Soluble Protein Nitrogen Research Articles

Nutritional Potential of Raw and Free α-Galactosides Lupin (Lupinus albus Var. multolupa) Seed Flours. Effect of Phytase Treatment on Nitrogen and Mineral Dialyzability

The effect of the removal of alpha-galactosides from Lupinus albus L. var. multolupa on the chemical composition of the prepared flour and the dialyzability of N, total P, Ca, Mg, Fe, Zn, and Mn was studied. The extraction process caused a significant increase in total and insoluble nitrogen contents and decreased the amount of soluble protein nitrogen. However, neither these changes nor treatment with phytase seemed to considerably affect in vitro protein digestibility. Except for Ca and Cu, total mineral contents were significantly reduced by the extraction process. The process also caused a significant reduction in the dialyzability of all the minerals studied except P. The decrease in mineral dialyzability was partially counteracted by phytase treatment in amounts of 250-500 phytase units/kg of lupin flour. In the case of Fe, mineral dialyzability did not differ significantly between the two lupin flours studied with treatment with 500 phytase units/kg. Zinc dialyzability was the most efficiently improved by phytase treatment (P < 0.0001), followed by P, Fe, and Mn, and finally by Ca and Mg (P < 0.05).

Effects of germination on the composition and nutritive value of proteins in Pisum sativum, L

The effects of germination for 2, 4 or 6 d, with and without light, on the proteolytic activity, the contents of soluble protein and non protein nitrogen, and the amount of available starch of Pisum sativum, L, as well as their nutritive utilisation by growing rats were studied. Food intake increased significantly when the peas were germinated for 2 or 4 d. This improvement was correlated with the reduction of factors responsible for flatulence. Digestive utilization of nitrogen was similar (among all the groups fed germinated-pea flour) to raw-pea flour. The values for nitrogen balance, percentage of retained to absorbed nitrogen, protein efficiency ratio, and index of available carbohydrates were significantly higher among the animals that consumed peas allowed to germinate for 2 or 4 d than among the animals given the raw-pea or 6-day-germinated pea diets. We conclude that germination of peas for 2 d would be sufficient to significantly improve the palatability and nutritive utilisation of protein and carbohydrates from Pisum sativum, L. The presence or absence of light during the germination process did not affect the results achieved.

Impacts of elevated CO2 on the population abundance and reproductive activity of aphid Sitobion avenae Fabricius feeding on spring wheat

Abstract: Spring wheat (Triticum aestivum L. cv. Kehan 50) plants were grown in pots under three atmospheric CO2 concentrations (ambient, 550 and 750 p.p.m.) in field open‐top chambers (OTCs), with half of the plants subjected to aphid (Sitobion avenae Fabricius) infestation. Increase in CO2 levels increased host plant growth and grain yield, and decreased 1000‐grain dry weight compared with ambient CO2. On the contrary, aphids had a negative effect on 1000‐grain dry weight. Host plants grown at elevated CO2 generally had greater ear starch, sucrose, glucose, total non‐structure carbohydrates (TNCs), ratio of TNC : nitrogen, free amino acids and soluble protein and less ear fructose and nitrogen. However, the aphids did not affect the ear nitrogen and ratio of TNC : nitrogen. The responses of apterous and alate aphids to enrichment CO2 atmosphere were different. Local population of aphids, including apterous and alate forms infested on host plants in OTCs, increased with elevated atmospheric CO2 concentrations. Emigrating alate aphids captured on sticky yellow paper decreased with rising CO2. CO2 affected the reproductive activity of alate aphids. The alate forms deposited more offspring on plants grown at 550 and 750 p.p.m. CO2 compared with ambient CO2. Both population abundance of local aphids and reproductive activity of alate aphids correlated positively with ear starch, sucrose, glucose, TNCs, raito of TNC : nitrogen and free amino acids, while negatively with ear fructose and nitrogen. Moreover, emigration population abundance was related negatively with ear starch, sucrose, glucose, TNCs, ratio of TNC : nitrogen and free amino acids and positively with ear fructose and nitrogen.

