RESUMEN

Despite their global presence and multiple services including water storage and treatment, limited field studies have focused on quantifying water quality effectiveness of agricultural stormwater detention areas (SDAs; farm ponds). Limited information that does exist stems from unverified modeling studies. Economics is another neglected aspect of SDAs. An SDA in the Everglades basin of Florida was monitored to quantify its baseline nitrogen (N) treatment. Design flaws of underutilized surface storage in variably ponded areas and short-circuiting were rectified by retrofitting the SDA through compartmentalization, increase in outflow structure control elevation, and installing channel plugs. Post-retrofit total N retentions doubled (7500 from 3700 kg), a similar trend was also observed in surface water volume indicating that water retention drives N retention. Targeting enhanced water retention through retrofits can achieve reductions in downstream nutrient flows. The cost of additional N treatment from retrofits was $12/kg, an order of magnitude less than the published costs for other detention systems including newly constructed wetlands ($180/kg) and tailwater recovery systems ($214/kg). A scale-up showed that retrofitting SDAs could reduce the N discharge to an estuary in the Everglades by more than 50 %. A win-win payoff to farmers for SDA retrofits through a payment for environmental services program can achieve nutrient treatment economically and facilitate large-scale adoption.

RESUMEN

Hyperkalemia is common among patients with end stage kidney disease. Management involves diet modification. Hot water blanching is recommended to leach potassium in vegetables which results in losses of water-soluble and heat labile vitamins. Evidence on the effect of blanching in reducing potassium level of locally consumed vegetables in Kenya is limited. This study sought to establish effect of hot water blanching time-temperature on level of potassium, vitamin B1, B3 and C in kales (Brassica oleracea var. acephala) and spinach (Spinach oleracea) on potassium and vitamins B1, B3 and C retention/loss. The study adopted a full factorial experimental design. Vitamins were determined using high performance liquid chromatography. Potassium was quantified using atomic absorption spectrophotometry. To compare nutrient content between samples, independent t-test and Analysis of Variance were used at 95% confidence level. Nutrient content of fresh kales and spinach were potassium (102 mg/100 g and 615 mg/100 g), vitamin B1 (124 µg/100 g and 51 µg/100 g), vitamin B3 (1165 µg/100 g and 812 µg/100 g) and vitamin C (102 mg/100 g and 116 mg/100 g) respectively. In kales, blanching for 20 min at 1000°C resulted to retention of 86.9%, 55.6%, 27.6% and 12.9% of vitamin B1, B3, C and potassium respectively. In spinach, blanching for 20 min at 1000°C resulted in retention of 79.9%, 88.6%, 12.2% and 40.6% retention of vitamin B1, B3, C and potassium respectively. Vitamin C and Potassium were the most sensitive to heat and leaching. Time had a greater effect than temperature in this study. This study recommends blanching of kale at 15.2 min at 800°C, spinach at 17.7 min at 840°C. Further research on optimal blanching time-temperature for potassium and vitamin retention/loss is recommended.

RESUMEN

Soil erosion from agricultural fields is a persistent ecological problem, potentially leading to eutrophication of aquatic habitats in the catchment area. Often used and recommended mitigation measures are vegetated filter strips (VFS) as buffer zones between arable land and water bodies. However, if they are designed and managed poorly, nutrients - especially phosphorus (P) - may accumulate in the soil. Ultimately, VFS can switch from being a nutrient sink to a source. This problem is further aggravated if the field runoff does not occur as uniform sheet flow, but rather in concentrated form, as is usually the case. To assess the impact of concentrated flow on VFS performance, we have taken soil core samples from field-VFS transition zones at six sites in Lower Austria. We determined a multitude of physical and chemical soil parameters, focusing on P fractions and indices. Our results revealed that concentrated flow can lead to an accumulation of P in the VFS. P levels in the VFS inside the area of concentrated runoff can be equal to or higher than in the field, even though they receive no direct fertilization. However, the concentration and distribution of nutrients in the fields and VFSs were also site-specific and affected by local factors such as the age of the VFS, cropping, and fertilization. Accordingly, there is a need for more sophisticated, bespoke VFS designs that can cope with site-specific runoff volumes and movements of nutrients that occur.

