Equivalent Amount Of Nitrogen Research Articles

Soil Bacterial Community Structure and Function under the Substitution of Chemical Fertilizer with Maize Straw

The long-term extensive application of chemical fertilizers wreaks havoc on soil bacterial structure and function. To reduce the damage caused by chemical fertilizers, a six-year experiment was performed to study the effects of replacing 0% (CK), 25% (S25), 50% (S50), 75% (S75), and 100% (S100) of 225 kg ha−1 mineral nitrogen fertilizer with an equivalent amount of nitrogen from maize straw on the soil bacterial community structure, diversity, and function. The results showed that Proteobacteria, Acidobacteria, and Gemmatimonadetes were the dominant soil bacterial phyla after the replacement treatments. Replacing mineral nitrogen fertilizer with an equivalent amount of nitrogen from maize straw significantly reduced the number of Photobacterium and bacterial populations involved in genetic information processing in soil, but significantly increased the number of bacterial populations involved in organismal systems, human diseases, and environmental information processing. Compared with other treatments, the relative abundance of TK10 significantly increased by 33.52–76.36% in S25. The number of subgroup 6, Gram-negative, biofilm-forming, potentially pathogenic, and anaerobic bacteria significantly increased, whereas that of Chloroflexi and Blastocatellia subgroup 4 significantly decreased in S50 and S75 compared with CK. The number of TK10 and Blastocatellia subgroup 4 in S50 and S100, respectively, was significantly lower than that in CK. Bacterial species were significantly more present in S25 than in S75. The diversity of bacterial species in S75 was significantly lower than that in CK. S25 and S100 were more favorable to increasing the number of Gram-positive, aerobic, mobile-element containing, and stress-tolerant bacteria. Rhodobacteraceae, Pyrinomonadaceae, Xanthobacteraceae, Nocardioidaceae, and Vulgatibacteraceae with statistical differences in CK, S25, S50, S75, and S100, respectively, could be used as biomarkers. Chloroflexi, Acidobacteria, and Nitrospirae could be used as the main basis for the bacterial classification of soil samples in the equivalent substitution of nitrogen chemical fertilizer with maize straw. S25 is ideal for increasing soil bacterial species richness and abundance.

Vermicompost Amendment in Soil Affects Growth and Physiology of Zea mays Plants and Decreases Pb Accumulation in Tissues

Minimization of the possible harmful effects of soil pollution on agricultural production and food safety are the major challenges in modern agriculture. There is great scientific interest in the detailed understanding of the physiology of lead uptake and toxicity in Zea mays, together with the search for approaches to minimizing Pb accumulation in tissues. The aim of the present study was to explore the possibility of reducing Pb accumulation in Z. mays plants cultivated in Pb-contaminated soil, by means of vermicompost amendment. Z. mays plants were cultivated at three soil vermicompost amendment rates (10, 20, and 30%), with the addition of 1000 mg L−1 of Pb in the form of Pb(NO3)2 or an equivalent amount of nitrogen in the form of NH4NO3. Additional nitrogen had a significant stimulatory effect on plant growth and physiology, but only for control plants, and at a low vermicompost amendment rate. Independently, Pb had an insignificant negative effect on plant growth and biomass partitioning, but significantly negatively affected the mineral nutrition of Z. mays plants. At a 10 and 20% soil vermicompost amendment rate, the Pb concentration in plant leaves and roots decreased by 65%, while plant biomass increased four to five times in comparison to soil-grown control plants, together with accelerated flowering. It was concluded that vermicompost is one of the most promising soil amendments for reducing heavy metal uptake and accumulation in crop plants, while also being an efficient organic fertilizer.

Acute effect of an amino acid mixture in the rat glycemic profile.

