Risk Analysis for Latent Infection of Prune by Monilinia fructicola in California

ABSTRACT The quantitative relationships between incidence of latent infection (ILI) of prune by Monilinia fructicola and wetness duration (WD) for different bloom and fruit developmental stages and different inoculum concentrations were obtained. Three levels of ILI were considered as criteria for low, moderate, and high risks of latent infection, respectively. Seasonal patterns of WD leading to different risk levels of latent infection were obtained for low (IP(L)) and high (IP(H)) inoculum potential conditions in orchards. Longer WD was needed at a resistant than at a susceptible fruit developmental stage to induce similar levels of latent infection. The curves of WD leading to different levels of ILI over the growing season (risky WD curves) were used in risk analysis for latent infection. Multi-year historical WD data from 10 prune-growing locations in California were compared with risky WD curves. The percentage of days (P) with WD leading to a certain risk level of latent infection was calculated for each month from historical weather data. Under the IP(L) condition, the P distributions for low risk of latent infection were higher in March and April than in May and were the lowest in June for most locations. Under the IP(H) condition, the number of days that WD leading to low risk of latent infection in May increased compared with those under the IP(L) condition. The risk analysis approach was evaluated by using separate experimental data as incidence of fruit brown rot obtained from different prune orchards over years. Consistency between predicted overall risk levels of latent infection and observed incidence of fruit brown rot was obtained. The results demonstrated the usefulness of the risk analysis in decision support system for disease management.     

Control strategies using systemic fungicides for limiting disease development and resistance buildup: practical implications of a simulation model

A simulation model was used to assess the control efficacy of, and the buildup of resistant populations to, systemic fungicides as affected by preventive vs responsive (curative) treatments with a protectant fungicide, or with a mixture composed of a systemic and a protectant fungicide. The variables introduced in the model were: rate of fungicide weathering, coverage efficacy, and relative fitness of the resistant population of the pathogens. In all simulated epidemics (with different combinations of apparent infection rates, critical disease levels and rates of weathering of the fungicides), preventive treatments, before the critical disease levels were reached, were significantly more effective than responsive (curative) treatments. At low rates of weathering of the protectant fungicide (half-life of the protectant greater than or equal to that of the systemic), the buildup of the resistant population was significantly inhibited when a mixture was used either preventively or responsively. At high rates of weathering of the protectant fungicide (half-life of the protectant less than that of the systemic), both the buildup of the resistant population and the control efficacy were dependent on the control program used and on the different combinations of fungicide weathering, fitness of the resistant population, and coverage efficacy of both the protectant and systemic fungicides.     

The overwintering ofExserohilum turcicum in Israel

Exserohilum turcicum (Pass.) Leonard and Suggs, the causal agent of northern leaf blight of corn, overwinters onSorghum halepense L. plants and on corn debris (dead leaves). Spqrulating lesions ofE. turcicum were observed on sorghum plants in the winter (February). Spores from these lesions were pathogenic to susceptible sweet corn plants cv. ‘Jubilee’. Infected sporulating leaves of corn were stored for 1 year at 20°C (40-60% relative humidity), at 5°C (60% relative humidity), or buried 5 cm underground. During the storage period, 32% and 22% of the spores formed chlamydospores, at 20° and 5°C, respectively. Leaves buried 5 cm underground were totally decomposed after 6 months. After 4 months, 25% of the spores in the buried leaves had formed chlamydospores. Spores with chlamydospores were pathogenic to corn plants. The viability of spores without chlamydospores stored at 20°, 5°C or buried underground was 0, 60 and 0%, respectively. In a parallel experiment infected leaves were stored under similar conditions and allowed to sporulate. No sporulation occurred on infected leaves buried in soil. Spores produced on infected leaves stored at 20° and 5°C were highly pathogenic to corn plants. In leaves treated with 0.1N glucose, chlamy dospore formation was significantly inhibited.     

Effects of farrowing system on behavior and growth performance of growing-finishing pigs

