Estimation of the phosphorus requirement of weanling pigs fed supplemental phytase

Studies were conducted with crossbred weanling pigs to determine the level of phosphorus needed to be fed when a maize–soyabean meal–whey diet was supplemented with exogenous phytase (Natuphos™). In Trial 1, phytase was added at 1200 phytase units (PTU) kg⁻¹ as phosphorus decreased. The control diet in Phase I (0–14 days) contained 7.3 g kg⁻¹ phosphorus and in Phase II (14–28 days) contained 6.5 g kg⁻¹ phosphorus. Dietary phosphorus was calculated to decrease by 0.8, 1.6 or 2.4 g kg⁻¹ when phytase was supplemented. Chromic oxide was added for estimation of apparent absorption of phosphorus. Performance was optimum when 5.7 and 4.8 g kg⁻¹ phosphorus (analysed levels) were fed with 1200 PTU kg⁻¹ phytase in Phases I and II, respectively. The lowest dietary phosphorus levels did not reduce performance for the overall 28-day period. Apparent phosphorus digestibility was increased by phytase in Phase I when 5.7 g kg⁻¹ phosphorus was fed compared to the control diet and in Phase II when 6.0 g kg⁻¹ phosphorus was fed with phytase. Faecal phosphorus excretion decreased in both phases as dietary phosphorus decreased. Faecal phosphorus excretion was minimized at the lowest phosphorus level with no decrease in performance. The estimated requirement for dietary phosphorus, as determined by the NLIN procedure, is 5.0 g kg⁻¹ in Phase I and 4.3 g kg⁻¹ in Phase II when 1200 PTU kg⁻¹ is used. In Trial 2, phytase was supplemented at 500 PTU kg⁻¹ when phosphorus was decreased in the diet. The control diet contained 6.6 and 6.0 g kg⁻¹ phosphorus in Phases I and II, respectively, and phosphorus was calculated to decrease by 0.5, 1.0, 1.5, or 2.0 g kg⁻¹ when phytase was added. Daily gain decreased when 5.0 g kg⁻¹ phosphorus was fed in Phase I and when 4.6 or 4.2 g kg⁻¹ (analysed levels) phosphorus was fed in Phase II with 500 PTU kg⁻¹. Faecal phosphorus excretion decreased as dietary phosphorus decreased, but there were no treatment effects on apparent phosphorus digestibility. The dietary phosphorus requirement was estimated to be 5.7 and 5.0 g kg⁻¹ in Phases I and II, respectively, when phytase is fed at 500 PTU kg⁻¹. At the present recommendation of 500 PTU kg⁻¹ in starter feed, phosphorus can be decreased by 0.10 g kg⁻¹. However, higher levels of phytase are needed to actually increase apparent phosphorus digestibility.     

Non-phytin phosphorus requirements of commercial broilers and White Leghorn layers

Experiments were conducted to determine the optimum requirements of non-phytin phosphorus (NPP) in commercial broilers and White Leghorn layers. Five levels of NPP (2.5, 3.0, 3.5, 4.0 and 4.5 g kg⁻¹ diet) were tested to assess the NPP requirement of commercial broilers (3–30 days of age) fed maize–soya diets containing 10 g Ca kg⁻¹. Each level of NPP was fed to quadruplicate groups of ten chicks each. Inclusion of graded levels of NPP significantly (P < 0.01) influenced body weight gain, feed intake, tibia ash content, phosphorus content in serum, tibia ash and phosphorus retention. The predicted NPP requirements for body weight gain, P content in serum and tibia ash were 4.4, 4.48 and 4.1 g kg⁻¹ diet, respectively. The NPP requirement for tibia ash was the highest (7.4 g kg⁻¹ diet). Similarly, four levels of NPP (2.0, 2.5, 3.0 and 3.5 g kg⁻¹ diet) were tested with maize–soya diets containing 35 g Ca kg⁻¹ for White Leghorn layers (266–350 days of age). Each diet was tested on four groups of 12 hens in each. Egg production was not influenced by the variation in dietary NPP levels. The predicted NPP requirements for better egg weight and shell thickness were 2.6 and 2.4 g kg⁻¹ diet, respectively, while for the serum inorganic P level the value was 3.42 g kg⁻¹ diet. Therefore, it can be concluded that commercial broilers need about 4.4 g NPP kg⁻¹ diet for better performance, whereas, White Leghorn layers need not more than 2.0 g NPP kg⁻¹ diet for better egg production. However, layers require 2.6 g NPP kg⁻¹ diet to produce eggs with better egg size and shell quality.     

