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Diet and exercise are two management factors that affect bone density and strength. We proposed that bone density and calcium status would be affected by deconditioning for 12 wk and by dietary Ca concentration. Eleven highly conditioned Arabian horses were taken out of training and placed in stalls for 12 wk. Horses were walked on a mechanical walker in two 30-min sessions, 7 d/wk. Diets were designated CC (.36% Ca) and HC (.62% Ca). Data were collected every 21 d. Serum or plasma were analyzed for total and ionized Ca, parathyroid hormone, osteocalcin, hydroxyproline, electrolytes, and blood gases. Bone mineral content (BMC) of the left third metacarpal bone was estimated by radiographic photometry using an aluminum step wedge, which was exposed in each radiograph, as a reference standard for an image analysis system. During deconditioning, BMC decreased by approximately 1.1 g/2 cm, or .45% per week. This decrease was unaffected by dietary Ca. Serum Ca concentration increased with deconditioning. The results suggest that dietary Ca at twice the currently recommended level did not prevent the loss of BMC in response to deconditioning. Loss of BMC during 12 wk of stall confinement may weaken bones, increasing the risk of skeletal injuries when training is resumed.

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Experiential learning is a hallmark of undergraduate education programs in the agricultural sciences, and is aligned with constructivist learning theory. This interpretivist qualitative study used historical research methodology to analyze the epistemological underpinnings of constructivism and explore the construct's relationship to undergraduate research, a particular experiential learning context which extends a student's knowledge to scholarly application through discovery-based problem solving. Two pedagogical principles of constructivist learning theory emerged: that learning should be authentic, active and student-centered, and that it must also be facilitated through social negotiation. Both factors are inherent in the learning process when faculty mentors scaffold the creation of new knowledge via undergraduate research. Agricultural educators can take advantage of parallels between constructivism and the scholarship of discovery to enhance self-regulated learning of students and integrate institutional research and teaching missions.

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