Dietary Protein Degradability Research Articles

Effect of low dietary concentrations of Acacia mearnsii tannin extract on chewing, ruminal fermentation, digestibility, nitrogen partition, and performance of dairy cows

The supplementation of dairy cows with tannins can reduce the ruminal degradation of dietary protein and urine N excretion, but high concentration in the diet can impair ruminal function, diet digestibility, feed intake, and milk yield. This study evaluated the effect of low concentrations (0, 0.14, 0.29, or 0.43% of diet in DM basis) of a tannin extract from the bark of Acacia mearnsii (TA) on milking performance, dry matter intake (DMI), digestibility, chewing behavior, ruminal fermentation, and N partition of dairy cows. Twenty Holstein cows (34.7 ± 4.8 kg/d, 590 ± 89 kg, and 78 ± 33 d in lactation) were individually fed a sequence of 4 treatments in 5, 4 × 4 Latin squares (with 21-d treatment periods, each with a 14-d adaptation period). The TA replaced citrus pulp in the total mixed ration and other feed ingredients were kept constant. Diets had 17.1% crude protein, mostly from soybean meal and alfalfa haylage. The TA had no detected effect on DMI (22.1 kg/d), milk yield (33.5 kg/d), and milk components. The proportions in milk fat of mixed origin fatty acids (16C and 17C) and the daily secretion of unsaturated fatty acids were linearly reduced and the proportion of de novo fatty acids was increased by TA. Cows fed TA had linear increase in the molar proportion of butyrate and linear reduction in propionate in ruminal fluid, whereas acetate did not differ. There was a tendency for the ratio of acetate to propionate to be linearly increased by TA. Cows fed TA had a linear reduction in the relative ruminal microbial yield, estimated by the concentrations of allantoin and creatinine in urine and body weight. The total-tract apparent digestibility of neutral detergent fiber, starch, and crude protein also did not differ. The TA induced a linear increase in meal size and duration of the first daily meal and reduced meal frequency. Rumination behavior did not differ with treatment. Cows fed 0.43% TA selected against feed particles >19 mm in the morning. There were tendencies for linear decreases in milk urea N (16.1-17.3 mg/dL), urine N (153-168 g/d and 25.5-28.7% of N intake), and plasma urea N at 6, 18, and 21 h postmorning feeding, and plasma urea N 12 h postfeeding was reduced by TA. The proportion of N intake in milk (27.1%) and feces (21.4%) did not differ with treatment. Reductions in urine N excretion and milk and plasma urea N suggest that TA reduced ruminal AA deamination, whereas lactation performance did not differ. Overall, TA up to 0.43% of DM did not affect DMI and lactation performance, while there was a tendency to reduce urine N excretion.

Effects of dietary protein concentration and degradability on performance, carcass characteristics, net energy utilization, and metabolizable protein balance of finishing beef heifers receiving 0 or 400 mg of ractopamine hydrochloride

This study evaluated the effects of feeding beef cattle finishing diets with greater than 14.0% dietary CP and with or without ractopamine hydrochloride (RH) on growth performance, carcass merit, net energy utilization, and metabolizable protein balance. Heifers (n = 525) were assigned to 48 pens in a generalized complete block design, and pens of cattle were assigned randomly to 0 or 400 mg of RH/animal per day and 3 CP treatments in a 2 × 3 factorial arrangement (n = 8 pens/treatment) fed for 35 d before slaughter. Dietary protein treatments were steamflaked corn-based diets containing 13.9% CP, 8.9% RDP, and 5.1% RUP (CON); 20.9% CP, 14.4% RDP, and 6.5% RUP (High RDP); or 20.9% CP, 9.7% RDP, and 11.2% RUP (High RUP) on a DM basis. No RH × CP interactions were observed. Final BW, ADG, water disappearance, DMI, and G:F were not different among CP treatments. Dressing percentage was greater for cattle fed High RDP than for those fed High RUP, but other carcass outcomes did not differ. The MP balance was greatest for High RUP, intermediate for High RDP, and least for CON. Cattle receiving 400 mg of RH had greater final BW, ADG, G:F, and hot carcass weight. The LM area was greater and KPH was less for 400 versus 0 mg of RH. Carcass-adjusted final BW, ADG, and G:F were greater for cattle consuming 400 mg of RH. Cattle fed 400 mg of RH had greater performance-adjusted and observed:expected NEm and NEg. The MP balance was less for 400 versus 0 mg of RH. Dietary CP requirements were greater for cattle fed 400 compared with 0 mg of RH but did not exceed the CP supplied by CON, High RDP, or High RUP. Feeding greater than 14.0% CP does not negatively affect performance or carcass characteristics of finishing cattle, and the absence of interactions between CP and RH suggests that RH does not increase CP requirements above those provided in a typical finishing cattle diet.