Asunto(s)

RESUMEN

Modeling of watershed Ecosystem Services (ES) processes has increased greatly in recent years, potentially improving environmental management and decision-making by describing the value of nature. ES models may be sensitive to different conditions and, therefore, should ideally be validated against observed data for their use as a decision-support instrument. However, outcomes from such ES modeling are barely validated, making it difficult to assess uncertainties associated with the modeling and justify their actual usefulness to develop generalizable management recommendations. This study proposes a framework for the systematic validation of one of such tools, the InVEST Nutrient Delivery Model (NDR) for nutrient retention estimates. The framework is divided into three stages: 1) running the NDR model inputs, processes, and outputs; 2) building a long-term reference dataset from open access water quality observations; and 3) using the reference data for model calibration and validation. We applied this framework to twenty watersheds in the Commonwealth of Puerto Rico, where data availability resembles thar of watersheds across the United States. Long-term water quality data from monitoring stations facilitated model calibration and validation. Our framework provided a reproducible method to linking the vast monitoring network in the U.S. and its territories for evaluating the InVEST's NDR model performance. Beyond the framework development, this study found that the InVEST NDR model explained 62.7 % and 79.3 % of the variance in the total nitrogen and total phosphorus between 2000 and 2022, respectively, supporting the suitability of the model for watershed scale ecosystem services assessment. The findings can also serve as a reference to support the use of InVEST for other locations in the tropics without publically available monitoring data.

RESUMEN

Estuaries are a significant source of nutrients to the marine environment. The magnitude of this source is a function of nutrients load reaching the estuary and removal (attenuation) within estuaries. Most estuarine research is conducted in large estuaries, which do not reflect the processes in small estuaries in urban and semi-arid regions where flood water is a substantial portion of the annual discharge and the estuarine baseflow is often low and dominated by wastewater. To improve the understanding of nutrient attenuation and load into the Mediterranean, we conducted high-resolution nutrient sampling in the eutrophic Alexander micro-estuary as a test case. We sampled once per month during baseflows (years 2014-2019) and hourly during floods (years 2016-2018). The concentrations of inorganic nutrients (phosphorous (P) and nitrogen (N)) were extremely high during baseflows. Dissolved ammonium and particulate P were the only nutrients that were in the estuary (by 55 % and 30 %, respectively). Floods were rare, occurring ~4 % of the time, but contributed 62 % of the annual water discharge of the Alexander micro-estuary (14.7 ± 3.8 106 m3 y-1). The concentration of all dissolved nutrients decreased during floods but was higher than expected (DIN 584 ± 50 µmol L-1, phosphate 21 ± 2 µmol L-1), accounting for 42 % and 55 % of the overall annual DIN (123.5 ± 44.9-ton yr-1) and P (6.7 ± 1.9 ton yr-1) loads to sea, respectively. The N:P ratios were 16 and 34 during baseflow and flood events, respectively. Previously, nutrient loads were calculated by multiplying baseflow-measured concentrations by the total water volume of baseflow and floods. Our calculations, based on high-resolution sampling, revealed lower annual loads of P and N to the sea that were 56 % and 89 % of previous estimates, which is a considerable difference in an oligotrophic system such as the eastern Mediterranean.

RESUMEN

Eutrophication is a main threat to continental aquatic ecosystems. Prevention and amelioration actions have been taken under the assumption of a stable climate, which needs reconsideration. Here, we show that reduced precipitation can bring a lake ecosystem to a more productive regime even with a decline in nutrient external load. By analyzing time series of several decades in the largest lake of the Iberian Peninsula, we found autocorrelated changes in the variance of state variables (i.e., chlorophyll and oxygen) indicative of a transient situation towards a new ecosystem regime. Indeed, exceptional planktonic diatom blooms have occurred during the last few years, and the sediment record shows a shift in phytoplankton composition and an increase in nutrient retention. Reduced precipitation almost doubled the water residence time in the lake, enhancing the relevance of internal processes. This study demonstrates that ecological quality targets for aquatic ecosystems must be tailored to the changing climatic conditions for appropriate stewardship.

