Degree Type


Date of Award


Degree Name

Master of Science


Animal Science


Animal Science

First Advisor

Stephanie L. Hansen


Recent advances in technology support the use of heterotrophic microalgae for the production of oils for bioenergy. Oil is extracted and the resultant product includes a combination of both partially deoiled microalgae (PDM) and soyhulls, resulting in an algae meal (ALG) with a unique profile of protein, fiber, and fat. However, this novel feedstuff and the role it may play in the ruminant diet has not been previously characterized. Since PDM is not available commercially to producers separate from soyhulls, the whole product was used for the current research. Thus, the ensuing research trials were designed to: 1) determine the impact of replacing soyhulls with the PDM portion of ALG on lamb total tract nutrient digestibility, 2) evaluate the effects of ALG when fed at the expense of corn on total tract nutrient digestibility of finishing lambs, and 3) identify the impact of replacing corn with increasing inclusions of ALG on steer performance, mineral status, carcass characteristics, and steak fatty acid composition. Within our first research objective PDM was readily consumed by lambs when included at up to 30% of the diet DM. Additionally, changes in digestibility of specific nutrients with increasing inclusions of PDM at the expense of soyhulls suggest that PDM is more characteristic of a concentrate than a fibrous feedstuff. Within our second research objective, ALG increased DMI as well as NDF, ADF, and ether extract digestibility. However, overall DM digestibility did minimally decrease. Still, results suggested that ALG is readily consumed by lambs and in relation to corn offers a comparable digestibility. Finally, the addition of ALG to feedlot diets showed minimal effect on live and carcass based performance. However, because DMI was linearly increased by ALG, feed efficiency decreased suggesting that ALG may have a lesser feeding value than corn. While no differences were noted in the PUFA, MUFA, SFA, or the ratio of PUFA-to-SFA in the longissimus thoracis of ALG fed steers, there was a favorable linear decrease in the atherogenic index. Feeding ALG may offer producers a viable way to improve the health benefits of meat by favorably altering the fatty acid profile. The findings of our experiments suggest that ALG offers a unique nutrient profile and may be a viable component of ruminant diets. Further research is warranted to determine how this feedstuff will be best utilized in the livestock industry, including synergies with other feedstuffs and commonly utilized technologies as well as the role this feedstuff may have in supplementing high forage diets.


Copyright Owner

Rebecca Sue Stokes



File Format


File Size

125 pages