Assessment Of Lighting Needs By Laying Hens Via Preference Test

Considerable research has gone into light intensity and rhythm for laying hens to achieve high production efficiency. However, much less is known concerning desired light intensity and rhythm from the hen’s standpoint. Such information is valuable as concerns about animal welfare intensify. Preference test is one of the best ways to assess the animal’s biological or physiological demand.A light-proof preference test system, located in an environmentally-controlled room, was used in the study. The number of birds and feed intake in each compartment were auto calculated using Matlab and other developed code. In addition, sample methods for behavioral validation in preference test was estimated. Five light intensities of<1,5,15,30 and 100 lux were used in the preference tests of W36 laying hens. The resultd provide the following findings:(1) The preference test system (light tunnel) was designed and constructed successfully. The system was divided into five compartments with camera system and load-cell system, allowing 5 different lighting factors tested simultaneously. Light tunnel is light-proof, easily operated and providing an enviroment where the animals can express their behavior without interrupted. The system is being used to delineate responses of poultry to various lighting conditions.(2) Algorithms of how to automaticly calculate birds’ number and feeding bahvior were developed, which could record data at Is interval continuously for 24h and process the data automaticly. These algorithms can save an amount of time and laber compared to traditional methods. Results obtained through the software programs were compared to those through manual labeling, and the two showed 98% agreement.(3) Effects of sample methods with different invervals on behavioral results were investigated using 4 parameters which are means, standard diviation, correlations coefficients and regression coefficients. For the time spent of long duration behaviors, the sample intervals won’t have effect on the result when the sample intervals are ≤30min for both instantaneously and time sanple mthods, compared with continuous results. For inter-conpartment movements of short duration behavors, the effects are different for instantaneously sample and time sample mthods: when the sample intervals are ≤ 60s for instantaneously sample and ≤30min for time sample, the results are no significant different with continuous ones.(4) Preference of staying in dimmer light (5 lux) over 15 or 30 lux, with 100 lux being least preferred during light period. The 14 h daily light period was distributed as 6.4 h (45.4%) in 5 lux,3.1 h (22.2%) in 15 lux,3.0 h (22.1%) in 30 lux, and 1.5 h (10.4%) in 100 lux. Preference to feed in 5 lux (28.4 g/hen, 32.5% of daily feed intake) with a feeder light of 30 lux or<1 lux (24.8 g/hen,28.4%) without feeder light. Strong preference of laying egg in ’dark’(<1 lux) over light, with 61.9% of their eggs laid in<1 lux. A daily overall photoperiod of 14L:10D. However, the intermittent hourly light and dark time was distributed quite consistently throughout the day, with time spent in the ’dark" (<1 lux) condition averaging 25.0 ± 0.4 min per hour.