Refinar búsqueda
Resultados 1-10 de 98
Genetic diversity of some Ghanaian pigs based on microsatellite markers Texto completo
2016
Ayizanga, R.A. | Kayang, B.B. | Adomako, K. | Adenyo, C. | Inoue-Murayama, M. | Asamoah, L.
A knowledge of the level of genetic diversity is very important in ensuring the sustainable utilisation of animal genetic resources. To this end, the genetic diversity of some local pigswas assessed by genotyping 86 unrelated pigs in four regions of Ghana namely Northern (Tingoli = 9), Upper West (Papu = 31 and Babile = 32) and Upper East (Gia = 14) using 12 microsatellite markers.The number of alleles (Na), number of effective alleles (Ne), observed heterozygosity (Ho), expected heterozygosity (He) and inbreeding coefficient (FIS) were used to assess the level of genetic differentiation among the five populations in this study. All loci studied were polymorphic and the mean number of alleles ranged from 4.58 (Yorkshire) to 10.58 (Papu) with an overall average of 7.65 alleles. At all the 12 loci studied, inbreeding coefficient (FIS) deviated significantly from zero with a mean of 0.32. When the Nei’s standard genetic distance based on the proportions of shared alleles was used to construct a neighbour joining tree, pigs from the different communities sampled in the Upper West region emerged with the highest bootstrap value of 90%. Generally, the sampled pigs represent distinct populations with a moderate amount (12%) of genetic differentiation but considerable amount of inbreeding (29%) has taken place within these populations over the years. This is the first report of the genetic diversity of Ghanaian local pigs using microsatellite markers.
Mostrar más [+] Menos [-]Growth performance of Woyto-Guji and Central Highland goat breeds under traditional management system in Ethiopia Texto completo
2016
Zergaw, N. | Dessie, Tadelle | Kebede, K.
The study was conducted to evaluate the productive and reproductive performance of Central Highland and Woyto-Guji goat breeds in Meta-Robi and Konso districts, respectively. A total of 240 farmers were interviewed using semi-structured questionnaires to describe kidding pattern, kidding interval, weaning age and milk production. On-farm performance traits were recorded on 730 goats of 157 households. In Konso, majority of kidding occurred in May, whereas in Meta-Robi it was in September. There was a difference in the average kidding interval and age at weaning between the breeds. Kids birth weight (2.03 Vs. 2.68kg) and does postpartum weight (26.6 Vs. 28.2kg) were lower in Woyto-Guji goats than in Central Highland goats. Average 90 day kids' weight and average daily weight gain between birth and 90 days were not different among the breeds. Average 180 day weight (15.7 Vs. 11.5kg) and average daily weight gain between 91 and 180 days (65.4 Vs. 31.9 g/day) were better in Central Highland goats than in Woyto-Guji goats.
Mostrar más [+] Menos [-]Tree damages by icing in Scots pine (Pinus sylvestris L.) stands and factors affecting them Texto completo
2016
Baders, E., Latvian State Forest Research Inst. Silava, Salaspils (Latvia) | Adamovics, Andis, Latvian State Forest Research Inst. Silava, Salaspils (Latvia) | Purins, M., Latvian State Forest Research Inst. Silava, Salaspils (Latvia) | Dzerina, B., Latvian State Forest Research Inst. Silava, Salaspils (Latvia)
Icing notably increases the mass of a tree crown, causing damage to the tree. So far, a very limited number of studies have assessed the icing influence on coniferous trees, none of them in Latvia. The aim of the study was to assess the influence of tree parameters and recent thinning on the proportion of damaged trees and the type of damage in Scots pine stands. The study sites were located in the eastern part of Latvia, damaged in December 2012. In total, 98 pine dominated stands of different age were selected randomly. Eight (mean) plots per stand were established; in each plot, all trees larger than 2.1 cm were measured and the type of damage assessed. The above-ground biomass from 12 randomly selected stands (57 dominant trees) of different age was weighted with and without icing. The biomass of pine with icing exceeded that without 1.5 ± 0.27 times. The mean proportion of damaged trees in pine dominated stands was 26%; the proportion of broken trees peaked in the middle-aged stands (41 – 70 years old), but the largest proportion of pooled bent and uprooted trees was found in the young (11 – 20 years old) stands. The proportion of damaged dominant trees was affected by the slenderness coefficient – a higher proportion of such trees was found among more slender trees. The results suggest that the risk of icing damage could be reduced by silvicultural measures boosting individual tree stability.
