Disposition of gentamicin in the genital tract of cows

The distribution of gentamicin (G) in plasma and uterine lumen was studied following intramuscular (i.m.) and intrauterine (i.u.) treatment. A Foley catheter was inserted into one uterine horn and retained in place by inflation of the cuff. This provided a closed system for collection of uterine lumen samples and analysis of the concentration of gentamicin for 6 h following treatment. Four normal cycling and healthy cows in dioestrus were given i.m. injections of 4 mg gentamicin/kg BW and another two were given i.m. injections of 2 mg gentamicin/kg BW gentamicin. The uteri were infused with 50 ml saline containing phenolsulphonphthalein (PSP) indicator. Blood and infused solution (IS) samples were periodically collected during the 6-h period following i.m. administration. Six hours after injection, approximately 183.7 micrograms gentamicin and 39.4 micrograms gentamicin were accumulated in the uterine lumen of cows receiving 4 mg gentamicin/kg BW and 2 mg gentamicin/kg BW, respectively. The amount of gentamicin reaching the blood stream after i.m. administration of 4 mg gentamicin/kg BW was 2.89 times that reached after administration of 2 mg gentamicin/kg BW based on the area under the curve of plots of plasma concentration of gentamicin versus time. Four normal-cycling and healthy cows in dioestrus were given i.u. infusions of gentamicin (225-275 mg) diluted in 50 ml saline containing PSP indicator using a Foley catheter in a closed system. Samples from the IS and blood were collected at various intervals for 6 h after infusion. Following i.u. infusion of gentamicin, an average of 29.4% of the dose was absorbed into the bloodstream. The majority of the dose of gentamicin (70.6%) remained in the uterine lumen throughout the 6-h period.     

Demonstration and quantitation of immunoglobulins in bovine serum, follicular fluid, and uterine and vaginal secretions with reference to bovine viral diarrhea and infectious bovine rhinotracheitis.

Immunoglobulin concentrations (IgG, IgM, and IgA) in bovine serum, follicular fluid, and uterine and vaginal secretions were determined. The specificities of IgG, IgM, and IgA for virus-neutralizing antibody against bovine viral diarrhea (BVD) and infectious bovine rhinotracheitis (IBR) viruses were also examined. High concentrations of IgG were present in both serum and follicular fluid. The IgG, IgM, and IgA concentrations were low in uterine and vaginal secretions. There was more IgG in the uterus during estrus than at any other time. Virus-neutralizing antibodies against BVD and IBR in serum of cows were mainly the IgG class. There was positive correlation between serum and follicular fluid virus-neutralizing antibody titers fro BVD and IBR. These antibodies may provide some protection for recently ovulated ova.     

Linkage between the intestinal microbiota and residual feed intake in broiler chickens

Background: Intestinal microbiota plays a key role in nutrient digestion and utilization with a profound impact on feed efficiency of livestock animals. However, the intestinal microbes that are critically involved in feed efficiency remain elusive.Methods: To identify intestinal bacteria associated with residual feed intake(RFI) in chickens, male Cobb broiler chicks were individually housed from day 14 to day 35. Individual RFI values were calculated for 56 chickens.Luminal contents were collected from the ileum, cecum, and cloaca of each animal on day 35. Bacterial DNA was isolated and subjected to 16 S rRNA gene sequencing. Intestinal microbiota was classified to the feature level using Deblur and QIIME 2. High and low RFI groups were formed by selecting 15 and 17 chickens with the most extreme RFI values for subsequent LEfSe comparison of the difference in the microbiota. Spearman correlation analysis was further performed to identify correlations between the intestinal microbiota composition and RFI.Results: No significant difference in evenness, richness, and overall diversity of the microbiota in the ileum, cecum,or cloaca was observed between high and low RFI chickens. However, LEfSe analysis revealed a number of bacterial features being differentially enriched in either high or low RFI chickens. Spearman correlation analysis further identified many differentially enriched bacterial features to be significantly correlated with RFI(P 0.05). Importantly,not all short-chain fatty acid(SCFA) producers showed a positive association with RFI. While two novel members of Oscillibacter and Butyricicoccus were more abundant in low-RFI, high-efficiency chickens, several other SCFA producers such as Subdoligranulum variabile and two related Peptostreptococcaceae members were negatively associated with feed efficiency. Moreover, a few closely-related Lachnospiraceae family members showed a positive correlation with feed efficiency, while others of the same family displayed an opposite relationship.Conclusions: Our results highlight the complexity of the intestinal microbiota and a need to differentiate the bacteria to the species, subspecies, and even strain levels in order to reveal their true association with feed efficiency. Identification of RFI-associated bacteria provides important leads to manipulate the intestinal microbiota for improving production efficiency, profitability, and sustainability of poultry production.     

