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Acorn production is one of the most important products in silvopastoral systems in the Mediterranean region. In the present study we carried out two preliminary trials to analyze the distribution of production over time and the effect of pruning. The objective was to develop tools to manage this valuable resource within these systems. In the first part of the study, we analyzed the total acorn production of a holm oak stand, and its seasonal distribution (October–January) over two years (1997–1998 and 1998–1999) in five sites in the southwest of Spain. Mean total acorn production ranged from 590 to 830 kg ha−1. There was considerable variation between the different sites and years studied, as was expected from studies on other oak species. A comparison was also made of acorn production, comparing annual acorn production between 40 pruned and 40 non-pruned trees, for the period 1994–1999. There was an interaction between ‘pruning treatment’ and ‘year’. Pruning, significantly decreased acorn production in all but two years when production was above the average, whereas production was not affected by pruning the three years that acorn yield was below the average. The study of acorn production and the analysis of the effect of pruning, needs to be studied over a longer time period.  相似文献   
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REASONS FOR PERFORMING STUDY: The assessment of belief that equine conformation is associated with performance and durability is a fundamental concept of horsemanship. Surprisingly, there is almost no quantitative evidence to support these beliefs. OBJECTIVES: To assess the prevalence and heritability of conformational traits in Thoroughbred yearlings, and investigate their significance for subsequent turf flat-racing performance and durability. METHODS: Nine selected conformational traits were assessed in a consistent, qualitative manner by a single veterinary observer and entered into a database together with details of pedigree and racing records. RESULTS: Conformational data were collected from 3916 Thoroughbred yearlings sold at public auction during the 7 year period 1993-1999. Most of the horses (72%) raced in the UK in turf flat races; just 7% of the yearlings failed to race. Prevalence of conformational defects for the UK horses was reported, with turned out feet the most commonly recorded defect (30% of all horses). There was a tendency towards a greater proportion of horses with defects in the group of unraced horses compared with horses that raced, but this was not statistically significant. There were some significant associations between racing performance and conformational defects but these were found to be almost completely explained by an effect of sire. All of the conformational traits showed considerable evidence of genetic influence, with heritability indices ranging 0.16-1.00. CONCLUSIONS AND POTENTIAL RELEVANCE: Overall, there were only weak associations between performance and conformation that could not be accounted for by the very strong relationship between pedigree and conformation. Further study of potential association between highly heritable conformation traits and racing durability and racing performance should be undertaken utilising validated, quantitative methods and technology.  相似文献   
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Objective To document an ovine disease attributed to the consumption of Lythrum hyssopifolia (lesser loosestrife). Procedures Historical and histological review of field and experimental cases. Results 1–20% mortality occurred in sheep flocks grazing paddocks where L. hyssopifolia was the predominant green vegetation. Well‐documented disease outbreaks occurred in summer on nine farms across Victoria between 1974 and 2002. Liver damage occurred in all nine outbreaks, with kidney damage in at least eight. Hepatocyte necrosis was usually zonal to midzonal (zone 2) in the liver samples from four farms and periacinar (zone 3) in those from three farms, but some livers showed only single‐cell necrosis. Multinucleate hepatocytes near necrotic areas were a feature in six cases. Proximal tubular epithelium appeared to be the primary renal target and brown granules were often present in renal tubules. Biochemical and histological evidence of liver and kidney damage was obtained from two sheep experimentally pen‐fed harvested L. hyssopifolia. Conclusion Chemicals in L. hyssopifolia are toxic to ovine hepatocytes and renal tubular epithelial cells.  相似文献   
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Lambs with the G2 allele at the ovine major histocompatibility complex (mhc) class II locus DRB1 has previously been shown to have lower faecal nematode egg counts than lambs with the I allele at this locus. This association has been confirmed in separate cohorts from the same farm. Other alleles within the mhc have also shown associations with nematode resistance in other breeds of sheep. Therefore, variation in the mhc is responsible for part of the observed genetic variation in resistance to nematode infection. In addition to the specific effect of particular alleles, heterozygotes are also more resistant than homozygotes. This heterozygote advantage is capable of maintaining the high levels of polymorphism observed within the mhc.  相似文献   
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Infection of sheep with the abomasal nematode Teladorsagia circumcincta can cause a relative protein deficiency and reduce growth rate in growing lambs. A key event appears to be the destruction of junctions between epithelial cells. If the infection is heavy or prolonged, this leads to increased mucus production, hyperplasia, decreased acid production, gastrinemia, inappetance and pepsinogenemia. The severity of the infection depends upon the extent of concurrent infection, the nutritional status of the host and genetically controlled variation in the ability to mount protective immune responses.  相似文献   
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The improvement of biotechnical methods connected with fast and precise semen quality assessment and its utilization in assisted reproductive techniques is an urgent necessity in felids. The aim of this study was to evaluate some quality parameters (i.e. the viability and share of cells with intact plasma membrane) of epididymal sperm of cats using the flow cytometry method and computer‐assisted sperm analysis (CASA) examination. The material consisted of epididymal spermatozoa flushed from 22 pairs of epididymes after routine neutering procedures obtained from domestic cats aged between 8 and 36 months. The epididymes were cut and incubated with an extender without egg yolk. The samples were assessed for sperm viability (Live/Dead Sperm Viability Kit®), percentage of subtle membrane changes (Apoptosis Detection Kit®) and motility using FACScalibur flow cytometer and assisted sperm analyser htm ivos version 12.2. The flow cytometry method revealed 71.3% and 84.4% of live sperm using Live/Dead Sperm Viability Kit and Apoptosis Detection Kit respectively. The population of early‐apoptotic and late‐apoptotic sperm were 0.8% and 1.1% respectively. The CASA examination found 51.5% of motile sperm. However, the motility examination under light microscope revealed 69.5% of motile sperm. The data revealed an indistinctive per cent of apoptotic cells and 18.9% and 15.6% of dead cells using Live/Dead Sperm Viability Kit and Apoptosis Detection Kit, respectively, which indicate that the sperm obtained after flushing the epididymis possess potential properties for further assisted reproduction techniques.  相似文献   
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