Ambush-hunting snakes have long been of great interest in the biology of fasting and starvation, as they are adapted to withstand well over a year without taking a meal. Well-justified ethical constraints have limited our understanding of their biology at the limits of these abilities. Unfortunate circumstances, in which the California Department of Fish and Wildlife confiscated over 50 Western Rattlesnakes (Crotalus oreganus) from an animal hoarder that had long neglected them, culminated in the euthanized animals ending up in the hands of our lab. Some of these snakes were extremely starved, being only one-half to one-third of the weight of wild snakes of the same length. We used dissection to determine the effects of starvation on the mass of their hearts, livers, kidneys, gallbladders, testes, and body fat. We also desiccated their hearts, livers, and kidneys to investigate effects on tissue water content in those organs. We used nano-indentation and photo analysis of bone cross sections to assess whether starvation had impacts on the material properties and structural integrity of their bones. We demonstrate that all measured organs dramatically shrink in response to starvation, with the exception of the gallbladder that shows the opposite response. The tissue water content of the liver and kidneys increases with the extent of starvation, and that of the heart appears to be unaffected. We found no evidence for changes in the material properties or structural integrity of rattlesnake bones in response to starvation. These results provide insight into how the body of one of the most fasting-adapted species of vertebrate responds to extreme starvation. Future work may need to act opportunistically to better understand these processes at different levels of biological organization.

Laying hen welfare is gaining importance in the United States and several states have passed legislation for a welfareriendly housing environment, which has forced the egg industry to explore alternative housing environments. For this reason, our first objective was to determine the effect of housing environment and laying hen strain on production performance and egg quality. Results showed that production performance of the hens raised in the alternative housing system was similar to the conventional system. The second objective was to compare the eggshell and cloacal microbiology. Our results indicated that the microbial load observed was higher in the alternative system compared to the conventional system. The third objective was to determine the effects of housing environment and laying hen strain on tibia and femur bone properties. The results demonstrated that the alternative system provided better tibia and femur bone characteristics, but it varied among laying hen strains.

Dissertation summarizes the results of computational and experimental modeling in the field of biomechanics engineering. Analyses are focused on selected variables that complement or can supplement existing methods of prediction of bone fractures. In terms of computational modeling the variables are based on stress strain analysis. The greater part of the work has been aimed on experimental modeling which is used for monitoring the two dominant components of bone tissue, which are minerals and collagen fibers. The current most widely used variable for the description of bone loss (osteopenia, osteoporosis) is areal bone mineral density (BMD). This variable does not however provide any information about the change in total volume consequently change of mineral and collagen. Proposed mechanical values follow the loss of the two components during simulation of minerals loss (demineralization) and simulation of collagen loss (deproteinization) in vitro for long turkey bones