Protein Synthesis In Rumen Research Articles

Effects of Dietary-SCFA on Microbial Protein Synthesis and Urinal Urea-N Excretion Are Related to Microbiota Diversity in Rumen

Two experiments were performed in this study. In Experiment 1, twenty goats were fed with an isonitrogenous diet, containing 28% Non-Fiber Carbohydrate (MNFC group, n = 10) or 14% NFC (LNFC group, n = 10). In the MNFC group, the ruminal concentration of Short Chain Fatty Acids (SCFA) increased, and pH declined. Compared with those in the LNFC group, the microbial protein synthesis in rumen and mRNA abundance of urea transporter B (UT-B) in rumen epithelium increased in the MNFC group, although serum urea-N (SUN) did not differ significantly between groups. Simultaneously, urinal urea-N excretion was reduced in the MNFC group. Significant correlations were found between rumen SCFA and UT-B and between UT-B and urinal urea-N excretion. Furthermore, the abundances of SCFA receptor of GPR41 and GPR43 increased in the rumen epithelium of the MNFC group. These results suggest that increases of SUN transported into the rumen and incorporated into microbial protein and decreases of urinal urea-N excretion are related to ruminal SCFA. This is supported by data from our previous study in which added SCFA on the mucosal side caused increases of urea transport rate (flux Jsm urea) from the blood to the ruminal lumen side. In Experiment 2, we used 16S rRNA Amplicon Sequencing to analyze the structure of the ruminal microbiota community in relation to SCFA. An additional eight goats were assigned into the MNFC (n = 4) and LNFC (n = 4) groups. The dietary ingredients, chemical composition, and feeding regimes were the same as those in Experiment 1. Constrained correspondence analysis (CCA analysis) revealed NFC promoted the expansion of microbiota diversity, particularly of SCFA-producing microbes. The function prediction of 19 upregulated Kyoto Encyclopedia of Genes and Genomes (KEGG) ortholog groups showed an NFC-induced increase of the types and abundances of genes coding for enzymes catalyzing N and fatty acid metabolism. Based on our present and previous investigations, our results indicate that, in goats consuming a MNFC diet, the facilitated urea transport in the rumen and improved urea N salvage are triggered by an expansion of ruminal microbiota diversity and are signaled by ruminal SCFA. This study thus provides new insights into the microbiota involved in the dietary modulation of urea-N salvage in ruminant animals.

Intake, digestibility, rumen protein synthesis, and growth performance of Malawi Zebu steers fed diets containing rangeland-based protein sources.

The study evaluated effects of feeding Malawi Zebu steers with diets containing baobab (Adansonia digitata) seed meal and white thorn tree (Vachellia polyacantha) leaf-meal as alternative protein sources to soybean meal on dry matter intake (DMI), total tract nutrient digestibility, rumen microbial nitrogen supply and growth performance. Thirty Malawi Zebu steers (181 ± 21.4kg and 29months), put into individual pens, were randomly assigned to three treatments (10 steers per treatment) made up of rangeland hay and maize bran with either baobab seed meal (baobab diet), V. polyacantha leaf-meal (Vachellia diet), or soybean meal (soybean diet, control) as the protein source. Steers fed the soybean and baobab diets had higher (P ≤ 0.05) DMI, final BW, average daily gain (ADG), and total tract nutrient digestibility of DM, NDF, CP and crude fat than those fed the Vachellia diet. Steers fed the soybean diet had the highest feed conversion ratio followed by those fed the baobab and Vachellia diets, respectively (P ≤ 0.05). Steers fed the baobab diet had the highest rumen microbial N followed by the soybean- and Vachellia-fed steers in that order (P ≤ 0.05). Steers fed the baobab diet had higher microbial N supply, comparable DMI, ADG, FCR, and nutrient digestibility to the soybean diet. The baobab seed meal could be an alternative protein source to the soybean meal for beef production in Malawi.

Replacement of dicalcium phosphate by rock phosphate in cattle diets: nutrients digestibility, plasma parameters, ruminal fermentation and microbial synthesis efficiency

This study was conducted in order to evaluate the effects of replacing dicalcium phosphate by rock phosphate in diets of growing steers. It was determined the following aspects: apparent digestibility of diets; phosphorus (P), calcium and fluorine apparent absorption; ruminal pH; ruminal ammonia concentration; microbial efficiency and plasma P. Five rumen fistulated Holstein steers weighting 275 - 283 kg were used. Experimental design was a 5 × 5 Latin square and diets consisted of 0, 25, 50, 75 and 100% of dicalcium phosphate replacement by rock phosphate in the mineral supplement. Addition of rock phosphate in the diets produced a linear increase on intake, rumen outflow and fecal output and total disappearance of fluorine. Diets did not differ to apparent absorption of calcium as well as dry matter, organic matter, crude protein, neutral detergent fiber and non-fiber carbohydrates intake, excretion, digestion and partial and total apparent digestibility. Plasma phosphorus was not influenced by diets and the average was 5.93 mg/dL. There was no difference for ruminal pH and ruminal ammonia concentration. Dicalcium phosphate replacement did not affect apparent and true protein microbial synthesis. Total replacement of dicalcium phosphate by rock phosphate in growing steer mineral supplement did not affect ruminal environment and protein synthesis in rumen. Considering this, dicalcium phosphate replacement in growing steer diets decreases P absorption and depending on its requirements it should be carefully seen.

