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Even with the many advances made in the understanding of the pathophysiology, new treatments and preventative measures, laminitis continues to plague the equine population. Identification of risk factor and at-risk individuals remains the best approach with this disease. 相似文献
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Ying Zhi Gao Shi Ping Wang Xing Guo Han Quan Sheng Chen Zhi Yong Zhou Bob Dale Patton 《植物养料与土壤学杂志》2007,170(1):115-122
Two species, Artemisia frigida Willd. (C3, semishrub, and dominant on overgrazed sites) and Cleistogenes squarrosa (Trin.) Keng (C4, perennial bunchgrass, and dominant or codominant on moderately grazed sites) were studied to determine the effects of defoliation, nitrogen (N) availability, competition, and their interactions on growth, biomass, and N allocation in a greenhouse experiment. The main treatments were: two nitrogen levels (N0 = 0 mg N pot–1, N1 = 60 mg N pot–1), two defoliation intensities (removing 60% of total aboveground biomass and no defoliation), and three competitive replacement series (monocultures of each species and mixtures at 0.5:0.5). Our results were inconsistent with our hypothesis on the adaptive mechanisms of A. frigida regarding the interactive effects of herbivory, N, and competition in determining its dominant position on overgrazed sites. Cleistogenes squarrosa will be replaced by A. frigida on overgrazed sites, although C. squarrosa had higher tolerance to defoliation than did A. frigida. Total biomass and N yield and 15N recovery of C. squarrosa in mixed culture were consistently lower than in monocultures, whereas those of A. frigida grown in mixtures were consistently higher than in monocultures, suggesting higher competitive ability of A. frigida. Our results suggest that interspecific competitive ability may be of equal or greater importance than herbivory tolerance in determining herbivore‐induced species replacement in semi‐arid Inner Mongolian steppe. In addition, the dominance of A. frigida on overgrazed sites has been attributed to its ability to shift plant‐plant interactions through gap colonization, root niche differentiation, and higher resistance to water stress. 相似文献
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Testosterone concentration in the seminal plasma of cocks 总被引:1,自引:0,他引:1
Testosterone concentrations in the seminal plasma of cocks ranged from 0.46 to 5.05 ng/ml and were substantially lower than in blood plasma. No significant variation was noted in seminal plasma testosterone concentrations during the light phase of the day, whereas the concentration in blood declined over this period. Spermatozoal concentration and seminal testosterone decreased in the third sample of the semen collected sequentially at 3 h intervals. Testosterone concentrations in seminal plasma (1.57 +/- 0.17 ng/ml) and in the semen from the ductus deferens (1.34 +/- 0.24 ng/ml) were not significantly different. 相似文献
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Testosterone concentrations in the semen plasma of the cocks of the laying type were analyzed. The levels in semen plasma were substantially lower than in peripheral blood and were found at the interval of 1.58 to 13.30 nmol . 1(-1), the average values amounted to 5.5 nmol . 1(-1). At the repeated samplings of the same animals, considerable variability of hormone levels was observed, which suggested a possibility of the pulsation character of the changes in the androgen also in this biological material. The correlation coefficients between the testosterone levels in semen plasma and ejaculate volume, as well as between the sperm concentration were positive, however, statistically insignificant. The relation between testosterone and the weight of testes was at the significance limit. 相似文献