This paper is concerned with the effects of photoperiod on ovarian morphology and carcass traits at sexual maturity in egg-type hens. Two hundred fifty-six commercial egg-type pullets were initially subjected to a photoperiod of 23L:1D, which was reduced to 22L:2D at 1 wk, to 18L:6D at 2 wk, and to 16L:8D at 3 wk. From 4 to 20 wk, the photoperiod was 8L:16D. At 20 wk, 32 pullets were individually caged in individually lit cages, with 8 cages per unit. Two cage units were placed into 4 photoperiods of 17L:7D, 15L:9D, 13L:11D, and 11L:13D, respectively. Each bird was processed when it reached sexual maturity (SM), and carcass and ovarian morphology were assessed. The results showed that photoperiod had an effect on the timing of SM, and the age at first egg was 5.7 d earlier for hens exposed to the 17L:7D photoperiod than the 11L:13D photoperiod. However, photoperiod had no effect on BW at SM. A photoperiod of 11L:13D limited ovarian follicle formation and increased carcass protein and lipid compared with birds on longer photoperiods, whereas the 17L:7D photoperiod restricted ovary and oviduct full development. These results indicated that excessively long and short photoperiods can restrict reproductive development in egg-type hens.

Hy-Line Gray commercial pullets were maintained under 8-h photoperiods, 16-h photoperiods and 16-h photoperiods supplemented with a diet containing 20 or 200 mg/kg melatonin (MEL) to investigate the role of MEL in sexual development. A total of 256 Hy-Line Gray commercial pullets were placed, four birds to a cage, in four similar light-proof rooms (8-h photoperiod) at 6 weeks of age. At 70 day, three rooms containing a total of 192 birds were transferred to a 16-h photoperiod, whereas 64 birds were maintained under the 8-h photoperiod. Diets containing MEL at 20 and 200 mg/kg were fed to birds in two of the rooms under 16-h photoperiods. Birds maintained under an 8-h photoperiod matured 11.25 day later than those maintained under a 16-h photoperiod (p < 0.05). The group of birds receiving 20 mg/kg MEL matured 1.19 day later than those maintained under the 16-h photoperiod and 10.06 day earlier than those maintained under the 8-h photoperiod. The group of birds receiving 200 mg/kg MEL matured 3.13 day later than those maintained under a 16-h photoperiod and 8.12 day earlier than those maintained under an 8-h photoperiod. The average body weight of birds maintained under the 8-h photoperiod was greater than that of birds maintained under the 16-h photoperiod (p < 0.05) and was similar between the different MEL groups. The abdominal fat weight was lower in 16L:8D group compared with 8L:16D group (p < 0.05). The concentrations of follicle-stimulating hormone, luteinizing hormone, oestrogen and insulin did not differ significantly among the groups. The melatonin concentration in 200 mg/kg melatonin group was higher than that observed in the other groups; however, this concentration did not differ significantly (p > 0.05). These data suggest that the birds did not perceive the final 8-h photoperiod as being part of the night when they were given the MEL diets; continuously high plasma MEL was not observed in birds that responded as if they were in constant darkness. However, the later maturity of the groups administered MEL diets compared with the groups maintained under a constant 16-h photoperiod clearly indicated that MEL has some influence on the sexual maturity of pullets.

Photoperiod and nutrition are major factors that affect the reproductive efficiency particularly in female animals. In this study we examined the interaction of photoperiod and food restriction on growth, sexual maturation and receptor mRNA expressions of leptin, melatonin, and estrogen in abdominal fat and the ovary of pullets. There were no interaction effects between photoperiod and feeding level on body weight, abdominal fat weight, ovary weight at both 14 wk and 18 wk. Abdominal fat weight of feed restriction group was significantly lower compared with the control group at the age of 14 wk, 18 wk, and age of the first egg (AFE) (p<0.05). Ovary LEPR (Leptin receptor) gene expression showed an interaction effect of the first egg. Restricted feeding significantly inhibited ovary ER (Estrogen receptor), LEPR and MELR1B (Melatonin 1B receptor) gene expression at 14 wk, 18 wk and the first egg. At 14-week-old, abdominal fat LEPR gene expression was significantly lower in long photoperiod group compared with the short photoperiod group. At the first egg, short photoperiod and feed restriction group reduced abdominal fat LEPR gene expression. The results indicated that the reproductive activity of pullets is sensitive to feed intake and photoperiod. Feed restriction down regulated the ER, LEPR, MELR1A (Melatonin 1A receptor) and MELR1B mRNA expression of the ovary at 14 wk, 18wk and AFE. Long photoperiod enhanced the LEPR, MELR1A and MELR1B mRNA expression of abdominal fat at AFE.

This study investigated the effects of dietary Ferula supplementation on productive performance, egg quality, follicular development, serum levels of reproductive hormones, and reproductive gene expression in aged laying hens. A total of 300 Dawu pink laying hens (65 weeks old) were assigned to four treatments with six replicates per treatment and 10 hens per replicate. The birds were individually housed in wire cages and fed a corn-soybean meal-based diet with added Ferula at doses of 0, 50, 100, and 200 mg/kg for 12 weeks. The results showed that the laying rate in the 100 mg/kg Ferula-supplemented group was higher than in birds of the control group during weeks 1 to 12 (p<0.05). The average egg weight in the 100 mg/kg Ferula-supplemented group was significantly higher than in the other groups (p<0.01), while the feedto-egg ratio was significantly lower than in other groups (p<0.01). The numbers of small yellow follicle, middle white follicle, and small white follicle were higher in the 100 mg/kg Ferula-supplemented birds than in the other groups (p<0.01). On weeks 69, the serum levels of estradiol, follicle-stimulating hormone, and luteinizing hormone were significantly higher in the 100 mg/kg Ferula-supplemented group than in the other groups (p<0.05). Additionally, expressions of ERα, FSHR, and LHR in the ovarian tissue were up-regulated by Ferula supplementation, especially in the 100 mg/kg group (p<0.01). These results indicate that the Ferula supplementation can significantly improve productive performance, egg quality, reproduction of hormonal profile, and reproductive gene expression of aged laying hens.