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Non-genetic factors affecting early growth traits and survival in Horro sheep
2002
Abegaz, Solomon | Duguma, G. | Gelmesa, U. | Terefe, F. | Negussie, E. | Rege, J.E.O.
Factors affecting the early growth and survival of indigenous Ethiopian Horro sheep were identified and the influence of each was assessed, based on data collected from 1978 97 from 4031 lambs at Bako Research Centre, Ethiopia. Year of birth, sex, type of birth or rearing, and parity had significant (P < 0.01) effects on birth weight (BWT), weaning weight (WWT), and six month weight (6MWT). With the exception of parity, the same factors affected yearling weight (YWT). Male lambs were heavier by 0.14, 1.1, 1.9, and 4.2 kg than females in BWT, WWT, 6MWT, and YWT. Single born lambs were heavier by about 0.5 kg than multiple born lambs at birth. Lambs born from primiparous ewes were lighter by 0.2 0.3 kg than lambs born from multiparous ewes at birth. With the exception of effect of type of birth and ewe age on survival to 3 and 7 days of age, respectively, year of birth, ewe (dam) age, type of birth, and BWT had significant (P < 0.01) effect on survival from three days to one year of age. The survival of multiple-born lambs was 0.8, 3.7, 8.3, 12.2, and 12.496 lower than single-born lambs at the age of 3, 30, 90, 180, and 365 days, respectively. Lambs born from primiparous ewes had lower survival rates compared to those born from multiparous ewes. Survival was very low in lambs with low BWT and improved with increase in BWT. In general, there are indications that there exists a critical BWT (about 2.6 kg) below which the survival of lambs declines drastically.
Show more [+] Less [-]Survival, growth and reproductive performance in F1 crossbred cattle produced and managed on station in the Gambia
2004
Diack, A. | Sanyang, F.B | Corr, N.
In a trial whereby a large number of cows were needed to calve at approximately the same time, opportunity was taken to establish a crossbred cow population at the International Trypanotolerance (ITC). A slight improvement in the traditional husbandry system revealed a great productivity potential of these crossbreds. Their survival rate to one year (i.e., 90.0%for the Jersey X N’Dama (J X N) and 71.2% for the Friesian X N’Dama was proved satisfactory in the local environment, though conclusions are that more attention is needed for rearing Friesian type F1 calves in the tropical environment. With an overall mean birth weight of 17.7±4.1 kg and an overall mean daily weight gain (DWG) of 0.220±0.104 kg they attained an average weight of 100.6±29.9 kg at one year. Their relatively retarded growth recommended a better management. Puberty was attained at 478.2±13.9 days, age at first calving 970.5±94.1 days and the overall mean calving interval and open period were 400±82.5 and 117±83.2 days, respectively.
Show more [+] Less [-]Growth of Fagus sylvatica in young mixed stand: case study in central Latvia
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.
Show more [+] Less [-]Genetic differences in needle cast damage of Scots pine (Pinus sylvestris L.)
2016
Polmanis, K., Latvian State Forest Research Inst. Silava, Salaspils (Latvia);Latvia Univ. of Agriculture, Jelgava (Latvia) | Klavina, D., Latvian State Forest Research Inst. Silava, Salaspils (Latvia) | Gaitnieks, T., 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)
The impact of climatic and genetic factors on needle cast damage, as well as relationship between the degree of damage and survival and growth of trees was evaluated in the study. The analysis was done in two series of experiments, both established in two locations in Latvia (central and eastern part). Needle cast damage (in 5 grade scale) as well as the height and height increment, diameter of root collar and survival of trees were assessed. Results suggest that the degree of needle cast damage was influenced by the genetic, as well as climatic factors, and also their interaction. The average degree of needle cast damage in experiment of open-pollinated families was 4.7 ± 0.01 in central and 4.6 ± 0.03 in eastern Latvia; in the experiment of control-crossed families it was 4.6 ± 0.02 in central and 3.4 ± 0.04 in eastern Latvia. The impact of genetics on the needle cast damage degree was statistically significant (p is less than 0.05), and this effect was observed when any of growth traits (diameter, height or height increment) was used as a covariate in analysis. Results suggest the potential to select more resistant families, since the genetic correlation of grade of the damage between locations was significant (r = 0.40 - 0.72) and therefore improve also the growth of trees, since the grade of the damage had a negative correlation with growth traits both at provenance and family mean level (r = -0.69 and r = -0.42; p is less than 0.01).
