Influence of orally administered CpG-ODNs on the humoral response to bovine serum albumin (BSA) in chickens

Synthetic oligodeoxynucleotides containing CpG motifs (CpG-ODNs) have been reported to be effective mucosal adjuvants in mice when given orally. Studies on their effectiveness in chickens are currently very limited. This study investigated whether CpG-ODNs could adjuvant the immune response to BSA when given orally to a commercial line of SCWL chickens. In two experiments, performed over time, chickens were given selected concentrations of CpG-ODNs with BSA followed by 6 consecutive days of ad libitum access to drinking water containing 1.4 mg/ml BSA. Serum responses, and in some cases intestinal specific antibodies, were measured out to 33 days post-immunization. Birds receiving a single dose of CpG-ODN had consistently higher IgG, IgM, and IgA titers in the serum, dependent upon dose, and in specific areas of the intestine when compared to the non-immunized and BSA only groups. These findings suggest that a single oral CpG-ODN administration can accelerate the kinetics of antigen specific antibodies of all three isotypes in commercial-strain chickens immunized via the drinking water using common protein antigen.     

Influence of diet, phytase, and incubation time on calcium and phosphorus solubility in the gastric and small intestinal phase of an in vitro digestion assay

To determine the influence of incubation time, diet, and particle size on Ca and P solubility in vitro, experimental diets were formulated to contain 0.89% Ca and 0.40% available P (positive control; PC) or 0.76% Ca and 0.27% available P (negative control; NC). The PC was supplemented with 0 or 1,000 phytase units (FTU) of microbial phytase/kg and the NC with 0, 1,000, or 5,000 FTU/kg diet of microbial phytase for a total of 5 experimental diets. In Exp. 1, diets were exposed to simulated gastric digestion containing HCl and pepsin for 42 min, or a small intestinal digestion phase containing NaHCO(3) and pancreatin for 60 min. In Exp. 2, diets were ground to pass a 1- or 2-mm screen and exposed to gastric digestion for 5, 10, or 20 min. Phosphorus and Ca solubility were similarly influenced by diet and digestion phase (Exp. 1), and there was no interaction. Phytase supplementation improved (P < 0.001) Ca and P solubility in both the PC and NC diets (Exp. 1) and increased P (P < 0.001) and Ca (P < 0.001) solubility in the gastric phase of the in vitro digestion model (Exp. 2). Phytase continued to release P in the gastric test over time, which resulted in a diet × time interaction (P < 0.05). Calcium solubility reached an asymptote at 5 min and both Ca and P solubility was reduced (P < 0.05) in diets ground to pass a 2 mm screen compared with diets ground to pass a 1-mm screen. In addition, P and Ca solubility did not change over time in diets not supplemented with phytase. In conclusion, phytase or particle size altered the kinetics of Ca and P release in a non-parallel fashion, which may be associated with the precipitation of Ca with phytate and the sequential dephosphorylation of phytate by a microbial 6-phytase. In the presence of phytase, considerable Ca and P hydrolysis occurred within 5 min of a simulated gastric digestion. However, the solubility of Ca and P reached a plateau in the gastric phase of digestion and no further improvements in solubility are apparent in the small intestine. Therefore, absorption of Ca and P may be complicated by conditions within the gastrointestinal tract, particle size, precipitation with anti-nutrients, and differential rates of delivery to the small intestine.     

Distribution of lesions in fetal brains following experimental infection of pregnant sheep with Toxoplasma gondii

Six ovine fetal brains were harvested 33 to 35 days postchallenge from 5 ewes, each of which was given 3000 Toxoplasma gondii oocysts on day 90 of pregnancy. Histopathologic examination of transverse sections taken at 13 levels in the fetal brains revealed the presence of toxoplasmosis-related lesions in all 6 brains. However, lesions were not randomly distributed (P = .007); they were most numerous at the level of the optic tract, the rostral margin of the pons, and 4 mm caudal to the ansate sulcus and were absent in all sections at the level of the caudal cerebellum. Lesion distribution may be due to hemodynamic factors, differences in the expression of endothelial surface receptor molecules at the level of the blood-brain barrier, or the presence of localized permissive/inhibitory factors within the brain. The results have implications for the selection of areas of brain from aborted ovine fetuses to be examined histopathologically for laboratory diagnosis.     

Electron temperatures and densities in the venus ionosphere: pioneer venus orbiter electron temperature probe results

Altitude profiles of electron temperature and density in the ionosphere of Venus have been obtained by the Pioneer Venus orbiter electron temperatutre probe. Elevated temperatutres observed at times of low solar wind flux exhibit height profiles that are consistent with a model in which less than 5 percent of the solar wind energy is deposited at the ionopause and is conducted downward through an unmagnetized ionosphere to the region below 200 kilomneters where electron cooling to the neutral atmosphere proceeds rapidly. When solar wind fluxes are higher, the electron temperatures and densities are highly structured and the ionopause moves to lower altitudes. The ionopause height in the late afternoon sector observed thus far varies so widely from day to (day that any height variation with solar zenith angle is not apparent in the observations. In the neighborhood of the ionopause, measuremnents of plasma temperatures and densities and magnetic field strength indicate that an induced magnetic barrier plays an important role in the pressure transfer between the solar wind and the ionosphere. The bow, shock is marked by a distinct increase in electron current collected by the instrument, a featutre that provides a convenient identification of the bow shock location.     

