No description available.

No description available.

Call number: LD2668 .T4 1949 E15 / Master of Science

No description available.

The objectives in these four experiments were to observe the effectiveness of sodium bisulfate and clinoptilolite and different methods of application of sodium bisulfate, ferrous sulfate heptahydrate and Micro Aide® on atmospheric ammonia level in the broiler house and on broiler performance. The first experiment was conducted to determine the optimum effective level of the litter application of sodium bisulfate. Atmospheric ammonia at 4 weeks and litter moisture at 3 weeks treated-pens were significantly lower in sodium bisulfate (488 g/m²) than in the untreated control pens. However, broiler performance was not significantly affected with any treatment. Litter application of sodium bisulfate at 244 g/m² and 488 g/m² were comparable and better than the 122 g/m² and untreated control. In Experiments 2 and 3 comparisons of litter chemical treatments of liquid Micro Aid® (8.75 ml/L H₂O) applied at 0, 2, 4,and 6 weeks; granular Micro Aid® (0.5 mg/g of feed) fed continuously throughout the experiment, and litter application of ferrous sulfate (732 g/m²); clinoptilolite (2443 g/m²), sodium bisulfate (244 g/m²) and ferrous sulfate (732 g/m²) were made for 7 week periods. Ferrous sulfate-treated pens (732 g/m²) had significantly lower litter pH at 2, 4 and 6 weeks than untreated control and significantly lower atmospheric ammonia levels at 3 and 6 weeks than the clinoptilolite (2443 g/m²), sodium bisulfate (244 g/m²) and untreated control in the other experiment. In the fourth experiment, sodium bisulfate was applied twice (244 g/m²/application) at 0 and 4 weeks, sodium bisulfate applied once (488 g/m²) and ferrous sulfate applied once (732 g/m²) prior to the experiment. At 4 weeks mean body weights and feed conversion were significantly better with one sodium bisulfate application than the untreated control. At 7 weeks feed conversion (P<0.08) and male body weights (P<0.1) were slightly better in one sodium bisulfate application than in the untreated control while mortality was significantly lower in the untreated control pens. Most mortality occurred after 4 weeks and were due primarily to Sudden Death Syndrome. Atmospheric ammonia levels at 0, 1, 2, 3 and 4, weeks and litter pH levels at 0, 1, 2, 3, and 4 weeks were significantly lower in pens with one application of sodium bisulfate than in pens untreated. Litter application of sodium bisulfate once (488 g/m²) seemed to be the best litter treatment in reducing atmospheric ammonia. / Graduation date: 1991

No description available.

During the early existence of the science of genetics, the area of single gene effects was the more active area of interest. Throughout the initial development of this science, studies of qualitative traits provided the basis on which the later principles were founded. [...]

No description available.

Biological and economic efficiencies of major genes for feather reduction (naked neck and frizzle) and body size reduction (dwarf) in a dual purpose layer strain were evaluated in the subtropical coastal region of South-East Africa (Maputo, Mozambique). The experimental material consisted of eight different genetic groups, two diets (14.4 and 16.2% crude protein) and two climatic seasons. Birds were caged individually in an open-side shelter with natural light. Traits measured were: temperature and relative humidity, body weight, age at first egg, egg weight, egg production, egg quality, feed intake and mortality. The following were calculated: temperature-humidity index (THI), growth rate, persistence, egg mass, feed efficiency, feed conversion, biological efficiency (EM/BWO.75) and productivity (EN/BWo. 75). The main results show that: (1) none of the feather-reduced genes significantly improved egg production or the efficiency of feed utilization, although the naked neck (Na) excelled in terms of the number and mass of eggs produced per metabolic body weight; (2) the dwarf gene (dw) was associated with delayed sexual maturity, production of fewer and lighter eggs, higher persistence, better feed conversion and higher survivability; (3) climatic seasonal effects were observed in all traits analysed, with elevated temperatures restraining body weight gain, the number and weight of the eggs produced, and voluntary feed intake; (4) the lower dietary protein content resulted in decreased egg weight. It was concluded that the normal feathered dwarf is the most suitable genetic group for peri-urban and rural production systems in this region. / Thesis (PhD (Animal Science))--University of Pretoria, 2007. / Animal and Wildlife Sciences / unrestricted

No description available.