Estimating the proportion of in situ rumen-undegraded crude protein from chemical crude protein and fiber fractions in tropical forage grasses and legumes

Advanced methods exist to estimate dietary crude protein (CP) degradation in the rumen from the concentrations and/or proportions of chemical nutrient fractions. These methods have been developed primarily for feeds in temperate climates. Therefore, their accuracy and precision to predict proportions of rumen-undegraded CP (RUP) in tropical forages is uncertain. The objectives of the present study were (1) to assess the accuracy and precision of the estimates of in situ RUP proportions from CP fractions using established algorithms, and (2) to identify chemical nutrient fractions that accurately and precisely predict RUP proportions of tropical forages. The proximate nutrients, CP and fiber fractions of 23 unconserved forage grasses and 15 forage legumes commonly used as feeds for ruminants in the Tropics and Subtropics were analyzed. Their RUP proportions were determined at ruminal passage rates (Kp) of 2%, 5%, and 8%/hour using the in situ method (i. e., reference) and were also estimated from the analysis of the CP and fiber fractions using established equations. The RUP proportions determined with the in situ and the chemical method were evaluated using error index and dimensionless parameters. The nutritional composition variables that can predict RUP proportions of tropical forages (proximate nutrients, fiber, and CP fractions and their ratios) were selected using stepwise multiple linear regression models. The CP concentrations of our sample set ranged from 46 to 212 g/kg dry matter with in situ RUP proportions from 73 to 596 g/kg CP across all Kp. Previously established equations could not predict accurately and precisely RUP proportions of all forages. The concentrations of CP and fiber fractions and Kp were able to predict the proportion of RUP estimated in situ for tropical forages at Kp of 2%, 5%, and 8%/hour with an adjusted coefficient of determination ranging from 0.79 to 0.82 and a root mean square error ranging from 13% to 15% of the mean in situ RUP proportion. While equations established for temperate forages either over- or underestimate RUP proportions, algorithms developed in the present study might allow for an accurate and precise prediction of RUP proportions in forages commonly used in ruminant feeding in the Tropics and Subtropics.

352 A Century and a Half of Nitrogen and Protein Metabolism in Ruminants

Abstract By 1870, we knew plants and animals contained protein, and the participation of protein and urea in animal and human N metabolism was recognized. Nitrogen balance studies had been conducted, and the atomic theory was established. By 1900, research established the concepts of energy and protein metabolic interactions, the role for urea in ruminant metabolism, amino acids as constituents of protein molecules, and enzyme-catalyzed reactions. Research stations were publishing research results and feeding recommendations. By 1950, the concept of biological value was established, and we knew ruminal microorganisms use dietary NPN, degrade dietary protein, and form microbial protein as a source of amino acids for ruminant tissue protein. By 2000, hypothesis-driven, statistically valid experimental designs created quantitative information on metabolizable protein and essential amino acid requirements. Use of surgically altered animals, isotopically labelled molecules, and standardized laboratory analyses created quantitative information on ingestion, ruminal degradability of dietary protein, digestion, absorption, and metabolism of N-containing compounds. Research showed that ruminants respond to manipulation of postruminal amino acid supply. We had elucidated protein composition and structure, the role of protein turnover to determine the concentration of cellular proteins, and the quantitative significance of protein turnover to whole body protein metabolism. The internet and the advent of international symposia provided links among researchers around the globe. By 2020, proteomics and metabolomics enhanced description of underlying control mechanisms related to amino acid metabolism. Research quantified integration of amino acid supply and use among body tissues. Multidisciplinary research teams had created empirical and mechanistic models. Those models currently use or estimate rates and daily amounts of ruminal (in)degradability of dietary protein, ammonia production, urea recycling, microbial protein synthesis, postruminal protein digestion, metabolic fecal nitrogen, and amino acid absorption and metabolism. They predict use of metabolizable amino acids for maintenance, reproduction, postnatal growth, and lactation.

