Milk production and fertility performance of Holstein, Friesian, and Jersey purebred cows and their respective crosses in seasonal-calving commercial farms

peer-reviewedThere is renewed interest in dairy cow crossbreeding in Ireland as a means to further augment productivity and profitability. The objective of the present study was to compare milk production and fertility performance for Holstein, Friesian, and Jersey purebred cows, and their respective crosses in 40 Irish spring-calving commercial dairy herds from the years 2008 to 2012. Data on 24,279 lactations from 11,808 cows were available. The relationship between breed proportion, as well as heterosis and recombination coefficients with performance, was quantified within a mixed model framework that also contained the fixed effects of parity; cow and contemporary group of herd-year-season of calving were both included as random effects in the mixed model. Breed proportion was associated with all milk production parameters investigated. Milk yield was greatest for Holstein (5,217kg), intermediate for Friesian (4,591kg), and least for Jersey (4,230kg), whereas milk constituents (i.e., fat and protein concentration) were greatest for Jersey (9.38%), intermediate for Friesian (7.91%), and least for Holstein (7.75%). Yield of milk solids in crossbred cows exceeded their respective parental average performance; greatest milk solids yield (i.e., fat kg + protein kg) was observed in the Holstein × Jersey first-cross, yielding 25kg more than the mid-parent mean. There was no consistent breed effect on the reproductive traits investigated. Relative to the mid-parent mean, Holstein × Jersey cows calved younger as heifers and had a shorter calving interval. Friesian × Jersey first-cross cows also had a shorter calving interval relative to their mid-parent mean. Results were consistent with findings from smaller-scale controlled experiments. Breed complementarity and heterosis attainable from crossbreeding resulted in superior animal performance and, consequently, greater expected profitability in crossbred cows compared with their respective purebreds

Two-flow magnetohydrodynamical jets around young stellar objects

We present the first-ever simulations of non-ideal magnetohydrodynamical (MHD) stellar winds coupled with disc-driven jets where the resistive and viscous accretion disc is self-consistently described. The transmagnetosonic, collimated MHD outflows are investigated numerically using the VAC code. Our simulations show that the inner outflow is accelerated from the central object hot corona thanks to both the thermal pressure and the Lorentz force. In our framework, the thermal acceleration is sustained by the heating produced by the dissipated magnetic energy due to the turbulence. Conversely, the outflow launched from the resistive accretion disc is mainly accelerated by the magneto-centrifugal force. We also show that when a dense inner stellar wind occurs, the resulting disc-driven jet have a different structure, namely a magnetic structure where poloidal magnetic field lines are more inclined because of the pressure caused by the stellar wind. This modification leads to both an enhanced mass ejection rate in the disc-driven jet and a larger radial extension which is in better agreement with the observations besides being more consistent.Comment: Accepted for publication in Astrophysics & Space Science. Referred proceeding of the fifth Mont Stromlo Symposium Dec. 1-8 2006, Canberra, Australia. 5 pages, 3 figures. For high resolution version of the paper, please click here http://www.apc.univ-paris7.fr/~fcasse/publications.htm

Search for direct production of charginos and neutralinos in events with three leptons and missing transverse momentum in √s = 7 TeV pp collisions with the ATLAS detector

A search for the direct production of charginos and neutralinos in final states with three electrons or muons and missing transverse momentum is presented. The analysis is based on 4.7 fb−1 of proton–proton collision data delivered by the Large Hadron Collider and recorded with the ATLAS detector. Observations are consistent with Standard Model expectations in three signal regions that are either depleted or enriched in Z-boson decays. Upper limits at 95% confidence level are set in R-parity conserving phenomenological minimal supersymmetric models and in simplified models, significantly extending previous results

Integrating sequence and array data to create an improved 1000 Genomes Project haplotype reference panel

A major use of the 1000 Genomes Project (1000GP) data is genotype imputation in genome-wide association studies (GWAS). Here we develop a method to estimate haplotypes from low-coverage sequencing data that can take advantage of single-nucleotide polymorphism (SNP) microarray genotypes on the same samples. First the SNP array data are phased to build a backbone (or 'scaffold') of haplotypes across each chromosome. We then phase the sequence data 'onto' this haplotype scaffold. This approach can take advantage of relatedness between sequenced and non-sequenced samples to improve accuracy. We use this method to create a new 1000GP haplotype reference set for use by the human genetic community. Using a set of validation genotypes at SNP and bi-allelic indels we show that these haplotypes have lower genotype discordance and improved imputation performance into downstream GWAS samples, especially at low-frequency variants. © 2014 Macmillan Publishers Limited. All rights reserved