Location: Cell Wall Biology and Utilization Research
Title: Feed efficiency starts in the rumenAuthor
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Submitted to: Proceedings
Publication Type: Proceedings Publication Acceptance Date: 3/20/2024 Publication Date: 5/14/2024 Citation: Hall, M. 2024. Feed efficiency starts in the rumen. Proceedings. https:/DOI.org//www.naaic.org/Meetings/National/2024meeting/45-Sullivan.pdf. Interpretive Summary: Technical Abstract: An essential element of sustainability is the efficient use of resources. Optimally extracting nutrients from the diet to meet a cow’s nutrient requirements rather than producing manure falls into this category. Rumen microbes can convert fiber that is indigestible by mammals to energy and protein usable by the cow in the forms of volatile fatty acids and microbial cells. At the same time, use of water-soluble carbohydrates (WSC) or protein by rumen microbes can result in reductions in expected yields of nutrients. For example, both protozoa and bacteria convert some portion of WSC to microbial glycogen, an internal storage carbohydrate that they can ferment later. This can help to maintain a healthy rumen pH by slowing down fermentation and acid production, but results in a use of 1 ATP per hexose added to the glycogen chains – a loss of ATP that reduces potential microbial protein yield. At the same time, dietary WSC, especially bona fide “sugars” (e.g., sucrose) are often associated with increased milk fat yields. For protein, microbial action on rumen degradable protein converts some portion to microbial cell walls which are indigestible, and ammonia which may be used by the microbes or excreted. The microbes can also convert nonprotein nitrogen sources such as urea to microbial protein, making protein useful to the cow out of a material that was not. Essential to enhancing ruminal efficiency is understanding factors that affect it and translating those into approaches to diet formulation and management that support the desired results. |
