Effect of temporary transfers to 14 h on age at first egg in domestic pullets reared on 8-h photoperiods.
1. Brown-egg pullets were reared on 8-h photoperiods and temporarily transferred at 80 d of age to 14-h photoperiods for 2, 4, 6, 8, 10 or 12 d. Controls were either maintained on 8 h or permanently transferred to 14 h at 80 d. 2. Pullets given 8 or 12 long days matured 8-9 d earlier than constant 8-h controls, but 22-23 d later than pullets transferred permanently to long days. Mean age at first egg for the groups given 2, 4, 6 or 10 d of 14-h days were not significantly different from the 8-h controls. The mean weight of first egg and body weight at first egg for the temporarily-photostimulated groups were not significantly different from constant 8-h controls, but egg weights were > or = 5.1 g and body weights at first egg > or = 200 g heavier than the birds transferred permanently to 14 h. 3. It is concluded that up to 6 temporary long days may be given (from 80 d of age) without affecting the timing of sexual maturity, but that the provision of 8 or more long days will accelerate sexual development, thought not to the extent of a permanent transfer, in most birds within a flock. A regression analysis of the ages at which the first and last birds in the groups given 6, 8, 10 or 12 long days matured suggested that about 20 d of photostimulation are required to achieve a mean age at first egg similar to that of birds permanently transferred to long days.
Lewis
P D
PD
Animal and Poultry Science, University of KwaZulu-Natal, Pietermaritzburg, South Africa. northcot.7hg@dsl.pipex.com
Gous
R M
RM
D000822:Animal Husbandry; D000818:Animals; D002645:Chickens / Q000502:physiology*; D005260:Female; D008027:Light; D010058:Oviposition / Q000502:physiology* / Q000528:radiation effects*; D010063:Ovum / Q000502:physiology; D017440:Photoperiod; D012741:Sexual Maturation / Q000502:physiology / Q000528:radiation effects*; D013997:Time Factors