Chemical structures of manure from conventional and phytase transgenic pigs investigated by advanced solid-state NMR spectroscopy

Effects of feeding a pine-based biochar to beef cattle on subsequent manure nutrients, organic matter composition and greenhouse gas emissions

Biochar in ruminant diets is being assessed as a method for simultaneously improving animal production and reducing enteric CH₄ emissions, but little is known about subsequent biochar-manure interactions post-excretion. We examined chemical properties, greenhouse gas (GHG) emissions and organic matter (OM) composition during farm scale stockpiling (SP) or composting (CP) of manure from cattle that either received a pine-based biochar in their diet (BM) or did not (RM). Manure piles were monitored hourly for temperature and weekly for top surface CO₂, N₂O and CH₄ fluxes over 90 d in a semiarid location near Lethbridge, AB, Canada. Results indicate that cumulative CO₂, N₂O and CH₄ emissions were not affected by biochar, implying that BM was as labile as RM. The pH, total C (TC), NO₃-N and Olsen P were also not influenced by biochar, although it was observed that NH₄-N and OM extractability were both 13% lower in BM than RM. Solid-state ¹³C nuclear magnetic resonance (NMR) showed that biochar increased stockpile/compost aromaticity, yet it did not alter the bulk C speciation of manure OM. Further analysis by Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) revealed that dissolved OM was enriched by strongly reduced chemical constituents, with BM providing more humic-like OM precursors than RM. Inclusion of a pine-based biochar in cattle diets to generate BM is consistent with current trends in the circular economy, "closing the loop" in agricultural supply chains by returning C-rich organic amendments to croplands. Stockpiling/composting the resulting BM, however, may not provide a clear advantage over directly mixing low levels of biochar with manure. Further research is required to validate BM as a tool to reduce the C footprint of livestock waste management.

Improvements in pig agriculture through gene editing

Genetic modification of animals via selective breeding is the basis for modern agriculture. The current breeding paradigm however has limitations, chief among them is the requirement for the beneficial trait to exist within the population. Desirable alleles in geographically isolated breeds, or breeds selected for a different conformation and commercial application, and more importantly animals from different genera or species cannot be introgressed into the population via selective breeding. Additionally, linkage disequilibrium results in low heritability and necessitates breeding over successive generations to fix a beneficial trait within a population. Given the need to sustainably improve animal production to feed an anticipated 9 billion global population by 2030 against a backdrop of infectious diseases and a looming threat from climate change, there is a pressing need for responsive, precise, and agile breeding strategies. The availability of genome editing tools that allow for the introduction of precise genetic modification at a single nucleotide resolution, while also facilitating large transgene integration in the target population, offers a solution. Concordant with the developments in genomic sequencing approaches, progress among germline editing efforts is expected to reach feverish pace. The current manuscript reviews past and current developments in germline engineering in pigs, and the many advantages they confer for advancing animal agriculture.

Molecular speciation and aromaticity of biochar-manure: Insights from elemental, stable isotope and solid-state DPMAS 13C NMR analyses

The use of biochar (BC) in feedlot cattle diets has recently been explored as an approach to simultaneously improving animal production and reducing enteric methane (CH₄) emissions. This study examines the impact of BC on manure properties and whether BC affects manure composition and carbon (C) and nitrogen (N) outputs from feedlot steers offered a barley-based diet with BC at 0.0, 0.5, 1.0 and 2.0% (BC₀, BC_0.5, BC₁ and BC₂) of diet dry matter. Manure was sampled three times over a 235 day feeding trial conducted in southern Alberta, Canada. Results showed that BC₂ increased total C and the C/N ratio by 5.7 and 6.6% relative to BC₀, respectively (P < 0.05), while total N exhibited a quadratic response from BC₀ to BC₂ (P = 0.005). Manure ¹⁵δN signatures, ranging from +3.83 to +7.34‰, were not affected (P > 0.05) by BC treatment. DPMAS ¹³C NMR revealed similar structural features among BC₀ and BC₂; indigestible BC had a minor impact on the bulk-C speciation of manure organic matter (OM). Compositional changes were limited to the aromatic-C region of the ¹³C NMR spectra. Fused-ring domains, mainly pyrogenic-C, were increased by 1.56-fold at BC₂ relative to BC₀. Overall, results demonstrated that BC stabilizes recalcitrant-C in manure OM, potentially sequestering soil-C when applied to croplands. This approach provides an added value to its use in ruminant diets, mainly from a nutrient cycling perspective. However, whole-farm studies are further required to validate the incorporation of BC into beef production systems.

