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Search Results: 1 - 10 of 448665 matches for " J. L. Collier "
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Effect of Varying Light Intensity on Blood Physiological Reactions of Broiler Chickens Grown to Heavy Weights
H.A. Olanrewaju,J.L. Purswell,S.D. Collier,S.L. Branton
International Journal of Poultry Science , 2012,
Abstract: This study investigated effects of varying levels of light intensities (25, 10, 5, 2.5 and 0.2 lx) from 22 to 56 d of age at 50% RH on blood acid-base balance, metabolites and electrolytes of heavy broilers reared under environmentally controlled conditions. Four identical trials were conducted with two replications per trial. In each trial, 600 1-d-old Ross 308 chicks were randomly distributed into 10 environmentally controlled chambers (30 males and 30 females chicks/chamber). Each chamber was randomly assigned one of five light intensities from d 22 to 56 d of age. Birds were provided a four phase-feeding program (starter: 1 to 14 d, grower: 15 to 28 d, finisher: 29 to 42 d and withdrawal: 43 to 56 d). Feed and water were provided ad libitum. Venous blood samples were collected on d 21 (base line), 28, 42 and 56. The lowest light intensity of 0.2 lx significantly (p<0.05) increased pH, Na+, K+, Cl- and reduced pCO2, Hb and Hct. However, all these acid-base changes are still within the normal acid-base homeostasis physiological ranges. In addition, exposure of modern heavy broilers to varying light intensity produced no significant effect on pO2, sO2, Ca2+, mOsm, McHc, Angap, T3, T4 and CS. Acid-base regulation during light intensity exposure did not deteriorate despite a lower pCO2 which consequently increased blood pH that resulted in a compensatory mechanism for mild alkalosis. This study shows the positive impact on profits to commercial poultry facilities that are using low lighting environment to reduce hyperactivity, pecking damage and energy costs without the induction of physiological stress effects on broiler welfare.
Age-Related Effects of Varying Ammonia Concentrations on Hematophysiological Variables in Broiler Chickens
H.A. Olanrewaju,J.L. Purswell,S.D. Collier,S.L. Branton
International Journal of Poultry Science , 2009,
Abstract: This study examined the response of different aged birds of the same genetic strain exposed to ammonia (NH3) at set concentrations on blood gases, electrolytes and acid-base balance under environmentally controlled conditions. The experiment consisted of a 4x4 factorial with a randomized design. The 16 treatments consisted of 4 levels (0, 25, 50 and 75 ppm) of NH3 concentrations and 4 different ages (1-d, 7-d, 14-d and 21-d) of birds. Venous blood samples were collected at the end of each 7 d of atmospheric NH3 exposure. Partial pressure of CO2 (pCO2), pH, Hematocrit (Hct) and Hemoglobin (Hb) increased significantly (p<0.05), whereas partial pressure of O2 (pO2), bicarbonate (HCO3-) and K+ decreased with increasing NH3 concentration compared with 0 ppm. In addition, pO2, pCO2, HCO3-, Hct, Hb, Na+ and Anion gap (Angap) increased significantly (p<0.05), while pH, glucose and corticosterone decreased as bird’s age increased. Ammonia x age interactions were observed for pH, anion gap and HCO3-. Plasma corticosterone concentrations were significantly different for age and were not affected by NH3. The effect of age was more pronounced than that of NH3 on examined variables. This effect of age on examined blood physiological variables improved as the age of birds increased from 1-d to 21-d old birds. Most blood physiological variables of different aged birds of the same genetic strain respond differently to set NH3 concentrations of 0 to 75 ppm and younger birds have a more intense reaction to the NH3 than older birds.
Effect of Ambient Temperature and Light Intensity on Growth Performance and Carcass Characteristics of Heavy Broiler Chickens at 56 Days of Age
H.A. Olanrewaju,J.L. Purswell,S.D. Collier,S.L. Branton
International Journal of Poultry Science , 2010,
Abstract: The effects of ambient temperature, light intensity and their interaction on growth performance and carcass characteristics of broilers were investigated in 2 trials. The experiment was consisted of a factorial arrangement of treatments in a randomized complete block design. The 9 treatments consisted of 3 levels (Low = 15.6, Moderate = 21.1, High = 26.7oC) of temperatures from d 21-56 d of age and 3 levels (0.5, 3.0, 20 lx) of light intensities from 8-56 d of age at 50% RH. Five hundred and forty Ross 708 chicks were randomly distributed into 9 environmentally controlled chambers (30 males and 30 females chicks/chamber) at 1 d of age. Feed and water were provided ad libitum. Birds were provided a four phase-feeding program (starter: 1 to 14 d, grower: 15-28 d, finisher: 29-42 d and withdrawal: 43-56 d). At 56 d of age, both feed intake and birds’ weight were recorded for the growth performance. Also, 20 (10 males and 10 females) birds from each chamber were processed to determine weights and yields. Broilers subjected to high ambient temperature of 26.7oC had significantly (P<0.05) lower BW, BWG, FI, carcass weight and pectoralis major and minor weights along with a significant (P<0.05) increased in FCR when compared with low and moderate ambient temperatures broilers. Plasma corticosterone concentrations were not statistically affected by temperature, light intensity or their interaction, suggesting an absence of stress. These results indicate that exposure of modern heavy weight broilers to high ambient temperature of 26.7oC in comparison with low and moderate ambient temperatures has a negative effect on growth performance and carcass characteristics, suggesting that they need to be grown under lower ambient temperature than previously reported.
