Amino acid composition of rumen bacteria and protozoa in cattle
| Autor: | Hélène Lapierre, Doris Pellerin, Jeffrey L. Firkins, D.R. Ouellet, M. Sok |
|---|---|
| Rok vydání: | 2017 |
| Předmět: |
0301 basic medicine
Rumen Duodenum Microorganism Protozoan Proteins 03 medical and health sciences Hydrolysis Methionine Bacterial Proteins Genetics Animals Cysteine Food science Amino Acids chemistry.chemical_classification Alanine Bacteria biology Lysine 0402 animal and dairy science 04 agricultural and veterinary sciences biology.organism_classification Animal Feed 040201 dairy & animal science Amino acid 030104 developmental biology Biochemistry chemistry Protozoa Cattle Digestion Animal Science and Zoology Acid hydrolysis Composition (visual arts) Food Science |
| Zdroj: | Journal of Dairy Science. 100:5241-5249 |
| ISSN: | 0022-0302 |
| DOI: | 10.3168/jds.2016-12447 |
| Popis: | Because microbial crude protein (MCP) constitutes more than 50% of the protein digested in cattle, its AA composition is needed to adequately estimate AA supply. Our objective was to update the AA contributions of the rumen microbial AA flowing to the duodenum using only studies from cattle, differentiating between fluid-associated bacteria (FAB), particle-associated bacteria (PAB), and protozoa, based on published literature (53, 16, and 18 treatment means were used for each type of microorganism, respectively). In addition, Cys and Met reported concentrations were retained only when an adequate protection of the sulfur groups was performed before the acid hydrolysis. The total AA (or true protein) fraction represented 82.4% of CP in bacteria. For 10 AA, including 4 essential AA, the AA composition differed between protozoa and bacteria. The most noticeable differences were a 45% lower Lys concentration and 40% higher Ala concentration in bacteria than in protozoa. Differences between FAB and PAB were less pronounced than differences between bacteria and protozoa. Assuming 33% FAB, 50% PAB, and 17% of protozoa in MCP duodenal flow, the updated concentrations of AA would decrease supply estimates of Met, Thr, and Val originating from MCP and increase those of Lys and Phe by 5 to 10% compared with those calculated using the FAB composition reported previously. Therefore, inclusion of the contribution of PAB and protozoa to the duodenal MCP flow is needed to adequately estimate AA supply from microbial origin when a factorial method is used to estimate duodenal AA flow. Furthermore, acknowledging the fact that hydrolysis of 1 kg of true microbial protein yields 1.16 kg of free AA substantially increases the estimates of AA supply from MCP. |
| Databáze: | OpenAIRE |
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