A Magnetic Signature at Io: Initial Report from the Galileo Magnetometer

During the inbound pass of the Galileo spacecraft, the magnetometer acquired 1 minute averaged measurements of the magnetic field along the trajectory as the spacecraft flew by Io. A field decrease, of nearly 40 percent of the background jovian field at closest approach to Io, was recorded. Plasma sources alone appear incapable of generating perturbations as large as those observed and an induced source for the observed moment implies an amount of free iron in the mantle much greater than expected. On the other hand, an intrinsic magnetic field of amplitude consistent with dynamo action at Io would explain the observations. It seems plausible that Io, like Earth and Mercury, is a magnetized solid planet.     

Isotopic composition of the martian atmosphere

Results from the neutral mass spectrometer carried on the aeroshell of Viking 1 show evidence for NO in the upper atmosphere of Mars and indicate that the isotopic composition of carbon and oxygen is similar to that of Earth. Mars is enriched in (15)N relative to Earth by about 75 percent, a consequence of escape that implies an initial abundance of nitrogen equivalent to a partial pressure of at least 2 millibars. The initial abundance of oxygen present either as CO(2) or H(2)O must be equivalent to an exchangeable atmospheric pressure of at least 2 bars in order to inhibit escape-related enrichment of (18)O.     

The effects of lactation on the fertility of dairy cows

Lactation has been negatively associated with fertility because pregnancy rates in maiden heifers exceed those obtained after first or subsequent calvings. The extent of this difference is less in pasture-fed dairy cows (<10%) than in American Holsteins (>20%) fed grain and conserved forages. The latter cows have pregnancy rates to first insemination and oestrus detection rates of only 40 to 45%. This suggests that the subsequent fertility of inherently fertile Holstein heifers may be severely compromised by high levels of milk production. International comparisons show that pasture-fed dairy cows may experience extended periods of anovulatory anoestrum but have normal fertility (60% pregnancy rate to first insemination) once cycling. The high-producing American Holstein may ovulate within 4 weeks postpartum but is more likely to continue ovulating without being detected in oestrus. Both situations are associated with negative energy balances (NEB) during early lactation. The severity and duration of this NEB may vary with body condition at calving, age or parity, ration formulation, production level and environmental factors. Relative daily milk yield is not an absolute indicator of NEB, because some lower producing cows within a herd have lower feed intakes and more severe energy deficits. NEB is not simple to measure; nonetheless, it is correlated with genetic improvement for milk yield. A positive energy balance, greater weight gain and higher body condition score have all been shown to be positively correlated with plasma progesterone concentrations in early lactation. No studies have investigated the possibility that the rapid increase in metabolic rate at this time may also alter steroid concentrations with consequent effects on oestrous behaviour and fertility. Studies to more precisely define the effects of increasing milk yields in early lactation, especially in Holsteins, may need to be completed in Australia and New Zealand. Oestrus detection rates and pregnancy rates for American Holsteins of less than 50% are accepted widely in the USA. Such low detection rates confound studies on fertility. The objective should be to increase these 2 rates to at least 80% and 60% respectively. This may involve the use of controlled breeding, especially if oestrous behaviour is less overt in high-producing Holstein cows.     

Effect of prolonged heat stress in single-comb white leghorn hens on progeny resistance to Salmonella enteritidis organ invasion.

In our laboratory, we have often had difficulty infecting neonatal chickens with invasive salmonellae when ambient temperatures exceed 30 C. We hypothesized that this increased resistance in chicks during warmer months may be associated with heat stress-associated maternal factors. Presently, single-comb white leghorn hens were separated into a non-heat-stressed group, reared under temperatures from approximately 10 to 24 C, and a heat-stressed group, in which environmental temperature was incrementally elevated to near 37 C and maintained for the duration of the 13-wk study. For Expt. 1, eggs from heat-stressed or control hens, collected on days 8-14 of the study, were pooled respective to treatment and incubated. At the time of egg collection, mean hen-day egg production was 51.83% or 65% for heat-stressed or control hens, respectively. On day of hatch, progeny from hens in each group were orally challenged with 0.9 x 10(4) colony-forming units (CFU) Salmonella enteritidis (SE). Rates of SE organ invasion of 97.3% or 94.4% were obtained in progeny from heat-stressed or control hens, respectively. In Expt. 2, eggs from heat-stressed or control hens from days 30-42 of the study were collected and pooled by treatment for incubation. Mean hen-day egg production was 46.5% or 72.85% for heat-stressed or control hens, respectively. On day of hatch, progeny were orally challenged with either 2.2 x 10(3) or 2.2 x 10(4) CFU SE. A 100% incidence in SE organ invasion was observed in all groups. In Expt. 3, eggs were collected from days 43 through 56 of the study. Mean hen-day egg production was 19.8% or 76.8% for heat-stressed or control hens, respectively. On day of hatch, progeny were orally challenged with 2 x 10(3) CFU SE. Rates of SE organ invasion of 95.8% or 95.6% were obtained in progeny from heat-stressed or control hens, respectively. These data suggest that factors other than elevated temperature may be responsible for seasonal resistance to invasive salmonellae infection in neonatal chickens observed in our laboratory during warmer months in Texas.