Dietary protein degradability effect on performance of lambs experimentally infected with Haemonchus contortus and Trichostrongylus colubriformis.

The study investigated the effects of dietary protein degradation rate on growth performance and immune response of crossbred Dorper × short-tail Han ram lambs experimentally infected with Haemonchus contortus and Trichostrongylus colubriformis. Eighteen lambs were randomly assigned to three dietary treatments, rapidly degradable protein (RDP), moderately degradable protein (MDP), and slowly degradable protein (SDP) diets. Feed intake and body weight of the lambs were recorded weekly until 42days post-infection. The fecal egg count (FEC), FAMACHA scores, and immunoglobulins (IgG, IgM and IgA) were also monitored during the experimental period. A metabolic trial was conducted to assess apparent digestibility and volatile fatty acids were also determined. The lambs in SDP and MDP groups had higher feed, nutrient intake, weight gain, and feed efficiency than those in the RDP group. Feed conversion ratio (FCR) of the lambs in RDP group was higher than those in the SDP and MDP groups. A significant (P < 0.001) decrease in FEC was observed in the SDP and MDP groups. Dietary treatment had no significant effect on FAMACHA scores and concentration of serum antibodies. Concentration of acetic acid was higher (P < 0.013) in the lambs fed RDP than those fed the SDP and MDP diets. The lambs fed SDP diet had higher apparent digestibility than those fed the RDP diet. The poor performances in RDP group could be overcome by including SDP that ensures adequate post-ruminal protein supply reaching the small intestine.

Effect of dietary protease supplementation on growth performance, water quality, blood parameters and intestinal morphology of Nile tilapia (Oreochromis niloticus).

This study was conducted to evaluate the effect of using protease in diets of Nile tilapia on growth performance, water quality, blood parameters and intestinal morphology. The cost of these diets and their return on fish performance was calculated. A total of 360 fish were randomly allocated into four groups with triplicates (30fish per replicate). Four diets were formulated; two controls (without protease supplementation) and two experimental diets (supplemented with protease). The first control diet contained the normal protein requirement (30% CP; control +ve), while the second control had a low protein content (29% CP; control -ve). The third diet was supplemented with protease at a dose of 500g/ton, and its CP content was reduced to 29.0%, by reducing the fish meal content. The fourth diet contained the same CP level as the first control (30%) and supplemented with 250g protease per ton feed. The experiment lasted for 14weeks. The results showed that body weight and length, weight gain, specific growth rate, feed intake and feed conversion efficiency in the control -ve group (low CP) supplemented with protease were similar (p>0.05) to that of the control +ve with normal CP content. However, these performance parameters were lower (p<0.05) in fish fed low CP diet without protease supplementation. Providing protease to the control +ve diet improved all measured performance indices. The ammonia and nitrite concentrations of the water were reduced (p<0.05) in control -ve and protease-supplemented groups. The height and width of intestinal villi were increased (p<0.05) in fish fed diets containing protease. The inclusion of protease reduced the diet cost and also the feed cost of fish weight gain. In conclusion, supplementation of protease can improve the productive performance of fish, spare dietary protein and produce economical diets. Moreover, it can help in improving the water quality of fish via lowering the ammonia and nitrite contents, or through increasing the degradation of dietary protein.