Amino acid mixtures (AAM) are protein substitutes used for phenylketonuria treatment, but their metabolic effects have not been well characterized. The objective of this study was to compare the acute glycemic response to free amino acids (free AA) from AAM with the response to intact protein (iProtein). Male Wistar rats (n = 14) were administered by gavage a bolus of free AA (n = 7) or iProtein as albumin (n = 7) containing equivalent amounts of nitrogen. Blood glucose and insulin levels were measured at baseline and 15, 30, 60 and 120 minutes later, when gut GLP-1 content and pancreatic insulin, GLP-1 receptor and Ki67 expression were quantified at 120 minutes time point. After AAM, glucose area under the curve (free AA vs iProtein; P < 0.01), serum insulin levels at 120 minutes (free AA vs iProtein; P < 0.05), colon GLP-1 content (free AA vs iProtein; P < 0.01), pancreatic GLP-1 receptor (free AA vs iProtein; P < 0.01) and insulin expression (free AA vs iProtein; p < 0.01) were significantly lower as compared with iProtein. AAM increased Ki67 expression in pancreatic islets (free AA vs iProtein; P < 0.05). In conclusion, this study demonstrated that acute response to AAM differs from iProtein and is characterized by a lower glucose excursion, along with a decrease in gut GLP-1 and pancreatic GLP-1 receptor and insulin. This data suggests the modulation of glycemia by free AA is mediated by the incretin axis.

Expression of Soil Chemical and Biological Behavior on Nutritional Quality of Aromatic Rice as Influenced by Organic and Mineral Fertilization

The aim of the study was to evaluate changes in the yield and nutritional characteristics of aromatic rice as influenced by organic versus mineral fertilization. Aromatic rice was grown on four levels of cattle manure (CM; 5, 10, 15, and 20 Mg ha−1). Other treatments were equivalent amounts of nitrogen (N), phosphorus (P), and potassium (K) in different levels of manure fertilizer and mineral fertilizer. After 6 years of cropping, organically managed plots were superior to mineral-fertilized plots in terms of grain yields of rice at 5, 10, and 15 Mg ha−1. Cattle manure at 20 Mg ha−1 and its equivalent NPK through mineral-fertilizer treatment provided 41.1% and 37.9% increases in average grain yield (5.2 and 5.1 Mg ha−1) over the unamended control. Protein content was greater in mineral-fertilized rice grains at all levels of CM. Soil dehydrogenase, β-glucosidae, urease, and acid phosphatase activities were greater in soil treated with CM than soil treated with the corresponding mineral fertilizer at all levels. There was buildup of soil-available N, K, and iron (Fe) in soils treated with CM. Grain hardness increased with increasing rates of nutrient application for both mineral-fertilized and organically grown rice; in contrast, amylose content was lower in treatments receiving more nutrients, irrespective of nutrient sources. In terms of functional property, phenol content in rice grain increased with increasing nutrient supply. Potassium and Fe contents were more in CM-treated rice than in mineral-fertilized treatments at greater rates of application. Results suggest that after building up the soil nutrient status, comparable yield and better nutritional and functional qualities of rice can be achieved in organically managed soils than in mineral-fertilized soils.

Modulation of blackspot seabream (Pagellus bogaraveo) intermediary metabolic pathways by dispensable amino acids

The objective of the present work is to investigate the main metabolic pathways by which dispensable amino acids (DAA) are diverted towards lipid formation in blackspot seabream. For that purpose, a control diet was formulated to contain 45% of crude protein (7.2gN/100g dry matter) mainly supplied by fish meal (45P). In two other diets, 22.2% of the dietary nitrogen (1.6gN/100g dry matter) was replaced by an equivalent amount of nitrogen provided by two different mixtures of DAA: alanine and serine (diet AS) or aspartic and glutamic acid (diet AG). A fourth diet (diet 35P) only containing 35% of crude protein (5.6gN/100g dry matter) was included in order to analyze the possible additive effects of DAA. Compared to fish fed diet 35P, blackspot seabream appear to make a more efficient use of the nitrogen provided by alanine and serine than that provided by aspartic and glutamic acids in terms of growth. Contrary to fish fed AG, fish fed AS attained similar specific FAS activities as 45P fed fish, suggesting a further role of alanine and serine on this lipogenic pathway. Dietary nitrogen reduction (45P vs. 35P) or its replacement by a mixture of aspartic and glutamic acids (diet AG) were shown to up-regulate phosphoenolpyruvate carboxykinase (PEPCK) but without, however, any effect on plasma glucose levels. Dietary nitrogen level and nature seems to exert a complex regulation on energetic pathways through the gluconeogenesis/tricarboxylic acids cycle interaction.