PHOTOSYNTHESIS AND NITROGEN UTILIZATION IN LEAVES OF CINNAMOMUM BURMANNI GROWN UNDER ELEVATED ATMOSPHERIC NH3 CONCENTRATIONS AND SUPPLIED WITH DIFFERENT FORMS OF SOIL N

We investigated the effects of different forms of soil nitrogen additions (NO - 3-N, NH + 4-N or NH 4NO 3-N) and exposure to elevated atmospheric NH 3 concentrations on photosynthesis, nitrogen utilization and nitrogen allocation in photosynthetic components in leaves of Cinnamomum burmanni. The results showed that maximum rates of carboxylation (V cmax) and maximum rates of potential electron transport (J max) were achieved in plants grown with additions of NO - 3-N and under elevated atmospheric NH 3 concentrations compared to plants growing under ambient conditions. Both J max and V cmax declined in plants supplied with NH + 4-N or NH 4NO 3-N and grown under elevated atmospheric NH 3. Regardless of the different forms of nitrogen supply, leaf nitrogen content on an area basis (N a) significantly increased under elevated atmospheric NH 3 concentrations (p0.05). Thylakoid nitrogen (N T), Rubisco nitrogen (N R) and nitrogen associated with electron transport (N E) increased significantly in plants supplied with NO 3 --N and exposed to the elevated atmospheric NH 3 when compared to plants grown under ambient condition (p0.05); however, N a, N T, N R and N E all decreased in plants supplied with NH + 4-N or NH 4NO 3-N. These results suggest that increased atmospheric NH 3 promotes the utilization of nitrogen for the synthesis of photosynthetic components, but inhibits the partitioning of nitrogen to N T, N R, and N E in plants supplied with NH + 4-N or NH 4NO 3-N. The organic nitrogen content per unit dry mass increased in plants that were supplied with NO - 3-N or NH 4NO 3-N (but not NH + 4-N) when exposed to increased atmospheric concentrations of NH 3. The soluble protein nitrogen content also increased in plants grown with NO - 3-N additions but not in plants grown with additions of NH + 4-N. The results suggest that increased atmospheric NH 3 concentration enhances nitrogen absorption and utilization and promotes photosynthesis in plants supplied with NO - 3-N additions but inhibits photosynthesis and nitrogen in plants supplied with NH + 4-N or NH 4NO 3-N.

Chemical composition and ruminal nutrient degradabilities of fresh and ensiled Kura clover (Trifolium ambiguum M.B.)

Kura clover is a perennial rhizomatous forage legume mainly used for grazing in permanent pastures. A study was conducted to determine the ensiling potential of Kura clover by comparing the chemical composition and ruminal nutrient degradabilities of fresh and ensiled forage of two cultivars (Cossack and Endura). Ensiling characteristics were determined by ensiling forages in mini-silos for 50 d. Ruminal nutrient degradabilities of fresh and ensiled forages were determined by the nylon bag technique using two lactating cows fitted with ruminal cannulas. Results showed that silages of both cultivars were well preserved as indicated by low pH and high lactic acid concentration. Cultivar had little effect on the chemical composition of Kura clover silage. However, ensiling increased (P &lt; 0.05) soluble protein and non-protein nitrogen (NPN) and reduced (P &lt; 0.05) neutral and acid detergent insoluble protein fractions. Ensiling increased NPN and reduced true protein by 87 and 29%, respectively. Results of the in situ study indicated that cultivar had no effect on effective ruminal degradability of dry matter (DM), crude protein (CP), an d neutral detergent fiber (NDF). Relative to fresh forage, ensiled Kura clover had similar effective ruminal degradability of DM (712 g kg-1 of DM) and NDF (417 g kg-1 of NDF) but a higher (P &lt; 0.05) effective ruminal degradability of CP (806 vs. 725 g kg-1 of CP). It was concluded that Kura clover may be preserved as silage with minimal alterations in forage quality. These findings will increase the acceptability of Kura clover by widening possible utilizations. Key words: Forage quality, Kura clover (Trifolium ambiguum M.B.), protein fractions, ruminal degradability, silage

