Sirvi Autor "Kairisa, D." järgi
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Kirje Comparison of sire rams of the Latvian Dark-Head breed according to feed efficiency indicators as the beginning of genomic breeding research(Estonian University of Life Sciences, 2023) Trapina, I.; Kairisa, D.; Paramonova, N.In sheep (Ovis aries) farming, feed costs are the largest variable cost component. Breeders are showing an increased interest in breeding sire rams with improved feed efficiency characteristics because of the possibility that the offspring will have a higher value of this indicator. The result shows that for one ram, the progeny indicators tend to be variable. Currently, no marker has successfully explained enough of the variability of feed efficiency that they were used as part of a routine improvement program. The aim is to analyze feed efficiency indicators for lambs of sire rams of Latvian Dark-Head (LT; Latvijas tumšgalve) to identify sire rams producing lambs with potentially higher feed efficiency. Fattening data of 48 lambs from 13 sire rams were analyzed to determine the correlation of feed efficiency parameters. The average weight of lambs at birth was 4.08 ± 0.56 kg, while the average weight gain reached 47.43 ± 3.17 kg with an average fattening period of 73.27 ± 8.90 days. A strong and very strong correlation between the studied indicators of feed efficiency was revealed. The correlation between these indicators and live weight gain over for 60 days indicates their economic importance in meat production. Certain phenotypic and genotypic factors cause the influence on their value. The phenotypic influence may consist of environmental and external signs, but the genotypic influence is at the DNA level, which requires further study.Kirje Efficiency of the use of field beans in fattening lambs(2018) Kairisa, D.; Aplocina, E.The breeding and feeding of self produced pulses to livestock is one of the important directions of research for reducing the production costs of livestock products. Experiment on the effective using of the field beans to lambs for fattening was arranged in three replications using the Latvian Da rk - headed breed male lambs. The mixture of concentrated feed consisted of 50% of bean and 50% of oat. Lambs were weighed at the starting and ending of the trial. Carcass quality was assessed according to the European standard for the classification of carc asses of sheep. The fattening period lasted from 37 to 94 days, on average 63 ± 3.6 days. The average live weight gain per day was 247.4 ± 13.85 g, and live weight increased on average by 15.3 ± 0.94 kg. Significantly higher ( P < 0.05) growth rate during fattening period reached lambs of 3rd group, where lambs started fattening above 27 kg of live weight, reaching a 276.8 ± 26.26 g daily live weight gain. The quality of the obtained carcasses was an average, and score for musculatu re was from R to O class, but the average score for fat deposition was from 3 to 4 points. The mixture of field beans and oats provided 19.3% of crude protein and 12.1 MJ of metabolizable energy per 1kg of dry matter, and its unlimited feeding provided med ium lamb's growth rate. The level of feed conversion was 7.56 kg of dry matter .Kirje Feed efficiency indicators and hormones related to nutrient metabolism in intensive fattened lambs of sire rams of different sheep breeds in Latvia(Estonian University of Life Sciences, 2023) Trapina, I.; Kairisa, D.; Paramonova, N.The feed efficiency increase of each sheep indicates its profitability. Production costs and the environmental impact of animal husbandry are reduced as feed efficiency improves. The gastrointestinal tract is a source of hormones and is important in regulating feed intake and nutrient utilization. The study analyses the relationship between feed efficiency indicators and hormone levels in Latvian sheep breeds. After control fattening, blood samples were taken from 76 lambs, representatives of six Latvian breeds, for seven hormonal analyzes and seven feed efficiency indicators. Feed efficiency, Feed conversion ratio (FCR), Relative growth rate, Kleiber ratio (KR), Residual feed intake (RFI), Residual weight gain, and Residual intake were calculated from daily weight gain and amount of dry matter. Interbreed differences and relationships between indicators/hormones were identified. The best scores of feed efficiency were found for the lamb rams of the Dorper breed; the Latvian black-head was the second according to these indicators. The mean FRC for lambs was determined to be 5.13 ± 0.13 kg with a range of 2.98–10.15 kg; the mean KR was 18.11 ± 0.39 with a range of 8.78–26.88; the mean RFI was in the range of -0.51 to 0.42 kg. A statistically significant difference was found between the breeds for all feed efficiency indicators. Biochemical parameters (IGF-1, insulin, and glucose) were found to be in correlation with feed efficiency indicators. Our results show that Latvian sheep breeds differ in fattening performance. To improve breeds without crossing them, subsequent genetic analysis of breed differences is necessary.Kirje IGF1 and IGF2 gene polymorphisms are associated with the feed efficiency of fattened lambs in Latvian sheep breads(Estonian University of Life Sciences, 2024) Trapina, I.; Plavina, S.; Krasņevska, N.; Paramonovs, J.; Kairisa, D.; Paramonova, N.Feed