Oral N-acetyl-L-cysteine is a safe and effective precursor of cysteine

Relative bioavailability and toxicity of N-acetyl-l-Cys (NAC) were evaluated in 9-d chick growth assays. The bioavailability of NAC relative to Cys was determined by feeding young chicks a highly purified crystalline AA diet singly deficient in Cys. Bio-availability estimates were obtained using standard slope-ratio methodology. N-Acetyl-l-cysteine was shown to be as effective as Cys in supporting chick growth, and was assigned a relative bioavailability value of 100%. To assess toxicity, a nutritionally adequate corn-soybean meal diet was supplemented with graded concentrations of NAC (isomolar to 10, 20, 30, or 40 g/kg of Cys, as-fed). When NAC supplied 10 or 20 g/kg of Cys, chick growth performance was unaffected, but NAC supplying 30 or 40 g/kg of Cys reduced (P < 0.05) BW gain by 13 and 34%, respectively, relative to the unsupplemented control diet. Only plasma-free NAC was substantially increased (P < 0.05) because of excess dietary NAC; plasma-free Cys was unaltered. We concluded that dietary NAC is efficacious in supplying Cys in support of chick growth, and only large excesses of NAC are growth depressing. Hence, the human clinical benefits of oral NAC likely result from its ability to deliver Cys safely and effectively to the portal circulation.     

An Escherichia coli phytase expressed in yeast effectively replaces inorganic phosphorus for finishing pigs and laying hens

Two experiments determined the efficacy of an Escherichia coli phytase (ECP) added to P-deficient, corn-soybean meal diets fed to finishing pigs and second-cycle laying hens. Sixty finishing pigs (49 +/- 0.9 kg) were formed into blocks within sex based on weight and ancestry and allotted to a P-deficient diet unsupplemented or supplemented with 0.10% inorganic P (iP) from KH2PO4 or ECP at 250, 500, 1,000, or 10,000 phytase units (FTU)/kg. Individually fed pigs were allowed ad libitum access to the experimental diets until a BW of 120 +/- 3 kg was achieved, at which time the pigs were euthanized and the left fibula and fourth metatarsal were excised for determination of bone ash. Pigs were fed a 2-phase diet program for early- and late-finishing pigs; available P in the basal diets was set 0.10% below the requirement. Dietary supplementation of iP or ECP increased weight gain (P < 0.10) and G:F (P < 0.01); performance was not different (P > 0.13) among the phytase-supplemented groups. Fibula ash was greatest (P < 0.01) for pigs fed diets containing 10,000 FTU of ECP/kg. Two hundred forty second-cycle hens were allotted to a P-deficient diet or a P-deficient diet supplemented with 0.10% iP or ECP at 150, 300, or 10,000 FTU/kg for a 12-wk experiment. The basal diet was a corn-soybean meal diet with no added iP (17% CP, 3.8% Ca, 0.10% available P). Hens fed the P-deficient diet were removed from the experiment after 4 wk due to poor egg production. Supplementation of iP or ECP resulted in increased (P < 0.01) feed intake, egg weight, and egg production during the first 4 wk. During the entire 12-wk period, there were no differences (P > 0.28) between the iP- and ECP-supplemented groups in feed intake, egg weight, or egg production. These experiments reveal that ECP was as efficacious as supplemental iP and that supplementation of an excess dose of ECP was efficacious and without negative effects in finishing pigs and laying hens.     

Microbial and non-biological decomposition of chlorophenols and phenol in soil

The aerobic and anaerobic degradation of phenol and selected chlorophenols was examined in a clay loam soil containing no added nutrients. A simple, efficient procedure based on the high solubility of these compounds in 95% ethanol was developed for extracting phenol and chlorophenol residues from soil. Analysis of soil extracts with UV spectrophotometry showed that phenol,o-chlorophenol,p-chlorophenol, 2,4-dichlorophenol, 2,6-dichlorophenol and 2,4,6-trichlorophenol were rapidly degraded, whilem-chlorophenol, 3,4-dichlorophenol, 2,4,5-trichlorophenol and pentachlorophenol were degraded very slowly by microorganisms in aerobically-incubated soil at 23°C. Both 3,4,5-trichlorophenol and 2,3,4,5-tetra chlorophenol appeared to be more resistant to degradation by aerobic soil microorganisms at 23°C. None of the compounds examined were degraded by microorganisms in anaerobically-incubated soil at 23°C. Direct microscopic observation revealed that phenol and selected chlorophenols stimulated aerobic and to a lesser extent, anaerobic microbial growth in soil, and aerobic soil bacteria were responsible for the degradation of 2,4-dichlorophenol in aerobically-incubated soil at 23°C. Phenol,o-chlorophenol,m-chlorophenol,p-chlorophenol and 2,4-dichlorophenol underwent rapid non-biological degradation in sterile silica sand. Non-biological decomposition contributed, perhaps substantially, to the removal of some chlorophenols from sterile aerobically-incubated soil and both sterile and non-sterile anaerobically-incubated soil.     