Growth performances and carcass traits of Ovin Martinik lambs fed various ratios of tropical forage to concentrate under intensive conditions

Studies were conducted to determine the effects of supplementation upon intake, growth and carcass traits of Ovin Martinik hair sheep. Forty lambs weighing 20 ± 3.7 kg live weight (LW) were reared after weaning in individual pens during a 4-month experimental study. Four supplement levels were compared (10 lambs per treatment): the L0 group received the basal diet (tropical forage 0.75 UFL and 73 PDIN g kg⁻¹ DM, INRA system) without concentrate, the L150, L300 and L600 groups were offered in addition 150, 300 and 600 g day⁻¹ of concentrate (1.15 UFL and 151 PDIN g kg⁻¹ DM), respectively. Intake (5 days a week) and growth patterns (every fortnight) were measured on the 40 lambs, while digestibility measurements (five times throughout the experimental period) were determined on half of the animals fitted with faecal bags and which were slaughtered according to the standard procedure at 33–35 kg live weight for assessment of carcass traits and meat quality.The total dry matter intake (DMI) and digestibility increased (P < 0.01) with the inclusion ratio of the concentrate in the diet: 82 g DM kg W^−0.75 vs. 97 g DM kg W^−0.75 and 65% vs. 73% between the two extreme groups, whereas forage DMI decreased and the forage substitution ratio was calculated to be 0.65. Growth and feed/gain ratios significantly (P < 0.01) improved among the groups L0, L150 and L300, from an average of 134–188 g day⁻¹ and 7.0–5.7, respectively. The differences observed between L300 and L600 were not significant. Carcass weight and dressing out percentages significantly (P < 0.01) increased with the addition of concentrate to the ration: from 13.1 to 15.6 kg and from 39 to 46%, from L0 to L600, respectively. Consequently, the weights of the different cuts of the carcass varied. There was a significant effect of the supplementation level on the accumulation of internal fat tissues: the kidney fat weight increased from 107 to 237 g from the L0 to the L600 groups. No significant effect was observed on the carcass quality scores, the ultimate pH and the colour parameters of the meat.By increasing the nutritional density of the diet, it was possible to obtain well-conformed and heavier carcasses, with no apparent detrimental effect on the quality. The optimal supplement supply with good quality grass would be 300 g day⁻¹ in our conditions.     

Performance of West African dwarf goats fed Guinea grass–Verano stylo mixture,N-fertilized and unfertilized Guinea grass

The supplementary values of Verano stylo in a mixed Guinea grass (Panicum maximum cv. Ntchisi)–Verano stylo (Stylosanthes hamata cv. Verano) diet from a sown grass–legume mixture and N fertilized grass were compared in West African dwarf (WAD) goats. Liveweight (LW) gain, feed intake, digestibility and N utilization were determined using 15 goats in two trials lasting for 98 days. Goats were fed Guinea grass–Verano stylo mixture (GSM), N-fertilized (NFG) and unfertilized grass (UFG). The goats were divided into three groups of five animals each and randomly allocated to the dietary treatments in a randomized complete block design. Total DM and OM intakes of the goats did not vary significantly among the forage diets and averaged 55.1 and 50.4 g kg⁻¹ W^0.75 per day, respectively. CP intake (g kg⁻¹ W^0.75 per day) was highest with NFG (5.6) followed by GSM (4.8) and the UFG (3.5). Total N excreted followed the same trend as the CP intake. There was no significant difference between N-retention of GSM and NFG (28.5 and 26.7%), but goats on UFG had a negative N balance (−9.16%). Animals on GSM had significantly higher liveweight gain (31.9 g per day) than those of NFG (25.1 g per day) and UFG (21.9 g per day) which also differed significantly. The digestibilities of total DM, OM, CP, NDF were higher with GSM than NFG or UFG. It is concluded that growing Verano stylo in mixture with Guinea grass is a better option for improving the feed quality of forage diets for goats than direct application of inorganic fertilizer at 200 kg N ha⁻¹ to the pure grass.     