Factors affecting N immobilisation/mineralisation kinetics for cellulose-, glucose- and straw-amended sandy soils

The kinetics of N immobilisation/mineralisation for cellulose-, glucose- and straw-amended sandy soils were investigated in a series of laboratory incubations. Three Scottish soils expected to exhibit a range of biological activity were used: a loamy sand, intensively cropped horticultural soil subject to large inputs of inorganic fertilisers and pesticides (Balmalcolm - pH 7.2, organic matter 3.3%); a sandy loam soil highly enriched with organic manures and used for organic vegetable production (Strathmiglo - pH 7.1, organic matter 7.3%); and a loamy sand soil of low fertility in a zero-grazing, low intensity organic ley-arable rotation (Aldrochty pH 6.0, organic matter 5.0%). Incubations of soils with 1,000 mg cellulose-C kg^-1 soil at 8°C, showed peak N immobilisation of 71Lj, 92Lj and 65ᆣ mg N g^-1 added C for the Balmalcolm (after 34 days), Strathmiglo (after 34 days) and Aldrochty soils (after 63 days). The N remineralisation by the end of the incubation (>300 days) was 0, 50 and 22 mg N g^-1 cellulose-C in the Balmalcolm, Strathmiglo soil and Aldrochty soils, respectively. Only about 30% of the N immobilisation could be explained by soil microbial biomass N accumulation (much less than expected from model simulations). The C/N ratio of the extra microbial biomass was quite wide (19). Bacterial, protozoan and nematode biomass accounted for only 18%, 0.1% and 0.5% of the extra C immobilisation, respectively. These data suggest that fungal biomass growth and deposition of recalcitrant fungal metabolites are the main sinks for the N immobilised. With 1,000 mg glucose-C kg ^-1 added to the Balmalcolm soil, about 75 mg N g^-1 added C were immobilised after 6 days. Under less well aerated conditions at 15°C, immobilisation of only 10-20 mg N g^-1 added cellulose C took place in 2-4 weeks, but soluble organic C increased greatly. The N remineralised after 4-6 weeks.     

Colossal Magnetoresistance Without Mn3+/Mn4+ Double Exchange in the Stoichiometric Pyrochlore Tl2Mn2O7

Structural analysis from powder neutron and single-crystal x-ray diffraction data for a sample of the Tl2Mn2O7 pyrochlore, which exhibits colossal magnetoresistance (CMR), shows no deviations from ideal stoichiometry. This analysis gives an Mn-O distance of 1.90 angstroms, which is significantly shorter than the Mn-O distances (1.94 to 2.00 angstroms) observed in phases based on LaMnO3 perovskites that exhibit CMR. Both results in Tl2Mn2O7 indicate oxidation states very close to Tl23+Mn24+O7. Thus, Tl2Mn2O7 has neither mixed valence for a double-exchange magnetic interaction nor a Jahn-Teller cation such as Mn3+, both of which were thought to have an important function in CMR materials. An alternate mechanism for CMR in Tl2Mn2O7 based on magnetic ordering driven by superexchange and strong spin-fluctuation scattering above the Curie temperature is proposed here.     

Development and environment in Peninsular Malaysia: By Robert S. Aiken,C. H. Leigh,T. R. Leinbach and M. R. Moss. McGraw-Hill,Singapore. 1982. xx + 310 pp,numerous figures,plates and tables. 24·5 × 17·5 cm. ISBN 0 07099 204 5. Price: US$29·95

The accomplishments of the Government of India/UNDP/FAO Project in the conservation of three species of crocodiles during the period 1975 to 1982 are reviewed. Sixteen crocodile rehabilitation centres and eleven crocodile sanctuaries have been established. A total of 879 gharials, 190 estuarine crocodiles and 493 mugger have been released. A viable breeding population of gharials now exists in the National Ghambal Sanctuary. A Crocodile Breeding and Management Training Institute was established by the Government of India in 1980 and has trained 48 managers of crocodile stations. Improvements are required in the management of crocodile sanctuaries and the evaluation of crocodile habitat. Releases of crocodiles in the wild require monitoring of survival and movements. There is a need for educating the public about crocodile conservation.