Pd. Lewis et al., EFFECTS OF LIGHTING REGIMEN AND GROWER DIET ENERGY CONCENTRATION ON ENERGY-EXPENDITURE, FAT DEPOSITION AND BODY-WEIGHT GAIN OF LAYING HENS, British Poultry Science, 35(3), 1994, pp. 407-415
1. Mean metabolisable energy (ME) intakes and heat productions over a
laying year were calculated for laying hens which had been submitted t
o one of various lighting regimens and given either a normal or a high
energy ration during the rearing period. 2. Daily ME intake and heat
production per hen in the laying period were unaffected by either ligh
ting regimen or grower diet. ME intake per kg W0.75 and heat productio
n per kg W0.75 during lay increased significantly with laying photoper
iod, was non-significantly higher following an 8-h rather than an 11-h
rearing photoperiod, but was unaffected by dietary energy concentrati
on. The increase in heat production (/kgW0.75) associated with a 1-h i
ncrement in photoperiod was similar to predictions made from calorimet
ric measurements of diurnal variation. 3. Efficiency of conversion of
food to egg was unaffected by either lighting regimen or dietary energ
y concentration. 4. Fat weight gain in lay was not influenced by light
ing regimen, but was significantly lower in birds reared on the high,
compared to the normal, energy grower ration. Fat-free weight gain in
lay was unaffected by grower diet, but was significantly increased by
photoperiods longer than 8 h. 5. ME intake and heat production per kgW
0.75 were negatively correlated' with age at first egg, but ME intake
and heat production per bird d were not related to age at sexual matur
ity.