The place of experimental work in laboratories has always assumed a high profile at all levels of chemical education. This paper seeks to review the main strands of evidence available today and argues that the place of experimental work needs to be reconsidered at higher education levels. There is a need for a clarification of aims and objectives, and these need to be communicated to learners. It argues that higher education needs to be acutely aware of what goes on at school and to build on these skills. Pre-laboratory exercises are strongly supported by the evidence, while there needs to be a radical re-thinking of the use of laboratory manuals, with assessment being explored afresh. In addition, seeing the laboratory experience in the context of what goes on before and after, as well as other learning, will enhance the learning potential of this time. Examples of some ways forward are presented. Overall, it is argued that much more could be gained by the students if the laboratory experience, using similar experiments, was radically rethought. [Chem.
Weanling pigs (n = 132) were used to investigate the effects of three common stressors (and a control) and differing social status on behavior, immunity, plasma cortisol, blood chemical, and performance measures. Eleven blocks of 12 pigs each were evaluated. Each pen contained three pigs of dominant (DOM), intermediate (INT), or submissive (SUB) social status. Two weeks later, random pens of pigs experienced either a control treatment (CON) or they were stressed for 4 h by shipping (SHIP), heat-stressed (HEAT) with overhead heat lamps in their home pens, or cold-stressed (COLD) by direct application of water and an air current. Treatments did not influence body weights; however, percentage weight loss during SHIP was greater than for other treatments. Body weights were heavier for DOM pigs than for INT and SUB pigs. Social status had large effects on plasma cortisol, globulin, acute-phase proteins, body weight, and weight changes. Only acute shipping stress resulted in weight loss. Many immune and blood measures were not changed among acutely stressed pigs; however, the relationship between social status and mitogen-induced lymphocyte proliferation and natural killer cell cytotoxicity was disrupted during acute stress. Pig behavior was significantly changed by each stress treatment in a unique manner. During acute stress, behavioral changes seem to be the most consistent and reliable indicators.
Crossbred pigs were used to evaluate the effects of shipping stress on natural killer (NK) cell activity, leukocyte numbers, plasma cortisol, and BW changes. In the first study, pigs were bled at a commercial farm and, after shipping, resident and shipped pigs were bled again. Plasma cortisol concentrations were not different (P > .10) because of large variation in cortisol concentrations. Furthermore, NK cytotoxicity was nondetectable among all pigs. A second study showed that plasma cortisol concentration rose by approximately 2.6 ng/mL (P = .018) for each minute after pigs were aroused. In the third, more controlled study, pigs were housed in pens of three pigs each. Video recordings were made during the first 24 h pigs were grouped to identify socially dominant, intermediate, and submissive pigs. At time zero (before shipping), resident pigs and those to be shipped had similar plasma cortisol concentrations. However, after the 4-h shipping experience, shipped pigs had elevated (P < .05) plasma cortisol compared with resident control pigs. Shipped pigs lost 5.1% of their BW (P < .05) compared with resident pigs, which gained .02% of their BW. Body weight change during shipping and plasma cortisol were negatively correlated (r = -.34, P = .04), indicating pigs that had greater adrenal response to shipping also lost more weight during shipping. Shipping reduced (P < .05) NK cytotoxicity among pigs of intermediate and submissive social status compared with shipped, dominant pigs. At the end of shipping or control treatments, the correlation between NK cytotoxicity and plasma cortisol was positive (r = .35, P = .036), indicating that pigs with greater cortisol response had greater NK cytotoxicity.(ABSTRACT TRUNCATED AT 250 WORDS)
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