Enzyme supplementation of wheat-based diets for broilers: 1. Effect on growth performance and intestinal viscosity

The influence of enzyme supplementation on performance and intestinal viscosity of male broiler chickens fed with diets containing high amount of wheat was examined in three experiments. In the first experiment, addition with an enzyme preparation including different cell wall degrading enzymes to diets containing 63 g kg⁻¹ and 72 g kg⁻¹ of wheat improved (P<0.05) feed conversion efficiency in the 72 g kg⁻¹ wheat diet. In addition, intestinal viscosity of chickens fed with the 72 g kg⁻¹ wheat diet was reduced (P<0.05). Weight gain and feed intake were not influenced by enzyme addition. In Experiments 2 and 3, the inclusion level of wheat in the diets was more than 80 g kg⁻¹ and four different enzyme preparations were used (two xylanase preparations, two mixed preparations). Overall, a significant effect on performance and intestinal viscosity of chickens was obtained as a result of enzyme supplementation in both experiments. In the first 21 days, improvements (P<0.05) in weight gain and feed conversion efficiency were found to be on average 5% and 6% in Experiment 2 and 7% and 8% in Experiment 3, respectively. When weight gain and feed conversion efficiency were examined on a weekly basis it was shown that the significant response of enzyme addition was confined to the first 4 weeks. However, the effect of enzyme supplementation was still significant in the whole period from 21–42 days. Feed intake was not influenced by enzyme addition. The viscosity of intestinal content in both the jejunum and ileum was in general reduced (P<0.05) with enzyme supplementation, the xylanase preparations proving to be the most efficient. It was concluded that enzyme supplementation of wheat-based diets resulted in improved performance of broiler chickens, which was related to a concomitant reduction in intestinal viscosity. However, the response of enzyme supplementation was most pronounced in diets with a wheat content higher than 80 g kg⁻¹.     

Ruminal nitrogen disappearance from sod-seeded cereal grain forages in Northern Arkansas

Wheat (Triticum aestivum L.), oat (Avena sativa L.) and rye (Secale cereale L.) were overseeded into a dormant bermudagrass (Cynodon dactylon (L.) Pers.) sod and harvested on six dates throughout the spring. Plant growth stage was documented for each forage on each harvest date, and harvested forages were subsequently evaluated for forage quality characteristics. Four ruminally cannulated steers were used to evaluate disappearance kinetics of nitrogen (N) by an in situ method. All forages had high concentrations of N (≥31.1 g kg⁻¹ DM) throughout harvest dates in March. By 15 April, rye had reached a substantially more advanced growth stage than either wheat or oat. This trait, coupled with the concurrent taller growth habit, caused concentrations of N in rye to decline (P<0.05) rapidly between the 24 March and 4 May harvest dates. The effective ruminal disappearance of N remained high (≥790 g kg⁻¹ N) for all forages harvested through mid-April, thereby indicating that these cereal-grain forages exhibit the same characteristics of high N disappearance and low potential ruminal escape that are commonly observed in other high-quality cool season grasses harvested at similar growth stages. The effective disappearance of N reached a minimum (P<0.05) for all forages immediately before grain fill. Generally, substantial increases (P<0.05) in effective ruminal disappearance of N were observed as these forages partitioned N into the filling grain head. Fractional rates of N disappearance for wheat and rye were extremely rapid (≥0.383 h⁻¹) during grain fill. However, rye also exhibited an extremely rapid disappearance rate (0.548 h⁻¹) immediately prior to the onset of grain fill that was not observed for wheat (0.085 h⁻¹) at an identical growth stage. Parameters associated with disappearance kinetics can be related to growth stage at harvest by linear and polynomial regression techniques, although the best fit model was dependent on forage type.     

Effects of feeding crambe meal upon intake,gain, health and meat quality of broiler chicks

True metabolizable energy of crambe meal was determined with adult cecectomized turkeys to be 11.8 kJ(2.8 kcal)g⁻¹. Amino acid digestibilities were 90% or greater, indicating that protein quality of crambe meal was high. Growing broilers were fed diets containing 0, 50, 100 or 150 (g crambe meal) kg⁻¹ diet (control, 50C, 100C and 150C, respectively) for 56 days. Feed intake for the 150C birds was lower than the other treatments initially; at the end of the experiment, intake of the 150C birds compensated and was similar to the control birds. Weight gain patterns were similar to intake responses. Birds on the 150C treatment had reduced tibial ash content and locomotor difficulties in the first half of the experiment; these effects were absent in the second half of the experiment. Meat quality and serum chemistries were unaffected by feeding crambe meal. Broilers fed the 150C diet had increased liver and kidney weights. Broilers can be fed diets containing up to 50 (g crambe meal) kg⁻¹ diet with no adverse effects on gain and health and up to 100 g kg⁻¹ diet with minimal adverse effects on gain and health.     

