Effects of photoperiod on broodiness, egg-laying and endocrine responses in native laying hens

An innovative protocol to increase egg production of chicken layers

This study investigated the effects of different doses of limestone, light durations, light intensities, and vitamins on both the productive performance and egg quality. The study utilized two rearing houses (control and treatment), each accommodating 75000 Lohmann Brown Classic chicks reared in open-sided rearing cages from one day old until they reached 89 weeks of age. Throughout the laying period, the hens were subjected to a specific light regimen (light = 14 h; dark = 10 h a day). At the end of experiment, the treatment group displayed significant (p<0.05) differences compared to the control group across various parameters. Notably, the treatment group exhibited lower daily feed intake (treatment: 112 g/bird vs control: 115 g/bird), 9.6% higher egg production (treatment: 78.5% vs control: 68.9%), lower body weight (treatment: 2057 g vs control: 2073 g), lower feed conversion ratio (FCR)/egg (treatment: 1.44 vs control: 1.69), higher egg weight (treatment: 69.4 g vs control: 68.5 g), greater egg mass (treatment: 56.14 vs control: 48.76), greater shell thickness (treatment: 3.52 mm vs control: 3.44 mm), and greater shell weight (treatment: 9.3 g vs control: 8.79 g). However, the albumin weight, yolk weight, yolk diameter, shape index, and Haugh units (HU) were not significantly (p˃0.05) affected after 75 weeks of treatment when compared with those of the control group. Therefore, this study is the first of its kind to demonstrate that different ratios of limestone, different durations and intensities of light, and different vitamin supplementation doses in the treatment group (subjected to the novel rearing recommendations described in this study) may yield a profit of 180,541 USD, exceeding the baseline profit of the control group (subjected to conventional rearing methods).

Effects of the Calls and Presence of Roosters on Egg Incubation Behavior of Nagoya Laying Hens

The incubation behavior of the Japanese Nagoya chicken breed is a commercial issue because it often causes a sudden and sharp drop in egg production. In this study, whether the incidence of incubation behavior in Nagoya laying hens was associated with calls and the presence of roosters in the same laying house was investigated. Four experiments were conducted using commercial layer-type Nagoya hens where the hatching time of the experimental birds and the treatment order in the presence of males were changed . In Experiment 1, the proportion of incubation behavior in the presence of roosters kept in another pen located between pen-rearing hens (51.3%) was higher than that in their absence (15.9%) or with only rooster calls (23.8%). In Experiments 2, 3, and 4, the proportion of incubation behavior in the presence of roosters (47.3%, 33.3%, and 37.9%, respectively) was higher than that in their absence (33.3%, 17.4%, and 25.6%, respectively). In all experiments, approximately 70% of the incubating hens observed in the absence of roosters exhibited incubation behavior, even in the presence of roosters. Therefore, the presence of roosters may enhance egg incubation behavior in Nagoya laying hens.

Endocrine and molecular regulation mechanisms of follicular development and egg-laying in quails under different photoperiods

Photoperiod is a key environmental factor in regulating bird reproduction and induces neuroendocrine changes through the hypothalamic-pituitary-gonadal (HPG) axis. OPN5, as a deep-brain photoreceptor, transmits light signals to regulate follicular development through TSH-DIO2/DIO3. However, the mechanism among OPN5, TSH-DIO2/DIO3, and VIP/PRL in the HPG axis underlying the photoperiodic regulation of bird reproduction is unclear. In this study, 72 laying quails with 8-week-old were randomly divided into the long-day (LD) group [16 light (L): 8 dark (D)] and the short-day (SD) group (8 L:16 D), and then samples were collected on d 1, d 11, d 22, and d 36 of the experiment. The results showed that compared with the LD group, the SD group significantly inhibited follicular development (P < 0.05), decreased the P4, E2, LH, and PRL in serum (P < 0.05), downregulated the expression of GnRHR, VIP, PRL, OPN5, DIO2, and LHβ (P < 0.05), reduced the expression of GnRH and TSHβ (P > 0.05), and promoted DIO3, GnIH gene expression (P < 0.01). The short photoperiod downregulates OPN5, TSHβ, and DIO2 and upregulates DIO3 expression to regulate the GnRH/GnIH system. The downregulation of GnRHR and upregulation of GnIH resulted in a decrease in LH secretion, which withdrew the gonadotropic effects on ovarian follicles development. Slow down of follicular development and egg laying may also arise from lack of PRL potentiation to small follicle development under short days.