Relationship between feed protein content and faeces nitrogen content in early lactation dairy cows

Relationship between feed protein content and faeces nitrogen content in early lactation dairy cows

386 Past, present and future of protein and N metabolism in ruminants

Abstract By 1900, research identified urea, ammonia, and protein as the basic components of N metabolism in ruminants. Energy and protein metabolic interactions were outlined, amino acids were individually recognized as constituents of protein molecules, and the concept of enzyme-catalyzed reactions was established. Research stations were publishing research results and feeding recommendations. By 2000, the National Research Council built on the work of Henry and Morrison to create and revise publications of nutrient requirements for various classes of ruminants. Use of surgically altered animals, isotopically labelled molecules, and standardized laboratory analyses created quantitative information on ingestion, digestion, absorption, and metabolism of N-containing compounds. Protein composition and structure as well as the role of protein turnover to determine the concentration of cellular proteins were elucidated. Hypothesis-driven, statistically valid experimental designs created quantitative information on protein and amino acid requirements. Methionine was identified as the likely first-limiting amino acid for several ruminant species and production states. The internet and the advent of international symposia provided links among researchers around the globe. Today, multidisciplinary research teams are needed to enlarge the data base, to describe proteomics and metabolomics, and to integrate “big data” into insightful and useful models. Those models currently use or estimate rates and daily amounts of ruminal (in)degradability of dietary protein, ammonia production, urea recycling, microbial protein synthesis, postruminal protein digestion, metabolic fecal nitrogen, and amino acid absorption and metabolism. They predict use of metabolizable amino acids for maintenance, milk yield, growth, and fetal growth. Directions of future research include integration of functional roles of amino acids into recommended dietary supply and requirements, and focus on solutions to challenges presented by climate change, (in)sustainability of livestock production, and changes in public perception of humans’ use of ruminants and other animals.

PSXI-19 Levels of a blend of clove, castor and cashew oils and microencapsulated active ingredients (eugenol, thymol and vanillin) against some ruminal Prevotella

Abstract This study was conducted to evaluate the effect of a blend of vegetable oils and active ingredients (Ruminatus® - safeeds@safeeds.com.br) on ruminal population density of Prevotella albensis, Prevotella bryantii and Prevotella ruminicola. The blend contained clove (Eugenia caryophyllata), castor (Ricinus communis) and cashew (Anacardium occidentale) oils and microencapsulated active ingredients (eugenol, thymol and vanillin). The experiments were designed using each bacteria exposed to doses of 1.5; 3.0; 4.5 and 6.0 mg/ml of the product and having six replicates. Bacteria were cultivated on Hobson’s M2 medium in Hungate tubes. Cultures cultivated without the addition of any oils were considered as control. Bacteria were cultivated overnight and freshly inoculated into new tubes containing medium. The antimicrobial activity was evaluated using a Spectrophotometer Evolution 201 UV-visible (Thermo Scientific) at 600 nm. Readings were performed at 0, 8, 12 and 24 hours after inoculation. Data were analyzed using the linear mixed models and the NLME Procedure in R software. The use of the blend reduced (P &amp;lt; 0.05) the population density of P. albensis and P. bryantii in comparison to the control treatment. P. ruminicola population only decreased (P &amp;lt; 0.05) when 3.0 mg/ml of the blend was used. Growth impairment of Prevotellaceae prevent excessive degradation of dietary protein, increasing protein digestibility. In addition, there is a reduction on ammonia synthesis, the end product of proteolysis, which is excreted in animal waste. Therefore, the combined action of clove, castor and castor essential oils and microencapsulated active ingredients influences the growth of Gram-negative bacteria and can be used as a rumen modulator.

Diet‐derived microbial metabolites in health and disease

AbstractThe gut microbiota helps us digest food and has been associated with both good health and risk of disease. Although compositions of the gut microbiota are highly divergent, the gut microbiota exhibits a high level of functional redundancy making it difficult to reliably link gut microbiome patterns to health and diet across individuals. Thus, there is a need to move beyond profiling of the gut microbial composition to the assessment of gut microbial metabolic activity in order to expand knowledge on the impact of the gut microbiota on health. Metabolomics has already proven its utility in identifying gut‐derived microbial metabolites, which may be mediators of diet‐induced host–microbial crosstalk important for health. These diet‐derived metabolites include, among many others, the short‐chain fatty acids originating from bacterial degradation of dietary fibres and proteins, secondary bile acids derived from primary bile acids, microbial tryptophan catabolites resulting from proteolysis, imidazole propionate produced from histidine and trimethylamine N‐oxide, a host–microbial co‐metabolite of nutrients such as phosphatidylcholine, choline and L‐carnitine, present in high‐fat foods. These co‐metabolites have been associated with beneficial and detrimental effects in the host. However, the vast majority of metabolites measured by untargeted metabolomics in human blood and excreta remain unknown and may include additional microbial molecules of importance for health. Thus, there is great potential, yet to be explored, for identifying additional diet‐derived microbial products that affect the host. Herein, we review key advances, challenges and limitations in our understanding of diet–microbiome interactions and diet‐derived microbial metabolites in relation to human health and discuss how metabolomics may shed light on inter‐individual differences in dietary responses.