Mostrar más [+] Menos [-]Growth of Fagus sylvatica in young mixed stand: case study in central Latvia Texto completo
2016
Purina, L., Latvian State Forest Research Inst. Silava, Salaspils (Latvia) | Adamovics, Andis, Latvian State Forest Research Inst. Silava, Salaspils (Latvia) | Katrevics, J., Latvian State Forest Research Inst. Silava, Salaspils (Latvia) | Katrevica, Z., Latvian State Forest Research Inst. Silava, Salaspils (Latvia) | Dzerina, B., Latvian State Forest Research Inst. Silava, Salaspils (Latvia)
Climatic changes are shifting the potential tree distribution limits of many tree species northwards. One of such species is Fagus sylvatica, currently represented in Latvia only by a few stands. In order to increase knowledge on its potential use in the forest management, the aim of our study was to characterize the growth of beech in a young stand in the central part of Latvia. The stand of beech and spruce, mixed in rows with an initial spacing of 2.5 x 2.5 m in Oxalidosa forest type was assessed. Survival of European beech in clear cutting was similar to that observed for the native Norway spruce (73% and 79%, respectively), but both height and diameter were notably and significantly superior for wildlings at the mean age of 15 ± 2 years, reaching on average 7.4 ± 0.30 m and 8.9 ± 0.69 cm, respectively. Increasing ring width with increasing tree age for both tree species was observed until the last four years, when large and increasing superiority of beech over spruce, coinciding with reduction of ring width of spruce, was noted. It was most likely caused by intensified competition due to very wide crowns formed by young beech trees in the plantation with wide spacing: average crown radius reached 2.4 ± 0.16 m, for few trees exceeding even 4 m.
Mostrar más [+] Menos [-]Impact of needle cast damage on sanitary condition in young Pinus sylvestris stands in central Latvia Texto completo
2016
Polmanis, K., Latvian State Forest Research Inst. Silava, Salaspils (Latvia);Latvia Univ. of Agriculture, Jelgava (Latvia) | Miezite, O., Latvian State Forest Research Inst. Silava, Salaspils (Latvia) | Baumanis, I., Latvian State Forest Research Inst. Silava, Salaspils (Latvia) | Lazdins, A., Latvian State Forest Research Inst. Silava, Salaspils (Latvia)
Recent studies have demonstrated the occurrence of different needle cast (Lophodermium spp.) species in young Scots pine Pinus sylvestris L. stands in different regions of Latvia. The impact of these fungi has been known also historically, but is predicted to increase in future due to climate changes that are forecasted to have a positive impact on presence and vigour of various species of fungi. The aim of the study was to characterize the needle cast damage in young Scots pine stands in central Latvia. Material was collected in 12 Scots pine stands at the age of 3 to 26 years in 28 plots with a total area of 8.1 ha in the middle of two consecutive growing seasons (years 2012 and 2013). The impact of disease was visually assessed using a 5 grade scale, depending on the proportion of damaged (brown) one-year old needles. Incidence of damaged trees (P, %) and damage intensity (R, %) was calculated and used to characterize the occurrence and severity of the infection in the stands as well as its link to other stand parameters. Damage incidence (ranging from 20 to 100%), as well as the intensity (from 4 to 35%) was slightly (incidence-also significantly) higher in 2013 in comparison to 2012; correlation between those two parameters was strong in both years (r = 0.94 and r = 0.84, respectively). The stand age, density (ranging from 1200 to 6900 trees haE-1) and tree height did not significantly correlate with the damage incidence or intensity. Forest type (Hylocomiosa or Myrtillosa mel.) was not a significant factor, too.
