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Silvopastoral systems offer an alternative to the conventional cow-calf segment of the beef industry in the Midwestern region of the United States. Little information exists for transitioning from a conventional pasture-based beef operation to a silvopastoral system utilizing multiple deciduous tree species. Nine pastures approximately 1 ha in size were established with a mixture of cool-season grasses and legumes to investigate tree protection methods and cattle performance. Four tree species (Juglans nigra, Gleditsia triacanthos, Quercus rubra, & Carya illinoensis) were planted within six of these pastures. Three methods of protection were tested, and included a no protection control (Con), foliar application of 0.20% denatonium benzoate (TreeGuard™), or a single strand of electrified poly-wire (EF) in each of the two grazing years. Cattle damage to young trees was prominent during the two years for Con and TreeGuard™. EF offered acceptable protection. Red oak trees suffered the highest degree of damage from livestock. Establishing trees within grazed pastures did not hinder performance of beef cattle. Transitioning from conventional pastures to silvopastures can be accelerated utilizing an electrified fencing system to prevent cattle damage. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   
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This study evaluated the efficiency of taper functions and the application of mixed-effect modelling for diameter estimation along the stems of Tectona grandis. We sampled 266 trees of Tectona grandis, measuring the diameter at relative heights for volume determination, grouping the data according to three form-factor classes. Six taper functions were fitted, selecting the function with better fit performance. Six taper functions were fitted, selecting the function with better fit performance. The selected function was fitted in its basic formulation, and with the mixed non-linear modelling technique in different scenarios, and for the stem stratified in three portions of the total height. The precision and selection of the adjusted models were evaluated regarding the coefficient of determination, standard error of estimate, the Akaike information criterion, bias, quadratic error and absolute bias. According to the statistical criteria used, the model of Kozak was selected for the adjustments. For diameter estimation, the scenario with two coefficients as random effects provided an accuracy increase of 11.91%, and the mixed non-linear modelling better estimated the stem diameter for the stratified stems. In conclusion, the model of Kozak can be used to describe the stem shape of Tectona grandis, and the mixed-effect non-linear model approach was the best technique to estimate diameter along the stem of Tectona grandis.  相似文献   
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Environmental variation can shape phenotypic variation in organisms, but most evidence for trait differentiation comes from analyses of dichotomous habitat types that differ in only one or few key environmental factors. In reality, environmental variation is often more subtle, gradual and multifarious. Here, we investigated geographic variation in body shape of two darter species (Etheostoma spectabile and Etheostoma flabellare; Percidae) that occur along river gradients. This study addressed three specific questions: Is there intraspecific geographic variation in the two species across different sites in the Ozark Highlands of Oklahoma (USA)? Is phenotypic variation across sites correlated with abiotic environmental conditions? Do the two species share site‐specific (i.e. convergent) phenotypic variation in areas where they occur together? Our results indicated significant body shape variation in both species. Population differences in body shape were particularly correlated with variation in substrate composition. The combined analysis of both species indicated a small but significant effect of convergence on body shape wherever they are sympatric; shared variation, however, was not related to any environmental variables included in the analysis. While it remains unclear whether phenotypic variation in these species is due to heritable differentiation or environmentally induced plasticity, our results indicate that even subtle and gradual environmental variation can induce substantial variation in phenotypes on a relatively small spatial scale.  相似文献   