Pregnant ewes exposed to multiple endocrine disrupting pollutants through sewage sludge-fertilized pasture show an anti-estrogenic effect in their trabecular bone

Pregnant ewes were maintained on pastures fertilized, twice yearly, with either sewage sludge (2.25 tonnes dry matter/ha; Treated; T) or inorganic fertilizer containing equivalent amounts of nitrogen (Control; C), to determine effects on maternal and fetal bone structures, density and mechanical properties of exposure to environmental concentrations of multiple endocrine disrupting compounds (EDCs) and heavy metal pollutants. The ewes were maintained on the respective pastures from the age of about 8 months until they were 4–6 years of age and they were slaughtered at 110 d gestation. Metaphyseal parts of adult ewe femurs exhibited a significantly reduced mean, total cross sectional area (CSA, − 4%; p < 0.05), lower trabecular bone mineral content (BMC, mg/mm; − 18%; p < 0.05), trabecular bone mineral density (BMD, mg/cm 3, − 8.0%; p < 0.05) and trabecular CSA, mm 2, − 11.1%; p < 0.05) in T compared with C animals. Femurs of T ewes were stronger than those of C ewes but this may reflect greater body weights. At the mid-diaphyseal part of the fetal bones, there was a reduction in endosteal circumference (− 6.7%, p < 0.05) and marrow cavity area (− 13.8%, p < 0.05) in the female T fetuses compared with female C fetuses. In the male fetuses the mid-diaphyseal part total bone mineral content was higher (+ 3.0%, p < 0.05) in T than in C animals. No treatment difference in biomechanical bending was detected in the fetuses. It is concluded that ewes grazing pasture fertilized with sewage sludge exhibited an anti-estrogenic effect on their trabecular bone in the form of reduced mineral content and density, despite increased body weight. It is suggested that human exposure to low levels of multiple EDCs may have implications for bone structure and human health.

Reactor temperature profile during autothermal methane reforming on Rh/Al 2O 3 catalyst by IR imaging

Catalytic autothermal reforming of methane was studied over a commercial rhodium catalyst as a function of feed flow rate, feed composition and oven temperature. The process is carried out in a catalytic fixed bed reactor inserted in a tubular oven. Temperature profile of the catalyst bed was measured by IR thermography and product composition was measured with a continuous gas analyzer. The effect of water addition at fixed flow rate on catalyst temperature profile was investigated in two ways. In one case, upon water addition, an equivalent amount of nitrogen was removed from the feed in order to keep oxygen and methane concentrations constant. With this protocol nitrogen to oxygen ratio varies as a function of amount of water in the feed. In the other case, upon water addition, nitrogen, oxygen and methane were all reduced to keep total flow rate constant, thus keeping both oxygen to methane and nitrogen to oxygen ratios constant. The effect of water addition on product composition was investigated as a function of reactor thermal level, regulated by acting on oven temperature.

Sodium fertilizer application to pasture. 8. Turnover and defoliation of leaf tissue