Asunto(s)

RESUMEN

1. Effects of cereal type and conditioning temperature (CT) on protein and carbohydrate (CHO) molecular structures, nutrient retention, carcass and blood characteristics, caecal microbial population and growth criteria of broilers fed pellet diet were evaluated for a total period of 35 d.2. In total, 336-day-old Cobb 500 broiler chicks were randomly allotted into a 2 × 2 factorial arrangement with two different cereal types (maize or wheat) processed in two different temperatures (CT; 68°C or 90°C) with seven pen replicates containing 12 birds each.3. Chicks fed the maize-based diets significantly gained higher body weight (BW) and lower feed conversion ratio (FCR) in comparison to the chicks fed wheat-based diets during the whole grow-out period (p < 0.01). Overall, the highest BW and feed intake (FI) were seen in birds fed wheat-based diets conditioned at 68°C, but the lowest FCR was observed in maize-based diet conditioned at 90°C at 7, 14 and 21 d of age (p < 0.01). However, BW was higher and FCR lower in chicks fed maize-based diets conditioned at 90°C in the grower period (28 and 35 d; p < 0.01).4. The α-helix height was higher in wheat-based starter diets in comparison to the maize-based diet (p < 0.01). Ratio of amide I to II area and total CHO peak height were increased when diets were processed at 90°C in both maize and wheat-based starter diet (p < 0.05). Increasing the CT from 68°C to 90°C reduced CHO peak 1 and 2 height by 11.6% and 3.95%, respectively, in maize-based starter diets, while increasing the CT from 68°C to 90°C reduced CHO peak 1 and 2 height by 54.3% and 57.2%, respectively, in wheat-based starter diets. In the grower diets, increasing the CT from 68°C to 90°C increased CHO peak 1 by 23% in maize-based diets, but reduced CHO peak 1 by 24.5% in wheat-based diets.5. Calcium and phosphorous retention were highest in chicks fed wheat-based diets conditioned at 90°C and lowest in chicks fed maize-based diets conditioned at 90°C (p < 0.01). Salmonella, E. coli and coliforms in the caeca reduced significantly (p < 0.05) in chicks fed wheat-based diets conditioned at 90°C on d 11 and increased with the same diet at 35 d of age compared to the chicks fed maize-based diets conditioned at both 68°C and 90°C or wheat-based diets conditioned at 68°C.6. Conditioning the wheat-based diets at 68°C improved production responses without causing any adverse effects on protein and CHO molecular structures, however increasing the conditioning temperature to 90°C impaired performance due to alteration of protein and CHO molecular structures. In contrast, conditioning of the maize-based diets at 90°C had the opposite effect, and improved production performance compared to diets conditioned at 68°C.

Asunto(s)

RESUMEN

The reduction of nitrogen (N) and phosphorus (P) in fattening pigs' diets is one possible approach to lower N and P excretion in livestock farming relative to N and P intake. Due to the implementation of the European Nitrates Directive and the consecutive amendments to the German fertiliser legislation since 2017, N- and P-reduced diets for fattening pigs are becoming more and more important and are increasingly used in practice. To investigate the effects of such diets on N and P balance and retention as well as on nutrient digestibility of contemporary fattening pigs, a balance experiment was performed with eight barrows (average live weight = 61.5 ± 2.1 kg) which were surgically fitted with a simple T-cannula at the terminal ileum. The pigs received a control diet meeting nutrient requirements (CON) and an N- and P-reduced diet (NPred) ad libitum (n = 4/diet) in a 3-phased feeding regimen (3 weeks/phase). In the last week of each phase, faeces and urine were collected quantitatively for 5 days followed by a 2 × 12 hours collection of ileal digesta. Daily feed intake, live weight gain and feed-to-gain ratio did not differ between CON and NPred. NPred-fed pigs consumed 10.5% (p = 0.006) and excreted 28.3% (p = 0.028) less N than CON-fed pigs. Phosphorus excretion was lowered by 15.1% in NPred-fed pigs (p = 0.012). N and P retention did not differ between CON and NPred, but were elevated in comparison to other studies. N and P efficiency, expressed as nutrient retention divided by nutrient intake, was higher in NPred - than CON-fed pigs (N: 68 vs 60%, P: 54.2 vs 49.3%). Apparent post-ileal digestibility coefficient (DCpost-ileal) and apparent total tract digestibility coefficient (DCtotal) of crude protein were higher in NPred - than CON-fed pigs (p < 0.013), but apparent precaecal digestibility coefficient (DCpc) of crude protein was unaffected by diet. DCpc, DCpost-ileal and DCtotal of P were similar for CON- and NPred-fed pigs. NPred-fed pigs showed an elevated DCpc and DCtotal of organic matter, N-free-extractives and starch compared to CON-fed pigs. DCpc of calcium was also higher in NPred-fed pigs. In conclusion, the results suggest that N- and P-reduced feeding of fattening pigs remains an effective strategy to lower the N and P release into the environment. Furthermore, results indicate that N- and P-reduced feeding leads to a higher N and P efficiency in contemporary fattening pigs.

