Evaluation of nutritional value of Ulva sp. and Sargassum horneri as potential eco-friendly ruminants feed

Abstract

Ulva sp. and Sargassum horneri has been bloomed in Korea. To utilize the biomasses of Ulva sp. and S. horneri as ruminant feed ingredients, their nutritional values were identified through rumen in situ and in vitro trials using two cannulated Holstein cows. In the in situ trial, the rumen dry matter, organic matter, and crude protein degradation characteristics of Ulva sp. and S. horneri were compared with those of the alfalfa hay. The dry matter effective rumen degradability of Ulva sp. was similar to that of the alfalfa hay, while S. horneri demonstrated the lowest values in this regard. The organic matter effective rumen degradability of Ulva sp. was lower than that of the alfalfa hay, and similar to that of S. horneri. The rumen undegradable protein of Ulva sp. and S. horneri were greater than those of the alfalfa hay. For the in vitro trial, total mixed rations containing Ulva sp. and S. horneri, respectively, at six concentrations (0, 0.5, 1, 2, 3 and 4% of dry matter) were formulated, maintaining protein, energy and fiber contents. The 4% inclusion of Ulva sp. decreased rumen CH4, NH3, and total volatile fatty acid production. The inclusion of S. horneri did not affect the total volatile fatty acid production but decreased rumen CH4 and NH3. In summary, the nutritional values of Ulva sp. and S. horneri as potential CH4 reducing feeds were verified. Utilizing Ulva sp. and S. horneri as ruminant feed would be an effective and innovative way to utilize the massive biomasses bloomed in Korea while also promoting sustainable development in the livestock industry.