Vanadium metabolism in sheep. III. Influence of dietary vanadium on kinetics of 48V administered orally or intravenously and comparison of compartmental and graphical models

Radiotracer techniques were used to investigate the influence of dietary stable V on the excretion, distribution and blood clearance kinetics of 48V in 14 rams averaging 58 kg body weight. Rams were fed a basal diet with added levels of 0, 50 or 200 mg/kg V as NH4 VO3 for 25 wk before either oral or iv administration of the isotope. A three-compartment model was determined by graphical logarithmic analysis of blood disappearance data from iv-dosed rams and compared with a simultaneous multicompartment model, which made it possible to ascribe physiological processes to the components of the graphical model. The principal route of excretion of 48V administered iv was via urine, whereas the isotope given orally was excreted almost entirely by way of feces, resulting in low tissue and urinary 48V levels. Increasing dietary V increased (P less than .05) the percentage of dose excreted in urine regardless of dosing route, but dietary V had no effect on 48V excreted in feces. Stable dietary V had no effect on blood clearance rates of orally or iv-dosed rams. Dietary V addition decreased 48V concentration in kidney (P less than .01), liver, spleen, testes and muscle (P less than .05) of iv-dosed rams, but had no effect in rams dosed orally. Kidney, bone, liver and spleen retained the highest levels of 48V activity 144 h after dosing. Dietary V appeared to have a minimal effect on V kinetics in rams.     

Genetic screening of FecB,FecXG and FecXI mutations and their linkage with litter size in Barki and Rahmani sheep breeds

Characterization of fecundity genes offers the opportunity to improve production efficiency, and the consequent increase in litter size in livestock industry, through utilizing them in breeding programs. The main objective of this study was to detect the BMPR‐IB, BMP15 and GDF9 gene mutations and to investigate whether these mutations are associated with litter size in Egyptian sheep breeds. To achieve this goal, 73 adult ewes representing Barki (n = 33) and Rahmani (n = 40) breeds were used. Polymerase chain reaction–restriction fragment length polymorphism (PCR‐RFLP) screening approach was used to detect the presence of FecB, FecX^G and FecX^I mutations in the two selected breeds. Results of this study showed that the three different candidate gene mutations, namely FecB, FecX^G and FecX^I are not present among these selected populations of the Egyptian breeds. Further studies regarding other mutations and/or other genes, which may influence ovulation rate, should be carried out to determine the type and mode of inheritance of such genes in Egyptian sheep breeds.     

Simultaneous Measurement of Local Gain and Electron Density in X-ray Lasers

X-ray lasers (XRLs) have experimental average gains that are significantly less than calculated values and a persistently low level of spatial coherence. An XRL has been used both as an injected signal to a short XRL amplifier and as an interferometer beam to measure two-dimensional local gain and density profiles of the XRL plasma with a resolution near 1 micrometer. The measured local gain is in agreement with atomic models but is unexpectedly spatially inhomogeneous. This inhomogeneity is responsible for the low level of spatial coherence observed and helps explain the disparity between observed and simulated gains.     

Bacterial 5-nucleotidase in aquatic ecosystems: a novel mechanism of phosphorus regeneration

Zooplankton excretion and algal alkaline phosphatase are presumed to be responsible for phosphorus recycling in aquatic ecosystems; the role of bacteria has been unclear. High levels of bacterial cell-surface 5-nucleotidase were discovered in samples of picoplankton from California coastal waters. 5-Nucleotidase rapidly generated orthophosphate from 5-nucleotide added in nanomolar amounts and could supply half the orthophosphate required by plankton. Unlike alkaline phosphatase, 5-nucleotidase was not inhibited by orthophosphate at any concentration found in aquatic environments. Initial results indicate even greater 5-nucleotidase activity in fresh water (Lake Hodges, California) and brackish water (Baltic). Release and uptake of orthophosphate were tightly coupled.     