Reducing light exposure enhances the circadian rhythm of the biological clock through interactions with the gut microbiota

Light mainly synergistically regulates the central biological clock system. In farming, long-term light exposure may induce metabolic disorders and increase the load on the liver in laying hens. In contrast, intermittent photoperiods can reduce light exposure and increase rest time to improve the health of laying hens. The circadian rhythms of gut microbes are essential for the health of the host. However, the circadian rhythms of gut microbes and how those microbes interact with the host under intermittent photoperiods are not clear. We used laying hens as a model to evaluate the circadian rhythms of gut microbes and biological clock genes under different intermittent photoperiods. Intermittent photoperiod 1 (IP1, 16 [3 h -L/1 h -D]: 8 D) enhanced the circadian rhythms of cBmal1, cBmal2, cCry1, and cCry2 in the hypothalamus and increased the expression of cClock, cBmal1, and cCry2 in the liver and seven clock genes in the cecal wall. The intermittent photoperiod also significantly altered the composition and metabolic function of the cecal microbiota via the melatonin pathway. The concentrations of short-chain fatty acids (SCFAs) and the abundance of SCFA-producing genera such as Odoribacter significantly increased under the IP1 treatment and might have further fed back into and strengthened the peripheral and central rhythms by activating the SCFA receptor gene pathway in cecal wall. These findings clarify the mediation mechanisms for the circadian rhythms of the central circadian clock and highlight the role of intermittent photoperiod-induced regulation of the interaction between the host clock and the cecal microbial community.

Lighting pattern and photoperiod affect the range use and feather cover of native laying hens under free range condition

The study aimed to investigate the effects of lighting pattern and photoperiod on range use, feather cover and gait score of native laying hens. Six hundred and thirty 19-wks-old Beijing You Chicken (BYC) pullets were randomly allocated to 6 groups with 105 birds each, 3 replicates per group, reared in individually lit indoor pens with separate covered shed and outdoor areas. A 2 × 3 factorial experiment (2 lighting patterns: continuous and intermittent lighting; 3 photoperiods: 16 h, 14 h, 12 h) was arranged indoors, including 16L:8D (6:00-22:00) for group 1; 12L:2D:4L:6D (6:00-18:00,20:00-24:00) for group 2; 14L:10D (6:00-20:00) for group 3; 10L:2D:4L:8D (6:00-16:00,18:00-22:00) for group 4; 12L:12D (6:00-18:00) for group 5, and 8L:4D:4L:8D (6:00-14:00,18:00-22:00) for group 6, respectively. The number of hens in indoor pen, covered shed and outdoor area were counted at 8:00, 9:00, 10:00, 11:00, 12:00, 13:00, 14:00 for consecutive 3 sunny days at 34 wks and 36 wks of age, feather cover and gait score of the laying hens were assessed at the end of 36 wks. The results showed that daily average hen percentage was the highest in continuous 12 h group (63.67%), and the lowest in intermittent 14 h group (58.36%) in indoor pen (P < 0.05); the daily average hen percentage was the lowest in continuous 12 h group (16.05%), and the highest in intermittent 14h group (21.22%) in outdoor area (P < 0.05). Lighting pattern significantly affected hen percentage in indoor pen and outdoor area, the hen percentage in indoor pen was higher in continuous lighting groups than in intermittent lighting groups (62.09% vs. 59.23%) (P < 0.05), the hen percentage in outdoor area was lower in continuous lighting groups than in intermittent lighting groups (16.60% vs. 19.95%) (P < 0.05). Photoperiod had no effect on the hen percentage (P > 0.05), but time of day affected the hen percentage in different areas (P < 0.05). The feather cover score was higher in intermittent lighting groups than in continuous lighting groups (17.43 vs. 15.04, P < 0.05). The average hen percentage in indoor pen is strongly negatively correlated with the feather cover score (r = -0.880, P = 0.050), and the hen percentage in outdoor area is strongly positively correlated with the feather cover score in intermittent lighting condition (r = 0.811, P < 0.05). The present study suggested that more range use is beneficial for the feather cover and physical health of laying hens under free range condition, and intermittent lighting is more conducive to range use and feather cover of native laying hens, which may be related to its affecting hens' rhythmic activities, increasing adaptation to outdoor environment, and reducing the incidence of feather pecking and parasites.