Invited review: Nitrogen in ruminant nutrition: A review of measurement techniques

Nitrogen is a component of essential nutrients critical for the productivity of ruminants. If excreted in excess, N is also an important environmental pollutant contributing to acid deposition, eutrophication, human respiratory problems, and climate change. The complex microbial metabolic activity in the rumen and the effect on subsequent processes in the intestines and body tissues make the study of N metabolism in ruminants challenging compared with nonruminants. Therefore, using accurate and precise measurement techniques is imperative for obtaining reliable experimental results on N utilization by ruminants and evaluating the environmental impacts of N emission mitigation techniques. Changeover design experiments are as suitable as continuous ones for studying protein metabolism in ruminant animals, except when changes in body weight or carryover effects due to treatment are expected. Adaptation following a dietary change should be allowed for at least 2 (preferably 3) wk, and extended adaptation periods may be required if body pools can temporarily supply the nutrients studied. Dietary protein degradability in the rumen and intestines are feed characteristics determining the primary AA available to the host animal. They can be estimated using in situ, in vitro, or in vivo techniques with each having inherent advantages and disadvantages. Accurate, precise, and inexpensive laboratory assays for feed protein availability are still needed. Techniques used for direct determination of rumen microbial protein synthesis are laborious and expensive, and data variability can be unacceptably large; indirect approaches have not shown the level of accuracy required for widespread adoption. Techniques for studying postruminal digestion and absorption of nitrogenous compounds, urea recycling, and mammary AA metabolism are also laborious, expensive (especially the methods that use isotopes), and results can be variable, especially the methods based on measurements of digesta or blood flow. Volatile loss of N from feces and particularly urine can be substantial during collection, processing, and analysis of excreta, compromising the accuracy of measurements of total-tract N digestion and body N balance. In studying ruminant N metabolism, nutritionists should consider the longer term fate of manure N as well. Various techniques used to determine the effects of animal nutrition on total N, ammonia- or nitrous oxide-emitting potentials, as well as plant fertilizer value, of manure are available. Overall, methods to study ruminant N metabolism have been developed over 150 yr of animal nutrition research, but many of them are laborious and impractical for application on a large number of animals. The increasing environmental concerns associated with livestock production systems necessitate more accurate and reliable methods to determine manure N emissions in the context of feed composition and ruminant N metabolism.

Effect of dietary crude protein degradability and corn processing on lactation performance and milk protein composition and stability

The present study aimed to evaluate the effect of crude protein degradability and corn processing on lactation performance, milk protein composition, milk ethanol stability (MES), heat coagulation time (HCT) at 140°C, and the efficiency of N utilization for dairy cows. Twenty Holstein cows with an average of 162 ± 70 d in milk, 666 ± 7 kg of body weight, and 36 ± 7.8 kg/d of milk yield (MY) were distributed in a Latin square design with 5 contemporaneous balanced squares, 4 periods of 21 d, and 4 treatments (factorial arrangement 2 × 2). Treatment factor 1 was corn processing [ground (GC) or steam-flaked corn (SFC)] and factor 2 was crude protein (CP) degradability (high = 10.7% rumen-degradable protein and 5.1% rumen-undegradable protein; low = 9.5% rumen-degradable protein and 6.3% rumen-undegradable protein; dry matter basis). A significant interaction was observed between CP degradability and corn processing on dry matter intake (DMI). When cows were fed GC with low CP degradability, DMI increased by 1.24 kg/d compared with cows fed GC with high CP degradability; however, CP degradability did not change DMI when cows were fed SFC. Similar interactions were observed for MY, HCT, and lactose content. When cows were fed GC diets, high CP degradability reduced MY by 2.3 kg/d, as well as HCT and lactose content, compared with low CP degradability. However, no effect of CP degradability was observed on those variables when cows were fed SFC diets. The SFC diets increased dry matter and starch total-tract digestibility and reduced β-casein (CN) content (% total milk protein) compared with GC diets. Cows fed low-CP degradability diets had higher glycosylated κ-CN content (% total κ-CN) and MES, as well as milk protein content, 3.5% fat-corrected milk, and efficiency of N for milk production, than cows fed high-CP degradability diets. Therefore, GC and high-CP degradability diets reduced milk production and protein stability. Overall, low CP degradability increased the efficiency of dietary N utilization and MES, probably due to changes in casein micelle composition, as CP degradability or corn processing did not change the milk concentration of ionic calcium. The GC diets increased β-CN content, which could contribute to reducing HTC when cows were fed GC and high-CP degradability diets.

