Effects of spirulina as a protein source on ruminal microbial fermentation in the dual-flow continuous culture fermenter system

The objective was to evaluate the effect of a supplemental source of spirulina as a protein source on ruminal microbial fermentation in a dual-flow continuous culture fermenter system. The study consisted of three periods of 11 days with 7 days of adaptation and 4 days of sampling, using 6 dual-flow continuous culture fermenters in a 3×3 replicated latin square design. Experimental treatments included a control (CON) diet consisting of a basal diet including corn silage, dry corn, grass hay, and dried distillers grains with solubles; a spirulina-substituted diet (SPL) consisting of the basal diet with 8% spirulina in place of dried distiller grains with solubles; and a soybean meal-substituted diet (SOY) consisting of the basal diet with 8% soybean meal in place of dried distiller grains with solubles. Spirulina contained 53.7% crude protein on a DM basis with desirable levels of indispensable amino acids such as methionine, leucine and arginine, which are often limited in forage-based diets. Each fermenter was fed 80 g of DM/d, maintained at a constant temperature of (39 °C), and operated with solid (5%/h) and liquid (7%/h) dilution rates. Data were analyzed using the MIXED procedure of SAS 9.4 (SAS Inst. Inc., Cary, NC) with treatment, time, and treatment × time interaction as fixed effects; fermenter and period were considered as random effects. Significance was declared when P ≤ 0.05. Fermenter pH was not affected (P = 0.74) by the interaction of treatment × time but was affected by treatment (P < 0.01) as fermenters fed SPL had a lesser pH than CON and SOY. Fermenters fed SPL had a greater total VFA concentration (P < 0.01) with increased molar proportions of acetate, propionate, and isovalerate (P < 0.01) compared with CON and SOY. Treatment × time effects were detected (P < 0.01) for ammonia where fermenters fed SPL had a greater concentration from h 1 to 4, indicating increased protein availability for microbial use compared with CON and SOY. Fermenters fed SPL had a greater apparent OM digestibility (P = 0.03) compared with CON and SOY. Fermenters fed SPL diets had lesser hydrogen production (P < 0.01) than CON and SOY, indicating a metabolic shift in fermentation pathways, independent of methanogenesis. Fermenters fed SPL had a lesser effluent nitrogen concentration and flow rate (P < 0.01) compared with SOY, indicating increased efficiency of nitrogen utilization. There were no effects of treatment on microbial efficiency (P = 0.12). In summary, spirulina as a protein source had effects on rumen microbial fermentation by adjusting pH, increasing VFA and ammonia concentration, improving apparent OM digestibility, reducing hydrogen, and enhancing nitrogen utilization efficiency, without affecting microbial efficiency.

Name thesis:degree_name

M.S.

Level thesis:degree_level

Thesis

Discipline thesis:degree_discipline

Animal Sciences

Grantor

University of Illinois Urbana-Champaign

Year dc:date

2025

Author dc:creator

• Chen, Wei

Contributors dc:contributor

• McCann, Joshua C
• Shike, Daniel W
• Berger, Larry L.

• Spirulina
• Dual-flow Continuous Culture Fermenter System
• Microalgae

Statement dc:rights

• Copyright 2025 Wei Chen

Language dc:language

en, eng

Handle dc:identifier

https://hdl.handle.net/2142/129338

OAI record oai:identifier

https://www.ideals.illinois.edu/oai-pmh?verb=GetRecord&metadataPrefix=etdms&identifier=oai%3Awww.ideals.illinois.edu%3A2142%2F129338