Effect of Changes in Photoperiods on Melatonin Expression and Gut Health Parameters in Laying Ducks

We investigated the effect of photoperiod on ileal morphology, barrier function, short-chain fatty acid (SCFA) contents, microbial flora, melatonin expression, and synthesis in laying ducks. After adaption, a total of 180 Jinding laying ducks (252 days old) were randomly divided into three treatments, receiving 12L (hours of light):12D (hours of darkness), 16L:8D, or 20L:4D. Each treatment had six replicates with 10 birds each. The formal experiment lasted 58 days. Compared with 12L:12D, the significantly higher values of villus height and goblet cell percentage (GCP) were observed in 16L:8D treatment, accompanied with the higher mRNA relative expression of zonula occludens-1, zonula occludens-2, zonula occludens-3, claudin-1, occludin, and mucin 2 (P < 0.05). Besides, significantly higher values of acetate and propionate, butyrate and total SCFA concentrations were simultaneously observed in ileal chyme of 16L:8D treatment (P < 0.05). For the ileal microbial community, the results of principal coordinate analysis (PCoA) visually presented that three photoperiod groups were mainly scattered into three clusters, indicating that the microbiota composition in different photoperiod treatments were quite dissimilar. Lower values of Shannon indicators were observed in the 20L:4D treatment (P < 0.05), meaning that the microbiota α-diversity decreased in the 20-h photoperiod. The relative abundance of Actinobacteria, Fusobacteria, and Proteobacteria at phylum level and Fusobacterium, Clostridium_sensu_stricto_1, and Pectobacterium at genus level kept an appropriate balance in the 16L:8D photoperiod. Melatonin level in serum decreased with the increasing photoperiods at 6:00 and 12:00, which was consistent with melatonin receptor expressions in the hypothalamus and ileal tissue. Meanwhile, the adenosine 3′,5′-cyclic phosphate (cAMP) contents were significantly downregulated in the pineal gland (P < 0.05), in response to the increase in photoperiod. In conclusion, an appropriate photoperiod could improve ileal morphology, barrier function, SCFA profile, and microbial flora, which may be attributed to the appropriate regulation of the circadian rhythm through melatonin as well as its receptor expression, and 16 h could be an adequate photoperiod for laying ducks.

Effects of light regime on circadian rhythmic behavior and reproductive parameters in native laying hens