Mostrar más [+] Menos [-]Quality changes during summer–autumn long-term storage of Scots pine (Pinus sylvestris L.) roundwood Texto completo
2016
Magaznieks, J., Latvia Univ. of Agriculture, Jelgava (Latvia) | Millers, M., Latvia Univ. of Agriculture, Jelgava (Latvia) | Gzibovska, Z., Latvia Univ. of Agriculture, Jelgava (Latvia)
Latvia at the moment does not have precise data about long-term storage of Scots pine. Long-term storage in warm season may lead to significant damages for high priced timber, income reduction for timber sellers and quality loss risk for timber buyers, therefore, roundwood is transported as soon as possible, because of the risk of blue stain, crooks and insect damages. Results of this study on Scots pine were obtained during summer–autumn season of year 2015. Scots pine timber quality changes in long-term storage were analysed in 4 sample stacks – set up in summer (25 July) and stored for 100 days. In every sample plot there was a control pile, a pile with harvester spike damages, a pile with bark damages and a pile with harvester spike and bark damages. There were 32 timber assortments in every pile in order to determine also the emplacement effect in stack. In this study a high correlation was found between pine timber quality changes and meteorological conditions, side surface damages and storage length. By analysing the proportion of blue stain in cross-section and its changes during storage between control assortments and assortments with bark and harvester damages, significant differences were observed, therefore it can be concluded that not only bark damages influence the proportion of blue stain, but also harvester spike rollers. Based on the results of this study, we can predict maximum storage duration during summer–autumn period in Latvia, and it is set from 9 – 16 days.
Mostrar más [+] Menos [-]Impact of wood ash and potassium sulphate fertilization on growth of Norway spruce stand on organic soil Texto completo
2016
Okmanis, M., Latvian State Forest Research Inst. Silava, Salaspils (Latvia) | Skranda, I., Latvian State Forest Research Inst. Silava, Salaspils (Latvia) | Lazdins, A., Latvian State Forest Research Inst. Silava, Salaspils (Latvia) | Lazdina, D., Latvian State Forest Research Inst. Silava, Salaspils (Latvia)
Wood based ash can be used as a liming material and fertilizer in forest, thus providing a solution for utilization of wood ash and formation of additional increment of trees, especially on organic soils, where lack of potassium and phosphorus is a well-known factor limiting the growth of trees. Yet, many studies have been made with adverse results mostly because of different soil types and species investigated. However, by now the best results on fertilization with wood ash have been found on drained peatlands, where some nutrient deficiencies have emerged. The aim of this study was to find out the growth response of Norway spruce on drained organic soils after spreading of potassium sulphate (K2SO4) and wood ash (WA). The experiment was carried out in three middle aged Norway spruce (Picea abies) stands on drained mineral and peat soil. Experiment consisted of three replications of each treatment in each stand including WA, K2SO4 and the control on 400 square meter sub-sample plots each. The diameter and height of trees were measured. The samples of increment cores were collected 4 years after fertilization to determine the additional volume increment, which varied from 8.5 m**3 haE-1 in WA plots and from 9.7 m**3 ha-1 to 17.2 m**3 haE-1 on K2SO4 plots. Both - the wood ash and potassium application - significantly increased the increment of Norway spruce on drained mineral and peat soil, although no significant differences were found between the treatments (p = 0.82, α = 0.05).
