Thesis (M.S.)--University of Wisconsin--Madison, 1974. / Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (M.S.)--University of Wisconsin--Madison, 1958. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (M.S.)--University of Wisconsin--Madison, 1962. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 61-63).

Thesis (Ph. D.)--Michigan State University, 2005. / Includes bibliographical references (leaves 88-93)

Male progeny of 15 sires each mated to 2 dams from the University of British Columbia's New Hampshire flock were reared in 2 environmental treatments, an environment chamber or a standard floor pen. Birds reared in the chamber were transferred to the floor at 3 weeks of age where they were reared with the birds of the floor treatment to 7 weeks of age. Six experiments were conducted involving a total of 339 birds. Individual body weights were recorded for the progeny at hatch and at weekly intervals until 7 weeks of age. Chamber temperatures were started at 95°F for experiment 1 and 90°F for experiments 2-6 and reduced 3°F every 3 days to 3 weeks. Relative humidity was held constant at 50%. Birds on the chamber treatment were heavier at 7 weeks of age than birds raised on the floor from hatch to 7 weeks. This difference was attributed to the high 1-3 week growth rate of chamber reared birds. Using multiple linear regression techniques the 1-3 and 3-7 week growth periods were found to be the important periods in accounting for the variability in 7-week weight for the floor and chamber birds respectively. Heritability estimates of body weight based on σ²s for floor and chamber birds were found to be high (0.82) and relatively the same between the 2 environmental treatments from hatch to 2 weeks of age. They diverged to 0 and 1 by the 5th week for the floor and chamber, respectively. The high heritability based on σ²s for chamber reared birds at the time of transfer was attributed to an increase in selectable genetic variance due to stress. The effect of stress after transfer was reflected in low growth rates during the 3-4 week period. Average 1-week weight, average 1-3 week growth rate and average 3-7 week growth rate were regressed on the heritability (based on σ²s) of 7-week body weight. For floor reared birds the early growth period was the important period in accounting for variability in heritability of 7-week weight while for chamber birds the 3-7 week growth period was the most meaningful period. It was concluded that the environment controls the variability of weekly growth rate and changes the importance of these growth periods in accounting for the genotypic variability in 7-week weight. In a theoretical selection program based on 7-week weight the percentage of progeny each sire contributed to the selected population depended upon the environment in which the progeny were reared. However a small number of sires were able to maintain their percentage contribution in both environments. For the floor treatment more selected birds had an above average 1-3 week growth rate than 3-7 week growth rate. For the chamber treatment more selected individuals had an above average 3-7 week growth rate than 1-3 week growth rate. Although growth rate from 1-3 weeks of age raised the mean 7-week weight of chamber birds, it was the individual’s ability to grow under the stress conditions which placed it in the selected population. Birds which were below average with respect to 1 or 2 of the traits, 1-week body weight, 1-3 week growth rate and 3-7 week growth rate were present in the population of birds which had been selected on the basis of 7-week body weight. The percentage of selected individuals carrying any particular combination of these traits depended upon the environment in which the birds were reared. It was concluded that selection based on individuals which were above average with respect to all 3 of the aforementioned traits as well as 7-week weight would improve the selection response when compared to selection based upon 7-week weight alone. / Land and Food Systems, Faculty of / Graduate

Genetic parameters were estimated for 2403 purebred Landrace pigs ever a two year period, representing 21 sires. The traits studied included average daily gain, age adjusted to 91 kg, ultrasonic measurements of backfat at the midback and loin positions, total and adjusted total ultrasonic backfat and corresponding carcass backfat measurements. Least squares analyses were used to estimate and adjust for the effects of sex, season and sex by season interaction. Heritabilities and genetic correlations were calculated for all traits using both half and full-sib estimates. Adjusted age and adjusted total ultrasonic backfat measurements were found to be the nest appropriate predictors of carcass value. Estimates of heritability for adjusted age and adjusted total ultrasonic backfat were 0.24±0.10 and 0.26±0.10 based on half-sib and 0.56±0.07 and 0.41±0.06 from full-sib analyses. Genetic correlations between these two traits were -0.07±0.28 and -0.01±0.10 based on the two respective methods. The total phenotypic correlation was -0.01±0.02. A selection index example was developed from half-sib estimates of the genetic parameters and economic factors were estimated from fixed and variable costs for adjusted age and the Canadian market index system. / Land and Food Systems, Faculty of / Graduate

No description available.

Thesis (Ed.D.)--Boston University.

Note:

The ability to accurately predict object weight is essential for skilled manipulation and recent studies suggest that such prediction is based, in part, on learned size-weight maps associated with families of objects. Weight prediction based on size-weight maps is also involved when judging weights; there is strong evidence that weight judgments are biased by expected weight, based on size. This bias is revealed by the size-weight illusion (SWI) whereby the smaller of two equally weighted and otherwise similar objects is judged to be heavier because it is heavier than expected based on its size. The overall aim of the current set of studies was to examine how size-weight maps for different families of objects are organized and represented at the perceptual and sensorimotor levels. We found that distinct and independent size-weight maps, used to predict weight, were used when lifting objects and judging their weights. At the perceptual level, interference between size-weight maps for the different sets of cubes was observed; participants could learn the inverted size-weight relationship for the green cubes when experienced alone but not when experienced along with the black cubes with a normal size-weight relationship. However, about half of participants learned to scale lift forces accurately for both sets of cubes indicating that the sensorimotor system can learn, without interference, opposite size-weight maps. We further investigated why not all participants learned to accurately scale their lift forces and found that learning to lift objects with different and arbitrary size weight maps involves visuomotor working memory resources. Moreover, an outside task that steals attentional resources can interfere even after previous learning of the size-weight maps. / Thesis (Master, Psychology) -- Queen's University, 2011-09-30 12:51:49.413