The paper aimed to study the effects of light regime on circadian rhythmic behavior and reproductive parameters in a native laying hen, Beijing You Chicken (BYC) during 22 to 30 wk. A total of 630 19-wk-old BYC female chicken were allocated to 6 light regime groups with 3 replicates per group and 35 birds per replicate, reared in individually lit floor pens with separate outdoor areas. A 2 × 3 factorial experiment (2 lighting patterns: continuous and intermittent lighting; 3 photoperiods: 16 h, 14 h, 12 h) was arranged, including 16L:8D for group 1; 12L:2D:4L:6D for group 2; 14L:10D for group 3; 10L:2D:4L:8D for group 4; 12L:12D for group 5, and 8L:4D:4L:8D for group 6, respectively. The circadian rhythmic behavior of the hens, including feeding, egg-laying and sleeping behaviors were observed by scan sampling and target sampling method for consecutive 3 d every other week during 22 to 30 wk. Infrared cameras were set outside each pen to record the rhythmic behaviors of the birds every other hour (6:00–7:00;8:00–9:00;10:00–11:00;12:00–13:00;14:00–15:00;16:00–17:00;18:00–19:00;20:00–21:00;22:00–23:00;0:00–1:00;2:00–3:00;4:00–5:00). Theovarian weight, oviduct weight, oviduct length, the number of large yellow follicles (LYF), and small yellow follicles (SYF) were measured at the end of 30 wk. The egg-laying rate during 22 to 30 wk was measured. The results showed that the highest feeding frequency was given by the 16L:8D, and the lowest given by the 12L:12D (P < 0.05). The average feeding duration was the longest in the 8L:4D:4L:8D at 6:00 to 8:00 (18.67 min/hen) (P < 0.05), and the shortest in the 8L:4D:4L:8D at 18:00 to 20:00 (3.75 min/hen) (P < 0.05). The highest egg-laying frequency was given by the 8L:4D:4L:8D (0.28), the lowest given by the 10L:2D:4L:8D (0.21) (P < 0.05). The shortest egg-laying duration occurred at 6:00 to 8:00, was given by the 16L:8D (8 min/hen), and the longest egg-laying duration occurred at 18:00 to 20:00, was given by 16L:8D and 8L:4D:4L:8D (>20.5 min/hen) (P < 0.05). The highest sleeping frequency was given by the 12L:2D:4L:6D, the lowest was given by the 12L:12D (P < 0.05). At 6:00 to 8:00, the shortest sleeping duration was given by 12L:2D:4L:6D (1.5 s/hen), at 18:00 to 20:00, the longest given by 8L:4D:4L:8D (14.3 s/hen) (P < 0.05). Lighting pattern and photoperiod alone or in interaction had no effect on egg-laying rate during 22 to 30 wk (P > 0.05), but had significant effects on ovarian weight, oviduct weight, oviduct length, the number of LYF and SYF (P < 0.05), and the continuous groups were all significantly higher than the intermittent groups (P < 0.05). The present study indicated that light regimes affected the frequency and duration of circadian behavior in BYC laying hens, and the continuous light was more beneficial to the reproductive development than the intermittent light in the early laying period.

Effect of smooth switching the light on/off under intermittent LED lighting on the productivity of laying hens

The influence of smooth switching the light on/off on the productivity and viability of laying hens of the SP-789 cross was studied. In the experiments, three identical groups of 120-day-old birds were formed. In the first preliminary experiment, poultry was raised up to 410 days of age, in the second main experiment it was raised up to 350 days of age. All birds were kept in cage batteries under intermittent LED lighting. The light was turned on at 2-3 am, 8-12 am, and 2-5 pm. In both experiments, lights were switched on and off instantaneously in the control group. In the first preliminary experiment, the sunrise and sunset imitations took place each time the light was switched on and off, and lasted 3 minutes in the experimental group No.1 and 6 minutes in the experimental group No. 2. In the second main experiment, in the experimental group No.1 the mode of imitation of sunrise and sunset was similar to that of the experimental group No. 1 of the first preliminary experiment. In the experimental group No. 2, sunrise was simulated only during the first light turn on, and sunset was simulated during the last light turn off (3 min). The best results were obtained in the group with smooth switching the light on at the beginning of the first photoperiod and smooth switching the light off at the end of the last photoperiod (for 3 min). As compared with control, this group showed an increased livestock livability (91.7%) by 1.9%, egg production (171.6 eggs) and yield of egg weight (9.81 kg) per initial and average laying hen by 7.3% and 6.5%. Feed efficiency per 10 eggs (1.33 kg) and 1 kg of egg weight (2.32 kg) decreased by 5.0% and 4.5% respectively.