Asunto(s)

RESUMEN

Owing to their availability, cost effectiveness and environmental-friendly nature, plant extracts are promising additives for fish farming. This study aims to determine the optimal dosage of fermented herbal extract (FHE)-composed of Morus alba (33.3%), Curcuma xanthorrhiza (33.3%), and Boesenbergia rotunda (33.3%)-for growth enhancement and feed utilisation efficiency of Oreochromis niloticus fingerlings. Fermentation was conducted using probiotics Lactobacillus casei (Yakult®, Tokyo, Japan) and Saccharomyces cereviceae (commercial baker's yeast). The FHE was high in flavonoid and alkaloid, vitamin C, potassium, natrium, lipase and protease. Four doses of FHE treatments, namely treatment A (0 mg/kg of feed); treatment B (100 mg/kg of feed); treatment C (300 mg/kg of feed); treatment D (500 mg/kg of feed) were compared. After subjected to 35 days of culture, tilapias subjected to FHE-coated feed exhibited better weight gain (WG), specific growth rate (SGR), and feed efficiency (FE) compared to control. The best dosage that gave the highest growth and feed efficiency was treatment C (300 mg/kg of feed). Furthermore, the feed efficiencies of FHE-incorporated treatments were positively influenced by the increased in length and density of intestinal villi, number of goblet cells, lymphocytes, as well as nutrient retention to support growth. The results of this study indicate that FHE is a promising functional feed additive to stimulate growth and improve feed efficiency in tilapia farming.

RESUMEN

BACKGROUND: The study aimed to investigate the effect of urea molasses mineral blocks (UMMB) on nutrient digestibility, productive performance and blood biochemical profile of indigenous yaks under various feeding systems. A total of sixteen yaks were randomly divided into four groups (n = 4 animal per group) and offered the, following feeding systems: (A) stall feeding, (B), urea molasses mineral block (UMMB) + stall feeding, (C) yard feeding and (D) UMMB + yard feeding. Trial lasted for 40 days. RESULTS: Results showed that nutrients intake (g) and nutrient digestibility (%) of dry matter (DM), organic matter (OM), crude protein (CP), ether extract (EE) and crude fiber (CF) were significantly higher (p < 0.05) in stall and yard feeding groups with UMMB licking. Blood zinc, cobalt, hemoglobin (Hb), red blood cell (RBC), glucose and serum glutamate private transaminase (SGPT) significantly (p < 0.05) increased in stall and yard feeding with UMMB licking. Milk yield, Ca and monounsaturated fatty acid except milk composition improved significantly (p < 0.05) in stall and yard feeding groups with UMMB licking. CONCLUSION: It was concluded that feeding of UMMB improved utilization of low-quality roughages and best results were obtained from stall and yard feedings with UMMB licking as compared to other groups.

