Co-Authors:
Yahav, S., Institute of Animal Science, ARO, Bet Dagan, Israel, Institute of Animal Science, Volcani Center, PO Box 6, Bet Dagan 50250, Israel
Shinder, D., Institute of Animal Science, ARO, Bet Dagan, Israel
Razpakovski, V., Institute of Animal Science, ARO, Bet Dagan, Israel
Rusal, M., Institute of Animal Science, ARO, Bet Dagan, Israel
Bar, A., Institute of Animal Science, ARO, Bet Dagan, Israel
Abstract:
1. The effects of relative humidity (rh=40% to 70%) at high ambient temperature (Ta) on the performance of laying hens at different ages (8 to 10 months, Trial 1; and 16 to 18 months, Trial 2) was evaluated. Laying hens were exposed to 25°C (control) for 3 weeks and thereafter acclimated for 1 week to 35°C and 4 different rh. 2. Body weight declined significantly in young and older hens exposed to 60% or 70% and 70% rh, respectively. Food intake declined with increasing Ta, except in the case of older hens exposed to 60% rh, for which it remained relatively constant. Water consumption, however, increased with increasing Ta but the increase was significant in young hens exposed to 70% rh only. 3. Egg production was not affected by the changes in Ta. However, a decrease in egg production was observed in older hens exposed to 60% rh. 4. Egg weight (EW), shell weight (SW) and shell thickness (ST) were significantly reduced by exposure to elevated Ta, whereas % breakage significantly increased. In young hens, a response to rh was exhibited in ST which was significantly higher in hens exposed to the low rh (40% to 45%) than in those exposed to the highest rh (70% to 75%). 5. It can be concluded that Ta is the main environmental factor affecting young and older laying hens while the effect of rh is minor. © 2000, British Poultry Science Ltd.
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