Dietary phosphorus and calcium in feed affects miRNA profiles and their mRNA targets in jejunum of two strains of laying hens

Phosphorus (P) and calcium (Ca) are critical for egg production in laying hens. Most of P in plant-based poultry diet is bound as phytic acid and needs to be hydrolysed before absorption. To increase P bioavailability, exogenous phytases or bioavailable rock phosphate is added in feed. There is growing evidence of the importance of miRNAs as the epicentre of intestinal homeostasis and functional properties. Therefore, we demonstrated the expression of miRNA profiles and the corresponding target genes due to the different levels of P (recommended vs. 20% reduction) and/or Ca (recommended vs. 15% reduction) in feed. Jejunal miRNA profiles of Lohmann Selected Leghorn (LSL) and Lohmann Brown (LB) laying hens strains were used (n = 80). A total of 34 and 76 miRNAs were differentially expressed (DE) in the different diet groups within LSL and LB strains respectively. In LSL, the DE miRNAs and their targets were involved in calcium signaling pathway, inositol phosphate metabolism, and mitochondrial dysfunction. Similarly, in LB miRNAs targets were enriched in metabolic pathways such as glutathione metabolism, phosphonate metabolism and vitamin B6 metabolism. Our results suggest that both strains employ different intrinsic strategies to cope with modulated P and Ca supply and maintain mineral homeostasis.

Enhancement of Soil Phosphorus Bioavailability by Arbuscular Mycorrhizae and Earthworms Through Regulating Soil Bacterial Community and Plant Nutrient Balance Under Salt Stress

Aims Soil salinization is an important factor limiting plant phosphorus (P) uptake and crop production. This study aimed to investigate the effects of arbuscular mycorrhizal fungi (AMFs) and earthworms in enhancing soil P bioavailability by regulating soil salt ions and altering the soil bacterial community under salt stress. Methods Treatments with or without earthworms and with or without AMFs in a high-salinity soil were applied. Results The results showed that the maize biomass and plant P, Ca and Mg contents were significantly increased by earthworms and AMF inoculation, and the highest plant P, Ca and Mg contents were observed with earthworm application alone. Earthworms and AMFs significantly decreased the soil stable inorganic P (hydroxyapatite) proportion and increased the soil available dicalcium phosphate proportion. AMFs significantly increased soil phosphatase activity and inorganic P fraction contents. Earthworms and AMFs significantly increased soil bacterial Chao1 and phylogenetic diversity. Structural equation model analysis showed that the most important driver of soil P mineralization was soil bacterial diversity, followed by soil Ca2+ and total salt concentration. Network analysis suggested that the response of bacteria to soil Ca2+ but not salt concentration positively correlated with soil P availability. Earthworms and AMFs could stimulate certain bacteria harbouring the phoX alkaline phosphatase gene to increase soil phosphatase activity and soil P availability. Conclusions In conclusion, earthworms and AMFs could enhance soil P bioavailability by stimulating soil P-cycling bacteria to activate soil stable inorganic P and by improving the plant cation nutrient balance under salt stress.

Differing Phosphorus Crop Availability of Aluminium and Calcium Precipitated Dairy Processing Sludge Potential Recycled Alternatives to Mineral Phosphorus Fertiliser

The European dairy industry generates large volumes of wastewater from milk and dairy food processing. Removal of phosphorus (P) by complexing with metal (e.g., aluminium, calcium) cations in P rich sludge is a potential P source for agricultural reuse and P recycling. However, there is a significant knowledge gap concerning the plant availability of this complexed P in comparison to conventional mineral P fertiliser. The current absence of information on plant P bioavailability of dairy processing sludge (DPS) limits the ability of farmers and nutrient management advisors to incorporate it correctly into fertiliser programmes. The present study examined the most common types of dairy sludge—(1) aluminium-precipitated sludge (“Al-DPS”) and (2) calcium-precipitated lime-stabilised sludge (“Ca-DPS”) at field scale to assess P availability in grassland versus mineral P fertiliser over a growing season. The experimental design was a randomised complete block with five replications. Crop yield and P uptake were assessed for 4 harvests. The initial soil test P was at a low level and the experimental treatments were super phosphate at 15, 30, 40, 50 and 60 kg P ha−1, two dairy sludge applied at 40 kg P ha−1 (comparison was made with mineral P at same application rate) and a zero P control applied in a single application at the beginning of the growing season. Results showed a significant positive slope in the relationship between P uptake response and mineral P application rate indicating the suitability of the experimental site for P availability assessment. The P bioavailability of Al- and Ca-DPS varied greatly between treatments. The P fertiliser replacement value based on the 1st harvest was 50 and 16% increased to 109 and 31% cumulatively over the four harvests for Al- and Ca-DPS, respectively. The Al concentration in Al-DPS did not limit P bioavailability, but low P bioavailability from Ca-DPS can be associated with its high Ca content that can lead to formation of low soluble Ca-P compounds at alkaline pH conditions with a high Ca/P ratio. These findings show that P availability from dairy sludge can be quite different depending on treatment process. Consequently, it is critical to have P availability information as well as total P content available to ensure the application rate meets crop requirements without creating environmental risk by over application.