Asunto(s)

RESUMEN

Floodplains provide critical ecosystem services to people by regulating floodwaters and retaining sediments and nutrients. Geospatial analyses, field data collection, and modeling were integrated to quantify a portfolio of services that floodplains provide to downstream communities within the Chesapeake Bay and Delaware River watersheds. The portfolio of services included floodplain sediment and nutrient retention and flood regulation. Sediment and nutrient retention were quantified and valued for all non-tidal wadable streams in the Chesapeake Bay and Delaware River watersheds. Predicted nitrogen fluxes from measurements of streambanks and floodplain geomorphic changes were summarized at various scales (river basin, state, and county) and valued using a benefits transfer approach. Floodplain flood regulation services were assessed through a pilot study focused on the Schuylkill River watershed in the Delaware River watershed. Geospatial analysis and published flood frequency estimates were used to assess baseline and counterfactual (i.e., floodplain storage removed) scenarios. Flood regulation was valued using the Federal Emergency Management Agency's Hazus model to compare differences in structural damage to private residences under baseline and counterfactual scenarios. The estimated value of floodplain sediment and nutrient retention was $223 million United States dollars (USD) per year in the Chesapeake Bay watershed and $38 million USD per year in the Delaware River watershed. Sediment and nutrient retention benefits were offset by a streambank erosion cost of $123 million and $14 million USD annually in the Chesapeake and Delaware watersheds, respectively. In the Schuylkill River watershed floodplain flood regulation was valued at $860,000 USD per year, with an additional $7.2 million USD annually provided through floodplain sediment and nutrient retention. Together this portfolio of floodplain ecosystem services indicates that floodplains provide substantial benefits to people by trapping nutrients and storing floodwaters.

Asunto(s)

RESUMEN

Lentic water bodies, including lakes, reservoirs, and wetlands, retain excess nutrients in runoff from agricultural and urban activities, and protect downstream water bodies from eutrophication. To develop effective nutrient mitigation strategies, it is important to understand the controls on nutrient retention in lentic systems and what drives variability between different systems and geographical regions. Efforts to synthesize water body nutrient retention at the global scale are biased toward studies from North America and Europe. Numerous studies published in Chinese Language journals exist in the extensive China National Knowledge Infrastructure (CNKI), but are missing from global synthesis due to their absence in English language journal databases. We address this gap by synthesizing data from 417 waterbodies in China to assess hydrologic and biogeochemical drivers of nutrient retention. In this study, we found median retention of 46 and 51% for nitrogen and phosphorus, respectively, across all water bodies in our national synthesis, and on average, wetlands retain more nutrients than lakes or reservoirs. The analysis of this dataset highlights the influence of water body size on first-order nutrient removal rate constants, as well as how regional temperature variations affect nutrient retention in water bodies. The dataset was used to calibrate the HydroBio-k model, which explicitly considers the effect of residence times and temperature on nutrient retention. Application of the HydroBio-k model across China reveals patterns of nutrient removal potential, where regions with a higher density of small water bodies retain more nutrients than others, such that regions like the Yangtze River Basin with a greater proportion of smaller water bodies have greater retention rates. Our results emphasize the importance of lentic systems and their function in nutrient removal and water quality improvement, as well as the drivers and variability of these functions at the landscape scale.

Asunto(s)

RESUMEN

Increases in food production to meet global food requirements lead to an increase in the demand for nitrogen (N) fertilizers, especially urea, for soil productivity, crop yield, and food security improvement. To achieve a high yield of food crops, the excessive use of urea has resulted in low urea-N use efficiency and environmental pollution. One promising alternative to increase urea-N use efficiency, improve soil N availability, and lessen the potential environmental effects of the excessive use of urea is to encapsulate urea granules with appropriate coating materials to synchronize the N release with crop assimilation. Chemical additives, such as sulfur-based coatings, mineral-based coatings, and several polymers with different action principles, have been explored and used for coating the urea granule. However, their high material cost, limited resources, and adverse effects on the soil ecosystem limit the widespread application of urea coated with these materials. This paper documents a review of issues related to the materials used for urea coating and the potential of natural polymers, such as rejected sago starch, as a coating material for urea encapsulation. The aim of the review is to unravel an understanding of the potential of rejected sago starch as a coating material for the slow release of N from urea. Rejected sago starch from sago flour processing is a natural polymer that could be used to coat urea because the starch enables a gradual, water-driven mechanism of N release from the urea-polymer interface to the polymer-soil interface. The advantages of rejected sago starch for urea encapsulation over other polymers are that rejected sago starch is one of the most abundant polysaccharide polymers, the cheapest biopolymer, and is fully biodegradable, renewable, and environmentally friendly. This review provides information on the potential of rejected sago starch as a coating material, the advantages of using rejected sago starch as coating material over other polymer materials, a simple coating method, and the mechanisms of N release from urea coated with rejected sago starch.

