Diallel analysis of field resistance to brown streak disease in cassava (<Emphasis Type="Italic">Manihot esculenta</Emphasis> Crantz) landraces from Tanzania

Cassava brown streak disease (CBSD) is an economically important virus disease causing significant losses to cassava root yield and quality in east, central and southern Africa. Breeding for resistance in cassava requires an understanding of the underlying genetic control of CBSD resistance. Sources of CBSD resistance are available but little is known on the value of those varieties as parents for CBSD resistance breeding. Two resistant and two susceptible varieties were crossed in a half diallel design and 35 F₁ progeny from each of the six families, plus parents, were screened at two locations in a randomised complete block design with four replications in warm sub-humid environments of coastal Tanzania in 2008. Screening for CBSD field resistance was done using disease severity scoring on a scale of 1–5. Significant variations in disease severity were observed for crosses, general combining ability (GCA) and specific combining ability (SCA) at both locations. The CBSD shoot symptom severity scores ranged from 1 to 4.4 while root necrosis ranged from 1.3 to 4.5. The contribution of GCA to the total sum of squares of crosses for disease scores ranged from 86.9 to 95.2 % compared to SCA that ranged from 4.8 to 14.2 %. Additive gene effects were more important than non-additive effects indicating that CBSD resistance is genetically determined and that selection should be successful to improve resistance. Selection of parents with good GCA effects will be important for success in CBSD resistance breeding.     

Thoracoscopic versus open partial pericardectomy in dogs: comparison of postoperative pain and morbidity

OBJECTIVE: To evaluate postoperative pain and morbidity in dogs undergoing open thoracotomy and partial pericardectomy versus thoracoscopic pericardectomy. STUDY DESIGN: Research study in normal dogs. ANIMALS OR SAMPLE POPULATION: Fourteen mixed breed healthy dogs. METHODS: Seven dogs had a partial pericardectomy through a standard left lateral thoracotomy at the fifth intercostal space. The remaining seven dogs underwent selective lung ventilation and thoracoscopic partial pericardectomy. Surgery sites in both groups were bandaged and each dog received a single postoperative dose of morphine (0.2 mg/kg, intramuscularly [i.m.]). Postoperative pain was evaluated using a standard pain score table at 1, 5, 9, 17, 29, and 53 hours after surgery. Dogs receiving a pain score of six or greater received an additional dose of morphine. At each observation point, blood samples were taken to measure blood glucose and plasma cortisol concentrations. Pain scores, blood glucose, and plasma cortisol concentrations were compared between the two groups using two-way ANOVA. RESULTS: Blood glucose concentrations, plasma cortisol concentrations, and pain scores were significantly different between the two groups, with the thoracotomy dogs having higher values at 1, 5, and 9 hours postoperatively. Three of the open thoracotomy dogs required additional analgesia after the initial dose of morphine. In addition, two dogs that underwent open thoracotomy were lame in the left forelimb and two others developed dehiscence of their wounds. CONCLUSIONS AND CLINICAL RELEVANCE: Thoracoscopic partial pericardectomy has several advantages over open partial pericardectomy including decreased postoperative pain, fewer wound complications, and more rapid return to function.     

Effect of darglitazone on glucose clearance and lipid metabolism in obese cats

OBJECTIVE: To examine the effect of darglitazone, a compound of the thiazolidinedione class, on glucose clearance and lipid metabolism in obese cats. ANIMALS: 18 obese and 4 lean adult neutered female cats. PROCEDURE: IV glucose tolerance tests with measurements of glucose, insulin, and nonesterified fatty acid (NEFA) concentrations were performed before and 42 days after daily administration of darglitazone (9 obese cats) or placebo (9 obese and 4 lean cats). Additionally, cholesterol, triglyceride, leptin, and glycosylated hemoglobin concentrations were measured. RESULTS: Darglitazone-treated cats had significantly lower cholesterol, triglyceride, and leptin concentrations, compared with placebo-treated obese cats. A significant decrease in the area under the curve for NEFAs, glucose, and insulin during an i.v. glucose tolerance test was seen in darglitazone-treated cats. The drug was well tolerated. CONCLUSION AND CLINICAL RELEVANCE: The response of obese cats to darglitazone was similar to the response to thiazolidinediones in obese humans and rodents Darglitazone was effective in improving insulin sensitivity and glucose and lipid metabolism in obese cats.     

Is moisture really the most important influencing factor on the mechanical properties of claw horn? Modulus of elasticity and dry-matter content in flat and contracted claws

The modulus of elasticity (E) and dry matter content (DMC) of horn samples from two types of claw deformity (contracted and flat claws) were determined according to EN-ISO 527 and ASTM D 638-03. The overall E values for all segments combined were 168 +/- 154 MPa (mean +/- SD, n = 79) and 248 +/- 196 (n = 90) for contracted and flat claws, respectively. These values were approximately 60% and 40% less than the E value of sound claw material.The high correlation between E and DMC, as previously found for sound claw horn material was not present in horn obtained from these types of pathologically altered claws.     