Effects of untreated and heat-treated canola presscake on milk yield and composition of dairy cows

Five primiparous and five multiparous Holstein cows were used in two Latin square design experiments to determine effects of feeding unheated and heated canola presscake on milk yield and composition, and milk fatty acid concentrations of lactating dairy cows. Five diets that differed in level and source of dietary fat were formulated: a low fat control diet with 30 g kg⁻¹ fat from tallow, an unheated canola presscake supplemented diet (50 g kg⁻¹ fat), a heated canola presscake supplemented diet (50 g kg⁻¹ fat), a high tallow plus unheated canola meal supplemented diet (50 g kg⁻¹ fat), and a high tallow plus heated canola meal supplemented diet (50 g kg⁻¹ fat). In sacco ruminal degradability of heated and unheated canola presscake was compared with that of heated and unheated canola meal in a randomized complete block design using two ruminally fistulated cows. Heat treatment reduced ruminal DM and CP degradability of canola presscake. Multiparous cows fed diets supplemented with heated or unheated canola presscake produced more milk than those fed diets containing similar levels of fat from tallow with heated or unheated canola meal, respectively. High levels of fat from any diet reduced milk fat percentage for cows of either parity. Feeding heated canola products increased milk and milk protein yields in primiparous cows only, but cows of both parities fed diets containing canola presscake produced milk with lower concentrations of C12:0, C14:0, and C16:0 fatty acids than cows fed the canola meal and tallow diets, although concentrations of C18:1 n-9 were unaffected by fat source or level. Feeding canola products to dairy cows can alter milk fatty acid profile, but only primiparous cows have increased productivity as a result of feeding heated, versus unheated, canola presscake.     

Effects of soybean oligosaccharides on intestinal microbial communities and immune modulation in mice

BackgroundSoybean oligosaccharides (SBOSs) are potential prebiotics that may be used to improve immune function. Here, we investigated the effects of intragastric administration of SBOSs in mice to determine the effects on autochthonous intestinal microbial communities and immunological parameters. Results E: After 22-day administration, 4.0 g kg body weight (BW)⁻¹ SBOSs significantly enhanced the proliferation of bifidobacteria and lactic acid bacteria (LAB) as compared to the control. This dose of SBOSs also significantly increased numbers of enterococci and decreased numbers of Clostridium perfringens. Treatment with 4.0 g kg BW⁻¹ SBOSs also significantly increased the percentage of T-lymphocytes and lymphocyte proliferation as compared to the control, suggesting that SBOSs promoted cellular immunity in mice. Additionally, 4.0 g kg BW⁻¹ SBOSs induced significant differences in hemolysin production, natural killer (NK) cell activity, phagocytic activity, cytokine production, and immunoglobulin levels compared to the control. Conclusion: Our data demonstrated that intragastric administration of SBOSs at a dose of 4.0 g kg BW⁻¹ improved the numbers of beneficial intestinal microbes and enhanced immunological function of mice. Therefore, these data supported that SBOSs may have applications as a prebiotic to improve immune responses in humans. Further studies are warranted.     

Effects of ambient temperature and methionine supplementation of a low protein diet on the performance of laying hens

The effects of ambient temperature and the supplementation of methionine to a low protein diet on egg production, egg quality, blood constituents and nitrogen excretion of laying hens were studied. The objective was to derive an environmental friendly feed formulation for warm climate. Seventy-two 29-week-old commercial White Leghorn hens of Babcock ISA white strain were used in this trial. The design is a completely randomized design with a 2×3 factors arrangement of treatments. Two constant ambient temperatures were 24±1°C and 34±1°C with 85% relative humidity. The three dietary treatments were 170 g kg⁻¹ crude protein, 140 g kg⁻¹ crude protein and 140 g kg⁻¹ crude protein supplemented with methionine 1.4 g kg⁻¹. Hens were allotted into six groups according to egg production and body weight. Birds were raised in individual wire cages for the experimental feeding period of five weeks. At the end of the feeding trial, one replicate of laying hens (four birds) from each treatment were selected for a four-day metabolic study for the daily collection of the excreta. The blood samples were withdrawn from the wing vein for analysis of hematocrit, blood glucose, sodium, potassium, magnesium, calcium, phosphorus and uric acid. Experimental results indicate that increases in ambient temperature significantly depress feed intake, egg production, egg weight and live weight of laying hens. High ambient temperature also caused inferior egg quality, including shell weight, shell thickness, shell breaking strength and specific gravity. Ambient temperature also changes the egg components with heavier egg albumin and yolk in the low-temperature group. Increasing ambient temperature also caused an increase in pH value in the plasma. This increase revealed a trend of depressed glucose (P<0.05) in the plasma of the laying hens. The dietary treatments, however, did not significantly influence feed intakes. Except egg weight, laying hens that were fed with the low protein (140 g kg⁻¹) with methionine supplemented diet produced similar numbers of egg and feed conversion as the layers fed with the high protein diet. The low protein with methionine supplemented diet produced significantly lighter eggs than the high dietary protein diet under the high ambient temperature, but produced heavier egg under the low ambient temperature. The concentration of uric acid in the plasma and nitrogen in the excreta of the high protein group was significantly higher than the other two low protein dietary groups (P<0.05).     

