Photostimulated changes in egg production and reproductive performance of the Guinea fowl in a sub-humid tropical environment.

Abstract

The effect of photo-induced changes on egg production and reproductive performance of female guinea fowl was studied by exposing the birds to three photo-regimens, namely natural daylight all day for 12 weeks (NDL), 8 hours of light per day for 8 weeks (8L-16D) plus supplementary light for 16 hours per day for 4 weeks (16L-8D) (RSL), and provided natural daylight all day for 8 weeks plus supplementary light at 16 hours per day for 4 weeks (SL). Weight gain during the pre-laying period was similar (P>0.05) in all the treatment groups between 20-36 weeks of age. The reverse was the case during the laying period between 36-52 weeks, which coincided with the age at sexual maturity. Feed intake was similar (P>0.05) for the NDL and SL groups during the pre-laying period but the RSL group had significantly lower (P<0.05) feed intake than the others. Overall laying mortality was lowest in the RSL birds. There was no significant difference (P>0.05) in body weight for all the groups. Age at first egg was significantly lower (P<0.05) in the RSL (207 d) than in the NDL (249 d) and SL (235 d) birds which were similar (P>0.05). The guinea fowls which received 8 weeks of restricted light (RSL) responded more rapidly in terms of day-to-first-egg after exposure to 16 hours of light and achieved significantly higher (P<0.05) level of egg production than the other two groups. The overall economy of production, in terms of cost, revealed that RSL birds performed better than the NDL and SL, in that it cost N36.58 and 127.05 more to produce each NDL and SL guinea fowl at point of lay respectively. The results indicate that different light regimes altered the time during which egg production response took place and apparently affected the genetic potentials of the groups with regard to egg mass and total number of eggs laid during the period covered by this trial.