A preliminary study on the molecular weight profile of soluble protein nitrogen in live food organisms for fish larvae

The solubility of protein nitrogen at pH 8 in the organisms used as live food for fish larvae (rotifers and Artemia) was determined and the molecular weight profile of soluble protein nitrogen was analysed by HPLC-gel filtration chromatography. Soluble nitrogen accounted for 61% of total nitrogen in microalgae-fed rotifers, 47% in starved rotifers and 54% in newly hatched Artemia. A remarkable similarity in the profile of molecular weight distribution of soluble nitrogen was noticed among these three types of live food. The molecular weights of soluble nitrogen was partitioned as follows, respectively, in rotifers and Artemia: 84–88% and 89% >500 Da (corresponding mainly to proteins, poly- and oligopeptides), 8–11% and 4% from 200 to 500 Da (corresponding mainly to di- and tripeptides), 3–4% and 7% <200 Da (corresponding mainly to free amino acids). According to these results, nitrogen of both live food organisms would be available in nearly identical forms and proportions in the intestine of fish larvae. Thus, it is suggested that artificial diets for fish larvae should have a nitrogen solubility and molecular weight profile similar to that found in live food.

Are contents of Rubisco, soluble protein and nitrogen in flag leaves of rice controlled by the same genetics?

Genetic relations among the contents of Rubisco, soluble protein and total leaf nitrogen (N) in leaves of rice (Oryza sativa L.) were studied by quantitative trait loci (QTL) analysis with a population of backcross inbred lines (BILs) of japonica Nipponbarexindica Kasalath. The ratio of Rubisco to total leaf N in leaves is the main target in improving photosynthetic N-use efficiency in plants. QTLs controlling Rubisco content were not detected near QTLs for total leaf N content. These results indicate that contents of Rubisco and total leaf N are controlled by different genetics. QTLs that controlled the ratio of Rubisco to total leaf N (CORNs) were detected. These results suggest that some mechanism(s) may be involved in determining this ratio, while the contents of Rubisco and total leaf N are controlled in other ways. In elite BILs, the ratios of Rubisco to total leaf N were higher than those of both parents. These results suggest a good possibility of improving N-use efficiency by CORNs in cultivated rice. A QTL controlling Rubisco content was mapped near a QTL for soluble protein content on chromosome 8 at 5 d after heading and on chromosome 9 at 25 d. In each chromosome region, the peaks of both QTLs overlapped accurately, giving a high possibility of pleiotropic effects by the same genes. Different QTLs controlling soluble protein or Rubisco were detected from those detected at 5 d or 25 d after heading. This suggests that these traits are genetically controlled depending on the growth stages of leaves.

Free amino acids and proteolysis involved in ‘salchichon’ processing

Changes in free amino acid and nitrogen fraction contents involved in salchichón manufactured by industrial processing at different times of curing process were analysed. An increase in the free amino acid concentration and non protein fraction was observed during the curing process, specially between the fermentation stage and the second week of drying while soluble protein nitrogen decreased. The predominant amino acids in the initial mix of salchichon were Glutamic acid, Cysteine, Carnosine, Alanine and Taurine summing up the 73.7% of the total. During the last two weeks of drying, the concentration of some of the free amino acids went on increasing (Aspartic acid, Glutamic acid, Serine, Asparragine, Glycine, Taurine, Threonine, Alanine, Carnosine, Tryptophan and Lysine) but some others decreased significantly (Proline, Tyrosine, Valine, Methionine, Cysteine, Isoleucine and Leucine). The curing stage of salchichon might be estimated approximately based on the concentration of Aspartic acid, Glutamic acid, Serine, Glycine, Asparragine, Threonine and the total free amino acid content amino acids. The majority of amino acids that showed the greatest concentration in the final product were recorded as having `bitter' flavour characteristics.