Steps toward sustainable ranching: An emergy evaluation of conventional and holistic management in Chiapas, Mexico

Conventional ranching in Chiapas, Mexico typically includes annual pasture burns and agrochemical use that decrease the biodiversity and forest cover of ranch lands. Members of a holistic ranching “club” in the Frailesca region of Chiapas, Mexico have moved away from this conventional management by eliminating burns and agrochemicals from their systems after decades of use because they believed that the land and their production process were growing unhealthy; they were further motivated by extension courses on holistic ranching. They have also implemented sophisticated systems of rotational grazing and diversified the use of trees. For this study all seven holistic ranchers and 18 neighboring conventional ranchers were interviewed about their cattle ranches and production strategies. An emergy analysis was conducted to compare the resource use, productivity and sustainability of the conventional and holistic ranches. Holistic ranches were found to have double the emergy sustainability index (ESI) values of conventional ranches, and the emergy yield ratio was 25% higher in holistic systems. Government assistance programs were found to have a negative impact on the ESI and were variably administered among holistic ranchers during the year of emergy evaluation. Overall improved emergy sustainability did not decrease milk nor cattle productivity. Transformities and specific emergies, the emergy of one type required to make a unit of energy (transformity) or mass (specific emergy) of another type, did not differ between conventional and holistic systems. Transformities for milk production ranged between 3.4E5 and 1.2E7 solar emjoules/joule (sej/J). Specific emergy for cattle production ranged from 3.5E10 to 1.5E11 sej/g. To improve the ESI assistance programs could be re-targeted toward incentive programs for increased forest cover in ranching systems and startup costs for holistic ranching. The results from this study show that productivity can be maintained as the sustainability of rural dairy ranches is increased. These results also show that local knowledge and understanding of the surrounding ecosystem can drive positive environmental change in production systems.     

Response of advance lodgepole pine regeneration to overstory removal in eastern Idaho

Twenty-two stands of advance lodgepole pine released with overstory removal were sampled to determine height growth response. Tree and site characteristics correlated with release response were identified, and a mathematical model was developed to predict height growth in years 6 through 10 after release as a function of residual overstory basal area, height at release, percent rock cover, five-year cumulative growth prior to release, logging damage, stand elevation, and habitat type. Lodgepole pine responded to release with increased height growth in 97% of the trees sampled. Growth was similar to that of unsuppressed trees. Height growth is best when the entire overstory is removed and logging damage is avoided. Taller trees generally do not respond as well as shorter trees. However, trees growing fast before harvest continue to grow fast regardless of their height at release. Recommendations for selecting stands of advance lodgepole pine to release are provided.     

Effects of pocket gophers,bracken fern,and western coneflower on planted conifers in northern Idaho – an update and two more species

Grand Fir Mosaic forests innorthern Idaho are difficult to regenerate afternatural or human-caused disturbances. Sparseconifer regeneration appears to be associated withhigh populations of northern pocket gophers (Thomomys talpoides) plus expansion by bracken fern(Pteridium aquilinum (L.) Kuhn) and invasionof western coneflower (Rudbeckia occidentalisNutt.). This report updates an earlier study(Ferguson and Adams 1994) that quantified theeffects of four treatments on survival and growth ofplanted conifers: unweeded with gophers, weeded withgophers, unweeded without gophers, and weededwithout gophers. Weeding removed only bracken fernand western coneflower. Subalpine fir (Abieslasiocarpa (Hook.) Nutt.), grand fir (Abiesgrandis (Dougl.) Lindl.), and western larch (Larix occidentalis Nutt.) had over 80% mortalityfrom pocket gophers and other causes. Lodgepolepine (Pinus contorta var. latifoliaEngelm.) had 49.2% mortality from pocket gophersand 6.8% mortality from other causes, but snowdamage is a problem for lodgepole pine. Engelmannspruce (Picea engelmannii Parry ex Engelm.)had 42.2% gopher-caused mortality and 8.4%mortality from other causes. Spruce suffered littletop damage from snowpacks and was stout enough towithstand senescing bracken fern fronds. Westernwhite pine (Pinus monticola Dougl.) had only24.1% mortality from pocket gophers after 4 years,and only 11.8% of the white pine died from causesother than gophers. Of the mortality caused bypocket gophers, 76.8% occurred the first summer andnext two winters after planting. The recommendedspecies for reforestation are Engelmann spruce andwhite pine.