Effects of Broiler Rearing Environment on Transmission of F-Strain Mycoplasma gallisepticum from Commercial Layer Hens to Broiler Chickens: Role of Acid-Base Balance
H.A. Olanrewaju,J.L. Purswell,S.D. Collier,S.L. Branton
International Journal of Poultry Science , 2009,
Abstract: Two trials were conducted concurrently to determine and compare, blood pH, blood gases, hematocrit and hemoglobin in F-strain Mycoplasma gallisepticum (FMG) inoculated layers and FMG contact-infected broilers. At the termination of the study, FMG-inoculated layers had the highest partial pressure of O2 and the lowest partial pressure of CO2 as compared with the other treatment groups. Blood pH values were unaffected by FMG inoculation. Hematocrit and blood concentrations of hemoglobin were slightly higher and HCO3- levels were lowest in FMG contact-infected broilers in comparison to the other treatments groups. Mycoplasma gallisepticum inoculated layers also resulted in a significant increase in blood concentrations of K+, a decrease in Na+, but no significant effects on blood concentrations of Ca2+ and Cl-. There were no differences in plasma glucose, cholesterone, triglyceride and anion gap, but osmolality was significantly reduced in FMG contact-infected broilers. Results indicate that inoculation of layers with FMG vaccine results in changes in plasma acid-base status along with changes in other blood metabolic variables. However, the FMG inoculation did not prevent homeostatic regulation of acid-base balance, as indicated by constant blood pH. The significant increase in pO2 in FMG inoculated layers is generally associated with an oxygen-dependent improvement in tissue oxygenation. Elevated arterial partial pressure of oxygen is beneficial to maximize oxygen transport capacity along with high concentrations of hemoglobin and hematocrit to carry oxygen throughout the body. It was concluded that in addition to protecting birds from MG infection, an FMG vaccine may improve the layer chicken’s ability to withstand the harmful effects of stressors on their performance and well-being.
Effect of Varying Light Intensity on Growth Performance and Carcass Characteristics of Broiler Chickens Grown to Heavy Weights
H.A. Olanrewaju,J.L. Purswell,S.D. Collier,S.L. Branton
International Journal of Poultry Science , 2011,
Abstract: This study investigated the effects of varying levels of light intensities (25, 10, 5, 2.5 and 0.2 lx) on growth performance and carcass characteristics of broiler chickens grown to heavy weights. Four identical trials were conducted with two replications per trial. In each trial, 600 1-d-old Ross 308 chicks were randomly distributed into 10 environmentally controlled chambers (30 male and 30 female chicks/chamber). Each chamber was randomly assigned one of five light intensities from d 22 to 56. Feed and water were provided ad libitum. Birds were provided a four phase-feeding program (starter, grower, finisher and withdrawal). Birds and feed were weighed on 0, 14, 21, 28, 42 and 56 d of age for growth performance. Also at 56 d of age, 20 birds (10 males and 10 females) from each chamber were randomly selected and processed to determine weights and yields. There was no effect of light intensity on growth performance, except significant (p<0.054) difference in FCR on 28 d of age under 25 and 5 lx. Broilers reared under 5 lx had significantly higher live weight (p<0.046) and carcass weight (p<0.026) in comparison with 0.2 and 25 lx. Birds reared under 5 and 10 lx had significantly higher fillet (p<0.025) and tender (p<0.034) weights when compared with birds reared under 0.2 and 25 lx. Mortality was not affected by light intensity treatments. In addition, plasma corticosterone concentrations were not statistically affected by light intensity, suggesting an absence of physiological stress. These results indicate that the range of light intensity used in this study has no effect on most production performances of broilers reared up to 56 d of age, but did affect some carcass characteristics. Therefore, using lower lighting intensity may be beneficial to commercial poultry facilities that are using low lighting environment to reduce hyperactivity, pecking damage and energy costs without physiological stress effects on broiler welfare.
Spatial correlation between lightning strikes and whistler observations from Tihany, Hungary
J. ?ster,A. B. Collier,A. R.W. Hughes,L. G. Blomberg
South African Journal of Science , 2010, DOI: 10.4102/sajs.v105i5/6.98
Abstract: A whistler is a very low frequency (VLF) phenomenon that acquires its characteristics from dispersive propagation in the magnetosphere. Whistlers are derived from the intense VLF radiation produced in lightning strikes, which can travel great distances within the Earth-ionosphere waveguide (EIWG) before penetrating the ionosphere, and exciting a duct. Field-aligned ducts of enhanced plasma density guide the propagation from one hemisphere to the other. The location of the duct, relative to the strike that causes the whistler, is unknown. Whistler time series from Tihany, Hungary, have been cross-correlated with lightning data obtained from the World Wide Lightning Location Network (WWLLN). The results show that whistlers observed at Tihany originate mainly from lightning strikes in an area with a radius of approximately 1 000 km surrounding the magnetic conjugate point in the Indian Ocean just east of East London, South Africa. A clear diurnal distinction was seen in that the correlation is maximised when the whistler station and the source region are in darkness. This is believed to relate to the diurnal variation of the ionosphere, which becomes more transparent to VLF waves at night.