Preventive effect of rikkunshito on gastric motor function inhibited by l-dopa in rats

We previously reported that ghrelin prevented l-dopa (LD)-induced inhibition of gastric emptying (GE) of a non-nutrient solution in rats. Parkinson's disease treatment involves the combined administration of l-dopa with the enzyme l-amino acid decarboxylase inhibitor, carbidopa (CD) to reduce peripheral formation of dopamine. We investigated the effect LD/CD given orogastrically (og) on GE of a non-nutrient or nutrient meal and whether og pretreatment with rikkunshito, a kampo medicine clinically used to treat gastroparesis, influenced LD/CD effect on GE and postprandial antral and duodenal motility in conscious rats. LD/CD (20/2 mg kg⁻¹) decreased significantly GE to 26.3 ± 6.0% compared to 61.2 ± 3.2% in og vehicle monitored 20-min after a non-nutrient meal and to 41.9 ± 5.8% compared to 72.9 ± 5.2% in og vehicle monitored 60 min after a nutrient meal. Rikkunshito (0.5 or 1.0 g kg⁻¹) reduced the LD/CD (20/2 mg kg⁻¹) inhibition of GE of non-nutrient meal (36.9 ± 7.4% and 46.6 ± 4.8% respectively vs. 12.1 ± 7.4% in og vehicle plus LD/CD) while having no effect alone (56.6 ± 8.5%). The ghrelin antagonist, [d-Lys³]-GHRP-6 (1 mg kg⁻¹) injected intraperitoneally partially reversed rikkunshito preventive effect on LD/CD-inhibited GE. Rikkunshito (1.0 g kg⁻¹) blocked LD/CD (20/2 mg kg⁻¹)-induced delayed GE of a nutrient meal and the reduction of postprandial antral motility. In 6-hydroxydopamine-induced Parkinson's disease rat model, rikkunshito (1.0 g kg⁻¹, og) also prevented LD/CD-inhibited gastric emptying of a nutrient meal and enhanced fasting plasma levels of acylated ghrelin. These data indicate that oral rikkunshito alleviates the delayed GE induced by LD/CD in naïve and PD rat model in part through ghrelin-related mechanisms.     

Diet and nutrition of range goats on a sarcocaulescent shrubland from Baja California Sur,Mexico

Botanical composition of diets of range goats was studied to determine seasonal preference indices of forage species and nutritional quality of selected diets on a sarcocaulescent shrubland from the Sonoran desert in Baja California Sur, Mexico. Extrusas from five esophageal cannulated adult female goats (40 kg of BW) were collected at the beginning and at the end of each season from April of 2001 to March of 2002. At the end of spring, goats selected higher amounts of browse legumes and cacti species, but during late summer, autumn and winter goats mainly preferred browse non-legumes followed by forb species. Goats selected a constant diet in truly digestible crude protein (annual mean = 11 ± 0.4% DM) and metabolizable energy (2.4 ± 0.1 Mcal kg⁻¹) throughout the year. However, during late spring and early summer, goats selected diets higher in non-structural carbohydrates (NSC), truly IVDOM and truly digestible NSC. Dietary Ca, Mg, K, Mn, Fe were in substantial amounts to meet requirements of a range goat weighing 40.0 kg BW consuming 76.3 g DM kg^0.75 d⁻¹ in all seasons. It is concluded that range goats may require supplementary protein and energy to overcome pregnancy and lactation requirements throughout the year. Copper content appeared marginally deficient almost the entire year and Zn during late summer and autumn.     