Effect of Three pFSH Doses on Superovulation and Embryo Quality in Goats During Two Breeding Seasons in North‐eastern Mexico

The aim of this research was to evaluate the effectiveness of three pFSH doses (80 mg; 145 mg and 215 mg) on ovarian response and on quantity and quality of transferable embryos of goats during the breeding and the non‐breeding seasons. Ovary structures were exposed (laparatomy under general anaesthesia) and numbers of follicles and corpora lutea were registered. Surgical embryo flushing was conducted to count and classify embryos. There were more follicles (3.4 ± 1.1) in does administered 80 mg of pFSH (p < 0.05) than in goats administered 145 mg of pFSH (2.2 ± 1.1) and 215 mg of pFSH (0.9 ± 0.6). Numbers of corpora lutea, blastocysts, and recovered and transferable embryos of goats administered 145 mg pFSH (13.4 ± 3.7, 2.42 ± 1.0, 3.4 ± 1.2 and 3.2 ± 1.1, respectively) and those of goats administered 215 mg pFSH (11.6 ± 2.6, 3.2 ± 0.9, 5.7 ± 1.5, and 5.6 ± 1.5) were greater (p < 0.05) than values obtained from goats administered 80 mg pFSH (4.0 ± 1.5, 0.5 ± 0.3, 1.0 ± 0.5, and 0.8 ± 0.5). Numbers of morula of does administered 80 and 145 mg pFSH (0.4 ± 0.4 and 0.8 ± 0.3) were lower (p < 0.05) than those obtained from animals treated with 215 mg pFSH (2.4 ± 0.9). There was no effect of season upon the analyzed variables. In conclusion, under the prevalent conditions in north‐eastern Mexico, administration of 145 or 215 mg pFSH in a decreasing dose schedule over 3.5 days to bred goats provided a satisfactory superovulatory result.     

Inhibition of Angiotensin‐Converting Enzyme Increases Oestradiol Production in Ewes Submitted to Oestrous Synchronization Protocol

This study aimed at evaluating the effects of angiotensin‐converting enzyme inhibitor (enalapril) and angiotensin II antagonist (valsartan) on the oestradiol and progesterone production in ewes submitted to oestrous synchronization protocol. The animals were weighed and randomly divided into three groups (n = 7). A pre‐experiment conducted to verify the effectiveness and toxicity of enalapril (0.5 mg/kg LW) and valsartan (2.2 mg/kg LW) showed that, in the doses used, these drugs were effective in reducing blood pressure without producing toxic effects. In the experiment, all animals were subjected to oestrous synchronization protocol during 12 days. On D10, D11 and D12, animals received saline, enalapril or valsartan (same doses of the pre‐experiment), according to the group randomly divided. The hormonal analysis showed an increase in oestradiol on the last day of the protocol (D12) in animals that received enalapril (p < 0.05), but not in other groups, without changing the concentration of progesterone in any of the treatments. It is concluded that valsartan and enalapril are safe and effective subcutaneously for use in sheep and that the angiotensin‐converting enzyme (ACE) inhibition with enalapril leads to an increase in oestradiol production near ovulation without changing the concentration of progesterone. This shows that ACE inhibition may be a useful tool in reproductive biotechnologies involving induction and synchronization of oestrus and ovulation in sheep.     

Influence of dietary lead and calcium on tissue lead accumulation and depletion, lead metabolism and tissue mineral composition in sheep

Two experiments were conducted to study the metabolism and tissue accumulation and depletion of dietary Pb in sheep. In Exp. 1, a feeding trial, 33 wethers, 56 kg initially, were assigned randomly to two dietary treatments: .25% Ca plus 1,000 ppm Pb or .50% Ca plus 1,000 ppm Pb. Supplemental Ca and Pb were supplied as reagent grade calcium carbonate or reagent grade lead acetate. The experiment was divided into two phases of 75 and 180 d; during the first phase, diets contained 1,000 ppm supplemental Pb and during the second phase, diets contained 3 ppm Pb. Calcium level remained constant within treatments throughout both phases. Sheep were slaughtered at various intervals during both phases and tissue samples taken. Lead increased in all tissues during the accumulation period and decreased during the depletion period; however, kidney was the only tissue in which Pb concentration declined to control values by 180 d. Dietary Ca reduced (P less than .05) the concentration of Pb deposited in liver, but not in other tissues. Interactions of dietary Ca and Pb on tissue concentration of various minerals occurred. In Exp. 2, a balance trial, 27 wethers, 53 kg initially, were allotted randomly to four treatments in a 2 X 2 factorial arrangement. Diets contained either 0 or 1,000 ppm supplemental Pb as reagent grade lead acetate and .25 or .50% total Ca with supplemental Ca from calcium carbonate. Increasing dietary Pb increased (P less than .05) percentage of Pb retained and increased (P less than .01) whole blood Pb concentration (1.0 vs 1.42 micrograms/ml).