Speciation Transformation of Phosphorus in Poultry Litter during Pyrolysis: Insights from X-ray Diffraction, Fourier Transform Infrared, and Solid-State NMR Spectroscopy

Converting poultry litter (PL) into biochar by slow pyrolysis is a promising approach for recycling organic waste with enhanced phosphorus (P) utilization efficiency, which needs fundamental knowledge of in situ P speciation transformation for optimizing the biochar conversion conditions. In this study, solid-state NMR spectroscopy was employed to characterize solid-state P and C speciation of raw PL and PL-derived biochars prepared at various pyrolysis temperatures. The NMR analysis indicated that phytates were decomposed while hydroxyapatite (Ca₁₀(PO₄)₆(OH)₂) formed during conversion of PL to PL-derived biochar at a pyrolysis temperature above 300 °C. With increasing pyrolysis temperature to above 500 °C, farringtonite (Mg₃(PO₄)₂) formed. The higher pyrolysis temperature also favored the formation of calcite and provided deeper carbonization (i.e., greater dominance of thermally stable aromatic structures) in the biochar products. Water extractable P decreased significantly from 2.9 g/kg in PL to less than 0.3 g/kg in the PL-derived biochars prepared above 300 °C, indicating the inhibition effect of pyrolysis on the P lability mainly through transformation of labile phosphates in PL into less soluble forms. Overall, this study suggested that different pyrolysis temperatures should be considered for selective conversion of PL to biochar products with distinct agricultural and environmental applications that demand special P release patterns.

Chemical structures and characteristics of animal manures and composts during composting and assessment of maturity indices

Changes in physicochemical characteristics, chemical structures and maturity of swine, cattle and chicken manures and composts during 70-day composting without addition of bulking agents were investigated. Physicochemical characteristics were measured by routine analyses and chemical structures by solid-state 13C NMR and FT-IR. Three manures were of distinct properties. Their changes in physicochemical characteristics, chemical structures, and maturity were different not only from each other but also from those with addition of bulking agents during composting. Aromaticity in chicken manure composts decreased at first, and then increased whereas that in cattle and swine manure composts increased. Enhanced ammonia volatilization occurred without addition of bulking agents. NMR structural information indicated that cattle and chicken composts were relatively stable at day 36 and 56, respectively, but swine manure composts were not mature up to day 70. Finally, the days required for three manures to reach the threshold values of different maturity indices were different.

Hydrothermal carbonization of municipal waste streams

Hydrothermal carbonization (HTC) is a novel thermal conversion process that can be used to convert municipal waste streams into sterilized, value-added hydrochar. HTC has been mostly applied and studied on a limited number of feedstocks, ranging from pure substances to slightly more complex biomass such as wood, with an emphasis on nanostructure generation. There has been little work exploring the carbonization of complex waste streams or of utilizing HTC as a sustainable waste management technique. The objectives of this study were to evaluate the environmental implications associated with the carbonization of representative municipal waste streams (including gas and liquid products), to evaluate the physical, chemical, and thermal properties of the produced hydrochar, and to determine carbonization energetics associated with each waste stream. Results from batch carbonization experiments indicate 49-75% of the initially present carbon is retained within the char, while 20-37% and 2-11% of the carbon is transferred to the liquid- and gas-phases, respectively. The composition of the produced hydrochar suggests both dehydration and decarboxylation occur during carbonization, resulting in structures with high aromaticities. Process energetics suggest feedstock carbonization is exothermic.