The effects of application of sodium fertilizer on the turnover and defoliation of leaf tissue were investigated in a perennial ryegrass (Lolium perenne) pasture grazed by dairy cows. Eight plots were allocated to treatments either with or without sodium fertilizer, with the former receiving 32 kg Na ha–1 applied in five applications of NaNO3 over the grazing season. An equivalent amount of nitrogen was given to the controls as ammonium nitrate, the application of which was reduced in the sodium treatment to equate nitrogen fertilizer applications for the two treatments. In nine periods between April and September, marked tillers were recorded to measure leaf turnover, leaf lamina growth and specific leaf weight and, when combined with tiller density measurements, gave an estimate of herbage flux for the sward. The defoliation and net growth of the marked tillers were monitored at 3‐day intervals and the data were combined with tiller density and specific leaf weight data to determine the intake of the expanding, penultimate and oldest live leaf laminae. Sodium fertilizer application did not affect the rate at which leaves appeared, but it retarded their rate of disappearance. The extension rate and the specific weight of green laminae were both increased by sodium fertilizer application and therefore the net gravimetric growth rate was increased. Tiller density was not affected by sodium fertilizer application and hence the estimated herbage growth and net herbage flux were increased by sodium fertilizer application. Application of sodium fertilizer did not affect lamina length, and in both treatments the penultimate laminae were approximately twice as long as expanding and oldest live laminae. Defoliation frequency decreased from the expanding to the oldest live laminae in the control treatment without sodium. Sodium fertilizer application increased the frequency of defoliation of the oldest live leaf and also increased the length of the expanding leaf that was defoliated. For penultimate leaf laminae sodium fertilizer application reduced the defoliation frequency and length of foliage grazed. The dry‐matter (DM) intake of the oldest live laminae was increased by the application of sodium fertilizer. It is concluded that sodium fertilizer application increases net herbage growth both by increased extension rate of leaf laminae and specific leaf weight and by delayed laminae senescence, and that it increases herbage DM intake by increasing the defoliation frequency of the oldest live leaf laminae.

Modulation of immune response with ornithine A-ketoglutarate in burn injury: an arginine or glutamine dependency?

Enterally administered ornithine alpha-ketoglutarate (OKG) is an efficient complement of nutritional support in trauma situations, especially after burn injury. A typical feature observed in this intense catabolic state is insufficient production of glutamine (Gln) and arginine (Arg), two amino acids (AAs) involved in the immune response. As OKG in vivo metabolism generates these two AAs, we investigated, in burned rats, the action of OKG with regard to modulation of immunity. Male Wistar rats were randomly allocated to four groups. On day 0, 12 rats were burned with boiling water (20% body surface area). After a 24-h fast, they were enterally refed for 48 h using Osmolite, as a low-calorie low-nitrogen regimen, supplemented with either 5 g OKG x kg(-1) x d(-1) (n = 6) or an equivalent amount of nitrogen in the form of glycine (n = 6). Non-burned pair-fed controls treated with glycine (n = 6) and healthy rats fed ad libitum (n = 6) were also studied. Nitrogen balance was assessed from daily measurement of total nitrogen excretion. On day 3, thymus, Anterior tibialis muscle and proximal jejunum weights were recorded. Muscle and intestinal AA concentrations were also quantified. OKG counteracted (P<0.01) the thymic involution that occurs with burn injury, and increased the concentrations of Gln and Arg in both the muscle (P<0.01 and P<0.05, respectively) and the jejunum (P<0.01 for Gln). When all groups were taken together, a positive correlation was found between thymus weight, and Gln and Arg muscle concentrations (r = 0.71, P<0.001 and r = 0.58, P<0.01, respectively). Furthermore, as expected, OKG improved nitrogen balance. As it is known that total number of thymocytes parallels thymic weight, and as Gln and Arg are essential nutrients for activated immune cells, our results suggest that Gln and Arg derived from OKG are responsible for the immunomodulating properties of this molecule in burn injury.

A Field Demonstration of the Efficacy of Bioremediation to Treat Oiled Shorelines Following the Sea Empress Incident

Bioremediation was investigated as a method of treating a mixture of Forties Crude Oil and Heavy Fuel Oil stranded on Bullwell Bay, Milford Haven, UK after the grounding of the Sea Empress in 1996. A randomised block design in triplicate was used to test the efficacy of two bioremediation treatments: a weekly application of mineral nutrients dissolved in seawater and a single application of a slow-release fertilizer. Each treatment supplied an equivalent amount of nitrogen and phosphorus. Concentrations of residual hydrocarbons normalised to the biomarker 17α(H),21β(H)-hopane showed that after two months the oil was significantly (p<0.001) more biodegraded in the treated plots than in the controls. On average, the oil in the nutrient amended plots was 37% more degraded than that found in the controls. There was no evidence that the bioremediation treatments increased the toxicity of the oiled sediment. The results confirm that bioremediation can be used to treat a mixture of crude and heavy fuel oil on a pebble beach. In particular, the data suggest that the application of a slow-release fertilizer alone may be a cost-effective method of treating low-energy, contaminated shorelines after a spill incident.