A study was conducted to compare growth performance and behaviors of group-farrowed pigs with those of confinement-farrowed pigs. A total of 216 pigs (8 wk of age) were used, with an equal number of group-farrowed or confinement-farrowed pigs from 1 farrowing batch. Group-farrowed pigs were farrowed in bedded, individual pens and mingled into a group of 8 litters at 12 (±1.3) d of age. Pigs were weaned at 33 (±1.3) d and remained in the farrowing room until 8 wk of age. Confinement-farrowed pigs were farrowed in farrowing crates. At weaning (32 ± 2.0 d of age), confinement-farrowed pigs were mixed and moved to pens of 9 pigs in a confinement nursery and remained there until 8 wk of age. At 8 wk of age, pigs from the 2 housing systems were allocated to 24 pens of 9 pigs in a confinement growing-finishing barn, with 12 pens from each of the housing systems. Within farrowing system, pigs from different groups or pens were mixed upon entering the growing-finishing barn. Individual BW was recorded at allotment (wk 0) to the growing-finishing barn and every 2 wk thereafter for 14 wk. Feed intake and G:F were monitored on a pen basis every 2 wk between wk 0 and 14 of the study period. Behaviors of pigs were video recorded in 6 pens of each housing treatment for 24 h on the day of mixing (d 0), d 7, and d 14 after mixing in the finisher barn. The video recordings were scanned at 5-min intervals to calculate behavioral time budgets for lying, standing, eating, drinking, and belly nosing. Data were analyzed using the Proc Mixed model of SAS with repeated measures. Compared with confinement-farrowed pigs, group-farrowed pigs spent more time lying (85.7 vs. 82.7%; SE = 0.75; P < 0.001) and belly nosing (0.05 vs. 0.02%; P < 0.05) and less time standing (5.8 vs. 7.5%; SE = 0.49; P < 0.01) and eating (7.3 vs. 9.3%; SE = 0.40; P < 0.001). The difference in behavioral time budgets was associated with differences in performance of pigs from the 2 housing systems. Group-farrowed pigs exhibited greater ADG (866 vs. 814 g; SE = 10.3; P < 0.01) for the initial 2 wk after mixing, less ADFI (2,004 vs. 2,188 g; SE = 42.5; P < 0.05), and improved G:F (0.431 vs. 0.393; SE = 0.0078; P < 0.01) for the entire 14-wk study period compared with confinement-farrowed pigs. These results suggest that group-farrowed pigs were more efficient than confinement-farrowed pigs in utilizing dietary energy for BW gain by lying more and standing and eating less during the growing and finishing period.     

Volumetric capnography curves as lung function test to confirm bronchoconstriction after carbachol challenge in sedated dogs

This study investigated volumetric capnography (VC) in detecting airway responsiveness following airway challenge using carbachol in seven sedated dogs via face mask. Nebulised saline was administered, followed by increasing concentrations of nebulised carbachol until airflow limitation occurred (EP). Dead space (DS) variables and shape indices of the VC curve were calculated automatically after entering arterial carbon dioxide tension. Airway DS, airway DS to tidal volume (V(T)) ratio and the intercept of slope 2 of the VC curve decreased significantly at EP by 10%, 13% and 16%, respectively, minute ventilation, V(T) and alveolar DS increased significantly at EP by 49%, 22% and 200%, respectively. We conclude that VC and derived indices may be used to verify a reaction to airway challenge caused by carbachol in sedated dogs.     

Genetic and phenotypic relationships of serum leptin concentration with performance, efficiency of gain, and carcass merit of feedlot cattle

Leptin is the hormone product of the obese gene that is synthesized and predominantly expressed by adipocytes. This study estimated the genetic variation in serum leptin concentration and evaluated the genetic and phenotypic relationships of serum leptin concentration with performance, efficiency of gain, and carcass merit. There were 464 steers with records for serum leptin concentration, performance, and efficiency of gain and 381 steers with records for carcass traits. The analyses included a total of 813 steers, including those without phenotypic records. Phenotypic and genetic parameter estimates were obtained using SAS and ASREML, respectively. Serum leptin concentration was moderately heritable (h2 = 0.34 +/- 0.13) and averaged 13.91 (SD = 5.74) ng/mL. Sire breed differences in serum leptin concentration correlated well with breed differences in body composition. Specifically, the serum leptin concentration was 20% greater in Angus-sired steers compared with Charolais-sired steers (P < 0.001). Consequently, ultrasound backfat (27%), carcass 12th-rib fat (31%), ultrasound marbling (14%), and carcass marbling (15%) were less in Charolais- than Angus-sired steers (P < 0.001). Conversely, carcass LM area (P = 0.05) and carcass lean meat yield (P < 0.001) were greater in Charolais- compared with Angus-sired steers. Steers with greater serum leptin concentration also had greater DMI (P < 0.001), greater residual feed intake (P = 0.04), and partial efficiency of growth (P = 0.01), but did not differ in feed conversion ratio (P > 0.10). Serum leptin concentration was correlated phenotypically with ultrasound backfat (r = 0.41; P < 0.001), carcass 12th-rib fat (r = 0.42; P < 0.001), ultrasound marbling (r = 0.25; P < 0.01), carcass marbling (r = 0.28; P < 0.01), ultrasound LM area (r = -0.19; P < 0.01), carcass LM area (r = -0.17; P < 0.05), lean meat yield (r = -0.38; P < 0.001), and yield grade (r = 0.32; P < 0.001). The corresponding genetic correlations were generally greater than the phenotypic correlations and included ultrasound backfat (r = 0.76 +/- 0.19), carcass 12th-rib fat (r = 0.54 +/- 0.23), ultrasound marbling (r = 0.27 +/- 0.22), carcass marbling (r = 0.76 +/- 0.21), ultrasound LM area (r = -0.71 +/- 0.19), carcass LM area (r = -0.75 +/- 0.20), lean meat yield (r = -0.59 +/- 0.22), and yield grade (r = 0.39 +/- 0.26). Serum leptin concentration can be a valuable tool that can be incorporated into appropriate selection programs to favorably improve the carcass merit of cattle.     

