (redness), and b* (yellowness) were measured in each batch.

Four diets that contained each of the four batches of DDGS were formulated. DDGS was the only source of crude protein and amino acids in the diets. A nitrogen-free diet was used to determine the endogenous losses of crude protein and amino acids. Ileal digesta were collected after a five-day adjustment period to the diets, and analysed for protein and amino acids to determine values for apparent and standardised ileal digestibility of crude protein and amino acids in each batch of DDGS.

Read the full report here.  

Wet Distiller's Grain
Wet Distiller's Grain (Photo credit: agrilifetoday)
 

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