Ornithine alpha-ketoglutarate modulates tissue protein metabolism in burn-injured rats.

Enterally administered ornithine alpha-ketoglutarate (OKG) displays whole body anabolic and anticatabolic properties in trauma situations, especially after burn injury. The aim of this study was to get information about the anabolic effect of OKG at tissue level. Thirty-six male Wistar rats (95 +/- 7 g) were allocated to four groups. Eighteen rats were burned by water (20% body surface area). After a 24-h fast (day 0-day 1), rats were enterally refed for 48 h (day 1-day 3) by use of Osmolite as a low-calorie, low-nitrogen regimen supplemented with either 5 g OKG.kg-1.day-1 (B-OKG) or an equivalent amount of nitrogen in the form of glycine (B-Gly). Nonburned pair-fed controls treated with glycine (C-Gly) and healthy rats fed ad libitum were also studied. On day 3, protein synthesis rates (large dose method), free glutamine concentrations, and total protein content were assessed in tissues. Myofibrillar degradation was assessed by measuring urinary 3-methylhistidine excretion daily from day 0 to day 3. With regard to tissue protein synthesis rates, we demonstrate for the first time that OKG displays anabolic properties in the jejunum [fractional synthesis rate (FSR) in %/day, ad libitum = 101.9 +/- 4.0; C-Gly = 84.7 +/- 3.1, P < 0.01 vs. ad libitum; B-Gly = 84.5 +/- 1.6, P < 0.01 vs. ad libitum; B-OKG = 97.5 +/- 3.2, P < 0.05 vs. C-Gly and B-Gly] as well as in the liver (FSR in %/day, ad libitum = 75.9 +/- 3.7; C-Gly = 53.2 +/- 3.8, P < 0.01 vs. ad libitum; B-Gly = 70.2 +/- 2.0, P < 0.01 vs. C-Gly; B-OKG = 98.7 +/- 4.6, P < 0.01 vs. ad libitum, C-Gly and B-Gly), the latter having previously been observed in vitro. Furthermore, we confirm that OKG inhibits myofibrillar degradation, counteracts the trauma-induced fall of muscle glutamine pool, and induces an increase in glutamine concentration in the jejunum.

841 PB 387 PHOSPHORUS RATES AND MEDIA FOR PRODUCTION OF TOMATO TRANSPLANTS USING THE FLOAT SYSTEM

Tomato transplants were grown in plastic foam trays floated in nutrient solutions using a system adapted from tobacco transplant growers. Nutrient solutions were compared which contained equivalent amounts of nitrogen and potassium and either 35 or 70 mg·liter-1 phosphorus (P). Growing media tested were 1) Jiffy-Mix*, 2) Pro-Mix®, 3) horticultural vermiculite, or 4) perlite. The higher P rate caused increases in stem diameter, and in plant fresh and dry weight. Plant height, root dry weight and leaf area were not affected by P rate. Transplants grown in Pro-Mix® had significantly greater plant height and stem diameter than other media. Leaf area, and plant fresh and dry weight did not differ between Pro-Mix* and Jiffy-Mix@. Vermiculite and perlite produced smaller tomato transplants and should not be considered when using this production system.

Performance of dicyandiamide in the north central states

Abstract The effectiveness of the nitrification inhibitors, nitrapyrin and dicyandiamine, in reducing nitrogen loss from soil and preventing reduction in crop yield was evaluated in field studies conducted over dozens of site years in Illinois, Iowa, Minnesota, and Wisconsin on corn, wheat, and a vegetable crop, potato. Both chemicals were effective in retarding the nitrification of ammoniacal fertilizers, including nitrogen from liquid animal manures, but this inhibitor did not always result in yield increases above that obtained with equivalent amounts of nitrogen applied without inhibitor. Greatest benefits for nitrification inhibitor use was obtained on coarse‐textured soils under conditions that were conducive to nitrate nitrogen loss when nitrogen was applied at rates not considered to be excessive.

