Behavioural responses of broiler chickens during low atmospheric pressure stunning

Low atmospheric pressure stunning (LAPS) is a new irreversible stunning method for broiler chickens (Gallus gallus domesticus), which has the potential to improve welfare during routine slaughter. During LAPS, birds are placed in a hypobaric chamber that allows oxygen to be gradually removed from the environment by the controlled removal of air; the staged process takes 280s and reaches final decompression pressure that is 80.6 kPa below atmospheric pressure (nominally 101.3 kPa for an absolute vacuum pressure of 20.7 kPa). In this study, the behaviour of broilers (50 individuals and 50 focal birds killed in groups of 20) was observed during LAPS. Latencies, total durations, single bout durations and number of bouts were recorded for all behaviours. Three different decompression curves were applied during the process (based on automatically applied settings related to ambient temperature) and their effects on behaviour were investigated. Not all birds displayed all behaviours, but a subset of behaviours (ataxia, loss of posture, clonic and tonic convulsions and leg paddling) occurred in a consistent sequence. In individuals, mandibulation, headshaking and open bill breathing occurred earliest at 44.5 ± 31.6 s, 50.8 ± 38.3 s and 57.4 ± 35.8 s, respectively, after LAPS began. Ataxia was observed on average at 57.3 ± 11.5 s, with birds killed at colder temperatures taking slightly longer to succumb to ataxia than those at warmer temperatures. Loss of posture (LOP) is regarded as a behavioural marker for loss of consciousness and it occurred on average at 80.7 ± 17.7 s. Clonic and tonic convulsions were displayed after LOP at 110.5 ± 37.6 s and 117.4 ± 28.8 s after LAPS onset, respectively. Mean time to motionless was 199.4 ± 21.3 s. The group data were largely similar to that of individuals but were less reliable due to focal birds being obscured by neighbours. Based on LOP, the data suggest that birds are in a conscious state for longer during LAPS than in controlled atmosphere stunning with inert gases, but although the induction to unconsciousness is more gradual, other behavioural responses were equivalent. The occurrence of mandibulation, head shaking, and open bill breathing may be an indication of reduced welfare or may be indications of a non-painful physiological responses to hypoxia in a hypobaric atmosphere. These behaviours occurred at similar levels as seen in CAS with inert gases in poultry and the lack of escape behaviours as well as absence of signs of severe dyspnoea suggest that LAPS is a humane approach to stunning of poultry

Metabolic regulation during early embryo development

The preimplantation embryo must satisfy dynamic changes in energy demand during development to the blastocyst stage. Energy is provided through regulated metabolic pathways including glycolysis, β-oxidation and oxidative phosphorylation. Oxygen consumption rate (OCR), representing overall oxidative metabolism, has been reported in several species but few studies have examined the bioenergetics of embryo development.Several methods were optimised to measure components of OCR by individual embryos. On average, 66% of blastocyst OCR was coupled to ATP synthesis, the majority being complex I-dependent. A further 13% was of non-mitochondrial origin, while maximal OCR was 189% of basal, providing a spare respiratory capacity of +89%. This profile allows re-interpretation of existing data to estimate ATP production by the bovine embryo.The endogenous triglyceride store of the oocyte is increasingly considered a vital energy source in preimplantation development. In the present study, β-oxidation was manipulated during embryo culture. Inhibition of β-oxidation led to i) increased OCR ii) increased lipid content, iii) increased pyruvate uptake and iv) decreased lactate release at the blastocyst stage. Enhancing β-oxidation caused i) OCR at blastocyst stage to fall, ii) decreased lipid content during early cleavage, iii) decreased pyruvate consumption and iv) increased lactate release. Neither treatment affected blastocyst development rate or differential cell count, while both led to mitochondrial depolarisation.These metabolic observations were hypothesised to have legacy effects on gene expression. Groups of 10 blastocysts with similar metabolic profiles were analysed using transcription and DNA methylation microarray platforms. Following manipulation of β-oxidation, gene transcripts involved in mitochondrial function, metabolism, key signalling cascades, recognition of pregnancy, stress response, protein modification and transcription were differentially expressed. Genes involved in transcription, protein modification, key signalling cascades and disease were differentially methylated, potentially linking dysregulated β-oxidation to deleterious conditions in later development.These data highlight the plasticity of metabolic regulation in the embryo, allowing successful preimplantation development despite an apparently deleterious phenotype, yet indicate that metabolic activity has subtle effects on development

Heterogeneous distribution of Al-26 at the birth of the Solar System

It is believed that Al-26, a short-lived (t1/2 = 0.73 Ma) and now extinct radionuclide, was uniformly distributed in the nascent Solar System with the initial Al-26/Al-27 ratio of ~5.2\times10-5, suggesting its external stellar origin. However, the stellar source of Al-26 and the manner in which it was injected into the solar system remain controversial: the Al-26 could have been produced by an asymptotic giant branch star, a supernova, or a Wolf-Rayet star and injected either into the protosolar molecular cloud or protoplanetary disk. Corundum (Al2O3) is thermodynamically predicted to be the first condensate from a cooling gas of solar composition. Here we show that micron-sized corundum condensates from O-16-rich gas (Big Delta O-17 ~ -25%) of solar composition recorded heterogeneous distribution of Al-26 at the birth of the solar system: the inferred initial Al-26/Al-27 ratio ranges from ~6.5x10-5 to <2x10-6; ~50% of the corundum grains measured are Al-26-poor. Other Al-26-poor, O-16-rich refractory objects include grossite (CaAl4O7)- and hibonite(CaAl12O19)-rich calcium-aluminum-rich inclusions (CAIs) in CH chondrites, platy hibonite crystals in CM chondrites, and FUN (fractionation and unidentified nuclear isotopic anomalies) CAIs in CV, CO, and CR chondrites. Considering the apparently early and short duration (<0.3 Ma) of condensation of refractory O-16-rich solids in the solar system, we infer that Al-26 was injected into the collapsing protosolar molecular cloud and later homogenized in the protoplanetary disk. The apparent lack of correlation between Al-26 abundance and O-isotope compositions of corundum grains put important constraints on the stellar source of Al-26 in the solar system.Comment: Astrophysical Journal Letters 733, L3