High-throughput retrotransposon-based fluorescent markers: improved information content and allele discrimination

Background  

Dense genetic maps, together with the efficiency and accuracy of their construction, are integral to genetic studies and marker assisted selection for plant breeding. High-throughput multiplex markers that are robust and reproducible can contribute to both efficiency and accuracy. Multiplex markers are often dominant and so have low information content, this coupled with the pressure to find alternatives to radio-labelling, has led us to adapt the SSAP (sequence specific amplified polymorphism) marker method from a ³³P labelling procedure to fluorescently tagged markers analysed from an automated ABI 3730 xl platform. This method is illustrated for multiplexed SSAP markers based on retrotransposon insertions of pea and is applicable for the rapid and efficient generation of markers from genomes where repetitive element sequence information is available for primer design. We cross-reference SSAP markers previously generated using the ³³P manual PAGE system to fluorescent peaks, and use these high-throughput fluorescent SSAP markers for further genetic studies in Pisum.     

Determinants of high vitamin A supplementation coverage among pre-school children in Mali: the National Nutrition Weeks experience

OBJECTIVES: To assess vitamin A supplementation (VAS) coverage of children aged 6-59 months and the factors that favour or limit this coverage during the National Nutrition Weeks in Mali. DESIGN: Cross-sectional study. Interviews about demographic factors and children's adherence to the vitamin A capsule distribution programme were conducted. Professionals' knowledge of vitamin A and various aspects related to the supplementation strategy were assessed. SETTING: Five regions out of the eight regions in the country, in addition to Bamako District. Three rural communes were selected in three regions to represent rural areas. SUBJECTS: Parents or caregivers of children under 5 years of age, health agents who participated in the weeks, and community and administrative leaders. RESULTS: At least 80% of the children received the supplement. More 'traditional' communication channels (town criers, friends and family members) appeared to be more effective in reaching the target groups than modern methods, i.e. radio and television. Mothers' possession of a radio (Pearson chi2 = 5.03; P = 0.025) and fathers' education (Pearson chi2 = 19.02; P < 0.001), possession of a radio (Pearson chi2 = 8.93; P = 0.003) and listening to it (Pearson chi2 = 7.62; P = 0.006) all appeared to be statistically and significantly associated with children's coverage. In multivariate logistic regression analysis, only the study site (urban/rural) (P = 0.004), 'traditional channels' (P = 0.02) and fathers' education (P = 0.04) were significantly associated with children's coverage. Knowledge about VAS was high among community and administrative leaders, and health professionals. The planning and implementation of activities at the district level were found to be good in general. CONCLUSION: National Nutrition Weeks provide a successful example of a periodic VAS strategy with high coverage among children aged 6-59 months in Mali. Campaigns aimed at informing and sensitising populations during the Nutrition Weeks should also target children's fathers.     

蓝耳病清除的经验:防止再感染

蓝耳病（PRRS）不像伪狂犬病,没有终身带毒的猪存在,只有持续感染的猪,感染过一种亚型的蓝耳病病毒（PRRSV）后,便不会再感染同一亚型的病毒,但却可以感染其他亚型的PRRSV。在美国,猪场净化蓝耳病的成功率是相当高的,其清除并不难,但是净化的关键在于以后如何继续保持阴性,防止重新再感染。     

Ring tests to evaluate the performance of Porcine circovirus-2 (PCV-2) polymerase chain reaction (PCR) assays used in North American diagnostic laboratories

Two laboratory studies involving 11 laboratories were undertaken to assess the performance of North American Porcine circovirus-2 (PCV-2) polymerase chain reaction (PCR) assays. Laboratories received identical submissions containing randomly coded positive and negative control samples, and serially diluted PCV-2-spiked samples. In study 1 and 2, respectively, spiked samples contained measured amounts of PCV-2 virus or DNA. All but 1 assay detected DNA in the most concentrated spiked sample. There were no statistical differences in the proportion of positive or negative samples reported by quantitative (n = 7) versus non-quantitative (n = 6) assays. Across both studies, the false positive rate was 17% (4 out of 23), and 17% (2 out of 12) of assays cross-reacted with PCV-1. The most sensitive assay detected PCV-2 DNA levels about 100 000 times lower the least sensitive assay. This study demonstrated that the PCR assays available in North American diagnostic labs vary considerably in their detection limits and quantification.