A comparison of the isotope recovery and difference methods for determining nitrogen fertilizer efficiency

In an experiment with sorghum on a medium deep red soil (Udic Rhodustalf) at Patancheru, India, where15N-labeled urea was applied at different rates during the 1981 rainy season, the apparent (ARF) and isotope recovery fractions (15NRF) were appreciably different, particularly at lower rates of fertilizer application. The fertilizer rates were corrected for losses of fertilizer nitrogen, that were estimated from the differences in the amounts of15N recovered in the soil and the crop, and the known amounts of15N applied. Introducing these ‘effective’ fertilizer rates, the apparent discrepancy between ARF and15NRF could be explained if it were assumed that the15N immobilized in the organic soil fraction was not remineralized during the course of the growing season. In the difference method, the equivalent amount of nitrogen at natural abundance released in exchange for fertilizer nitrogen (5 atom % xs15N) immobilized in the organic nitrogen fraction is treated as ‘fertilizer nitrogen’, since no distinction is made between14N and15N. In the isotope-dilution method, the nitrogen at natural abundance mineralized during biological interchange is not considered fertilizer nitrogen, and therefore the assumed effective amount of fertilizer nitrogen available to the crop is less than in the difference method.

Some Effects of Coating Urea Prills with Sulphur and Wax on Nitrogen Utilization By Ruminants

In two experiments two prilled urea products coated with sulphur and wax were given to either adult cows or sheep. In the first experiment administration per rumen fistula of the sulphur and wax-coated urea products resulted in lower concentrations of ammonia in the rumen liquor and blood of cows than did equivalent amounts of nitrogen given as crystalline feed-grade urea. Crystalline urea produced the largest and most rapid increase in the concentration of urea in the blood. In the second experiment with sheep, the addition of either of the sulphur and wax-coated urea products or crystalline feed-grade urea to a basal concentrate diet did not increase the amounts of nitrogen excreted in the faeces, indicating that each supplement was apparently fully digested. This was in contrast with the observation that some partially intact sulphur and wax-coated urea prills were present in the faeces.

The Nitrogen Economy of Myrica Gale in the Field

SUMMARY (1) The growth and nitrogen content of Myrica gale have been measured over two growing seasons in a Myrica-Molinia community on relatively poorly aerated soil at a site in central Scotland. (2) The biomass and nitrogen content of Myrica were the same in early spring and late autumn. (3) Woody rhizomes accounted for 50-70% of the total biomass; during early spring (March-April) they contained c. 65% of the nitrogen in the plant, most of the rest being in aerial shoots. (4) Visible growth was preceded by a large transfer of nitrogen from old aerial stems and rhizomes to buds. (5) When the first leaves were opening (mid-June), a potential for reduction of acetylene developed in the nodules. It reached a peak in late July-early August and declined to zero in October. When the rate of acetylene reduction reached its peak, the net transfer of nitrogen from rhizomes to new shoots finally ceased. At this stage leaves contained c. 30% of the nitrogen in the plants. (6) Subsequently the nitrogen content of the rhizomes rose, and leaf nitrogen declined. By late October or early November all leaves were shed and the concentration of nitrogen in the rhizomes had returned to its early spring value. (7) The nitrogen lost from the plant in leaves is about 30 kg ha-' yr-. If there is no uptake of mineral nitrogen from the soil, an equivalent amount of nitrogen must be fixed.