Effect of salicylic acid on nodulation, nitrogenous compounds and related enzymes of Vigna mungo

Plants of Vigna mungo raised from seeds presoaked in salicylic acid (0.0, 0.01, 0.1 and 1.0 mM) and nodulated with the cowpea strain of Rhizobium leguminosarum were analysed 15 and 30 d after sowing. The foliar nitrate and nitrite contents were varying but soluble protein and total nitrogen contents were lower in treated than control plants. Nitrate reductase activity was increased at the two lower concentrations of 0.01 and 0.1 mM but was inhibited at the highest concentration used (1.0 mM). The number of nodules, their leghemoglobin and protein contents and nitrogenase activity of roots were reduced.

Using Natural Isotope Variations of Nitrogen in Plants as an Early Indicator of Air Pollution Stress

Model experiments (container experiments) were used to investigate whether natural variations of nitrogen constitute a suitable means for the early indication of harmful effects on plants and the level at which changes in nitrogen metabolism may occur. Wheat plants were exposed under near-ambient, controlled conditions (open-top chambers) to ozone for 2 or 6 weeks. The responses of the nitrogen metabolism in these plants were compared with non-exposed organisms at various biochemical levels. In the short-term experiment (2 weeks), wheat plants exhibited altered δ15N values under stress conditions right at the molecular level in the individual amino acids, whereas the biochemical N-fractions (structural protein (SP), soluble protein (LP) and non-protein nitrogen (NPN)) remained nearly unchanged. In the long-term experiment (6 weeks), the impact of ozone treatment and the combined effects of ozone and carbon dioxide on the wheat plants were examined. An increase in δ15N values was found as a reaction to ozone treatment in both the LP amino acids detected and in all biochemical N-fractions. Combined exposure to ozone and carbon dioxide was found to have a lesser impact at the level of the N-fractions and also at the molecular level of amino acids. The results show an example of how stable isotopes can be used as sensitive ecotoxicological indicators to provide early warning of environmental damage. © 1997 by John Wiley & Sons, Ltd.

Changes affecting the Longissimus dorsi, Triceps brachii caput longum and Rectus femoris muscles of young Friesian bulls during meat ageing

The chemical composition and post-mortem changes during 3–14 days of ageing were studied on three muscles ( Longissiums dorsi, Triceps brachii caput longum, Rectus femoris) from 13 young Friesian bulls. Chemical composition varied widely between animals ( p < 0.001) and muscles ( p < 0.001), and did not change during post-mortem storage. Significant changes affecting the non-protein nitrogen and soluble protein nitrogen contents were similar in all three muscles but differed from animal to animal. The increase in non-protein nitrogen can be considered as an indicator of proteolysis. Proteolysis extended to 14 days post mortem. The myofibril fragmentation index increased significantly ( p < 0.001) between 3 and 7 days post mortem along the same pattern, irrespective of the muscle and animal. A ceiling was reached at around 7 days post mortem, by which time maximum breakdown of the structure had probably occurred. No significant relationship was observed between chemical composition, changes in the soluble protein nitrogen, breakdown of structures and carcass characteristics.

Time-related changes in nitrogen fractions and free amino acids of lean tissue of frech dry-cured ham

The 80 hams of 40 pig carcasses from one slaughter batch were taken on the day after slaughter. The 40 left hams were dry-cured. Groups of 10 hams were taken for analysis at 74 days (end of rest), 81 days (end of heating), 179 days (mid-seasoning) and 273 days (end of seasoning) after the beginning of processing. A slice of about 150 g was taken in the middle of the Biceps femoris and used for analysis of nitrogen fractions and free amino acids by HPLC. Levels of insoluble nitrogen compounds did not vary significantly, while levels of soluble protein nitrogen decreased strongly from 26 to 16% of total nitrogen, with the fastest decrease observed between days 179 and 273. Levels of non-protein nitrogen increased regularly during the processing from 12 to 23% of total nitrogen. Nitrogen of free amino acids ranged from 3·6% in fresh muscle to 16·6% of total nitrogen at day 179, then decreased to 4·4% of the total nitrogen at the end of the processing. The HPLC method allowed the identification of 29 compounds, among which 27 were amino acids and 2 were dipeptides. The average levels of free amino acids of non-protein origin tended to decrease before day 74, then to increase until day 179 and to decrease again. The levels of compounds of protein origin increased or tended to increase from the beginning until day 179, then decreased.

