Diets of endangered silver chub (Macrhybopsis storeriana,Kirtland, 1844) in Lake Erie and implications for recovery

Silver chub (Macrhybopsis storeriana, Kirtland, 1844) is a native Cyprinid in Lake Erie, one of the Laurentian Great Lakes of North America. It is listed as endangered by the US state of New York and Canada, which has a recovery plan, and as special concern by the state of Michigan. Silver chub faces a potential threat to recovery from control efforts for invasive Grass carp (Ctenopharyngodon idella, Valenciennes 1844). Among the knowledge gaps for protection and restoration is current diet data. I describe the diet of silver chub from western Lake Erie in 2014, and I compare it to past studies to assess changes in diet through time. Silver chub captured in bottom trawls May–September 2014 were frozen in the field, and stomach contents were preserved in ethanol. Diet taxa were identified to the lowest practical taxonomic unit, then dried and weighed. Frequency of occurrence in silver chub diets was highest for Hexagenia spp. mayflies (79%). Dreissena spp. and Hexagenia spp. were both 41% of the diet by dry weight. Analysis of δ¹³C isotopes identified Hexagenia spp. as the primary source of carbon in silver chub. Compared to past studies, Dreissena spp. have mostly replaced Sphaeriidae and Gastropoda in silver chub diets. There also have been seasonal shifts in relative amounts of shelled organisms and Hexagenia spp. This study and past research suggest a functional link between silver chub and Hexagenia spp. abundance. Maintenance and recovery of silver chub may be dependent on maintaining Hexagenia spp. populations.     

奶牛非饲草来源纤维营养研究进展

本文在总结分析国内外最新研究成果的基础上,对非饲草来源纤维(NFFS)对奶牛的营养作用和生理影响及其机理进行了综述,主要从NFFS部分替代饲草对奶牛生产性能、瘤胃草垫层和瘤胃发酵的影响,以及NFFS部分替代精料对饲料效率、生产性能和亚急性瘤胃酸中毒(SARA)奶牛生理的影响等方面进行论述,旨在为NFFS饲料在奶牛饲粮中的科学合理利用提供理论参考和依据。     

Evaluation of the agreement of two oscillometric blood pressure devices with invasive blood pressure in anaesthetized chimpanzees (Pan troglodytes)

ObjectiveTo evaluate the agreement of two noninvasive blood pressure devices: a human device with the cuff placed on the wrist (Omron R1) and a veterinary device with the cuff placed on the upper brachium (Surgivet Advisor Vital Signs Monitor) with invasive blood pressure (IBP) measurement in anaesthetized chimpanzees.Study designProspective clinical study.AnimalsA convenience sample of 11 adult chimpanzees undergoing anaesthesia for translocation and routine health checks.MethodsSystolic (SAP) and diastolic arterial pressures (DAP) were continuously recorded via a transducer connected to a femoral artery cannula, and at 5 minute intervals from the two oscillometric devices. Agreement was explored using Bland-Altman analysis and bias defined as the mean difference between the two measurement methods. Spearman correlation coefficients were calculated. Significance was set at p < 0.05.ResultsBias and standard deviation for the Surgivet compared with IBP were 8.6 ± 18 for SAP and 8.4 ± 9.9 for DAP, showing a significant underestimation of both variables. Limits of agreement (LOA) were from –27 to 44 for SAP and from –11 to 28 for DAP. Correlation coefficients between the Surgivet and IBP values were 0.86 for SAP and 0.85 for DAP (p < 0.0001). Bias and standard deviation for the Omron compared with the IBP were –21 ± 25 for SAP and –18 ± 15 for DAP, showing a significant overestimation of both variables. LOA were from –70 to –28 for SAP and from –47 to 11 for DAP. Spearman correlation coefficients between the Omron and IBP values were 0.64 for SAP and 0.72 for DAP (p < 0.0001).Conclusions and clinical relevanceAlthough neither device met all the criteria for device validation, the Surgivet presented better agreement with IBP values than the Omron in adult anaesthetized chimpanzees.     

湖南省可再生能源开发现状及对策

描述了湖南省可再生能源开发现状，论述了可再生能源开发在湖南省经济可持续发展战略中的地位及作用，分析了影响开发速度的主要问题和障碍，并提出了加快开发可再生能源的政策、措施和建议。     

In vitro rumen fermentation and digestibility of buffaloes as influenced by grape pomace powder and urea treated rice straw supplementation

This study aimed to investigate the effect of grape pomace powder levels and roughage sources on gas kinetics, digestibility and fermentation of swamp buffaloes by using in vitro techniques. The experimental design was a 2 × 4 factorial arrangement in a completely randomized design. Factor A was two sources of roughage (untreated rice straw, RS, and 3% urea treated rice straw, UTRS) and factor B was four levels of grape pomace powder (GPP) supplementation (0, 2, 4, 6% of substrate) on a dry matter basis. Results revealed that GPP supplementation at 2, 4 and 6% of substrate influenced gas kinetics. Cumulative gas production tended to be lower in the supplemented group. In vitro true digestibility was higher in the GPP supplementation at 2% with UTRS while microbial mass was higher in the supplemented groups. Supplementation of GPP significantly increased the total volatile fatty acids, especially propionate. Calculated methane production was subsequently decreased in the supplemented groups. Bacterial population was higher while protozoal population was lower by GPP supplementation. It could be concluded that supplementation of GPP at 2% of the substrate with UTRS improved in vitro true digestibility, rumen fermentation end‐products as well as reducing methane production.     

Effect of Prosopis (mesquite) invasion and clearing on vegetation cover in semi-arid Nama Karoo rangeland,South Africa

The Nama-Karoo is the largest of the three biomes that comprise the semi-arid Karoo-Namib ecoregion of southern Africa. Large tracts of Nama-Karoo rangeland have been invaded by alien leguminous trees of the genus Prosopis. We assessed the impact of Prosopis invasion and clearing on vegetation cover in heavily grazed Nama-Karoo rangeland on two sheep farms in the Beaufort West district of the Western Cape province of South Africa. Our results suggest that, below critical threshold cover levels, Prosopis trees do not affect indigenous vegetation and add to overall rangeland vegetation cover. However, once Prosopis cover exceeds critical thresholds, the trees begin to negatively impact on indigenous vegetation (especially grasses) and overall vegetation cover. In addition, our data suggest that vegetation cover recovers after Prosopis clearing, being temporarily higher than pre-invasion levels possibly as a result of enhanced post-invasion soil fertility. Lastly, our results suggest that Prosopis trees reduce rangeland erosion potential at low cover and increase it after they exceed critical threshold cover. Information about thresholds of Prosopis impact can be used to direct clearing efforts for maximum benefit when resources are limited.