Environmental Impacts and Their Association With Performance and Excretion Traits in Growing Pigs

Heavy metal sorption on struvite recovered from livestock wastewaters and release properties of granular forms

Phosphorus recovery from wastewater is receiving more attention due to its non-renewable property. As copper (Cu) and zinc (Zn) usually occur in livestock wastewater, this study focused on metal sorption in struvite from swine wastewater and the release properties of granular struvite in solution with varying pH conditions (2, 4, 7). The results demonstrated pH values presented a slightly decreasing trend with increasing Cu/Zn ratio, and Zn exhibited higher sorption performance on struvite crystals than that of Cu. Under the high content of metals in the wastewater, Cu/Zn ratios in the wastewater contributed to varying metal binding forms and mechanisms, resulting in the difference in the leaching properties of nutrients and metal. For the granular struvite manufactured with the adhesion of alginate, the P release percentage achieved 30.3-40.5% after 96 h in the wastewater of pH 2, whereas they were only 5.63-8.92% and 1.05-1.50% in the wastewater of pH 4 and 7, respectively. Acid wastewater contributed to the release of two metals, and the release amount of Zn was higher than that of Cu, which is associated with their sorption capacity in crystals. During the latter soil leaching test of adding granular struvite, the NH4+-N and PO43--P concentration in the effluent ranged from 0.34 to 1.26 and 0.62 to 2.56 mg/L after 96 h, respectively. However, the Cu and Zn could not be measured due to lower than the detection limit under varying treatments. Struvite might be accompanied by quicker metal leaching and slower nutrient leaching when surface sorption dominates in wastewater with lower metal concentrations.

Divergent selection for feed efficiency in pigs altered the duodenum transcriptomic response to feed intake and its DNA methylation profiles

Feed efficiency is a trait of interest in pigs as it contributes to lowering the ecological and economical costs of pig production. A divergent genetic selection experiment from a Large White pig population was performed for 10 generations, leading to pig lines with relatively low- (LRFI) and high- (HRFI) residual feed intake (RFI). Feeding behavior and metabolic differences have been previously reported between the two lines. We hypothesized that part of these differences could be related to differential sensing and absorption of nutrients in the proximal intestine. We investigated the duodenum transcriptome and DNA methylation profiles comparing overnight fasting with ad libitum feeding in LRFI and HRFI pigs (n = 24). We identified 1,106 differentially expressed genes between the two lines, notably affecting pathways of the transmembrane transport activity and related to mitosis or chromosome separation. The LRFI line showed a greater transcriptomic response to feed intake than the HRFI line. Feed intake affected genes from both anabolic and catabolic pathways in the pig duodenum, such as rRNA production and autophagy. Several nutrient transporter and tight junction genes were differentially expressed between lines and/or by short-term feed intake. We also identified 409 differentially methylated regions in the duodenum mucosa between the two lines, while this epigenetic mark was less affected by feeding. Our findings highlighted that the genetic selection for feed efficiency in pigs changed the transcriptome profiles of the duodenum, and notably its response to feed intake, suggesting key roles for this proximal gut segment in mechanisms underlying feed efficiency.NEW & NOTEWORTHY The duodenum is a key organ for the hunger/satiety loop and nutrient sensing. We investigated how the duodenum transcriptome and DNA methylation profiles are affected by feed intakes in pigs. We observed thousands of changes in gene expression levels between overnight-fasted and fed pigs in high-feed efficiency pig lines, but almost none in the related low-feed efficiency pig line.

A systematic review of life-cycle GHG emissions from intensive pig farming: Accounting and mitigation

Pork accounts for approximately 35 % of the global meat supply, with approximately 747 million tons of CO2e greenhouse gas (GHG) emissions annually. To meet the increasing demand for pork, intensive farming is becoming the priority rearing system owing to its higher productivity. Given the climate transformation ambitions of the pig industry but the lack of knowledge and data, we conducted a systematic review of studies published in the period of 2010-2022 from a life-cycle perspective, with a focus on greenhouse gas emissions accounting and mitigation. The significant variations in systematic harmonized global warming intensities (GWIs) can be primarily attributed to differences in accounting approaches, activity data, technologies and geographical conditions. To understand more, we broke down the entire life cycle and revealed the underlying reasons for modelling mechanisms and data from the main emitters (e.g., feeding, pig rearing, and manure management). These findings are expected to support and improve the transparency, consistency, and comprehensiveness of life-cycle GHG emissions accounting in pig farming. Potential mitigation measures were also reviewed and discussed to provide insights to support the sustainable development of the pig industry.

Analysis of merged transcriptomic and genomic datasets to identify genes and pathways underlying residual feed intake in growing pigs

Improvement of feed efficiency (FE) in pigs is an important milestone in order to reduce the economic and environmental impact of pig production. The goal of finding biomarkers for FE has persisted for decades. However, due to the complexity of the FE trait, these goals have still not been met. Here, we search for quantitative trait loci (QTL), candidate genes, and biological pathways associated with FE using both genotype and RNA-seq data. We obtained genotype and colon epithelium RNA-seq data for 375 and 96 pigs, respectively. In total, a genome-wide association study (GWAS) and differential expression (DE) analysis led to detection of three QTL on SSC9 and 17 DE-genes associated with FE. Possible intersection points between genes located in QTL and DE-genes were found on levels of transcription factor-target interaction. Moreover, cis-eQTL analysis revealed associations between genotype and expression levels of three DE-genes and three genes located in the GWAS QTLs, which may establish the connection between genotype and phenotype through DE. Finally, single nucleotide polymorphism calling using RNA-seq data for genes located in GWAS QTLs revealed 53 polymorphisms of which eleven were missense variants.

Life Cycle Assessment Perspective for Sectoral Adaptation to Climate Change: Environmental Impact Assessment of Pig Production

Growing demand for sustainably driven production systems, especially pork, requires a holistic or system thinking approach. Life Cycle Thinking (LCT) offers a robust methodological background as one of the approaches to achieving system analysis for a product along its lifecycle. On the other hand, Life Cycle Assessment (LCA) can perform state-of-art system analysis characterising its sustainability fronts as a compelling set of tools. Pork, as the most consumed meat across Europe (circa 34 kg per capita per year), compounded with the sector’s contribution to global greenhouse gases (GHG) doubling over the past decade necessitated this research. Our objective was to map hotspots along the value chain and recommend the best available practices for realising the sectoral contribution to carbon neutrality and climate change adaptation. To achieve the objective, we compared organic and conventional production systems by basing our analysis on Recipe midpoint 2016 (H) V1.13 as implemented in OpenLCA 1.10.2 using AGRIBALYSE® 3.0 datasets for eleven indicators. We found that producing 1 kg of pig meat under an organic production system had almost double the environmental impact of conventional systems for land use, water consumption, acidification, and ecotoxicity. Feed production and manure management are the significant hotspots accounting for over 90% of environmental impacts associated with 1 kg pig meat Liveweight (LW) production. Similarly, efficient conventional systems were less harmful to the environment in per capita unit of production and land use compared with organic ones in ten out of the eleven impacts evaluated. Implementing increased efficiency, reduced use of inputs for feed production, and innovative manure management practices with technological potential were some of the best practices the research recommended to realise minimal impacts on the identified hotspots.