Effects of the Administration of Lactobacilli,Maltodextrins and Fructooligosaccharides upon the Adhesion of <Emphasis Type="Italic">E. coli</Emphasis> O8:K88 to the Intestinal Mucosa and Organic Acid Levels in the Gut Contents of Piglets

The influence of the administration of Lactobacillus plantarum, maltodextrin Maldex 150 and Raftifeed IPX fructooligosaccharides on the inhibition of adhesion of E. coli O8:K88 to the mucosa of the jejunum, ileum and colon as well as on the organic acid levels was investigated in 33 conventional piglets. The counts of E. coli K88 adhering to the jejunal mucosa were significantly decreased (p < 0.05) in Lact. plantarum + Maldex 150 and Lact. plantarum + Maldex 150 + Raftifeed IPX groups. The counts of E. coli K88 adhering to the colonic mucosa of Lact. plantarum + Maldex 150 + Raftifeed IPX and Lact. plantarum + Raftifeed IPX groups were significantly lower (p < 0.05) than in Lact. plantarum and Lact. plantarum + Maldex 150 animals. The acetic acid levels in the ileum and colon of the Lact. plantarum + Maldex 150 + Raftifeed IPX group and Lact. plantarum + Raftifeed IPX group were significantly higher (p < 0.05) than in the Lact. plantarum and Lact. plantarum + Maldex 150 group. The combination of Lact. plantarum, maltodextrin Maldex 150 and Raftifeed IPX proved to be the most effective one to inhibit the counts of E. coli O8:K88 adhering to the intestinal mucosa of the jejunum and colon of conventional piglets.     

“优力乐”对雏鸡肠道微生物菌群的影响

为探索"优力乐"对雏鸡肠道微生物菌群的影响,选择雏鸡400只,随机均分为4组,即对照组、试验Ⅰ组、试验Ⅱ组和试验Ⅲ组,对照组不使用任何微生态制剂,试验组分别饲喂"优力乐"0.005%、0.01%、0.03%,1日龄开始饲喂至56日龄结束,并对雏鸡肠道内容物进行细菌分离鉴定。结果:共分离出包括有害菌在内的8种细菌,优势菌为乳杆菌∶拟杆菌∶消化球菌∶双歧杆菌∶肠球菌=30∶25∶30∶40∶23。试验Ⅱ组和试验Ⅲ组与对照组相比大肠杆菌数量显著降低(P0.05),双歧杆菌、拟杆菌、消化球菌及肠球菌显著升高(P0.05),说明"优力乐"可以抑制大肠杆菌及其它有害菌的生长,使雏鸡消化道正常菌群迅速建立。试验Ⅱ组和试验Ⅲ组中无革兰氏阴性有害菌,各种微生物数量无显著差异(P0.05),从经济效益考虑,生产实践中可使用0.01%"优力乐"。     

荒漠草原不同放牧强度下土壤酶活性及养分含量的动态研究

研究了内蒙古荒漠草原不同放牧强度下土壤中4种酶活性及养分含量的动态变化.结果表明,土壤酶活性和养分含量随季节变化有着明显的变化,但各类群变化规律并不完全相同.放牧对蔗糖酶影响不显著,但显著增加了多酚氧化酶活性.轻度放牧显著或极显著增加了蛋白酶活性,脲酶活性略降低.重度放牧显著增加了脲酶活性,蛋白酶活性极显著降低.重度放牧降低了土壤中养分含量,围栏封育和轻度放牧有助于土壤肥力的保持和提高.     

Biological effect of tyrosine kinase inhibitors on three canine mast cell tumor cell lines with various KIT statuses

Tyrosine kinase inhibitors (TKIs) can be important in the treatment of canine mast cell tumor (cMCT). Meanwhile, some TKIs have been identified as substrates for ABCB1. The inhibitory effect of four TKIs (axitinib, imatinib, masitinib, and vatalanib) for proliferation and phosphorylation of c-Kit receptor as well as the expression and function of ABCB1 were investigated in three cMCT cell lines (HRMC, VIMC1, and CMMC1). The IC(50) values of the TKIs in HRMC, the only cell line with wild-type KIT, were clearly higher than those in CMMC1 and VIMC1. In HRMC and CMMC1, both the growth and phosphorylation of c-Kit receptor were suppressed proportionally by the TKIs. VIMC1 required higher concentrations for the inhibition of c-Kit receptor phosphorylation than those in cell growth. The treatment with cyclosporine increased the effects of the TKIs on VIMC1 since ABCB1 was expressed in VIMC1. The results indicated that cMCT cell lines harboring wild-type KIT had lower sensitivity to TKIs. The growth of VIMC1 was seemingly reduced by TKIs through the inhibition of other tyrosine kinases than c-Kit receptor. There was little influence of ABCB1 on TKI effects to the proliferation of VIMC1. These results will be helpful to understand the different sensitivity to TKIs in cMCT patients.