Extraction and identification of the chyme proteins in the digestive tract of growing pigs.

This study aimed to explore the rule of degradation of dietary proteins by identifying chyme proteins in different segments of the digestive tract of growing pigs, using proteomics techniques. Six growing pigs were fed a corn-soybean meal-based diet for 7 days. The feedstuff and chyme proteins were separately extracted and separated with SDS-PAGE. 2D LCMS/MS combined with protein database searching identified 1,513 proteins in different segments of the gastrointestinal tract, the number of identified exogenous proteins gradually decline from the stomach to colon, with large amounts in the duodenum to the large intestine. More corn proteins than soybean proteins were identified both in the feedstuff and chyme, and these were significantly decreased after digestion in the stomach. More membrane proteins than non-membrane proteins were identified in whole digestive tract. These results regarding the profiles of chyme proteins in different segments of the gastrointestinal tract would provide useful information for optimizing feed formula in pigs.

Bioactive polysaccharides and oligosaccharides as possible feed additives to manipulate rumen fermentation in Rusitec fermenters

Bioactive polysaccharides and oligosaccharides (POSs) have been used as safe non-antibiotic alternatives in animal diets; however, only limited data are available on their effects in rumen manipulation. This study was undertaken to systematically evaluate and compare the efficacies of six different bioactive POSs (10g/kg diet) with respect to ruminal fermentation, feed digestibility, biohydrogenation and bacterial population using a rumen simulation technique. The experiment consisted of 4 independent 12-d incubation periods (each including 8 d for acclimation, followed with 4 d for sample collection). The results demonstrated that Lycium barbarum polysaccharide had no effect and Astragalus polysaccharide only increased the total VFA production. Chitooligosaccharide decreased the propionate proportion with a corresponding increase of acetate to propionate ratio. Fructooligosaccharide increased fatty acid biohydrogenation and the abundances of R. albus, B. fibrisolvens and S. ruminantium. Both Lentinan polysaccharide and xylooligosaccharide increased the total VFA production, fatty acid biohydrogenation and the abundance of B. fibrisolvens. In addition, Lentinan polysaccharide increased 48-h dietary protein degradation and the abundance of R. flavefaciens, while xylooligosaccharide increased 24-h dietary fiber degradation and the abundance of R. albus. In conclusion, bioactive POSs, especially Lentinan polysaccharide and xylooligosaccharide, can serve as potential feed additives to manipulate rumen fermentation.

Substrate specificity and reaction mechanism of human prolidase

The refined structure coordinates as well as the corresponding structure factor amplitudes have been deposited in the PDB under the accession numbers 5M4G, 5M4J, 5M4L, and 5M4Q.