Show more [+] Less [-]Influence of altered precipitation regime on morphology of saplings of Scots pine and silver birch
2016
Krisans, O., Latvian State Forest Research Inst. Silava, Salaspils (Latvia) | Kalnins, J., Latvian State Forest Research Inst. Silava, Salaspils (Latvia) | Purins, M., Latvian State Forest Research Inst. Silava, Salaspils (Latvia) | Kapostins, R., Latvian State Forest Research Inst. Silava, Salaspils (Latvia) | Jansons, A., Latvian State Forest Research Inst. Silava, Salaspils (Latvia)
Prolonged summer drought periods are forecasted for the Baltic Sea region during the 21st century, thus increasing the risk of drought stress of saplings used in forest regeneration. Nevertheless, the vitality of young stands might be increased by the selection of suitable planting material. The aim of this study was to estimate the effect of changes in distribution of summer precipitation on height increment, biomass distribution and root morphology of Scots pine and silver birch planting material commonly used in the forest regeneration in Latvia. Containerized pine and bare rooted birch saplings, planted in three different soil types, were subjected to altered distribution of summer precipitation, provided by the use of automated shelter. Sheltered saplings were weekly irrigated with the sum of precipitation of a corresponding period, while afield planted saplings had an unchanged precipitation regime and served as control. Height increment was measured once per week and estimation of morphology of saplings was done after the end of every vegetation season. Significant (p is less than 0.05) differences in height increment, and shoot and root biomass were observed among the same planting material in different irrigation regimes and soil types. In the control plots of peat soil, pine had a significantly (p is less than 0.05) larger height increment while birch-significantly (p is less than 0.05) smaller compared to experiment. Forecasted longer drought periods might reduce the growth of Scots pine in fertile forest types but silver birch growth might be affected in fertile mineral soils in future.
Show more [+] Less [-]Climate suitability effect on tree growth and survival for Scots pine provenances in Latvia
2014
Rieksts-Riekstins, J., Latvian State Forest Research Inst. Silava, Salaspils (Latvia) | Jansons, A., Latvian State Forest Research Inst. Silava, Salaspils (Latvia) | Smilga, J., Forest Sector Competence Centre, SIA, Riga (Latvia) - MNKC | Baumanis, I., Forest Sector Competence Centre, SIA, Riga (Latvia) - MNKC | Ray, D., Forest Research, Roslin, Midlothian, Scotland (United Kingdom). Northern Research Station | Connolly, T., Forest Research, Roslin, Midlothian, Scotland (United Kingdom). Northern Research Station
Climate in Latvia has been changing in last decades, and it is predicted to continue changing; therefore, it is important for forestry sector to understand how these climatic changes might affect tree growth and survival. In order to assess climate suitability effect on Scots pine (Pinus sylvestris L.) provenances in Latvia, height and survival data from a Scots pine provenance trial located in three geographically distant places in Latvia were analysed together with several climatic indices. Provenances in the corresponding trial originated from Latvia, Poland, Germany, Belarus, Russia and Ukraine. Thirty year average climate data values from 1961 – 1990 for the 64 origins of provenances were acquired from the WorldClim project. Correlation analysis between provenance average values for height and survival and climate index values for the origins of the provenances confirm that there is a relation between these amounts, and the relation differs between the three site locations, indicating that suitability of climate is an important factor affecting the results of provenance trials. Cluster analysis confirmed that provenances from distant origins might have a very similar growth and survival rates; therefore, geographical location of the provenance origins cannot be considered as the only influential factor on these rates and the results from provenance trials have to be analysed together with climate data in order to make conclusions about the suitability of the provenances.
Show more [+] Less [-]Influence of sowing type, time and rate on the buckwheat yield forming elements
2012
Vilcans, M., Latvia Univ. of Agriculture, Jelgava (Latvia);Latvian Plant Protection Research Centre, Riga (Latvia) | Volkova, J., Latvian Plant Protection Research Centre, Riga (Latvia) | Gaile, Z., Latvia Univ. of Agriculture, Jelgava (Latvia)
There is a lack of an actual information concerning cultivation of buckwheat (Fagopyrum esculentum), on the best methods of sowing and seeding rates. The aim of the study was to investigate changes in the buckwheat yield forming elements depending on sowing type, time and rate. Trials were established in farm “Araji”, Kraslava area, during 2010. Previous crop was spring barley. Buckwheat cultivar ‘Aiva’ was used in the field trial. Sowing was done on six different dates – May 15, 20, 25 and 30, and June 4 and 9. Two different types of sowing were used – drill sowing, with 4 sowing rates 200, 300, 400, 500 fertile nutlets per 1 m2, and the column sowing with the three sowing rates 150, 250, 300 fertile nutlets per m2. Data analyses were run using MS Excel Two factor analyses of variance. Time of sowing and seed rate had a significant influence on the buckwheat yield forming elements. Evaluating the performance of plant density at column sowing, it was found that plants survival rate was higher than that in drill sowing. The highest individual productivity of the plant was observed in plots sown in columns. The yield of buckwheat was on average 30-50% higher in the plots that were sown from June 4th to 9th if compared to those sown from May 15th to 20th, i.e. earlier sowing times were not the most suitable for buckwheat sowing in 2010.
