Comparison of Postfire Soil Water Repellency Amelioration Strategies on Bluebunch Wheatgrass and Cheatgrass Survival

Soil water repellency can limit postfire reseeding efforts and thus increase the susceptibility of a site to weed invasion. We evaluated the effectiveness of wetting agents and simulated anchor chaining for improving seedling growth and survival in water-repellent soil, for the native perennial bluebunch wheatgrass (Pseudoroegneria spicata) and invasive annual cheatgrass (Bromus tectorum). Research was performed in a glasshouse, on 20-cm-diameter soil cores that were excavated from underneath burned Utah juniper (Juniperus osteosperma) trees. The experiment was arranged as a randomized split-plot design, with the two grass species sown separately under four soil treatments: 1) no treatment (control), 2) simulated anchor chaining (hereafter referred to as “till”), 3) wetting agent, and 4) till plus wetting agent. Soil water content was highest in the wetting agent treatment, lower for till, and lowest in the control. Overall, the response of bluebunch wheatgrass and cheatgrass was similar among treatments. At the conclusion of the study, wetting agent cores had twice as many seedlings as the control, while the till and control were similar. Despite a lower number of seedlings, tilling in general resulted in the same level of biomass as the wetting agent treatment. Overall, biomass in the till and wetting agent treatments was at least twofold higher than the control. No benefit was found in applying both till and wetting agent treatments together in comparison to just applying wetting agent. Because of a lack of correlation between glasshouse and field settings the results of this study need to be interpreted with caution. Our data may indicate that if cheatgrass is not already present on the site, anchor chaining or treating the soil with wetting agent can increase establishment of seeded species.     

奥普明与螯合微量元素对养猪生产的影响

主要微量元素的功用 微量元素如何调节动物的机体代谢,在许多方面尚不清楚,以下是我们已经了解到的部分内容,但什么是生长或繁殖的 最佳需要量,哪种化学结合最易被动物吸收利用,至今只有有限的研究资料,这为我们的生产带来许多不确定因素。特别 是重金属铜超量不仅能引发动物自身的毒害作用,同时还会造成严重的环境污染,甚至是肉品自身的污染。有限的研究资 料显示,微量元素的利用对动物健康作用显著,选择正确与否将对动物的繁殖性能及生长性能有显著的影响。     

Root-released organic acids and phosphorus uptake of two barley cultivars in laboratory and field experiments

A major portion of phosphorus (P) applied as fertilizers is bound in soils as P compounds of variable adsorption strength, reducing the effectiveness of P fertilization. Plant genotypes equipped with mechanisms for utilizing the adsorbed P more efficiently can, therefore, enhance the effectiveness of P fertilization. Such genotypes will also enrich plant gene pools for further analysis and upgrading of P efficiency by selection and breeding. We studied the variation and the mechanisms of P uptake of two winter barley (Hordeum vulgare L.) cultivars Marinka and Sonate (parents of existing 200 haploid progeny lines), by laboratory and field experiments. After cultivation in nutrient solution for 21 days, Marinka produced more roots than Sonate, but similar amounts of dry shoots of lower P content (Marinka 3.4±0.4 mg g⁻¹, Sonate 4.9±0.6 mg g⁻¹). The total P uptake per plant did not differ between the cultivars. Marinka retained more P in roots as indicated by the higher concentration of P in the roots (Marinka 3.9±0.3 mg g⁻¹ and Sonate 3.0±0.4 mg g⁻¹). In sterile nutrient solution culture, the cultivars differed mainly in release of organic acids from the roots, with Marinka releasing three times more citric acid and nearly two times more acetic acid than Sonate. The cultivars had similar root hair lengths and they did not differ (P>0.05) in depletion of available soil P fraction (extracted with 0.5 M NaHCO₃) in the rhizosphere. Marinka absorbed nearly twice as much P from the strongly adsorbed soil P fraction (extracted with 0.1M NaOH). Also under field conditions, Marinka absorbed more P and produced more shoot dry matter. The higher P uptake by Marinka than Sonate can be attributed to its ability to acquire P from strongly adsorbed soil P by releasing more organic acids, especially citric acid, from its roots.     

