Threats to at-risk salmonids of the Canadian Rocky Mountain region

Trout and charr, members of the salmonid family, have high conservation value but are also susceptible to anthropogenic threats in part due to the specificity of their habitat requirements. Understanding historical and future threats facing these species is necessary to promote their recovery. Of freshwater trout and charr in the Canadian Rocky Mountain region, westslope cutthroat trout (Oncorhynchus clarkii lewisi), bull trout (Salvelinus confluentus; a charr species) and Athabasca rainbow trout (Oncorhynchus mykiss) are of conservation concern. And indeed, range contractions and declining populations are evident throughout much of their ranges. Range contraction was most evident in the southern Alberta designatable unit (DU) of westslope cutthroat trout. Diminished populations were also evident in the downstream watersheds of the Alberta bull trout range, and throughout the Athabasca rainbow trout range. We assessed historical and future threats to evaluate the relative importance of individual threats to each DU and compare their impact among species. Individual threats fall into the broad categories of angling, non-native species and genes, habitat loss and alteration, and climate change. Severity of each threat varies by DU and reflects the interaction between species’ biology and the location of the DU. Severity of threats facing each DU has changed over time, reflecting extirpation of native populations, changes in management and industry best practices, expansion of non-native species and progressing climate change. The overall threat impact for each DU indicates a high probability of substantial and continuing declines and calls for immediate action.     

Beaver dams,streamflow complexity,and the distribution of a rare minnow,Lepidomeda copei

Freshwater fishes are threatened globally, and often too little is known about threatened species to effectively guide their conservation. Habitat complexity is linked to fish species diversity and persistence, and degraded streams often lack habitat complexity. Beaver Castor spp., in turn, have been used to restore streams and increase habitat complexity. The northern leatherside chub Lepidomeda copei is a rare, small‐bodied, drift‐feeding minnow that has anecdotally been observed to use complex habitats associated with beaver dams in the western United States. To investigate this anecdote, we conducted fish and habitat surveys, the latter focusing on quantifying habitat complexity, in a sub‐basin of the Upper Snake River Basin in the USA. Complementary generalised linear model and path analyses revealed that northern leatherside chub occurred more often at sites with complex streamflows, and streamflows were more complex when beaver dams were present and pools were deeper. Northern leatherside chubs were also more likely to occur when temperatures were warmer, aquatic macrophytes were abundant and stream channels were narrow and deep. The linkage between chubs, complex streamflows and beaver dams needs to be evaluated more broadly to completely understand its role in the rangewide status of the species. However, it does suggests that increased use of beaver reintroductions and dam analogues for stream restoration could be a boon for the northern leatherside chub, but such efforts should be monitored to determine their effectiveness to help adapt beaver‐based restoration approaches to best benefit the species.     

Fever and associated clinical haematologic and blood biochemical changes in the goat and other animal species

Summary Acute febrile diseases are characterized by specific and non-specific symptoms. The non-specific responses are presented under the headings: fever, inflammation and pain, experimental models for investigating febrile reactions, haematologic changes, blood biochemical changes, cardiovascular effects, changes in gastric function, and the effects of fever upon pharmacokinetics of drugs. It was the purpose of this review to describe present concepts of thermoregulation and fever, the associated reactions produced by bacterial pyrogens and the mechanisms of these reactions. The available data illustrate, that many questions have not yet been clearly answered. However, the entire field of research involving endogenous substances, such as interleukin-1, is now moving ahead with great speed. Furthermore, there is some evidence which suggests that fever and the associated lower plasma zinc and iron levels act together as a co-ordinated non-specific host defence mechanism. Since experimental fever has a distinct effect upon the pharmacokinetics of drugs, more attention should be given to this aspect.     

母体外激素对仔猪断奶后行为的影响

猪嗅觉系统高度发达 ,有多种外激素都能调节猪的行为和生理。外激素是动物分泌的一种化合物 ,它能影响其它动物个体的行为和生理。外激素还传递个体、性别或其它识别模式的信息。还有证据表明 ,母体外激素可调节哺乳仔猪的行为。行为学研究结果表明 ,用溶剂将泌乳母猪皮肤上的气味洗去 ,仔猪就会拒绝哺乳 ,还证明了仔猪会被粪便中或其他生物液体中的母体气味所吸引 ,并且会区分这些物质中的母体气味。Pageat(2 0 0 1)分离到了哺乳动物的皮肤分泌物 ,研制出了与母猪皮肤分泌物成分相类似的脂肪酸混合物。据认为 ,这种混合物中可能含有母体外…     

Effects of low and high calcium intake prepartum on calcium mobilization rate around parturition in dairy cows

Forty-one dairy cows were fed a low (LCa-13 g/d) and a high (HCa-83.5 g/d) calcium ration in the 8 weeks prior to parturition and the effect on the Ca mobilization rate around parturition was studied. Plasma Ca values were stable in the LCa group around parturition. In the older cows of the HCa group a very slight decrease in the mean plasma Ca was observed: 2.58 mmol/l at 12-36 h ante partum decreased to 2.38 mmol/l at parturition. Hypocalcaemia, which commonly occurs around parturition, did not occur in 40 of the cows. A subclinical hypocalcaemia (1.8 mmol/l) occurred in one cow (parity 10) from the HCa group. To assess the efficiency of Ca mobilization, a severe hypocalcaemia (1.0 mmol/l) with clinical signs was induced by means of Na2EDTA infusion (0.90 mmol/min), starting at 10 h post-partum. The older cows in the LCa group required more Na2EDTA than those in the HCa group. Higher urinary hydroxyproline excretion in the week before parturition in the LCa than in the HCa group suggested a higher bone turnover. Plasma PTH levels around parturition were not significantly different between the groups. The amount of colostrum milked out in the first 10 h post-partum did not influence Ca homeostasis around parturition. The results contradict those of many other experiments in which hypocalcaemia was observed in cows ingesting high levels of Ca. It is concluded that the restricted feed intake prepartum possibly had a favourable effect on Ca homeostasis.