Cuban Laurel Thrips (Thysanoptera: Phlaeothripidae) Biology in Southern California: Seasonal Abundance, Temperature Dependent Development, Leaf Suitability, and Predation

Gynaikothrips ficorum Marchal, the Cuban laurel thrips, reproduces within leaf galls formed as a result of feeding on young Ficus microcarpa leaves. Populations of thrips peak within mature galls during summer and again during winter. New galls are formed from midsummer through the fall, but not during the remainder of the year even though susceptible leaves are present. Development times from egg to adult ranged from 48.99 d at 15°C to 16 d at 30°C. Lower and upper temperature thresholds were observed at 12 and 35°C, suggesting that spring temperatures are not limiting thrips development. Infested young leaves were higher in soluble protein and total nitrogen but lower in latex content than infested mature leaves, indicating that young foliage is more suitable for thrips than mature foliage. In addition, the mature leaf galls were colonized by the predators Chrysoperla carnea (Stevens) and Macrotrachiella nigra Parshley. Both predaceous species consumed more adult thrips than immatures in preference tests; the number of individuals consumed within a 24-h feeding trial suggests that the predators may cause significant mortality within the mature galls. A slower rate of leaf expansion during the winter and spring combined with unsuitable environmental conditions for adult thrips outside the rolled leaves may limit the successful formation of leaf galls.

Population Responses of the Citrus Red Mite and Citrus Thrips to ‘Navel’ Orange Cultural Practices

Field-grown orange ( Citrus sinensis (L.) Osbeck) trees were subjected to all combinations of three levels of irrigation, three levels of fertilization, two levels of fungicidenematicide applications, and two levels of growth regulator treatments during 1985–1987. Densities of the citrus red mite, Panonychus citri (McGregor), and densities and fruit scarring caused by the citrus thrips, Scirtothrips citri (Moulton), were monitored in 1986 and 1987 to determine how variation in commercial orange grove management practices might alter the suitability of trees for use by both pest species. Fertilization was the only factor exerting a consistent, significant effect on thrips scarring and mite density. Citrus thrips scarring was highest on the most heavily fertilized trees, whereas mite densities were highest on the least fertilized trees. Although fertilization significantly altered concentrations of several individual amino acids, soluble protein, and total nitrogen content, variation in densities of neither arthropod was strongly related to variation in concentrations of any measured plant compounds. Differences in densities and scarring among treatments were low relative to conventional treatment thresholds, and variation in grove management practices, within practical limits, probably play only a minor role in promoting outbreaks of either of these two citrus pests.

THE RELATIONSHIP OF RUMEN CATIONS AND SOLUBLE PROTEIN WITH PREDISPOSITION OF CATTLE TO ALFALFA BLOAT

Rumen-fistulated cattle were fed fresh alfalfa herbage daily during two growing seasons. Samples of rumen fluid were collected daily prior to feeding and the frothiness of the rumen fluid was assessed. Concentrations of soluble protein nitrogen in the rumen fluid were higher in animals that subsequently bloated than in those that did not (P &lt; 0.01). There was no relation between soluble protein nitrogen and the occurrence of foam in the rumen prior to feeding. The concentrations of Na and K in the rumen fluid were negatively correlated. Bloat was associated with a low concentration of Na and a high concentration of K (P &lt; 0.01). Concentrations of Ca and Mg were lower than those of the two monovalent ions but were also positively associated with bloat (P &lt; 0.01). The high concentration of chlorophyll associated with a predisposition to bloat may be the result of a colloidal aggregation of chloroplast particles stabilized by cations. Key words: Pasture bloat, alfalfa, chlorophyll, ions, cattle

Evaluation of ammonium hydroxide as preservative for ground meat

Ammonium hydroxide when added at 0.134 to 0.67m to ground-meat, decreased the total number of aerobic bacteria and, to a lesser extent, Gram-negative bacteria at 37°C, 4°C and −20°C. The plate count at the same pH adjusted with 1m NaOH was considerably more than when 0.4m NH4OH had been used, indicating that NH4OH was acting as preservative for ground-meat and not the merely changing the pH. The changes in extract release volume, water holding capacity, soluble protein nitrogen and cook out losses were much less in ground meat containing NH4OH as compared to control (no preservative) or containing NaOH.

