KW - microbial protein synthesis

Microbial protein supply from the rumen.

Microbial protein synthesis in rumen and its ..

Methionine is one of the materials for protein synthesis. This study investigates the effects of dietary methionine deficiency followed by replenishment on growth performance and carcass characteristics of lambs. The results show that dietary methionine deficiency in early life retarded the growth and development of lambs. However, the growth rate was not retarded during the 28 days of subsequent methionine replenishment stage.

Effect of ammonia concentration on rumen microbial protein production in vitro.

Maximizing microbial protein synthesis in the rumen

The values of DMD, OMD and CFD in this study are higher than those in the treatment of 100% FOPFs used by Jamarun ., Mariani , Rahayu . and Febrina .,. This is because this treatment combines several feed ingredients such that the composition of nutrient substances donated, particularly the mineral content and s, was more complete. Minerals and more complex s optimize the metabolic activities in the rumen. Rumen microbes also optimally degrade feed ingredients, resulting in increased , and crude fiber feed digestibility.

Phosphate uptake into intracellular inorganic phosphorus and cellular phospholipids and the relationship between cell growth and phospholipid synthesis were studied with suspensions of washed ruminal bacteria in vitro with 33P-phosphorus. It was shown that ruminal bacteria accumulated inorganic phosphate at a low rate when incubated without substrate. Upon the addition of substrate, the rate of inorganic phosphorus uptake into the cells increased markedly, and phospholipid synthesis and cell growth commenced. There was a highly significant relationship (r = 0.98; P 33P incorporation into microbial phospholipids was higher for the high protein diet. Since there was a high relationship between phospholipid synthesis and growth, rumen contents were collected before and various times after feeding and incubated with 33P-phosphorus in vitro. The short-term, zero time approach was used to measure the rate of microbial phospholipid synthesis in whole rumen contents. In these studies the average specific activity of the intracellular inorganic phosphorus was used to represent the precursor pool specific activity. Microbial phospholipid synthesis was then related to protein (N × 6.25) synthesis with appropriate nitrogen-to-phospholipid phosphorus ratios. Daily true protein synthesis in a 4-liter rumen was 185 g. This represents a rate of 22 g of protein synthesized per 100 g of organic matter digested. These data were also corrected for ruminal turnover. On this basis the rate of true protein synthesis in a 4-liter rumen was 16.1 g of protein per 100 g of organic matter digested. This value represents a 30-g digestible protein-to-Mcal digestible energy ratio which is adequate for growing calves and lambs.


The high digestibility of T1 suggested that this combination of forages was more easily degraded by rumen microbes than the other treatments. Low lignin content is very helpful for rumen microbial breakdown of cellulose and hemicellulose feed. The contribution of tithonia to this treatment, in addition to donating proteins, was a reduction in the protozoan population () such that the number of bacteria significantly increased.

Daily true protein synthesis in a 4-liter rumen was 185 g.

Cattle and other ruminants can degrade fibrous feedstuffs owing to the consortium of bacteria, protozoa, fungi, and methanogens inhabiting their rumen and hindgut. This consortium ferments fiber and other feed components to short-chain fatty acids (SCFA) and, in the process, generates ATP that fuels microbial growth (synthesis of cellular protein in particular). This microbial protein supplies 60 to 85% of amino acids (AA) reaching the animal's small intestine (Storm et al., ). Maximizing efficiency of its production would consequently improve cattle productivity.

protein synthesis of microbial rumen was ..

Production of microbial protein is inefficient because microbes do not direct all ATP toward growth. Rather, microbes can direct some ATP toward maintenance functions, synthesis of reserve carbohydrate, or energy spilling (futile cycles that dissipate heat). The impact of maintenance functions on growth efficiency has been recognized for decades and for both pure and mixed cultures (Pirt, ; Russell and Cook, ). Only recently, however, have reserve carbohydrate accumulation and energy spilling been accurately quantified in mixed rumen microbes such that their impact on efficiency can be considered (Hackmann et al., ,; Denton et al., ). We will review these recent advances in the context of other factors that depress efficiency of microbial protein production.

Markers for Quantifying Microbial Protein Synthesis in …

Efforts to increase flow of unsaturated fatty acids stimulated by human health concerns about saturated fat have resulted in another aspect of manipulation of dietary lipid metabolism by rumen microbes. Controlling biohydrogenation to affect absorption of selected fatty acids has been shown to improve the nutritional qualities of milk.