The results secured from the series of tests appear to be conclusive enough to be used as a basis for certain recommendations. / Master of Science

published_or_final_version / Environmental Management / Master / Master of Science in Environmental Management

No description available.

Thesis (M.Sc. (Animal Production)) --University of Limpopo, 2010 / A study was conducted to determine the effect of vitamin E supplementation to the diets of Venda hens on egg production, hatchability and chick productivity. The first part of the study determined the effect of vitamin E supplementation to the diets of Venda hens on feed intake, number of eggs, egg weight, egg content, egg hatchability and chick hatch-weight. Supplementation levels of 0, 200, 400, 800 and 1000 mg of vitamin E per kg DM feed were used in a completely randomized design having five replications with two birds per replicate. Vitamin E supplementation did not have any effect (P<0.05) on number of eggs and feed intake of Venda hens. However, egg weight, egg content, hatchability and chick hatch-weight of Venda chickens improved (P<0.05) with vitamin E supplementation. Dietary vitamin E supplementation values for optimal egg white weight, egg yolk nitrogen content, egg white nitrogen content, egg hatchability and number of eggs were 476 (r2 = 0.756), 750 (r2 = 0.170), 750 (r2 = 0.182), 445 (r2 = 0.670) and 113 (r2=0.966) mg of vitamin E per kg DM feed, respectively. The second part of the study determined the effect of vitamin E supplementation to the diets of Venda hens on performance of their progenies between one and seven weeks old. A completely randomized design was used. All the chickens were fed the same commercial grower diet. Dietary vitamin E supplementation to the diets of Venda hens had no effect (P<0.05) on growth rate and mortality of their progenies between one and seven weeks. Feed intake, feed conversion ratio and live weight of progenies improved (P<0.05) with supplementation of vitamin E to the diets of Venda hens. Dietary vitamin E supplementation to the diets of Venda hens did not have any effect (P<0.05) on dry matter intake, dry matter digestibility, nitrogen retention and metabolisable energy of their progenies at seven weeks old. vi The third part of the study determined the effect of vitamin E supplementation to the diets of Venda hens on performance of their male progenies aged between eight and 13 weeks. A completely randomized design was used. All the chickens were fed the same commercial grower diet. Vitamin E supplementation to the diets of Venda hens did not improve (P<0.05) feed intake, growth rate, feed conversion ratio, live weight and mortality of their male progenies between eight and 13 weeks old. However, Venda hens supplemented with vitamin E produced male progenies with improved (P<0.05) dry matter intake, digestibility, nitrogen retention metabolisable energy, breast meat nitrogen content, gizzard weight, liver weight and heart weight at 13 weeks old. Carcass weight, breast meat yield, drum stick, thigh and wing weight of chickens at 13 weeks old were not affected (P>0.05) by vitamin E supplementation to the diets of the hens It is concluded that supplementation of vitamin E to the diets of indigenous Venda hens improved (P<0.05) egg weight, egg content and chick hatch-weight during the laying period. Vitamin E supplementation to the diets of Venda hens improved (P<0.05) feed intake, live weight, feed conversion ratio, gizzard and liver weight of their progenies. Production variables were optimized at different levels of vitamin E supplementation. Thus, this study provided new information on the effect of vitamin E supplementation to the diets of indigenous Venda hens on chick productivity and carcass characteristics of their progenies.

Thesis (Ph. D.)--University of Washington, 1997. / Vita. Includes bibliographical references (leaves [164]-176).

Thesis (M.Arch.)--University of Detroit Mercy, 2009. / "24 April 2009." Includes bibliographical references (p. 101).

Thesis (M.S.)--Brigham Young University. Dept. of Geology, 2005. / Includes Bibliographical Information (leaves 22-24).

Pacific salmon reared commercially off of the Coast of British Columbia suffer great mortality losses to Bacterial Kidney Disease (BKD), caused by the diplobacillus bacterium Renibacterium salmqninarum. This thesis investigates the effects of environmental conditions on the growth performance and disease susceptibility of salmonids reared in captivity. I found that growth rate of chinook salmon was significantly higher in fish fed to 100 compared to 67 % of satiation during the first 175 days of saltwater rearing but not during the first winter. Feed coversion rate was significantly higher for fish fed at 100 % of satiation compared to 67 % of satiation and higher during the winter compared to summer and fall, irrespective of feeding level. Mortality rates were significantly higher during the summer than during the fall or winter, irrespective of experimental treatment. The last BKD sampling period (day 263) revealed that infection rates were directly proportional to stocking densities of 1.5 to 4 kg.m⁻₃. Hatchery-reared chinook salmon held in freshwater aquaria had significantly lower hematocrit and plasma cortisol concentration increases in response to increased stocking density than did their wild counterparts. Crowding of hatchery-reared and wild chinook salmon resulted in equally increased mortality rates for both groups of fish. Day 33 plasma cortisol concentrations in Atlantic salmon held at three stocking densities were directly proportional to stocking densities of 8 to 64 kg.m⁻₃. The ability of anterior kidney lymphocytes from these fish to produce antibody-producing cells was inversely proportional to the density at which the fish were held. / Land and Food Systems, Faculty of / Graduate

During 1993- 1994, I investigated wildlife depredation at Intermountain West fish hatcheries to quantify losses, determined the reliability of bioenergetics models and hatchery manager perceptions to predict losses, and investigated the effectiveness of simple control measures. I observed predators and surveyed managers to quantify the extent of depredation losses and to identify the species responsible. Great blue herons (Ardea herodias), black-crowned night herons (Nycticorax nycticorax), ospreys (Pandion haliaetus), and California gulls (Larus californicus) were the most significant predators of hatchery fish in the field study, and were perceived as such by hatchery managers. Losses to avian predators at two hatcheries were 7.0% and 0.6% of annual production based on my observational data, but hatchery managers believed depredation losses were 15% at each hatchery. I estimated the consumption of rainbow trout (Oncorhynchus mykiss) by great blue herons using bioenergetics models of existence metabolism, existence metabolism plus reproductive costs, and field metabolic rate. compared the model-based predictions to observed consumption rates of free-ranging herons foraging at a fish hatchery. The fish consumption predicted by the existence metabolism model and observed consumption were similar from October- June. During the breeding season, observed consumption was higher than consumption predicted by the existence metabolism model but lower than that expected from the energy requirements for breeding individuals. This result was expected given that only a portion of the bird population was breeding. Although consumption predicted by the field metabolic rate differed significantly from observed consumption for more months than the existence metabolism models, predicted annual consumption from field metabolic rate and observed annual consumption were not signliJcantly different (.E < 0.05). Peak observed consumption occurred during August and September and was predicted by the model. Performance of the three models may be improved with estimates of population structure and more reliable population estimates. I evaluated the effectiveness of perimeter fencing in reducing heron depredation on fish raised in concrete raceways at a trout hatchery in Midway, Utah. Fences were constructed of single-strand monofilament line placed 20 cm above raceway walls. Fences had no impact on the number of birds foraging or their fish consumption rate.

None / Master of Science