Relationship between inbreeding and milk production traits in two Italian dairy sheep breeds

The effects of inbreeding in livestock species breeds have been well documented and they have a negative impact on profitability. The objective of this study was to evaluate the levels of inbreeding in Sarda (SAR, n = 785) and Valle del Belice (VdB, n = 473) dairy sheep breeds and their impact on milk production traits. Two inbreeding coefficients (F) were estimated: using pedigree (F_PED), or runs of homozygosity (ROH; F_ROH) at different minimum ROH lengths and different ROH classes. After the quality control, 38,779 single nucleotide polymorphisms remained for further analyses. A mixed-linear model was used to evaluate the impact of inbreeding coefficients on production traits within each breed. VdB showed higher inbreeding coefficients compared to SAR, with both breeds showing lower estimates as the minimum ROH length increased. Significant inbreeding depression was found only for milk yield, with a loss of around 7 g/day (for SAR) and 9 g/day (VdB) for a 1% increase of F_ROH. The present study confirms how the use of genomic information can be used to manage intra-breed diversity and to calculate the effects of inbreeding on phenotypic traits.     

Dislocation-driven deformations in graphene

The movement of dislocations in a crystal is the key mechanism for plastic deformation in all materials. Studies of dislocations have focused on three-dimensional materials, and there is little experimental evidence regarding the dynamics of dislocations and their impact at the atomic level on the lattice structure of graphene. We studied the dynamics of dislocation pairs in graphene, recorded with single-atom sensitivity. We examined stepwise dislocation movement along the zig-zag lattice direction mediated either by a single bond rotation or through the loss of two carbon atoms. The strain fields were determined, showing how dislocations deform graphene by elongation and compression of C-C bonds, shear, and lattice rotations.     

Pit and mound influence on soil features in an Oriental Beech (Fagus orientalis Lipsky) forest

Windthrow, i.e. the felling of trees by wind, occurs continually in forest ecosystems. The uprooting of old trees creates multiple microsites (e.g. pit and mound landscape) that are the main source of soil heterogeneity. To determine the impact of pit and mound landscapes on soil features, a beech forest of the Langa district (Mazandaran province, Northern Iran) was studied. An area of 25 ha was considered for this study wherein three microsites were distinguished, including pit bottom (pit), mount top (mound) and level areas (closed canopy). In this area, 22 uprooted trees were also found. Soil samples were collected at different depths (i.e. 0–15, 15–30 and 30–45 cm) from all microsites and analysed. Our study shows that windthrow events should be considered as an important factor in influencing forest ecosystem, as they affect physical (i.e. density, texture and water content), chemical (i.e. pH, organic C, total N, cation exchange capacity and available nutrients) and biological (i.e. soil microbial respiration and earthworm density/biomass) characteristics of soil, thus resulting in pit and mound microsites that may strongly differ with respect to the closed canopy.     

Seasonal changes in microbial nitrogen in an old broadleaf forest and in a neighbouring young plantation

Soil microorganisms are actively involved in many processes of the soil N cycle and are strong competitors with plants for soil N. Therefore, microbial dynamics are important factors in controlling forest productivity. Nevertheless, they are poorly studied especially in relation to forest age, which can produce strong effects on the microbial community by affecting the forest floor environment. In the present study, seasonal variations of soil microbial N (N_mic) were monitored in an old floodplain hardwood forest (270 years) and in a young hardwood plantation (19 years) in two soil horizons (0–15 and 15–30 cm). Although the differences according to time of sampling and soil horizon were statistically significant, N_mic was significantly higher in old than in young forest, especially for the deeper soil layer. However, the highest percentage of total N (N_tot) immobilised in microbial biomass was found in the surface soil layer of the young plantation. Soil organic C (C_org) explained 23% of the spatial–temporal variation of N_mic over all sampling periods in the old forest, whereas the linear combination of N_tot, total extractable soil N (N_totex) and the C/N ratio explained 59% of variation in N_mic when considering only the growing season. In contrast, C_org and N_totex explained 59% of variation in N_mic in the young stand when considering all sampling periods and 75% when the analysis was limited to growing season. Soil moisture did not show any significant correlation with N_mic in either site. The sensitivity of N_mic to variation in C_org and N_tot seems to be affected by forest age, being higher in young than in old forest. Finally our results indicate that during the growing season, when the N_totex availability is low, the dynamics of N_mic and N_totex are temporally interdependent, suggesting the existence of a reciprocal control whose mechanisms deserve to be elucidated.     

Carbon balance and soil carbon input in a poplar short rotation coppice plantation as affected by nitrogen and wood ash application

New Forests - The increasing importance of short rotation coppice (SRC) plantations for bioenergy production makes it crucial to evaluate their carbon (C) sink potential and to understand which...     

Soil carbon stock in olive groves agroforestry systems under different management and soil characteristics

The atmospheric concentrations of greenhouse gases have increased to unprecedented levels during last decades, raising concerns about their effect on climate change. Agriculture and land use change play an important role in atmospheric CO₂ emission and fixation, especially by affecting the soil carbon (C) storage. In this context, agroforestry systems (AFSs) could play an important role contributing to climate change mitigation. Given the importance of olive cultivation in the Mediterranean region, it is important to investigate soil C stock in olive groves, and to assess which agronomic practices could improve the soil C stock in these systems. For this reason, a study was conducted in different olive groves, including conventional and organic management, and a typical silvopastoral AFS. Furthermore, an abandoned olive grove and nearby forest were examined as a comparison. Soil samples were collected in each farm and analysed for C content and physico-chemical characteristics. This study indicates that, irrespective of the management, olive groves in the Umbria region of Italy are characterised by a high level of soil C stock if compared to those growing in other areas and to forest ecosystems, indicating that the practices adopted in the area are not negatively affecting soil C storage. A slightly lower soil C stock was measured in the silvopastoral AFS in comparison to the other farms, while high soil C stock was associated with the use of pomace, suggesting that this practice can be used to further increase soil C stock in olive orchards.

     

Genome‐wide analysis of homozygosity regions in european simmental bulls

The study of Runs of Homozygosity (ROH) is a useful approach for the characterization of the genome of livestock populations. Due to their high relationship with autozygosity, ROH allow to make inference about population genetic history, to estimate the level of inbreeding, to assess within breed heterogeneity and to detect the footprints of selection on livestock genomes. Aim of this study was to investigate the distribution of runs of homozygosity in bulls belonging to five European Simmental populations and to assess the relationship between three production traits (milk yield, fat and protein contents) and autozygosity. ROH count, distribution and ROH‐based coefficient of inbreeding (F_ROH) were calculated for 3,845 Simmental bulls of five different European countries: Austria (AT), Switzerland (CH), Czech Republic (CZ), Germany (DE) and Italy (IT). Average values of ROH number per animal, and total genome length covered by ROH were 77.8 ± 20.7 and 205 ± 74.4 Mb, respectively. Bulls from AT, DE and IT exhibited similar ROH characteristics. Swiss animals showed the highest (12.6%), while CZ the lowest (4.6%) F_ROH coefficient. The relationship between ROH occurrence and milk production traits was investigated through a genome‐wide ROH‐traits association analysis (GWRA). A total of 34 regions previously associated with milk traits (yield and/or composition) were identified by GWRA. Results of the present research highlight a mixed genetic background in the 5 European Simmental populations, with the possible presence of three subgroups. Moreover, a strong relationship between autozygosity and production traits has been detected.