RESUMEN

The transport of excess nutrients into freshwater systems constitutes a serious risk to both water quality and aquatic health. Vegetated buffer zones (VBZs) next to waterways are increasingly used in many parts of the world to successfully intercept and eliminate pollutants and other materials in overland flow, especially in warm or temperate regions. The major processes for the retention of pollutants in VBZ are microbial degradation, infiltration, deposition, filtration, adsorption, degradation, assimilation, etc. The effectiveness of the VBZ relies on several environmental factors, including BZ width, runoff intensity, slope, soil texture, temperature, vegetation type, etc. Among the reported factors, cold weather possesses the most detrimental impact on many of the processes that VBZ are designed to carry out. The freezing temperatures result in ice formation, interrupting biological activity, infiltration and sorption, etc. In the last twenty years, burgeoning research has been carried out on the reduction of diffuse nutrient pollution losses from agricultural lands using VBZ. Nonetheless, a dearth of studies has dealt with the problems and concerns in cold climates, representing an important knowledge gap in this area. In addition, the effectiveness of VBZ in terms of nutrient removal abilities varies from -136% to 100%, a range that reveals the incertitude surrounding the role of VBZ in cold regions. Moreover, frozen soils and plants may release nutrients after undergoing several freeze-thaw cycles followed by runoff events in spring snowmelt. This review suggests that the management and design of VBZ in cold climates needs close examination, and these systems might not frequently serve as a good management approach to decrease nutrient movement.

Asunto(s)

RESUMEN

This study aimed to investigate the effect of dietary lysolecithin (LYSO) and lipase supplementation on productive performance, nutrient retention, and meat quality of broiler chicken fed a low energy diet. For this purpose, a total of 360 chicks were randomly alienated into six treatments, having six replicates (no = 10) birds each replicate. The dietary treatments were followed as control (CON fed as normal energy diet), LE (CON-100 kcal/kg from BD. basal diet), LIP 0.04 (LE + 0.04% lipase), LYSO 0.04 (LE + 0.04% lysolecithin), LIP + LYSO 0.04 (LE + 0.04% lipase and lysolecithin), and LIP + LYSO 0.08 (LE. + 0.08% lipase and lysolecithin). The birds fed with LIP + LYSO 0.04 exhibited higher weight gain than LYSO 0.08 and CON (p < 0.05), and higher feed intake (F.I.) was also observed in LIP + LYSO 0.04 than CON. However, lipase and emulsifier dietary effects were non-significant on FCR. (p > 0.05). Effects of experimental diets on dry matter (DM), crude protein (CP), and fat digestibility were also non-significant (p > 0.05). Similarly, the blood biochemical profile (total cholesterol, triglycerides, LDL, HDL) of the broiler showed no significant difference (p > 0.05) by dietary treatments. Similarly, liver enzymes, AST and A.L.T., were also not statistically significant (p > 0.05) among all dietary treatments. Similarly, supplementation of LIP and LYSO had a non-significant (p > 0.05) effect on breast meat fatty acids composition. Conclusively, adding LIP + LYSO 0.08 to a low energy diet could demonstrate better growth performance and reduce the negative impact of a low-energy diet.

