Interpretive Summary: Effect of inclusion of distillers grains with solubles and crude glycerin in beef cattle finishing diets on ruminal fermentation and fatty acid biohydrogenation

By: Haley E Larson, Grant I Crawford, Ryan B Cox, Alfredo DiCostanzo

Inclusion of corn grain in cattle diets increases the dietary concentration of unsaturated fatty acids like linoleic acid. Ethanol co-products are most often made from corn grain in the United States and contain concentrated amounts of unsaturated fatty acids. Concerns with feeding ethanol co-products could arise for cattle producers because the increased unsaturated fat concentration of meat products can lead to shorter meat shelf life. Co-products from bio-diesel production, such as crude glycerin, can be used to replace grain and reduce total unsaturated fat without affecting dietary energy. This study evaluated the effect of ruminal microbes to transform unsaturated fatty acids to saturated fatty acids in diets where steam-flaked corn was replaced by co-products such as distillers grains and crude glycerin. When steam-flaked corn is replaced with distillers grains in beef cattle diets, the fat composition was shifted to a higher proportion of saturated fatty acids due to increased biohydrogenation by ruminal microbes. However, feeding crude glycerin in place of steam-flaked corn increased conjugated linoleic acid, an intermediate product of the fatty acid transformation pathway. Increased conjugated linoleic acid indicates glycerin may impact the ability of microbes to transform linoleic acid to a saturated form.