Basic principles of muscle development and growth in meat-producing mammals as affected by the insulin-like growth factor (IGF) system

This presentation aims to describe how the basic events in prenatal muscle development and postnatal muscle growth are controlled by the insulin-like growth factor system (IGF). The prenatal events (myogenesis) cover the rate of proliferation, the rate and extent of fusion, and the differentiation of three myoblast populations, giving rise to primary fibers, secondary fibers, and a satellite cell population, respectively. The number of muscle fibers, a key determinant of the postnatal growth rate, is fixed late in gestation. The postnatal events contributing to myofiber hypertrophy comprise satellite cell proliferation and differentiation, and protein turnover. Muscle cell cultures produce IGFs and IGF binding proteins (IGFBPs) in various degrees depending on the origin (species, muscle type) and state of development of these cells, suggesting an autocrine/paracrine mode of action of IGF-related factors. In vivo studies and results based on cell lines or primary cell cultures show that IGF-I and IGF-II stimulate both proliferation and differentiation of myoblasts and satellite cells in a time and concentration-dependent way, via interaction with type I IGF receptors. However, IGF binding proteins (IGFBP) may either inhibit or potentiate the stimulating effects of IGFs on proliferation or differentiation. During postnatal growth in vivo or in fully differentiated muscle cells in culture, IGF-I stimulates the rate of protein synthesis and inhibits the rate of protein degradation, thereby enhancing myofiber hypertrophy. The possible roles and actions of the IGF system in regulating and determining muscle growth as affected by developmental stage and age, muscle type, feeding levels, treatment with growth hormone and selection for growth performance are discussed.     

Human Impacts on Forest Biodiversity in Protected Walnut-Fruit Forests in Kyrgyzstan

We used a spatially explicit model of forest dynamics, supported by empirical field data and socioeconomic data, to examine the impacts of human disturbances on a protected forest landscape in Kyrgyzstan. Local use of 27 fruit and nut species was recorded and modeled. Results indicated that in the presence of fuelwood cutting with or without grazing, species of high socioeconomic importance such as Juglans regia, Malus spp., and Armeniaca vulgaris were largely eliminated from the landscape after 50–150 yr. In the absence of disturbance or in the presence of grazing only, decline of these species occurred at a much lower rate, owing to competitive interactions between tree species. This suggests that the current intensity of fuelwood harvesting is not sustainable. Conversely, current grazing intensities were found to have relatively little impact on forest structure and composition, and could potentially play a positive role in supporting regeneration of tree species. These results indicate that both positive and negative impacts on biodiversity can arise from human populations living within a protected area. Potentially, these could be reconciled through the development of participatory approaches to conservation management within this reserve, to ensure the maintenance of its high conservation value while meeting human needs.     

Estimation of Milk Production in Lactating Sows by Determination of Deuterated Water Turnover in Three Piglets per Litter

The milk intake in piglets from four lactating sows was measured in three 48 h periods, starting on days 3, 10 and 17 of lactation, using the deuterium oxide (D 2 O) dilution technique. The milk intake was estimated from the water turnover in the piglets corrected for the production of metabolic water. The water turnover was estimated from the water dilution space and the fractional turnover of body water, determined by the rate of D 2 O dilution. To determine the magnitude of isotopic recycling, a randomly selected piglet in each litter was not enriched with D 2 O. Milk production of the four lactating sows was also measured by the weigh-suckle-weigh (WSW) method on days 4, 11 and 18 of lactation. The average daily milk production determined by the D 2 O dilution technique (9.91 - 0.69 kg) was higher ( P <0.05) than that determined by the uncorrected WSW method (8.65 - 0.81 kg). Different procedures for selecting piglets were evaluated to obtain the best possible estimation of total milk production from three piglets in each litter. The total milk production of a sow based on three piglets in the litter was obtained from a quadratic model of the relationship between milk intake and daily gain. When the daily gain of all piglets were known the Pearson correlation between milk production determined for the whole litter ( n -1) and only three median piglets was 0.98.     