Forragens taniníferas na produção de caprinos e ovinos

Tannins are a complex group of polyphenolic compounds, derived from secondary plant metabolism. The aim of this study was to conduct a survey of information on the effects of using tanninipherous forage on ruminal parameters, intake and digestibility of nutrients, weight gain and carcass traits, milk production and composition, wool production activity and anti- helminth in sheep and goats. At moderate concentrations (20-40 g/kg DM), tannins reduce the ruminal degradation of dietary protein and increase the post-rumen flow of essential amino acids. In tannin rich diets (> 50 g/kg DM) there is formation of insoluble complexes, mainly with the protein diet, which damage the digestibility of nutrients, reduce voluntary intake due to diet astringency, and damage microbial activity and ruminal digestive efficiency. In the presence of soluble tannins, ruminal bacterial species responsible for endoglucanase activity and methanogenic bacteria are affected. To mitigate the effects of tannins and other secondary compounds in tropical and temperate fodder, polyethylene glycol (PEG) has been used. Positive effects are characterized by an increase in milk production, an altered fatty acid profile of milk and meat, wool growth, and weight gain. The parasitic infections are reduced with the tannins presence due to the reduction in the availability of nutrients for nematodes, complexing the tannins glycoprotein cuticle of the worms and toxic effect on the abomasal and intestinal mucosa. It is suggested that tannin concentrations do not exceed 6-7% of the diet dry matter. Therefore, more research is required in order to clarify the issues related to this topic.

Biochemical and genetic diversity of carbohydrate-fermenting and obligate amino acid-fermenting hyper-ammonia-producing bacteria from Nellore steers fed tropical forages and supplemented with casein.

BackgroundDietary protein plays a major role in ruminant nutrition, and protein supplementation is a widespread practice among farmers in the tropics. Ruminal bacteria are the main agents of dietary protein and amino acid degradation, yet few studies have focused on the isolation and characterization of hyper-ammonia-producing bacteria in animals fed tropical diets or supplemented with rumen-degradable proteins. This work investigated the bacterial community diversity of the rumen of Nellore steers fed tropical forages, with or without casein supplementation. We also isolated and characterized ruminal bacteria showing high levels of ammonia production.ResultsPolymerase chain reaction–denaturing gradient gel electrophoresis analysis indicated no differences in the ruminal bacterial community composition between the control and supplemented animals. Amino acid-fermenting bacteria (n = 250) were isolated from crossbred Nellore steers fed Tifton 85 (Cynodon sp.) using trypticase as the sole carbon and organic nitrogen source in the enrichment and isolation media. The deamination rates in isolates obtained from steers supplemented with casein showed a higher incidence of deamination rates >350 nmol NH3 mg protein−1 min−1 (P < 0.05), whereas isolates obtained from steers without supplementation showed deamination rates <200 nmol NH3 mg protein−1 min−1. Although most isolates (84%) could ferment carbohydrates, none could hydrolyze proteins or use urea to sustain growth. All isolates were sensitive to lasalocid and monensin (1 μmol l−1), and similarity analysis of the 16S rRNA sequences indicated a predominance of bacteria from the order Clostridiales, with variable homology (73–99%) to known bacterial species.ConclusionsThese results expand what is known about the biochemical and genetic diversity of hyper-ammonia-producing bacteria, and emphasize the role of carbohydrate-fermenting bacteria in ammonia production in the rumen.Electronic supplementary materialThe online version of this article (doi:10.1186/s12866-015-0369-9) contains supplementary material, which is available to authorized users.

Urea and Ammonia Metabolism and the Control of Renal Nitrogen Excretion

Renal nitrogen metabolism primarily involves urea and ammonia metabolism, and is essential to normal health. Urea is the largest circulating pool of nitrogen, excluding nitrogen in circulating proteins, and its production changes in parallel to the degradation of dietary and endogenous proteins. In addition to serving as a way to excrete nitrogen, urea transport, mediated through specific urea transport proteins, mediates a central role in the urine concentrating mechanism. Renal ammonia excretion, although often considered only in the context of acid-base homeostasis, accounts for approximately 10% of total renal nitrogen excretion under basal conditions, but can increase substantially in a variety of clinical conditions. Because renal ammonia metabolism requires intrarenal ammoniagenesis from glutamine, changes in factors regulating renal ammonia metabolism can have important effects on glutamine in addition to nitrogen balance. This review covers aspects of protein metabolism and the control of the two major molecules involved in renal nitrogen excretion: urea and ammonia. Both urea and ammonia transport can be altered by glucocorticoids and hypokalemia, two conditions that also affect protein metabolism. Clinical conditions associated with altered urine concentrating ability or water homeostasis can result in changes in urea excretion and urea transporters. Clinical conditions associated with altered ammonia excretion can have important effects on nitrogen balance.

