Effect of diets containing sulfate or chloride-based anionic salts,fed to grazing prepartum dairy cows,on concentrations of Ca in plasma,disease incidence and milk yield

AIMS: To compare the effect of two partial mixed ration diets containing either sulfate or chloride-based anionic salts, fed to grazing prepartum dairy cows, on concentrations of Ca, Mg, P and beta-hydroxybutyrate (BHB) in plasma, disease incidence and milk yield during the early postpartum period.

METHODS: The study was conducted on a seasonal-calving grazing dairy farm located in Benton (MO, USA). In August 2016, two groups of 200 cows were randomly assigned at 30 days before expected parturition to receive either a sulfate or chloride-based anionic diet, to achieve a dietary cation–anion difference (DCAD) of ?25?mEq/kg DM. Cows were fed partial mixed rations to provide 50% of their DM intake, with 50% provided by grazing fescue pasture. Urine samples were collected from 20 cows from each group once a week for 5 weeks until calving for pH assessment. At parturition, 42 cows per group were selected at random and blood samples collected on Days 1, 2, 3 and 7 postpartum. The study continued until 100 cows per group calved. Health events and cumulative milk yield until 30 days postpartum were recorded. Concentrations of Ca, P, and Mg in plasma at Days 1, 2, 3, and 7, and BHB in plasma at Day 7 postpartum were assessed.

RESULTS: Mean urine pH was lower in cows in the chloride than sulfate group (p≤0.06) on four of five sampling occasions. Mean concentrations of Ca in plasma on Day 1 were 2.00 (95% CI=1.94–2.05) and 1.91 (95% CI=1.88–1.97) mmol/L for the chloride and sulfate groups, respectively (p=0.15), and on Day 3 were 2.03 (95% CI=1.97–2.08) and 1.90 (95% CI=1.84–1.96) mmol/L, respectively (p=0.038). Concentrations of Mg, P and BHB in plasma and incidence of diseases postpartum were similar in both groups (p>0.05). There were no cases of clinical hypocalcaemia in either group.

CONCLUSIONS AND CLINICAL RELEVANCE: Prepartum cows fed a partial mixed ration with a negative DCAD containing chloride-based anionic salts and free access to a fescue pasture had lower prepartum urine pH, and higher concentrations of total Ca in plasma during the first week postpartum, than cows receiving a partial mixed ration containing sulfate-based anionic salts.     

Thalidomide pharmacokinetics in sheep

AIM: To determine the half life (T_1/2), time taken to reach maximum plasma concentration (T_max) and maximum plasma concentration (C_max) of thalidomide in sheep following I/V, oral and topical treatment with a single dose of thalidomide.

METHOD: Three groups of 4–6-month-old ram lambs were treated with thalidomide dissolved in dimethylsulphoxide (DMSO). The first group (n=10) was treated I/V with 100?mg thalidomide in 2?mL DMSO; the second group (n=8) received 400?mg thalidomide in 2?mL DMSO orally, and the third group (n=8) had 400?mg thalidomide in 4?mL DMSO applied topically. Plasma samples were collected up to 36 hours after treatment, snap-frozen at ?80°C and analysed for concentrations of thalidomide using high performance liquid chromatography.

RESULTS: Following I/V administration, T_1/2 was 5.0 (SEM 0.4) hours, volume of distribution was 3,372.0 (SEM 244.3) mL/kg and clearance was 487.1 (SEM 46.1) mL/hour.kg. Topical application of 400?mg thalidomide did not increase plasma concentrations. Following oral administration, thalidomide bioavailability was 89%, with T_1/2, T_max, and C_max being 7.2 (SEM 0.8) hours, 3.0 (SEM 0.4) hours and 1,767.3 (SEM 178.1) ng/mL, respectively.

CONCLUSION: Topical administration using DMSO as a solvent did not increase concentrations of thalidomide in plasma. The mean pharmacokinetic parameters determined following oral treatment with 400?mg of thalidomide were similar to those reported in humans receiving a single 400?mg oral dose (T_1/2 7.3 hours; T_max 4.3 hours and C_max 2,820?ng/mL). There is potential for thalidomide to be used as a model for the treatment of chronic inflammatory conditions in sheep, such as Johne's disease, where tumour necrosis factor alpha plays a pathogenic role.     

