Age at photostimulation and its effects on sexual maturity and sellable egg production in broiler breeders

摘要

In the previous issue of this column, the effect of long days on the onset of lay of broiler breeder hens was described. As part of the same research project, the effect of different ages at photostimulation on the onset of lay and settable egg produc tion of broiler breeder hens was researched Several experiments were conducted to gather a wide range of information and the summary is described in this article. Breeding manuals recommend that pullets are grown in light-tight facilities, subjected to s hort days (to dissipate juvenile photorefrac-toriness) and a growth profile that allows the pullets to achieve around 2100 g body weight at 20 weeks, when they are subjected to an increase in photoperiod. This practice is aimed at synchronising the sexua l maturity of most of the birds in the flock in order to start the laying cycle at about the same age. Although this recommendation is supposed to be the best to maximise production, broiler breeders show several anomalies (particularly during the first few weeks of the laying cycle). The production of very small eggs and double-yolked eggs are a problem since these eggs are not set, and are therefore a loss to the enterprise.