The production of ‘Orogo's’ — low alcoholic beverages from plantain (musa paradisica)

AbstractA laboratory version of orgoro; a low alcohol plantain beverage was found to possess a better odour, taste and colour after 7 days of fermentation compared with a native brew. The pH of the native brew decreased from 3.90 to 1.93 after 21 days of fermentation while the filterable acidity increased from 0.100 to 0.157%. The laboratory brew showed a decrease of pH from 4.60 to 2.72 and an increase in filterable acidity from 0.250 to 0.485%. Both brews had alcohol contents of 0.109 and 0.197% (v/v) respectively after this period. The total sugars content, soluble protein and total nitrogen contents of the native brew were 2.0 mg/ml, 1.3 mg/ml and 2.05 mg/ml respectively while values for the laboratory brew were 5.0 mg/ml, 2.2 mg/ml and 4.0 mg/ml respectively.

Changes in Leaf Quality Following Clipping and Regrowth of Urtica dioica, and Consequences for a Specialist Insect Herbivore, Aglais urticae

The hypothesis that interruption of normal plant phenology may provide opportunities for insect herbivores to escape the nutritional constraints imposed by their foodplant is tested using Urtica dioica and its specialist herbivore Aglais urticae. The changes in water content, total organic nitrogen, soluble protein nitrogen, insoluble organic nitrogen and fibre were measured in U. dioica leaves at one site for two years both before and after summer cutting. Leaf water content and nitrogen levels were high during the spring followed by a decline during flowering. Subsequent increases were noted in plants regrowing after being cut. Mature uncut plants did not show increases in water and total organic nitrogen. Growth rates of larvae feeding on regrowth plants were higher than those on mature plants and pupal weights were greater. Higher efficiencies of conversion of ingested and digested food appear to be the major contributors to this. The consequences of interrupted plant phenology for the life cycles of insects are discussed.

Composition of flesh from different edible parts of cod

Summary.Cod fillet, trimmings from the fillet, and tissue recovered from the skeleton after filleting were assayed over a 12 month period for nitrogen, moisture, hydroxyproline and water holding capacity. No significant differences were found in nitrogen or moisture content. However, the mean hydroxyproline contents were significantly different in all three tissues. Water holding capacity was significantly less in tissues recovered from the skeleton than in fillet or fillet trimmings. A seasonal trend was observed in moisture and nitrogen content. Soluble and myofibrillar protein nitrogen and non‐protein nitrogen were also measured on the three tissue types. No significant differences were found.

EFFECT OF DAILY WEATHER CONDITIONS ON BLOAT IN CATTLE FED FRESH ALFALFA

Daily weather records from seven consecutive growing seasons and daily nitrogen levels in alfalfa herbage from the last four seasons were studied in order to identify relationships with bloat in cattle. The cattle tended to bloat as a group rather than independently. Bloat occurred on at least 30% of the days observed in each season but in the two driest, warmest years the percentages increased to 46 and 63. Days on which bloat occurred were preceded by lower maximum and minimum temperatures on the average than days on which bloat did not occur but the difference in temperature was small. On a daily basis no differences were observed between days of bloat and no bloat in hours of sunshine, temperature range, precipitation, solar radiation flux or potential evapotranspiration. The concentration of total nitrogen, soluble nitrogen and soluble protein nitrogen in the feed was higher on days when bloat occurred than when it did not occur. Key words: Pasture bloat, alfalfa, cattle, climate, evapotranspiration