Synergistic effect of Se-methylselenocysteine and vitamin E in ameliorating the acute ethanol-induced oxidative damage in rat

The present study was conduced to investigate the synergistic effects of combined treatments with Se-methylselenocysteine (SeMSC) and vitamin E (Vit E) in reversing oxidative stress induced by ethanol in serum and different tissues of rats. Sixty female rats were randomly divided into six groups for 30 days’ consecutive pretreatments as followed: control (I), physiological saline (II), 2.8 μg kg⁻¹ Se as SeMSC (III), 2.8 μg kg⁻¹ Se as sodium selenite (Na₂SeO₃, IV), 5 mg kg⁻¹ α-tocopherol as α-tocopherol acetate (Vit E, V), 5 mg kg⁻¹ α-tocopherol as α-tocopherol acetate and 2.8 μg kg⁻¹ Se as SeMSC (VI). All animals in groups II–VI were treated by ethanol treatment to cause oxidative stress. After 6 h of ethanol treatment, the activities of superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), the contents of total antioxidant capacity (T-AOC), malondialdehyde (MDA), glutathione (GSH) and carbonyl protein (CP) in the serum, liver, heart and kidney were measured. The result showed that the individual SeSMC, Na₂SeO₃ and vitamin E could effectively increase the SOD, T-AOC, GSH-Px and GSH contents as well as significantly decrease the MDA and CP concentrations in the tissues of ethanol-induced rats. At the same dose on different forms of Se, SeMSC showed greater antioxidant activity than Na₂SeO₃. Moreover, group VI (SeMSC and α-tocopherol acetate) showed much better antioxidant activity than individual group III (SeMSC) and V (α-tocopherol acetate) due to the synergistic effect.     

Mercury levels assessment in hair of riverside inhabitants of the Tapajós River,Pará State,Amazon, Brazil: Fish consumption as a possible route of exposure

The study present evaluated the levels of mercury (Hg) and methylmercury (MeHg) in hair samples of people from Barreiras community, riverside inhabitants of the Tapajós River (Pará, Brazil), an area impacted by clandestine gold mining, as well as we analyzed the levels of Hg and Se (selenium) in nine fish species (carnivores and non-carnivorous) from the Tapajós River, which stand out as the main species consumed by riverside inhabitants, to evaluate a relationship between frequency of fish consumption and Hg concentration, and also to evaluate possible mechanisms of fish protection (or non-protection) to Hg exposure by Se. Furthermore we analyze the water quality to evaluate the environmental trophic state, fact responsible by creating conditions that can potentiate the effects of toxic mercury. Concentrations of Hg and MeHg were analyzed in hair samples of 141 volunteers in different age band. Of those, 84.40% of samples present values above the threshold for biological tolerance, which is 6.00 μg g⁻¹ of total Hg in hair. Total Hg, in men there was a variation of 2.07–24.93 μg g⁻¹, while for women the variation was 4.84–27.02 μg g⁻¹. Consequently, the level of MeHg in men presented a variation of 1.49–19.57 μg g⁻¹, with an average of 11.68 μg g⁻¹, while with women the variation was from 3.73 to 22.35 μg g⁻¹, with an average of 10.38 μg g⁻¹. In fish species, Hg concentrations in carnivorous species had an average of 0.66 μg g⁻¹, higher than that permitted by current legislation, ranging from 0.30 to 0.98 μg g⁻¹, while the non-carnivorous species have values below the recommended by the legislation averaging 0.09 μg g⁻¹, ranging between 0.02 and 0.44 μg g⁻¹. For Se in fish, show that among carnivores, the contents of Se ranged between 0.18 and 0.54 μg g⁻¹ with a mean of 0.34 μg g⁻¹, while for non-carnivores these values were of the order of 0.16–0.56 μg g⁻¹, with an average of 0.32 μg g⁻¹. In surface water quality variables at the sampling points all showed values in accordance with the range established by current legislation. In this regard, the results provided by this study, while not conclusive, are strong indicators that despite not having been shown the relationship between the concentration of mercury in hair and feeding habits along the Tapajós River basin communities showed that a plausible correlation exists between levels of mercury and selenium in fish. This fact may serve as a subsidy to research human health, because in the Amazon, there is still a lot to examine with regards to the full understanding of the Se cycle.     