efficiency is an economically important indicator in sheep farming. The most effective technology for selecting the best feed-efficient lambs for breeding is marker association selection of genetic variations in the sheep genome as potential biomarkers. In tissue growth and differentiation, insulin-like growth factors (IGFs) play a major role: IGF1 mediates the effects of growth hormone, and IGF2 is a growth regulator, regulating skeletal muscle growth. The study aims to find possible molecular markers for feed efficiency indicators in IGF1 and IGF2 genes for Latvian sheep breeds. The exonic regions of the IGF1 and IGF2 genes were sequenced for the first time in the genomic DNA of 76 controlled, intensively fattened lambs, to search for possible genetic biomarkers. Seven polymorphic loci in the IGF1 gene and sixteen in the IGF2 gene were detected. Statistically significant associations of the IGF1 SNP rs600896367 were found with residual indicators: Residual feed intake, Residual weight gain (RWG), and Residual intake and body weight gain (RIG), and with feed efficiency and feed conversion ratio in the overall group of samples. Additionally, IGF2 SNPs New_7 and rs429576107 exhibited associations with RWG and RIG specifically in the Latvian dark-head sheep group. On average, effect of the IGF1 SNP on associated feed efficiency residuals is 3.9%, with the most pronounced impact observed in RFI. In contrast, the influence of IGF2 SNPs is comparatively lower. Our results indicate that rs600896367 and New7/rs429576107 are potential molecular markers for marker-assisted selection in sheep breeding for residual feed efficiency indicators.Kirje MSTN gene polymorphisms are associated with the feed efficiency of fattened lambs in Latvian sheep breeds(Estonian University of Life Sciences, 2024) Trapina, I.; Plavina, S.; Krasņevska, N.; Paramonovs, J.; Kairisa, D.; Paramonova, N.The economic benefit for sheep farmers depends on the level of feed efficiency of the lambs raised. Promoting breed selection for feed efficiency could provide sheep farmers with higher quality and more economically profitable lambs. In livestock production, marker-assisted selection employs genetic biomarkers linked to specific traits. Myostatin (MSTN), a vital transforming growth factor-beta superfamily member, is pivotal in regulating myogenesis and negatively impacts mammal muscle growth and development. The study aims to find molecular markers related to feed efficiency parameters in the MSTN gene for Latvian sheep breeds. DNA extraction was made from blood collected from 76 controlled fatten lambs, with 63.16% belonging to the Latvian Dark-head (LT) breed. A complete gene sequencing analysis was conducted to identify variations in loci across different sheep breeds, aiming to discover statistically significant associations between identified polymorphisms and feed efficiency indicators. Polymorphic variants were identified in 23 loci of the MSTN gene among Latvian lambs, with the discovery of a novel SNP. Notably, SNP rs404916326 T>A exhibited statistically significant associations with indicators such as Residual feed intake, Residual intake, and body weight gain, specifically in the LT breed. Furthermore, SNP rs408469734 G>A showed associations with relative growth rate and Kleiber's ratio within the lamb group. These findings suggest that SNPs rs404916326 and rs408469734 within the MSTN gene are promising molecular markers for marker-assisted selection strategies in sheep breeding to improve feed efficiency indicators.Kirje Trends in milk yield productivity and emissions from the dairy sector in Latvia(Estonian University of Life Sciences, 2023) Paura, L.; Berzina, L.; Degola, L.; Aplocina, E.; Kairisa, D.; Jonkus, D.; Skiste, O.Dairy cow productivity continuously increased in Latvia in recent years. Despite decreasing numbers of dairy cow population dairy farms have been identified as an important source of greenhouse gas (GHG) emissions. Dairy sector emissions create the largest share of enteric fermentation emissions as well as emissions from manure in housing facilities, during long-term storage and field application within agriculture sector total emissions. The main objective of this study is to present the results of trend analysis in the productivity of the dairy sector and corresponding emission in Latvia. Research is focused on analysis of dairy cow productivity and feeding strategies to quantify the effect of increasing milk yield on GHG emissions. In the framework of this research, emissions were calculated and evaluated for low and high productivity dairy cows according to the methodology of ‘2019 Refinement to the 2006 Guidelines for National Greenhouse Gas Inventories’. During the last decade dairy cow productivity in Latvia has increased and the average milk yield in standard lactation was 8,320 kg per year in 2021. It was observed that 60% of the total number of dairy cows met the requirements of a high-productivity system, while 40% of the dairy cows belonged to low-productivity systems in Latvia. Research results show that total GHG emissions for high-productivity system can reach 5.3 kt CO2 eq. per 1,000 cows per year, however, for low-productivity system the total amount of emissions does not exceed 3.1 kt CO2 eq. per 1,000 cows.