Redistribution of Nitrogen in Urea-Treated and Soybean Meal—Treated Corn Silage

The redistribution of nitrogen when urea in three proportions (0.5, 0.75, and 1.0%) or equivalent amounts of nitrogen from soybean meal were added to whole corn plants at ensiling was studied with 294 plastic bag silos. The corn was harvested at three stages of maturity: Low dry matter (25.6%), medium dry matter (30.4%), and high dry matter (52.0%). Only the lowest level of urea and soybean meal was added to the high dry matter samples. Triplicate silages were prepared and analyzed for the various nitrogen fractions after 0, 0.5, 1, 3, 7, 21, and 42 days of storage.Dry matter decreased (P<.01) with storage time. Nonprotein nitrogen increased (P<.01) and protein nitrogen decreased (P<.01) in all silages with storage time. Only 25% of the urea nitrogen was recovered in the low and high dry matter silages, whereas 50% was recovered from the medium dry matter silage treated with 0.5% urea. Averaged over all levels of nitrogen supplementation, ammonia nitrogen was 19, 18, and 15% of the total nitrogen in urea-treated low, medium, and high dry matter corn silages and 6, 4, and 4% in similar soybean meal-treated samples after 42 days of storage. Nitrate reduction was greater in the soybean meal (70%) than in the urea-treated silages (55%).

Effect of Nitrogen Source, Stage of Maturity, and Fermentation Time on pH and Organic Acid Production in Corn Silage

Two hundred and ninety-four plastic bag silos were prepared to determine the effect of adding urea or soybean meal on the corn plant fermentation process. Urea was added at 0.5, 0.75, and 1.0% of fresh silage weight at ensiling. Equivalent amounts of nitrogen from soybean meal were added for a comparative treatment. The corn was harvested at three stages of maturity, 25.6, 30.4, and 52.0% dry matter. Only the lowest level of urea and soybean meal was added to the silage containing 52.0% dry matter. Triplicate silages were prepared and analyzed after 0, 0.5, 1, 3, 7, 21, and 42 days of storage.Over all treatments the average pH of urea-treated corn silage (4.85) was higher than that of soybean meal-treated corn silage (4.69). Differences between treatments after 42 days of fermentation were greater with either low or high dry matter silages than with medium dry matter. Total organic acid concentration declined from 11.94% of dry matter in low dry matter samples after 42 days of storage to 3.14% of dry matter in high dry matter samples averaged over all treatments. The concentration of these acids increased (P<.01) with storage time and was higher in the urea-treated samples. Contrary to what was observed with lactic acid, volatile fatty acids were higher with the lower nitrogen supplementation. Acetic acid comprised 90% of the total volatile fatty acids.

Effect of Level and Pattern of Essential Amino Acids on Nitrogen Retention of Adult Man

Two studies were conducted to determine the effect on nitrogen retention of increasing the dietary intake of essential and semiessential amino acids, patterned as in the poorly balanced protein of corn, when total nitrogen was held constant. Men were fed diets containing approximately 6.00 g nitrogen daily of which crystalline amino acids and diammonium citrate provided 5.50 g and ordinary foods, the remainder. During five experimental periods of study 1, the eight essential and four semiessential amino acids patterned as in corn protein provided 1.10, 2.20, 3.30, 4.40 and 5.50 g nitrogen daily. During the sixth experimental period, 2.20 g nitrogen was also provided by the essential and semiessential amino acids, but the level of isoleucine was increased to that in the FAO provisional pattern. Each increase in the intake of essential and semiessential amino acids was accompanied by an increase in nitrogen retention. Increasing the level of isoleucine to that in the FAO pattern had no effect on nitrogen retention. In the second study, nitrogen balance responses of men fed the corn and egg pattern were compared; equivalent amounts of nitrogen, 2.20, 3.30, or 5.50 g, were supplied by the essential and semiessential amino acids of the two patterns. When the essential nitrogen provided 3.30 or 5.50 g, more highly positive nitrogen balances were obtained when subjects were fed the egg pattern than when they were fed the corn pattern of amino acids.

Substitution of alpha-keto acids for five amino acids essential for growth of the rat.

SummaryYoung rats grew slowly on a diet in which the nitrogen was furnished exclusively by the 10 amino acids essential to the young rat plus glutamic acid. When leucine, isoleucine, valine, phenylalanine, and methionine were replaced in the diet by the corresponding keto acids plus an equivalent amount of nitrogen as glycine and 0.2% aspartic acid, the animals grew as well as they did on the basal diet.