The relationship between Pseudo-nitzschia (Peragallo) and domoic acid in Scottish shellfish

The diatom genus Pseudo-nitzschia (Peragallo) associated with the production of domoic acid (DA), the toxin reposnsible for amnesic shellfish poisoning, is abundant in Scottish waters. A two year study examined the relationship between Pseudo-nitzschia cells in the water column and DA concentration in blue mussels (Mytilus edulis) at two sites, and king scallops (Pecten maximus) at one site. The rate of DA uptake and depuration differed greatly between the two species with M. edulis whole tissue accumulating and depurating 7 μg g⁻¹ (now expressed as mg kg⁻¹) per week. In contrast, it took 12 weeks for DA to depurate from P. maximus gonad tissue from a concentration of 68 μg g⁻¹ (now mg kg⁻¹) to <20 μg g⁻¹ (now mg kg^‐1). The DA depuration rate from P. maximus whole tissue was <5% per week during both years of the study. Correlations between the Pseudo-nitzschia cell densities and toxin concentrations were weak to moderate for M. edulis and weak for P. maximus. Seasonal diversity on a species level was observed within the Pseudo-nitzschia genus at both sites with more DA toxicity associated with summer/autumn Pseudo-nitzschia blooms when P. australis was observed in phytoplankton samples. This study reveals the marked difference in DA uptake and depuration in two shellfish species of commercial importance in Scotland. The use of these shellfish species to act as a proxy for DA in the environment still requires investigation.     

Epiphytic lichen indication of nitrogen deposition and climate in the northern rocky mountains,USA

Lichen bioindication can provide economical and spatially extensive monitoring of climate and pollution impacts on ecological communities. We used non-metric multidimensional scaling of lichen community composition and generalized additive models to analyze regional climate and pollution gradients in the northern Rocky Mountains, U.S. Temperature extremes, relative humidity, and N-deposition were strongly related to lichen community composition. Eutrophic species (genera Physcia, Xanthomendoza, and Xanthoria) were associated with high N deposition, low precipitation, and temperature extremes. Estimated N deposition in our study ranged from <0.5 to 4.26 kg N ha⁻¹ year⁻¹ with degradation to lichen communities observed at 4.0 kg N ha⁻¹ year⁻¹, the indicated critical load. The resulting model can track changes in climate and N pollution related to lichen communities over time, identify probable sensitive or impacted habitats, and provide key information for natural resource management and conservation. The approach is broadly applicable to temperate ecosystems worldwide.     

Evaluation of phosphorus distribution and bioavailability in sediments of a subtropical wetland reserve in southeast China

The phosphorus (P) fractions and bioavailable P in the sediments from the Quanzhou Bay Estuarine Wetland Nature Reserve were investigated using chemical extraction methods for the first time to study the distribution and bioavailability of P in the reserve sediments. A hypothesis was presented suggesting that the bioavailable P in the sediments could be evaluated using the P fractions. The total phosphorus (TP), inorganic phosphorus (IP), organic phosphorus (OP), non-apatite phosphorus (NAIP), and apatite phosphorus (AP) contents in the sediments were in the ranges of 303.87–761.59 mg kg⁻¹, 201.22–577.66 mg kg⁻¹, 75.83–179.16 mg kg⁻¹, 28.86–277.90 mg kg⁻¹, and 127.36–289.94 mg kg⁻¹, respectively. The water soluble phosphorus (WSP), readily desorbable phosphorus (RDP), algal available phosphorus (AAP), and NaHCO₃ extractable phosphorus (Olsen-P) contents in the sediments were in the ranges of 0.58–357.17 mg kg⁻¹, 80.77–586.75 mg kg⁻¹, 1.09–24.12 mg kg⁻¹, and 54.96–676.82 mg kg⁻¹, respectively. The correlation analysis results showed that the NAIP was the major component of the bioavailable P and that the impact of the AP on the bioavailable phosphorus may be minimal. Due to the low TP content in the sediments of the Quanzhou Bay Estuarine Wetland Nature Reserve, the potential pollution risks of P in the sediments may not be very high. The results also show that the bioavailable P concentrations in the sediments of the Quanzhou Bay Estuarine Wetland Nature Reserve could not be evaluated by measuring the P fractions and that the hypothesis was untenable.     

