Absorption,distribution and residue evaluation of active substances used as feed additives

Summary

Administration of feed additives is based on the necessity of satisfying a need in human nutrition. Oral feed additive intake results in an equilibration level which is followed by a steady state after absorption. The equilibrium point of the blood (tissue) level can be calculated mathematically. 70 Per cent of the plateau of the steady state is reached within four times the half‐life.

Some compounds give rise to an ‘initial peak’ with higher concentrations than the expected plateau level (phase of adaptation). For residue evaluation these effects have to be considered. The relevance of different metabolic processes and the impact on a traditional monofactorial evaluation, neglecting the incidence of combination, is mentioned. Commonly used residue assessment is discussed and the safety margin of a toxicological threshold elucidated.     

Relationships between workplace well-being,job demands and resources in a sample of veterinary nurses in New Zealand

AIM: To use a job demands-resources model to examine the associations among perceived job demands, job resources, family-to-work enrichment, positive team relationships, work engagement, emotional exhaustion, cynicism and intention to leave, in a sample of New Zealand veterinary nurses.

METHODS: Data were collected by means of a self-reported online survey, with the help of eight New Zealand tertiary education providers and the New Zealand Veterinary Nurses’ Association. Nine measures or variables were assessed using questions or statements with responses categorised on a linear scale. Measurement models for each of the variables in the study were assessed to establish whether the variables represented the respective item-level data. Structural equation modelling was then used to test the hypothesised interrelationships among study variables.

RESULTS: There were 253 respondents; 17.1% of individuals who classified themselves as veterinary nurses in the 2013 New Zealand census. In the final structural model job demands were associated with emotional exhaustion (standardised regression coefficient β=0.57), which was related to cynicism (β=0.52) and intention to leave (β=0.56). Job resources were negatively related to emotional exhaustion (β=?0.32). Higher work engagement was associated with lower emotional exhaustion (β=?0.29) and lower intention to leave (β=?0.30). Job resources were associated with work-to-family enrichment (β=0.69), which was related to work engagement (β=0.57); and job resources were associated with positive team relationships (β=0.79).

CONCLUSION: It is important that job resources are available to help deal with demanding work. Without resources, demanding work is associated with exhaustion, cynicism and increased intention to leave, while positive spill over between work and family life are related to higher work engagement.     

兽医影像诊断学开展病例讨论教学的问卷调查思考

问卷调查是以提出问题进行资料搜集的一种方法.笔者研究在兽医影像诊断学课程实施病例讨论的教学方法,通过问卷调查的方式,对学生选择选修课的动机和态度、教学方法和效果,以及考核方式进行调查.结果显示:病例讨论的教学方法可以增强学生对知识点的掌握,培养学生应用理论知识进行疾病诊断的思路.该教学方法受到学生广泛的欢迎和认可.