Genetic Parameters of Disease Incidence,Fertility and Milk Yield of First Parity Cows and the Relation to Feed Intake of Growing Bulls

Abstract

Not much is known about the effect of light sources on behavioural development of laying hens. The effect of natural and artificial light, respectively, on feeding and perching of layers was studied. 126-day-old chicks were divided into 1) A8: 8h artificial light+16h darkness, 2) A16: 16h artificial light+8h darkness, 3) N8: 8h daylight+16h darkness. A8 and N8 birds did not differ in their feeding behaviour, whereas the mean proportion of A16 birds feeding was 0.056 lower than in A8 birds in daytime (P<0.001) and 0.019 lower in nighttime (P<0.0001). N8 birds tended to start nighttime perching earlier than A8 birds (hazard ratio=8.5; P=0.056). These results suggest that chicks can change their feeding behaviour depending on day length. Natural daylight was found to precipitate the onset of nighttime perching in the life of the pullet.     

Genetic variation of in vivo muscle glycerol,glycogen, and pigment in Danish purebred pigs

Heritability values of glycerol, glycogen and pigment concentrations measured on muscle biopsy samples from longissimus dorsi obtained from 85?kg boars of Danish purebred pigs (Landrace, Yorkshire, and Duroc) and their genetic correlations to performance and meat quality traits were calculated. The heritability values of glycogen, pigment, and glycerol were 0.38±0.02, 0.17±0.02, and 0.065±0.016, respectively. Glycogen was negatively related to the feed conversion ratio (FCR) (r _g =?0.25±0.06) and ultimate meat pH (r _g =?0.41±0.04), and positively to the carcass meat percentage (r _g =0.35±0.04), L* (lightness of meat, r _g =0.32±0.04) and a* (redness of meat, r _g =0.12±0.03). Pigment was positively related to the FCR (r _g =0.12±0.05), the meat percentage (r _g =0.28±0.05), and a* (r _g =0.59±0.04), and negatively to the L* (r _g =?0.46±0.06). The concentrations of pigment and glycogen (r _g =0.27±0.05) were interrelated. Based on the heritability values and the signs of the genetic correlations the present data suggest that it is possible to select for higher ultimate pH and improved colour by selection for either lower muscle glycogen or higher pigment concentration, respectively. However, the positive genetic correlation between these two traits may restrict the efficiency of simultaneous selection for lower glycogen and higher pigment. All genetic parameter estimates presented are calculated across three purebreds. Values for each breed are warranted for use in pig production. However, this requires more animals per breed.     

The phenology and population dynamics of Culicoides spp. in different ecosystems in The Netherlands

The Netherlands has enjoyed a relatively free state of vector-borne diseases of economic importance for more than one century. Emerging infectious diseases may change this situation, threatening the health of humans, domestic livestock and wildlife. In order to be prepared for the potential outbreak of vector-borne diseases, a study was undertaken to investigate the distribution and seasonal dynamics of candidate vectors of infectious diseases with emphasis on bluetongue vectors (Culicoides spp.). The study focused primarily on the relationship between characteristic ecosystems suitable for bluetongue vectors and climate, as well as on the phenology and population dynamics of these vectors. Twelve locations were selected, distributed over four distinct habitats: a wetland area, three riverine systems, four peat land areas and four livestock farms. Culicoides populations were sampled continuously using CO(2)-baited counterflow traps from July 2005 until August 2006, with an interruption from November 2005 to March 2006. All vectors were identified to species level. Meteorological and environmental data were collected at each location. Culicoides species were found in all four different habitat types studied. Wetland areas and peat bogs were rich in Culicoides spp. The taxonomic groups Culicoides obsoletus (Meigen) and Culicoides pulicaris (Linnaeus) were strongly associated with farms. Eighty-eight percent of all Culicoides consisted of the taxon C. obsoletus/Culicoides scoticus. On the livestock farms, 3% of Culicoides existed of the alleged bluetongue vector Culicoides dewulfi Goetghebuer. Culicoides impunctatus Goetghebuer was strongly associated with wetland and peat bog. Many Culicoides species were found until late in the phenological season and their activity was strongly associated with climate throughout the year. High annual variations in population dynamics were observed within the same study areas, which were probably caused by annual variations in environmental conditions. The study demonstrates that candidate vectors of bluetongue virus are present in natural and livestock-farm habitats in the Netherlands, distributed widely across the country. Under favourable climatic conditions, following virus introduction, bluetongue can spread among livestock (cattle, sheep and goats), depending on the nature of the viral serotype. The question now arises whether the virus can survive the winter conditions in north-western Europe and whether measures can be taken that effectively halt further spread of the disease.