Identification of bioactive grassland plants for reducing enteric methane production and rumen proteolysis using an in vitro screening assay

The aim of this study was to conduct in vitro rumen fermentation assays on a large number of grassland plants to discriminate them on the basis of their potential to combine high nutritive value for ruminants and a reduced impact on the environment. In total, 156 plant species collected from diversified grasslands in the French Massif Central were screened by measuring several parameters, including in vitro true organic matter digestibility (IVTOMD), methane (CH4) production and ammonia nitrogen (N-NH3) in the incubation medium as an indicator of dietary protein degradation in the rumen. The results were expressed relative to perennial ryegrass (PRG) values used as a reference. We observed that the fermentation of 13 plants produced 50% less CH4 per unit of OM truly digested than did fermentation of PRG. Among these plants, two (Bidens tripartita subsp. Tripartite and Scrophularia nodosa) reduced CH4 by more than 80%. In terms of protein degradation, the fermentation of 37 plants halved the ratio between N-NH3 and plant N content compared with PRG, of which six had values below the detection level of the assay. Interestingly, 16 plants showed simultaneously a reduction of more than 80% in N-NH3 production and 30% in CH4 production, including three plants (Sedum telephium subsp. maximum, Oenothera biennis and Geranium sylvaticum) with an IVTOMD higher than 80%. This study has provided more knowledge about the use of lesser-known plants as whole plant forage by ruminants, and has identified candidate plants for potential use as additives in the form of plant extracts.

Dietary starch source and protein degradability in diets containing sucrose: Effects on ruminal measures and proposed mechanism for degradable protein effects

A feeding study was conducted to evaluate ruminal effects of starch source (STA) and rumen-degradable dietary protein (RDP) in diets with added sucrose. The experimental design was an incomplete Latin square with three 21-d periods, 8 ruminally cannulated lactating cows, and a 2×2 factorial arrangement of treatments. Treatments were STA (dry ground corn or high-moisture corn) as more slowly and more rapidly fermenting starch sources, respectively, and relative amount of RDP (+RDP: added protein from soybean meal; −RDP: heat-treated expeller soybean product partially substituted for soybean meal). Diets were formulated to be isonitrogenous and similar in starch and neutral detergent fiber concentrations. Dry matter (DM) intake was 1 kg greater with +RDP compared with −RDP diets. For ruminal digesta measures made 2 h postfeeding, weight of digesta DM was unaffected by treatment; total kilograms of wet digesta and kilograms of liquid tended to be greater with +RDP than with −RDP, and no effect was observed of STA × RDP. Digesta DM percentage was greater with −RDP than with +RDP. At 2 h postfeeding, ruminal pool sizes (mol) of lactate and total AA were larger and those of total organic acids (OA) and ammonia tended to be larger with +RDP than with −RDP; no effects of STA or STA × RDP were detected. Rumen-degradable protein effects on lactate and OA pool sizes may be due to a protein-mediated increase in fermentation rate of carbohydrate. Organic acid concentrations at 2 h postfeeding did not show the same response pattern or significance as the pool size data; high-moisture corn tended to be greater than dry ground corn and no effect was observed for RDP or STA × RDP. Concentration and pool size for OA were more weakly correlated [coefficient of determination (R2)=0.66] than was the case for other ruminal analytes (R2 >0.80). Organic acid pool size and kilograms of digesta liquid were strongly correlated (R2=0.79), whereas concentration and kilograms of liquid were much less so (R2=0.21). The correlation of OA moles with kilograms of liquid likely relates to the homeostatic mechanism of water flux across the rumen wall to reduce the osmotic gradient with blood as intraruminal moles of solute change. This action compresses the range of ruminal OA concentrations. With kilograms of ruminal liquid differing across individual measurements, the ruminal OA concentration data are not on the equivalent basis required to be reliably useful for assessing the effect of treatments. Further evaluation of protein effects on carbohydrate fermentation and of methods that allow accurate comparison of treatments for their effect on ruminal OA production are warranted.