Initial Proteomics Analysis of Differentially Expressed Proteins from Mycoplasma gallisepticum Vaccine Strains ts-11 and F Detected by Western Blotting
S.D. Collier,G.T. Pharr,S.L. Branton,J.D. Evans
International Journal of Poultry Science , 2006,
Abstract: Mycoplasma gallisepticum (MG) is the causative agent of chronic respiratory disease in layer chickens. The live MG vaccine strains that are available for use in layer chickens include F, ts-11 and 6/85. The MG vaccine strains ts-11 and 6/85 are safer than F and they have little or no potential of spreading from bird to bird. However, ts-11 and 6/85 appear to be less efficacious than F-strain. Results from studies suggest that the use of MG vaccine strain F in replacement flocks over a period of time results in the displacement of the original field strain. Also, reports of MG breaks in layer flocks previously vaccinated with ts-11 or 6/85 have resulted in revaccination of these flocks with F. The continued use of F-strain in displacement and revaccination regimens necessitates the development of more rapid and sensitive field tests that will differentiate between wild-type and vaccine strains of MG. In the present study, ts-11 and F-strain whole cell extracts were analyzed by Western blotting and proteomic methodologies. Differentially expressed protein bands were excised, in-gel digested with trypsin, and analyzed by mass spectrometry. The proteins were identified as internal proteins and were predicted to be involved in such cellular processes as carbohydrate transport and metabolism, energy production and conversion, posttranslational modification, protein turnover, chaperone activity, transcription, and translation. The results of this study suggest that proteomics may aid in the characterization of proteins that could contribute to the development and improvement of current MG diagnostic tests.
Analysis of the Effect of Diluent for Rehydration of PoulVac MycoF on Vaccination Seroconversion Results
S.A. Leigh,S.L. Branton,S.D. Collier,J.D. Evans
International Journal of Poultry Science , 2011,
Abstract: Direct eye drop vaccination of poultry using live Mycoplasma gallisepticum vaccines provides the most efficient route of vaccination. The research reported in this study examines the effect of diluent used to rehydrate lyophilized M. gallisepticum vaccines on its ability to induce a measurable humoral immune response in the host. The results suggest that during the initial time period following vaccination, significant differences between the treatment groups are found. However, these differences between the diluents are unlikely to significantly impact the final outcome of vaccination when considered over the life of the host.
Are falling planets spinning up their host stars?
D. J. A. Brown,A. Collier Cameron,C. Hall,L. Hebb,B. Smalley
Physics , 2011, DOI: 10.1111/j.1365-2966.2011.18729.x
Abstract: We investigate the effects of tidal interactions on the planetary orbits and stellar spin rates of the WASP-18 and WASP-19 planetary systems using a forward integration scheme. By fitting the resulting evolutionary tracks to the observed eccentricity, semi-major axis and stellar rotation rate, and to the stellar age derived from isochronal fitting, we are able to place constraints on the stellar and planetary reduced tidal quality factors, Q's and Q'p. We find that for WASP-18, log(Q's)=8.21+0.90-0.52 and log(Q'p)=7.77+1.54-1.25, implying a system age of 0.579+0.305-0.250 Gyr. For WASP-19 we obtain values of log(Q's)=6.47+2.19-0.95 and log(Q'p)=6.75+1.86-1.77, suggesting a system age of 1.60+2.84-0.79 Gyr and a remaining lifetime of 0.0067+1.1073-0.0061 Gyr. We investigate a range of evolutionary histories consistent with these results and the observed parameters for both systems, and find that the majority imply that the stars have been spun up through tidal interactions as the planets spiral towards their Roche limits. We examine a variety of evidence for WASP-19 A's age, both for the value above and for a younger age consistent with gyrochronology, and conclude that the older estimate is more likely to be correct. This suggests that WASP-19 b might be in the final stages of the spiral-in process, although we are unable to rule out the possibility that it has a substantial remaining lifetime.
Enabling pulse compression and proton acceleration in a modular ICF driver for nuclear and particle physics applications
F. Terranova,S. V. Bulanov,J. L. Collier,H. Kiriyama,F. Pegoraro
Physics , 2005, DOI: 10.1016/j.nima.2005.12.040
Abstract: The existence of efficient ion acceleration regimes in collective laser-plasma interactions opens up the possibility to develop high-energy physics facilities in conjunction with projects for inertial confinement nuclear fusion (ICF) and neutron spallation sources. In this paper, we show that the pulse compression requests to make operative these acceleration mechanisms do not fall in contradiction with current technologies for high repetition rate ICF drivers. In particular, we discuss explicitly a solution that exploits optical parametric chirped pulse amplification and the intrinsic modularity of the lasers aimed at ICF.
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