Measurement of microbial protein synthesis in Iranian buffalo rumen (Mazandran Province) by purine derivatives excretion method

Rumen microbes are rich in nucleic acid: around 18% of total nitrogen is present on nucleic acids or 11% in purines. Rumen microbes constitue the major source of protein supply to the ruminant. The purines from the rumen microbes are metabolized and excreted in the urine as their end products: hypoxanthine, xanthine, uric acid and allantoin. In buffalo and cattle because of high xanthine oxidase activity in intestine and blood, hypoxanthine and xanthine convert to uric acid therefore only uric acid and allantoin excreted in urine way (Chen, X. B., Ørskov, E. R., 2003). This research carried out to use excretion of purine derivatives namely allantoin and uric acid as a parameter to estimate the microbial protein synthesis in the rumen of native swamp buffalo in north of iran, Mazandaran Province.

Effect of Feeding Sodium Bicarbonate on Rumen Fermentation and Efficiency of Microbial Protein Synthesis in Buffaloes

Abstract Nangia, O.P. and Sharma, R. 1994. Effect of feeding sodium bicarbonate on rumen fermentation and efficiency of microbial protein synthesis in buffaloes. J. Appl. Anim. Res., 6: 113–120. Three rumen fistulated buffaloes were used to assess the effects of sodium bicarbonate inclusion in their basal diet on rumen water kinetics, rumen fermentation and bacterial protein synthesis. The basal diet consisted of 60% concentrate and40% chopped wheat straw. Sodium bicarbonate increased voluntary water consumption, rumen volume, dilution rate and total outflow rate of rumen. Higher ruminal pH was associated with lower concentration of ruminal TVFA and NH3-N on supplementation with NaHCO3 on one hand and increased blood glucose and microbial protein synthesis in rumen on the other. The total ciliate protozoa population and Entodinia spp. were lower, while Holotrich population was higher in response to sodium bicarbonate. It may be concluded that incorporation of sodium bicarbonate in the diet altered ruminal dilution rate and improved efficiency of microbial protein synthesis.

Nitrogen Metabolism in Rumen and Whole Digestive Tract of Lactating Dairy Cows Fed Grass Silage

Effects of wilting of grass prior to ensiling on OM intake, ruminal digestibility, efficiency of bacterial protein synthesis, and amount and composition of duodenal N fraction were examined using four lactating Holstein cows. Direct-cut or wilted grass silages were fed for ad libitum intake and supplemented with 5.0 or 5.3kg of concentrate, respectively. Milk yield was 18.1 and 21.2 kg/d with direct-cut versus wilted silage, and milk protein and fat contents were 2.63 and 4.60% with direct-cut versus 2.75 and 4.27% with wilted silage, respectively. Wilting of the grass (from 17 to 38% DM) increased OM intake but had no effect on ruminal digestibility. Total N flow and amounts of different AA in proximal duodenum were increased, and the difference was principally of bacterial origin. The efficiency of bacterial protein synthesis in rumen was related to dilution rate of liquid phase and to the time devoted to ruminating. These results indicate that the passage of bacterial protein to the lower digestive tract is a key factor for improving the assimilation of the soluble N fraction of grass silage and that this phenomenon is related to chewing activity.

Protein supplement resistant against ruminal degradation as a factor improving utilization of urea in ruminant feeding.

The metabolic and productive effects of the blood meal and formaldehyde (FA) treated casein supplements (5-10% of crude protein content) given with urea concentrates in sheep and fattening bulls were investigated. The blood meal has a similar composition of essential amino acids (EAA) to casein. The mean solubility of the FA treated casein and the blood meal after 6 hours of incubation in the sterilized rumen contents amounted 10.5% and 8.5% respectively. The average rumen ammonia concentration and plasma urea level was the highest in bulls fed urea ration without protected protein supplement. The supplementation of this ration with blood meal diminished the large daily fluctuation of plasma AA level and increased plasma EAA/NEAA ratio. The blood meal supplement improved the nitrogen retention in sheep (14%) and body gains in bulls (9%) but did not influence digestible coefficients and rumen protein synthesis in sheep.

Microbial phospholipid synthesis as a marker for microbial protein synthesis in the rumen.

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 (33)P-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 < 0.01) between phospholipid synthesis and cell growth. The specific activity of the intracellular inorganic phosphorus did not equilibrate with phosphorus medium. When ruminal contents from sheep fed a high or low protein diet were incubated in vitro, the rate of (33)P 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 (33)P-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 x 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.

Utilization of blood urea in ruminants.

Utilization of injected urea and urea transfer from blood to rumen were investigated. First, urea ( ca. 5 mmole urea-N/kg body weight) was injected intravenously into mature sheep receiving a low-protein, carbohydrate-supplemented ration. Part of the injected urea was recovered in urine as excess over basal excretion. 52% (S.D. = 10) of injected urea was not recovered in urine nor remained in body fluids and presumably was utilized in rumen protein synthesis. Without dietary carbohydrate supplements utilization decreased to 22% (S.D. = 5). Second, ingesta of the rumeno-reticular cavity were replaced with saline; and accumulation of ammonia, representing a hydrolytic product of urea, was measured. Concurrent absorption of ammonia was estimated using arteriovenous urea and ammonia concentration data. Total urea-N transfer, the sum of ammonia-N accumulation and absorption plus salivary urea-N, for sheep was 5.2 mmole urea-N/hr. (S.D. = 0.8), of which 0.3 mmole/hr. was in saliva. Similar results were obtained in the goat.