This paper studies pre-pubertal photoperiod manipulation as an experimental intervention in Pengxian yellow pullets. The intervention changes daily light:dark exposure during 12 to 18 weeks, followed by gradual increase thereafter.
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pre-pubertal lighting schedule
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At 43 weeks, the 8L:16D group had higher GnRH-I, FSH-β, and LH-β mRNA abundances than the other two groups and achieved higher peak hen-day egg production than the 12L:12D group.
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Pullets of G1 group had significantly higher levels (P<0.05) of GnRH-I, FSH-β, and LH-β mRNA abundances at 43 weeks of age than other two groups and this corresponded with the percent (hen day) peak egg production (75.38%) in pullets in this G1 group that was attained at 32 weeks of age, while the peak production of 71.24% was attained at 30 weeks of age in G3 group.
In Pengxian yellow pullets, the 12L:12D group showed higher plasma FSH and LH levels and higher GnRH-I, FSH-β, and LH-β mRNA expression before egg laying than shorter-day groups.
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The result indicated that pullets of long day length (G3) group had higher plasma levels of FSH and LH and also better mRNA expression that regulates synthesis or/and secretion of GnRH-I, FSH-β, and LH-β before egg laying.
The 12L:12D group reached first egg earlier than the 8L:16D group by 8.8 days, with first egg at 151.3 days.
Quoted textsource-backed
The age at first egg (151.3 days) in pullets of G3 group receiving longer lighting hours (12L:12D) was 8.8 days less (P<0.05) compared to pullets of G1 group
The 8L:16D group had higher plasma LH and FSH than the 12L:12D group during the experimental period, corresponding with higher cumulative egg production.
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However, significantly higher (P<0.05) plasma levels of LH and FSH in pullets of G1 as compared to pullets belonging to G3 group corresponded with the higher (P<0.05) cumulative egg production during the experimental period
Lighting schedule had no effect on body weight during the experimental period.
Quoted textsource-backed
There was no effect of lighting schedule on body weight of pullets, recorded during experimental period, at all occasions; belonging to three groups (G1,G2 and G3) and receiving varying hours of photo-stimulation (P>0.05).
The study inferred that 8L:16D is the optimum lighting schedule during the 10-week pre-pubertal growth period for Pengxian yellow pullets.
Quoted textsource-backed
It was inferred that the optimum lighting schedule for Chinese native breed Pengxian yellow pullets during 10 weeks of pre-pubertal growth period is short hours of photo-stimulation (i.e 8L:16D).