RESUMEN

The purpose of this study was to investigate the effects of coating technology on the cysteamine (CSH) release in the digestive tract and the growth-promoting effect of enteric-coating CSH in broilers. First, using the self-developed computer-controlled simulated digestion system to mimic the digestion process in vitro, the release of 2 coated CSH (CSH-I and CSH-Ⅱ) were studied. The results showed that less than 10% of CSH-I was released after gastric digestion and 52.35% of CSH-I was released with additional 4 h of small intestinal digestion. In contrast, 83.62% of CSH-Ⅱ was released during the gastric digestion. In order to verify the growth-promoting effects of CSH-I, a feeding trial was conducted in a completely randomized block arrangement with 3 treatments in 6 blocks, 5 chickens per replicate. Broilers were fed with corn-soybean meal diet either supplemented with 0 (CON), 200 mg/kg uncoated CSH (CSH) or 200 mg/kg CSH-I from d 7 to 42, respectively. Body weight and FI was recorded at d 21 and 42. Excreta were collected from d 39 to d 42 to determine the total tract retention (TTR) of dietary nutrients. In comparisons with controls, birds fed with CSH-I had greater BW, ADG, and ADFI and increased TTR of DM, gross energy (GE), NDF and hemicellulose (P < 0.05). In addition, duodenal villi height and surface area were also greater in those CSH-I-fed birds. In contrast, the growth performance of birds fed with uncoated CSH did not significantly differ from controls. Although the TTR of DM and GE was higher in birds fed with CSH than controls, no differences in small intestine morphology were noted. Thus, the type I coating (CSH-I) could be good enteric-coating technology to increase CSH release in the duodenum, improve digestion and duodenal morphology, and therefore growth performance in broilers.

Asunto(s)

RESUMEN

This study aims to investigate the effects of nanoparticles of zinc oxide (Nano-ZnO) supplementation on productive performance, nutrient digestibility, mineral retention, and blood biochemistry of Californian male rabbits under hot climatic conditions. A total of 100 Californian male rabbits 90 days of age (BW: 1790 ± 13 g) were randomly assigned to one of five treatment diets: Nano-ZnO at 0, 25, 50, 75, or 100 mg/kg, respectively, for 90 days. The rabbits were raised in an open house system (average ambient temperature of 39 °C, relative humidity of 30-35%, and temperature-humidity index of 33.6-34.0). Each treatment had 20 rabbits, and each rabbit was considered as a replicate. During the entire study period, there were no significant differences (P > 0.05) in BW, BW gain, feed intake, or feed conversion ratio between the treatment groups. Nano-ZnO supplementation at 25, 50, 75, and 100 mg/kg enhanced the digestibility coefficient of crude protein (CP) and ether extract (EE) considerably (quadratically, P < 0.05) when compared to the control group. In addition, when Nano-ZnO was supplemented at 25, 50, 75, and 100 mg/kg, serum levels of creatinine, alanine aminotransferase (ALT), and aspartate aminotransferase (AST) were considerably lower than the non-supplemented control group. Furthermore, when comparing the control and Nano-ZnO-fed rabbits, serum testosterone concentrations increased significantly (P < 0.05) in the treated groups. In addition, compared to the other groups, the 50 mg/kg Nano-ZnO group had the highest cecal Lactobacilli spp. count. These findings suggest that supplementing Californian male rabbits with 50 mg/kg dietary Nano-ZnO enhanced CP and EE digestibility, cecal Lactobacilli spp., as well as serum testosterone levels, and decreased serum ALT and AST levels under hot climatic conditions.

Asunto(s)

RESUMEN

Nutrient retention in biochar amended soil has yielded variable results, with poorly understood mechanisms. Identification of changes on biochar surfaces during in situ soil aging can provide mechanistic information on the role of biochar on nutrient retention. In the current greenhouse study, we analyzed changes of biochar surface characteristics from aging in two soils with different iron levels and amended with two types of manure under corn. On pristine biochar surfaces, we detected no iron species. In contrast, after soil aging (70 days), a self-functionalization of biochar surfaces with iron oxides was observed, which can be explained by soil redox cycles allowing reduced iron(II) to migrate on biochar surfaces followed by its re-oxidation. This self-functionalization is proposed as an underlying mechanism explaining the significantly (p < 0.01) increased nitrate retention by 29-180 % in biochar amended soil. Significant (p < 0.05) reductions in leachate phosphate (18-41 %) and dissolved organic carbon (8.8-55 %) were also observed after biochar surface functionalization. Our results indicate that redox-driven iron oxide formation on surfaces of biochar in the soil can be a critical process explaining the dynamic nature of nutrient retention observed in biochar amended soils. Identifying soil environmental conditions most beneficial for such surface functionalization, which has the potential to increase nutrient retention, is critical for implementing efficient biochar amendment strategies and for increased resource efficiency in agroecosystems.

Asunto(s)