Isotopic Investigations of Nebular and Parent Body Processes with a High Sensitivity Ion Microprobe

NASA supported the development of the CAMECA ims 1270 ion microprobe at UCLA for applications in cosmochemistry. The primary investigations centered on measuring the microscopic distributions of key isotopic abundances in primitive meteoritic materials as a means of constraining the nature of important thermal and chemical processes in the solar nebula and the timescales associated with those processes. Our prior work on oxygen isotope anomalies in a wide variety of meteoritic materials had led us to a view of a spatially heterogeneous nebula, and in particular, a restricted region for CAI formation that is characterized by O-16-rich gas. Because of its production of CAIs in the energetic local environment near the protosun, the existence of a natural transport mechanism via bipolar outflows, and a general astrophysical plausibility, we were attracted to the fluctuating X-wind model which had been put forward by Frank Shu, Typhoon Lee, and colleagues. With our collaborators, we undertook a series of investigations to test the viability of this hypothesis; this work led directly to the discovery of live Be in CAIs and a clear demonstration of the existence of 160-rich condensates, which necessarily implies an O-16-rich gaseous reservoir in the nebula. Both of these observations fit well within the context of X-wind type models, i.e. formation of CAIs (or condensation of their precursors) in the reconnection ring sunward of the inner edge of the accretion disk, however much work remains to be done to test whether the physical parameters of the model can quantitatively predict not only the thermal histories of CAIs but also their radioactivity. The issue of spatial heterogeneity in the nebula, central to the X-wind model, is also at the heart of any chronology based on short-lived radioisotopes. In this work, we followed up on strong hints for presence of exireme:j: (53 day) short-lived Be-7, and have prepared a manuscript (in revision). We also measured A1-Mg systematics by a combined approach of high-precision multiple-collector SIMS analyses, traditional analyses on the UCLA ims 1270, and high-spatial resolution analyses using a NanoSIMS instrument. The data help to deconvolve effects due to partial resetting of the A1-Mg system by multiple thermal events. Finally, we initiated investigations related to nebular heterogeneity with a new initiative of in situ high-precision sulfur isotope analyses of sulfides from a wide variety of components of chondrites. The ultimate goal of all this work is to help develop a better understanding of the relationships between CAIs and chondrules, the astrophysical environments in which they formed, and the timescales of nebular processes. As detailed in Table 1, for the project period, 14 manuscripts were published and 17 abstracts were presented describing the work

Resonance overlap: effect of neighbouring resonances

The neutron flux in the region of, and beJow a resonance is considered. The results of Goldstein which give an asymétrie flux shape in the region of a resonanceqre adjusted to allow for neutron absorption in the resonance, and gives reasonable agreement with the computed results. A simple form.ula for the calculation of the absorption in a resonance is developed, and it is found that it satisfactorily expresses the dependence of absorption On the total scattering cross section, and the energy of resonance, but gives a greater variation with temperature than is so. The approximation is found to be suitable for estimating the flux perturbation effects caused by neutron absorption. Maximum flux depression occurs at about .9 of a moderator collision range above the resonance lethargy. Flux perturbations from a resonance cause slight variations in the absorption by a lower resonance, when the separation lethargy is about one moderator lethargy interval. This effect is estimated and compared with calculated values. A value of about 1 per cent increase in the reduction of absorption is found to occur for predominantly absorbing resonances

Development of a High Resolution-High Sensitivity Ion Microprobe Facility for Cosmochemical Applications

NASA NAGW-4112 has supported development of the CAMECA ims 1270 ion microprobe at UCLA for applications in cosmochemistry. The instrument has been brought to an operational status and techniques developed for accurate, precise microbeam analysis of oxygen isotope ratios in polished thin-sections. We made the first oxygen isotopic (delta(18)O and delta(17)O) measurements of rare mafic silicates in the most chemically primitive meteorites, the a chondrites (Leshin et al., 1997). The results have implications for both high temperature processing in the nebula and low-T aqueous alteration on the CI asteroid. We have performed measurements of oxygen isotopic compositions of magnetite and co-existing olivine from carbonaceous (Choi et al., 1997) and unequilibrated ordinary chondrites (Choi et al., in press). This work has identified a significant new oxygen isotope reservoir in the early solar system: water characterized by a very high Delta(17)) value of approx. 5 % per thousand. We have determined the spatial distributions of oxygen isotopic anomalies in all major mineral phases of a type B CAI from Allende. We have also studied an unusual fractionated CAI from Leoville and made the first oxygen isotopic measurements in rare CAIs from ordinary chondrites

An ion probe study of the sulphur isotopic composition of Fe-Ni sulphides in CM carbonaceous chondrites

From the Introduction: The CM chondrites have endured variable degrees of aqueous alteration [1] which has changed their original mineralogy. A detailed study of the petrology and mineralogy of the sulphides in a suite of increasingly aqueously altered CMs, combined with sulphur isotope data measured in situ, can provide clues as to whether differences in the CM group are a result of different degrees of aqueous alteration, or whether they are the result of nebular heterogeneity