Lack of response of laying hens to relative humidity at high ambient temperature.
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 degrees C (control) for 3 weeks and thereafter acclimated for 1 week to 35 degrees 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.
Yahav
S
S
Instute of Animal Science, ARO, Bet Dagan, Israel. vlyahav@agri.gov.il
Shinder
D
D
Razpakovski
V
V
Rusal
M
M
Bar
A
A
D000367:Age Factors; D000818:Animals; D001835:Body Weight; D002645:Chickens / Q000502:physiology*; D004435:Eating; D004528:Egg Shell / Q000737:chemistry / Q000502:physiology; D004531:Eggs; D005260:Female; D006358:Hot Temperature / Q000009:adverse effects*; D006813:Humidity / Q000009:adverse effects*; D010058:Oviposition / Q000502:physiology*