Evaluation of action thresholds for chronic rice insect pests in the Philippines. I. Less frequently occurring pests and overall assessment

Action thresholds as decision tools for insecticide application were developed and tested against the major insect pests of rice at four sites in the Philippines over a 13-year period. Action threshold treatments were compared to the farmers' practice, prophylactic insecticide usage, and an untreated check. Yield loss data using the insecticide check method partitioned yield losses over three crop growth stages in the same test fields. Chronic pests that exceeded action thresholds in 79% of fields were whorl maggot Hydrellia philippina Ferino (Diptera: Ephydridae), defoliators Naranga aenescens Moore and Rivula atimeta (Swinhoe) (Lepidoptera: Noctuidae), leaffolders Cnaphalocrocis medinalis (Guenée) and Marasmia patnalis Bradley (Lepidoptera: Pyralidae), and stemborers Scirpophaga incertulas (Walker) and S. innotata (Walker) (Lepidoptera: Pyralidae). Minor chronic pests reached threshold levels in only one site each: rice bug Leptocorisa oratorius (F.) (Koronadal), whitebacked planthopper Sogatella furcifera (Horvath) (Zaragoza) and green leafhopper Nephotettix virescens (Distant) (Guimba); brown planthopper Nilaparvata lugens (Stål) did not exceed a threshold in any field. Stemborers were the most important pest group in terms of yield loss. Despite the insecticide check method underestimating losses, a mean crop loss of 0.62 t/ha was measured which showed ample scope for corrective action. But loss was evenly distributed across crop growth stages (0.15?–?0.24 t/ha) reducing the impact of insecticides. Action threshold treatments overall outyielded the untreated check, more so in the two sites with highest pest density. The benefit of thresholds was to reduce insecticide usage, as a cost saving. However all the practices showed poor economic returns including the farmers' practice. Farmers' practice employed low insecticide dosages and timing was not consistent with pest damage, but yields were often similar to threshold treatments. Farmers appear to use insecticide more for risk aversion than for profit. The best threshold characters when evaluated against resulting pest density and yield loss criteria showed accuracies >?90% correct decisions. Future work is needed to improve the insecticide response rather than monitoring tools. Thresholds need to be incorporated into improved crop management, which was often found suboptimal by farmers, to take advantage of the high levels of tolerance in modern high tillering cultivars. Crop husbandry practices which improve yield potential such as selection of longer maturing varieties and nitrogen fertilizer may be a more effective pest management strategy than insecticides.     

The influence of weather on the population dynamics of the rice stink bug and the implications for integrated pest management

The influence of weather on the population dynamics of Oebalus poecilus, the principal insect pest of rice in South and Central America, is examined. Light trapping was used for one year, but was soon discarded in favour of the more reliable sweep netting which was utilised to monitor populations in fields and non-cropped habitats from autumn 1999 to spring 2002. The results indicate that O. poecilus feeds on alternative host grasses on levées surrounding the rice fields. Adult bugs move into the fields in mid-January and mid-August of each year. In fields there are typically four generations per season, which are approximately four weeks apart. Adults move off the crop in April and October. Data presented here indicate that rainfall is critical to the ‘off-season’ survival of O. poecilus, and high rainfall during April to July and November to January causes increases in O. poecilus populations. This is particularly important given the recent extreme perturbations in the normal bimodal rainfall patterns caused by El Niño and La Niña events. The ability to predict the severity of O. poecilus populations from weekly rainfall data will provide a significant input into the development of IPM programme for O. poecilus.     

