SEASONAL VARIATION AND PERFORMANCE EVALUATION OF BROILER BREEDER CHICKENS REARED IN ENCLOSED HOUSES.

In this field observational study three enclosed broiler breeder houses were selected to evaluate the effects of some environmental factors in different seasons along the year on F15 Hubbard broiler breeder chickens to provide reliable information and practical current knowledge for proper management conditions. Each house contains 4000 birds 25 Wk-old with average initial weight 2.560 ± 50.60 kg, with a total of 12000 birds for three studied houses. Productive performances of flocks were evaluated by measuring egg production, egg weight, feed consumption, feed conversion of eggs and mortality rate. Also, egg quality traits were done for each season alone, while the physiological performance determined by measuring some blood traits. Further, fertility, hatchability and chick quality traits were also evaluated. Ambient temperature (AT, °C), relative humidity (RH, %) and concentrations of ammonia (NH3, ppm), hydrogen sulfide (H2S, ppm), carbon dioxide (CO2, ppm) and dust (mg/m3), air velocity (AV, m/s) and static pressure (SP, Pa) were determined along the different seasons of the year. Results of the present study showed that air quality of breeder houses and either productive or physiological performance were significantly (P ≤ 0.05) affected due to seasonal changes along the year. High concentrations of different gases present in houses in winter season can negatively affect production and health of birds. In spring and summer seasons egg production and FCR were significantly (P ≤ 0.05) the best in comparison to the other different seasons. While, insignificant differences observed in egg weight due to seasonal changes. Mortality rate showed the highest percentage for birds reared in winter compared with the other seasons. In addition, there was evidence of an increased stress response due to elevation of environmental gases in winter and autumn seasons as judged by the increase of hetrophils, lymphocyte and H/L ratio and CS level reflecting the increase of stress due to environmental conditions. However, the levels of T3 and T4 recorded significantly higher (P ≤ 0.05) values for birds kept in winter season compared with the other seasons. Furthermore, egg quality traits had been significantly (P ≤ 0.05) affected due to seasonal changes, where the shell thickness recorded the highest (P ≤ 0.05) value during autumn and spring, while the lowest recorded for summer and winter seasons. Further, insignificant differences were detected for fertility, hatchability or chick quality traits due to seasonal changes. Based on the former results, it can be concluded that the tolerable temperature for the breeder was 19-28 °C, but decreasing AT to reach to 25 °C is required in summer season. Indeed, insufficient house environmental conditions were detected in winter season, which reduces the economic efficiency of enterprise due to lake of ventilation rate. However the quality of air in house is very important for obtaining good productive performance. Therefore, because of the difficult of achieving good environment in some housing types in different season, especially in winter, it is recommended that good care should be oriented to control of different gases generated in house in order to ensure good bird health and performance, when birds are most susceptible to harmful gases. In general an adequate environment within poultry houses is required for success in the poultry industry. [ABSTRACT FROM AUTHOR]