Phosphorus bioavailability, amino acid digestibility and metabolizable energy of broiler chick diets supplemented with low-oil distiller’s dried grains with solubles

Phosphorus (P) bioavailability, crude protein (CP), amino acid (AA) digestibility, and apparent metabolizable energy (AMEn) were determined in broiler chick diets, supplemented with one of two low-oil distiller´s dried grains with solubles (oil contents 6.54% and 5.35% for DDGS A and B, respectively). Diets were provided ad libitum in a mash form, from days 8 to 21 of age. In Experiment 1, one day old male broiler chicks (n=210) were assigned to one of 7 treatments, with 3 replicates of 10 birds each. Animals in treatment 1 (T1) were fed a basal diet formulated to be deficient in nonphytate P (0.14%). Birds in T2 and T3 received the basal diet supplemented with 0.05% or 0.10% of P from monodicalcium phosphate (MCP), respectively. Phosphorus from DDGS was added to diets in T4 (0.05% from DDGS A), T5 (0.1% from DDGS A), T6 (0.05% from DDGS B) and T7 (0.1% from DDGS B). Percent of inclusion of DDGS was dictated by total P content as determined by chemical analyses. Growth performance and P intake were assessed in all birds. Phosphorus bioavailability was determined using the slope ratio assay, with tibia ash as the response variable. For Experiment 2, one-day-old male broiler chicks (n=200), were assigned to 5 treatments with 4 replicates of 10 birds each. A sorghum-soya control diet was given to animals in T1. Treatments 2 and 3 included this same diet supplemented with either 5% or 10% of DDGS A. Birds in T4 and 5 received the control diet with either- 5% or 10% of DDGS B. Amino acid digestibility was measured from ileal contents in 7 euthanized birds from each group at day 21. Apparent metabolizable energy was determined in oven dried feces from all animals during the last 3 days of the experiment. Weight gain and feed consumption increased (P <0.001) with larger inclusion of dietary P in birds from experiment 1. Relative P bioavailability for DDGS A and B was 72% and 86% respectively, from a P total content of 0.85% and 0.94%.,. Growth performance was similar for all treatment groups in experiment 2 (P >0.05). The average apparent ileal amino acid digestibility coefficient for DDGS A 76.5% and B was 76.4%. No differences were found for essential AA coefficients between the two DDGS (P >0.05). The AMEn values on a dry matter basis were 2828 and 2854 kcal/kg for DDGS A and B, respectively.

Seasonal Variations and Thinning Effects on Soil Phosphorus Fractions in Larix principis-rupprechtii Mayr. Plantations

Thinning is a common management practice in forest ecosystems. However, understanding whether thinning treatment will change the availability of phosphorus (P) in soils, and the effect of thinning on the seasonal dynamics of soil P fractions, are still limited. The objective of the present study was to assess seasonal variations in soil P fractions under different forest thinning management strategies in a Larch (Larix spp.) plantation in northern China. To accomplish this, we examined soil P fractions, soil physical–chemical properties, and litter biomass under control (CK), light (LT), moderate (MT) and high thinning (HT) treatments. Data were collected during the growing season of 2017. We found that most P fractions varied seasonally at different soil depths, with the highest values occurring in the summer and autumn. When compared to CK, MT enhanced the inorganic P (Pi) concentration extracted by resin strip (R-Pi). Labile organic P (Labile Po), moderately labile P and total P (TP) also increased in both MT and HT treatments irrespective of season. In contrast, less-labile Pi and Po fractions were lower in LT than in CK, especially when examining deeper soil layers. Our results suggest that LT leads to a strong ability to utilize Po and less-labile Pi. Moreover, the effect of thinning did not tend to increase with thinning intensity, P availability was maximized at the MT. Ultimately, we show that MT can improve soil P bioavailability and is recommended in Larix principis-rupprechtii Mayr. plantations of North China. Our results emphasize that the effect of thinning management on soil microenvironment is an important basis for evaluating soil nutrients such as soil P bioavailability.

Novel composite materials as P-adsorption agents and their potential application as fertilizers

<p>The main objective of this study is to review the role of phosphorus in fertilizers, emphasizing in phosphate rock which is the primary source for phosphate fertilizer, with reference to harmful heavy metals as a consequence of their use. Simultaneously, this study examined the use of P-Adsorption agents as a potential application in agriculture, as the adsorbed phosphorus can be used as fertilizer or enriching soil conditioners. Therefore, it is generated a sustainable cycle taking into account a renewable resource-based Phosphorus Adsorption Agent (P-AA) leading to environmental protection and conservation of natural resources. Finally, this study highlighted new aspects that support P bioavailability of Humic-metal-P (HMP) in soils, correlating with novel materials in water purification.</p>

Phosphorus bioavailability in soybean grown after pasture under different fertility regimes

The aim of this study was to evaluate the residual effect of phosphorus (P) fertilizer applied to an Urochloa decumbens cv. Basilisk pasture on the P bioavailability to the following soybean crop. Low-productivity pasture, planted on an Oxisol in an experimental field at Embrapa Cerrados, was divided into three strips, each of 1.5 ha and fertilized by broadcasting annual applications of 0, 20 and 40 kg ha-1 of P2O5 for four years. After the pasture was desiccate with herbicide, soybeans were sown and fertilized with 0, 50 and 100 kg ha-1 of P2O5 applied within each strip, making a total of nine (3x3) P treatments. Residual available P content (Mehlich-1 and resin) from the pasture fertilization was lower than from soybean fertilization. However, the bioavailable residual P from the pasture, determined by P accumulated in plants, production of dry matter and grain yield, had similar availability to inorganic P applied to the soybean. Early P fertilization applied to pasture is technically feasible and can be used to maintain the pasture: it is recommended to replace corrective fertilization for following soybean crops.