Effect of Taurine and Melatonin in the Culture Medium on Buffalo In Vitro Embryo Development

This study was carried out to investigate the effect of supplementing culture medium with different concentrations of taurine and melatonin, on buffalo oocyte in vitro meiotic maturation and embryo development. In experiment 1, oocytes were matured in vitro and the cleaved embryos were cultured in the same following seven culture medium; (i) control (TCM 199 + 10% SS); (ii) control + 0.5 m m taurine; (iii) control + 1 m m taurine; (iv) control + 3 m m taurine; (v) control + 5 μ m melatonin; (vi) control + 10 μ m melatonin and (vii) control + 50 μ m melatonin. In experiment 2, based on the results of experiment 1, to examine the synergistic effect of antioxidants, the oocytes were matured in culture medium (TCM199 + 10% SS), supplemented with both taurine at 1 m m and melatonin at 10 μ m concentration and the cleaved embryos were cultured in the same medium. Supplementation of taurine at 1 m m concentration in the culture medium resulted in a higher (p < 0.05) transferable embryo (TE) yield when compared with control (20.6% vs 14.1%). Supplementation of melatonin at 10 and 50 μ m concentration in the culture medium resulted in a higher (p < 0.05) meiotic maturation rate (90.3% and 88.8% respectively) and TE yield (28.4% and 27.2% respectively), than the other treatments. In experiment 2, the TE yield did not improve by supplementing the culture medium with both taurine and melatonin, when compared with melatonin alone. In conclusion, the results of this study demonstrated that, enriching the culture medium with taurine and melatonin, improves in vitro embryo production efficiency in buffaloes. In particular, a high TE yield was obtained by enriching the culture medium with 10 μ m melatonin.     

A single progenitor population switches behavior to maintain and repair esophageal epithelium

Diseases of the esophageal epithelium (EE), such as reflux esophagitis and cancer, are rising in incidence. Despite this, the cellular behaviors underlying EE homeostasis and repair remain controversial. Here, we show that in mice, EE is maintained by a single population of cells that divide stochastically to generate proliferating and differentiating daughters with equal probability. In response to challenge with all-trans retinoic acid (atRA), the balance of daughter cell fate is unaltered, but the rate of cell division increases. However, after wounding, cells reversibly switch to producing an excess of proliferating daughters until the wound has closed. Such fate-switching enables a single progenitor population to both maintain and repair tissue without the need for a "reserve" slow-cycling stem cell pool.     

Comparison of antibody responses in cattle to outer membrane proteins from Pasteurella haemolytica serotype 1 and from eight untypeable strains.

Membrane associated proteins from 8 untypeable Pasteurella haemolytica strains were separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and compared with those of P haemolytica serotypes 1 and 2. Cattle antisera obtained from P haemolytica serotype 1 vaccine trials were used in immunoblotting assays to compare the membrane proteins from the 8 untypeable strains with those from P haemolytica serotypes 1 and 2. Densitometry was used to identify bands, and using linear regression analyses, the peak area optical densities (measuring antibody response) were correlated to lesion scores from the vaccinated calves. Significant antibody responses to proteins of 99, 69, 60, 55, 47, 45, 39, 33, 30, 16, and 14.5 kDa were detected for 4 or more of the 8 P haemolytica untypeable strains. Serotypes 1 and 2 of P haemolytica contained a comigrating 30-kDa protein. Antibody responses to proteins of 39, 33, and 32.5 kDa were significant for 3 of the untypeable strains and had significant correlation to lesion scores. Antibody responses to various other proteins were significant for 2 untypeable strains each.     

Tree Density and Germplasm Source in Agroforestry Ecosystems in Meru,Mount Kenya

Farmers use and conserve a large variety of tree species. In Meru, a tree census on 35 farms covering 60 ha was conducted. This study included farmer interviews and biological measurements, with about 63,000 trees and 297 species being recorded. This paper discusses tree densities per species and germplasm sources for trees and species. The low densities and limited influx of germplasm from outside the farming community for some species, may result in an increased vulnerability to inbreeding and genetic erosion. This paper aims to provide some baseline data for understanding genetic resource management in agroforestry systems. It also provides suggestions for interventions to lower the vulnerability for species in Meru. Farmers need to have increased access to germplasm to diversify their farms in terms of species evenness, by substituting trees of more common species with trees of rarer species, or by increasing trees of rarer species.