ABSTRACT Title of dissertation: GENETIC VARIATION IN NITROGEN AND PHOSPHORUS LEVELS IN BROILER EXCRETA: OPPORTUNITY FOR IMPROVING BOTH BIRDS AND THE ENVIRONMENT

The increase in poultry meat consumption has resulted in intensified poultry farming operations with consequent concentration of excreta in major production areas. The nutrient content in the soil surrounding the poultry farms has increased as a result of the high content of nitrogen (N) and phosphorus (P) in the poul-try excreta. The current study aimed to propose a strategy to reduce the N and P content in excreta through genetic selection of broilers for efficient nutrient uti-lization. The traits measured (on a dry matter basis) were the percentage of N in the excreta (PNE) and the percentage of P in the excreta (PPE). Individual 24-hr excreta samples were collected from 6 wk old birds. Excreta samples were collected from a commercial breeding farm at two different time periods from line A and line B birds respectively, and analyzed for PNE and PPE. Analysis of exc-reta samples collected during the first period (197 bird samples belonging to 15 sire families) and second period (278 birds belonging to 25 sire families) suggested a heritability of 0.08, 0.16 for PNE and 0, 0.20 for PPE, respectively. Phenotypic and genetic correlations between the measured traits from the two lines were ver