Increasing nitrogen depositions can reduce lichen viability and limit winter food for an endangered Chinese monkey

Increasing economic growth and industrial development in China is starting to impact even remote areas such as the Shennongjia nature reserve, where nitrogen pollution is becoming a major environmental threat. The epiphytic lichen flora is particularly rich in this area and is one of the components of this habitat most sensitive to nitrogen pollution. Since lichens represent an important food resource for the endangered monkey species Rhinopithecus roxellana, a reduction in lichen availability would have harmful consequences for the conservation of its habitat in the Shennongjia Mountains. To investigate the effects of increased nitrogen availability on the local lichen communities, so far scarcely considered, we conducted a one-year field experiment measuring growth, survival, and phosphomonoesterase activity of the widespread species Usnea luridorufa in response to nitrogen (up to 50 kg N ha⁻¹ year⁻¹ deposition) and phosphorus supply. Growth and survival of thalli and propagules of U. luridorufa decreased when treated with N deposition >12.05 kg N ha⁻¹ year⁻¹ and >2.14 kg N ha⁻¹ year⁻¹, respectively. The important role of phosphorus availability in relation to nitrogen supply was demonstrated by the increase in phosphomonoesterase activity with increasing nitrogen availability until a nitrogen toxicity threshold was reached. However, the high concentration of phosphorus in rainwater showed that phosphorus is not a limiting nutrient in the area.The results make a contribution to the knowledge of the negative effects of increased N deposition in the Shennongjia forest ecosystem.     

Protocorm culture of Dendrobium candidum in balloon type bubble bioreactors

Protocorm cultures of Dendrobium candidum were established in balloon type bubble bioreactors using Murashige and Skoog (MS) medium with 0.5 mg l⁻¹ α-naphthaleneacetic acid (NAA), 2.5% (w/v) sucrose, 5:25 mM NH₄:NO₃ and 1% (v/v) banana homogenate for the production of biomass and bioactive compounds. In 3 l bioreactor containing 2 l medium, a maximum protocorm biomass (21.0 g l⁻¹ dry biomass) and also optimum quantities of total polysaccharides (389.3 mg g⁻¹ DW), coumarins (18.0 mg g⁻¹ DW), polyphenolics (11.9 mg g⁻¹ DW), and flavonoids (4.5 mg g⁻¹ DW) were achieved after 7 weeks of culture. Based on these studies, 5 and 10 l bioreactor cultures were established to harvest 80 g and 160 g dry biomass. In 10 l bioreactors, the protocorms grown were accumulated with optimal levels of polysaccharides (424.1 mg g⁻¹ DW), coumarins (15.8 mg g⁻¹ DW), polyphenols (9.03 mg g⁻¹ DW) and flavonoids (4.7 mg g⁻¹ DW). The bioreactor technology developed here will be useful for the production of important bioactive compounds from D. candidum.     

Effect of different fertilization modes on soil organic carbon sequestration in paddy fields in South China: A meta-analysis

Evidences have shown that fertilizer application could affect soil organic carbon (SOC) content in cropland. South China is the main production region of rice, in which many different fertilization practices have been widely used during the last several decades, but the effect of different fertilization modes on SOC sequestration in paddy fields in this region was scarcely studied. Based on 274 samples taken from 44 paddy field experimental sites in South China, a meta-analysis was performed to quantify the relative annual change of SOC content (RAC) and SOC sequestration duration in paddy fields under five fertilization modes (inorganic nitrogen fertilization, N; inorganic nitrogen and phosphorus fertilization, NP; inorganic nitrogen, phosphorus, and potassium fertilization, NPK; organic fertilization, O; and inorganic combined with organic fertilization, OF). The results showed that the RAC under the five fertilization modes was 0–0.4 g kg⁻¹ yr⁻¹, with increments of 0.19 and 0.23 g kg⁻¹ yr⁻¹ in double cropping systems and triple cropping systems, respectively. The RAC under the O and OF treatments was higher than that under the N, NP and NPK treatments and was the highest (0.32 g kg⁻¹ yr⁻¹) under OF among the five treatments. The SOC accumulation rate decreased with time, and the SOC sequestration duration under N, NP, NPK, O and OF was approximately 23, 28, 46, 64 and 55 years, respectively. The accumulation enhancement rate of SOC over the whole SOC sequestration period under the N, NP, NPK, O and OF treatments was approximately 12.9%, 23.4%, 29.3%, 47.2% and 55.1%, respectively. The OF treatment performed the largest potential for SOC sequestration in paddy fields in South China under long-term conditions.