Mostrar más [+] Menos [-]Evaluation of ecosystem services in riparian forests using benefit transfer method Texto completo
2016
Saklaurs, M., Latvia Univ. of Agriculture, Jelgava (Latvia) | Krumins, J., Latvia Univ. of Agriculture, Jelgava (Latvia) | Straupe, I., Latvia Univ. of Agriculture, Jelgava (Latvia) | Jekabsone, I., Latvia Univ. of Agriculture, Jelgava (Latvia)
The aim of this paper is to evaluate ecosystem services in riparian forests of Latvia using benefit transfer method. The core of benefit-transfer method is to transfer economic costs from one economic situation to another by using pilot indicators, thus saving time and monetary resources of the research. This method also is applicable for transfer of value of ecosystem services to research territories where such values have not been set. As to the evaluation of ecosystem services in riparian forests, data derived from these indicators are compared with the situation in riparian forest stands. Successful application of this method depends on the quality of existing research and their transferability. For example, the data on research of non-timber values can be used to set these values in riparian forests. Value of ecosystem services for 1 ha riparian forest stand in Latvia judging by 1) N and P removal (N - 8.14 euro haE-1 yE-1; P - 2.16 euro haE-1 yE-1); 2) Valuing carbon capture (478.6 euro haE-1 y-E1); 3) Valuing noise buffering (2.02 euro haE-1 yE-1); 4) Valuing air purification (NOx - 1332.5 euro haE-1 yE-1, NH3 - 216 euro haE-1 yE-1, particulate matter - 792 euro haE-1 yE-1); 5) Valuing pollination (timber - 15.25 euro haE-1 yE-1, non-timber - 4 euro haE-1 yE-1) total at 2850.67 euro haE-1 yE-1, which is significantly more than just the traditionally viewed timber value.
Mostrar más [+] Menos [-]Dynamics of rural areas development in Poland - convergence analysis Texto completo
2016
Wojewodzka-Wiewiorska, A., Warsaw Univ. of Life Sciences (Poland) | Dudek, H., Warsaw Univ. of Life Sciences (Poland)
The article deals with the issue of rural development in Poland. The aim of the article is to determine the dynamics of change in the level of socio-economic development of rural communes in Poland (NUTS 5) in the years 2004 – 2014 through verification of the hypothesis of the existence of beta-convergence. The beta-convergence approach is verified by econometric modelling techniques. The statistical data came from the Local Data Bank (LDB) of the Central Statistical Office (CSO). Based on the analysis of changes in the development level of the rural areas in Poland it was stated that there is convergence. However, the strength of the convergence process is different depending on the dimensions of development. It reported a strong relationship between the average growth rate of aggregate indicators relating to the financial dimension. In other dimensions, such as labour market, living conditions, health and social care, education, demography and culture, it showed the occurrence of slow convergence processes.
Mostrar más [+] Menos [-]Productivity of Latvian and Lithuanian rural farms and main factors influencing it Texto completo
2016
Veveris, A., Latvia Univ. of Agriculture, Priekuli, Priekuli parish, Priekuli Municipality (Latvia). Inst. of Agricultural Resources and Economics | Sapolaite, V., Lithuanian Inst. of Agrarian Economics, Vilnius (Lithuania) | Dambina, L., Latvia Univ. of Agriculture, Priekuli, Priekuli parish, Priekuli Municipality (Latvia). Inst. of Agricultural Resources and Economics
The aim of the paper is the assessment of the changes in productivity expressed as the share of production costs in total output and its breakdown by major cost types of Latvian and Lithuanian farms over the period of the implementation of Rural Development Programme (RDP 2007 – 2013). The country’s agricultural productivity is determined by comparison of the total agricultural output value (in producer prices) and total inputs which include intermediate consumption expenditure, depreciation, labour costs and other external costs. The information for the analysis was sourced from the standardized Farm Accountancy Data Network (FADN) data. The results show that productivity level is higher in Lithuanian farms, although the tendency is that the share of costs in production value is increasing in Lithuania, so the difference between two countries is reducing. The changes of productivity in both countries infer the relative growth in the productivity in crop farming both in Latvia and Lithuania respective to dairy farming, as well as the productivity of large farms respective to small and medium farms. The comparisons of major cost items reveal an especially high level of energy costs in Latvia, as well as a high and soaring level of depreciation in Lithuania, especially in dairy farms. In the future policy making, it is worthwhile to design the measures targeting the confinement of risks and negative trends identified in the study.
Mostrar más [+] Menos [-]