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Expression of the GH receptor (GHR) gene and its binding with GH is essential for growth and fat metabolism. A GT microsatellite exists in the promoter of bovine GHR segregating short (11 bp) and long (16 to 20 bp) allele sequences. To detect SNP and complete an association study of genotype to phenotype, we resequenced a 1,195-bp fragment of DNA including the GT microsatellite and exon 1A. Resequencing was completed in 48 familialy unrelated Holstein, Jersey, Brown Swiss, Simmental, Angus, Brahman, and Brangus cattle. Nine SNP were identified. Phylogeny analyses revealed minor distance (i.e., <5%) in DNA sequence among the 5 Bos taurus breeds; however, sequence from Brahman cattle averaged 27.4 +/- 0.07% divergence from the Bos taurus breeds, whereas divergence of Brangus was intermediate. An association study of genotype to phenotype was completed with data from growing Brangus bulls (n = 553 from 96 sires) and data from 4 of the SNP flanking the GT microsatellite. These SNP were found to be in Hardy-Weinberg equilibrium and in phase based on linkage disequilibrium analyses (r(2) = 0.84 and D'= 0.92). An A/G tag SNP was identified (ss86273136) and was located in exon 1A, which began 88 bp downstream from the GT microsatellite. Minor allele frequency of the tag SNP was greater than 10%, and Mendelian segregation was verified in 3 generation pedigrees. The A allele was derived from Brahman, and the G allele was derived from Angus. This tag SNP genotype was a significant effect in analyses of rib fat data collected with ultrasound when bulls were ~365 d of age. Specifically, bulls of the GG genotype had 6.1% more (P = 0.0204) rib fat than bulls of the AA and AG genotypes, respectively. Tag SNP (ss86273136), located in the promoter of GHR, appears to be associated with a measure of corporal fat in Bos taurus x Bos indicus composite cattle.  相似文献   
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The vascular cell adhesion molecule 1 (VCAM1) has a strong influence on embryonic development and on the formation of the umbilical cord and placenta. These developmental processes are crucial to ensure the success of pregnancy. In this work, we have identified two T306A and C558T single nucleotide polymorphisms (SNP) at exons 2 and 3 of the pig VCAM1 locus, respectively. The T306A substitution involves a non conservative Asn to Lys replacement at amino acid position 102, whereas the C558T polymorphism is synonymous. An in silico prediction of the consequences of the Asn102→Lys102 mutation with the PolyPhen software revealed that it is not deleterious. The T306A SNP segregated in the Iberian, Piétrain, Duroc, Large White and Landrace breeds as well as in European wild boars. The C558T SNP also segregated and most of commercial standard breeds. The genotyping of the C558T SNP in an Iberian × Meishan intercross allowed to find a suggestive association (Bonferroni threshold, p < 0.004) between C558T genotype and time the newborn piglet needs to reach the udder (p = 0.013) as well as a significant one with time to make the first ingestion of colostrum (p = 0.003). The biological basis of these associations remains unclear and they should be interpreted with caution.  相似文献   
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AIMS: To establish the incidence, frequency and type of deliberate animal abuse seen in veterinary practice in New Zealand, and ascertain veterinarians' knowledge of human abuse within the families where animal abuse was occurring. To explore attitudes of veterinarians to and knowledge about the correlation between animal abuse and human violence, and their perceived role in dealing with such issues. METHODS: A postal questionnaire was sent to practising veterinarians in New Zealand. It covered demographics, frequency and type of animal abuse cases seen, awareness of violence towards humans, within families where animal abuse was seen, the methods used for managing animal and human abuse, the incidence of psychological abuse of animals, and the attitudes of veterinarians towards and their beliefs about the link between animal abuse and human violence. RESULTS: A total of 383/1,412 (27% response rate) questionnaires with useable data were returned. Within the group of respondents, the sexes were evenly represented; 40% of respondents worked in small-animal practice, 50% in mixed practice and 10% in large-animal practice. Deliberate animal abuse had been seen by 63% of respondents in the last 5 years; 37% of these had seen such cases once a year or less, while 9% had seen abuse cases at least four times a year. Dogs were the species most commonly reported as abused, followed, in numerical order, by cats, cattle and horses. Among respondents who had seen deliberate animal abuse, 16% either knew of (4%) or suspected (12%) human abuse within the families of the abused animals. A clear majority of responding veterinarians agreed with the statement that people who abuse their animals are more likely to abuse their children (77%) or spouse (70%). CONCLUSIONS: The survey indicated that the majority of respondents had seen cases of animal abuse within the previous 5 years, and dogs were the species most often reported abused. Responding veterinarians felt a strong ethical duty to deal with cases of animal abuse, but they were less comfortable about issues of human abuse, even though the awareness of the link between abuse of animals and abuse of humans was relatively high. CLINICAL RELEVANCE: The greater the awareness of animal abuse and its linkage with human abuse, the greater the possibility that veterinarians can contribute in a meaningful way to the reduction of violence in society.  相似文献   
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