Effect of Breed Strain, Disease, Environmental Conditions and Management on Mortality in Commercial Egg Type Layers

This study is based on a survey that was carried out to investigate the effects of strain of birds, feeding practice, diseases, environmental conditions and management on mortality at commercial layer farms in the four middle governorates of Jordan. The investigations were conducted on 54 farms that housed a total of 2.4 million laying hens. Farm managers were individually interviewed. The study period was between September and December, 2004. The information was collected by a questionnaire. The least square analysis revealed that the factors which significantly affected seasonal mortality were breed strain, farm design, distance from other farms, egg production at twenty weeks of age, vaccine type, vaccine solvent, disease, window size, light intensity, soybean meal, limestone, feed additives, feed energy level, water source, number of drinker lines, chick density, distribution of chicks to area, litter disinfections and manager experience. Winter mortality was 6.37 % with a maximum level of 13 %. The minimum mortality was 1.0 % in all four seasons. Summer mortality was 4.38 %. Babcock (both B300 and Brown varieties) and Hy-Line w97 strains had better tolerance to increasing and decreasing of environmental temperatures during summer and winter. Whereas, Hisex (Bovans, Neaman and white varieies) and Lohman LS strains types had better tolerance to temperature fluctuations and resulted in lower mortality throughout the year. Using skimmed milk as vaccine diluents instead of regular chlorinated water resulted in reduced mortality in winter and throughout the year laying hens. Bacterial diseases were the most important infectious diseases for laying hens during both rearing and production periods. Increasing window sizes of the laying hen houses lead to lower annual mortality than those which had smaller size windows. Mortality were lower for layer farms that were managed by experienced farm managers