Show more [+] Less [-]The survival of Listeria monocytogenes in cold-smoked sausages with and without starter culture
2012
Silins, I., Latvia Univ. of Agriculture, Jelgava (Latvia)
The survival of inoculated in a cold-smoked sausages Listeria monocytogenes wild strains was studied. The sausages were prepared with and without starter cultures. The survival limits of L. monocytogenes and lactic acid bacteria (LAB) were determined as colony forming units per gram (cfu gE-1) depending on water activity (aw) and pH on 0, 1st, 3rd, 5th, 7th, 14th and 21st days of maturation. The decreasing water activity conditioned by moisture (weight) loss during ripening and pH decrease ensured negative polynomial growth rate of inoculated L. monocytogenes - 0.27 lg (cfu gE-1) each day of ripening time, and - 0.65 lg (cfu gE-1) on the first 7 days of maturation. A significant Pearson’s correlation (p is less than 0.01) was established between decreased values of L. monocytogenes count, aw, salt concentration and LAB growth in sausages during the ripening period of 21 days. The main parameters, maintained negative exponential growth rate of L. monocytogenes in cold smoked sausages, are aw value decrease and LAB (starter culture), which stopped L. monocytogenes growth at the beginning of cold-smoked sausage maturation. If fermentation process went technically and hygienically correctly, the fermented (cold-smoked) sausages could be one of the safest meat products, because in real practice a low level contamination has been seen. The remaining count of L. monocytogenes in cold-smoked sausage depends on the possible initial contamination level and could exceed the European Union regulation value 2.0 lg (cfu gE-1) for ready-to-eat products when contamination at first is more than lg 5.0.
Show more [+] Less [-]Evaluation of forest regeneration results after stump extraction in Joint stock company ''Latvian State Forests''
2012
Zimelis, A., Latvia Univ. of Agriculture, Jelgava (Latvia);Latvian State Forest Research Inst. Silava, Salaspils (Latvia) | Lazdans, V., Latvian State Forest Research Inst. Silava, Salaspils (Latvia) | Lazdina, D., Latvian State Forest Research Inst. Silava, Salaspils (Latvia)
With the increase in demand for renewable energy resources, new studies are carried out about under - utilized resources, namely, stumps. To begin to use stumps in industrial application, it is necessary to find out stump extraction influence on the environment, biodiversity, forest regeneration and other important factors. In Zemgale forestry, Misas and Klīves forest districts managed by Joint stock company “Latvian State Forests” (LSF) study on stump extraction in woodlands where clear-cuttings done in 2006 was carried out in the block No. 177, compartments No. 1 and 5, as well as the block No. 176, compartments No. 3 and 9. In these territories two research objects were made where in November-December 2007 stump extraction as well as soil preparation were performed. Main tasks of the project were to evaluate the results of forest natural seeding and coppice ingrowths in natural regeneration areas and evaluate the use of different methods for artificial reforestation with spruce and pine containerized seedlings. It was observed that more seedlings were cut off in the areas where soil scarification with stump extractor was performed if compared to areas prepared with a disc trencher.
Show more [+] Less [-]Clinical outcome of cutaneous mast cell tumors in dogs
2014
Kokorevica, L., Latvia Univ. of Agriculture, Jelgava (Latvia) | Matise-Van Houtana, I., Latvia Univ. of Agriculture, Jelgava (Latvia)
A prospective study was performed on 15 client-owned dogs to assess the clinical outcome after surgical excision of canine cutaneous mast cell tumors (MCTs) depending on histologic grade and completeness of surgical margins. The surgical margins were evaluated as complete, close or incomplete if they were more than 3 mm, from 1 to 3 mm or less than 1 mm wide, respectively. Survival time for dogs with low grade MCT (based on grading by M. Kiupel et al.) was 409 days compared with only 60 days for dogs with high grade tumor. Dogs with high grade tumors had significantly shorter survival time and worse prognosis than dogs with low grade tumors (p=0.013). Complete excision was associated with lower possibility and longer time to tumor recurrence, as well as longer survival, however, marginal surgical border status did not have a significant impact on time to tumor recurrence and survival. It was also found that tumor duration but not tumor size had a significant impact on surgical margin status (p=0.047). Tumor size significantly affected survival time with larger tumors being correlated with shorter survival (p=0.03). The results of our study suggest that grade, tumor size and recurrence are significant factors for MCT prognostication.
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