Effects of lighting regimes on performance, pineal melanopsin expression and melatonin content in native laying hens aged from 19 to 34 weeks

Melanopsin, a key light sensitive pigment, plays an important role in the regulation of bio-rhythm and photo-adaptation in poultry. This study aimed to investigate the effects of different lighting regimes on performance, pineal melanopsin expression and melatonin content in a native chicken, Beijing You Chicken (BYC) aged from 19 to 34 wk. A total of 900 nineteen-wk-old BYC female chicken having no significant body weight differences were randomly allocated to 3 groups with 3 replicates each, 100 birds each replicate, reared in individually lit floor pens with separate outdoor areas. Three different lighting regimes were used, including continuous 16 h (16L:8D, 6:00–22:00) for group 1, intermittent 16 h (12L:2D:4L:6D, 6:00–18:00, 20:00–24:00) for group 2, and continuous 12 h (12L:12D, 6:00–18:00) for group 3, respectively. The performance was measured for 19 to 34 wk. Serum melatonin (Mel), prolactin (Prl), luteinizing hormone (LH), and 17-beta estradiol (E2) contents were measured at 24 wk, 29 wk, and 34 wk of age, the relative expression of pineal melanopsin gene (Opn4 mRNA) was measured on 1 d at 9:00, 13:00, 17:00, 21:00, 1:00, and 5:00 at 29 wk of age, and at the end of 29 wk and 34 wk. The results showed that the egg mass, egg-laying rate, and feed egg ratio of BYC were not affected by lighting regimes for 19 to 34 wk (P > 0.05), except for the average feed intake (AFI) (P < 0.05). The AFI in the 12L:12D group was significantly higher than that in the 16L:8D group (P < 0.05), but had no difference with that in the 12L:2D:4L:6D group. The pineal Opn4 mRNA level was significantly upregulated in the 12L:2D:4L:6D group and downregulated in the 12L:12D group when compared with 16L:8D group at 29 and 34 wks of age (P < 0.05). The Mel content in the 16L:8D group was lower than that in the other 2 groups at 29 wk of age (P < 0.05), there was no difference in Mel content between 16L:8D group and 12L:2D:4L:6D group at 34 wk of age (P > 0.05). The present study suggested that the pineal melanopsin expression of the birds in the intermittent 16 h lighting group was higher than in the continuous 16 h and 12 h lighting group, and a significant negative correlation was found between melanopsin expression and Mel content at 34 wk of age, which may interact to promote the photo-adaptation of the native chicken and affect the future laying performance.

Ovarian transcriptome profile from pre-laying period to broody period of Xupu goose

Xupu goose, a breed from Hunan province, produces high quality and quantity of meat and liver. However, its egg production rate is low, with poor reproductive traits but strong broody performance. These characteristics decrease the economic value of Xupu goose significantly. Here, RNA-seq was used to analyze the transcriptome changes of ovaries of Xupu goose at different stages to explore the molecular mechanism of reproduction from the pre-laying period to the broody period. A total of 258 genes were differentially expressed in the 3 stages. These genes are associated with inflammation, reproduction, mutual recognition and adhesion between cells, and cytoskeleton formation, and so on. In particular, we report, for the first time, the expression patterns of MRP126, serglycin, TXNIP, and FZD2 during the pre-laying, egg-laying, and broody periods of goose ovaries. Functional analysis by GO annotation revealed that GO terms were mainly involved in actin, cell signal transduction and regulation, and cellular components. Three pathways, including focal adhesion (gga04510), ECM-receptor interaction (gga04512), and N-Glycan biosynthesis (gga00510), were significantly enriched in the three groups. These findings provide a basis for further exploration of profiles of goose ovaries to improve egg production of Xupu goose.

The transcriptomic blueprint of molt in rooster using various tissues from Ginkkoridak (Korean long-tailed chicken)

BACKGROUND

Annual molt is a critical stage in the life cycle of birds. Although the most extensively documented aspects of molt are the renewing of plumage and the remodeling of the reproductive tract in laying hens, in chicken, molt deeply affects various tissues and physiological functions. However, with exception of the reproductive tract, the effect of molt on gene expression across the tissues known to be affected by molt has to date never been investigated. The present study aimed to decipher the transcriptomic effects of molt in Ginkkoridak, a Korean long-tailed chicken. Messenger RNA data available across 24 types of tissue samples (9 males) and a combination of mRNA and miRNA data on 10 males and 10 females blood were used.

RESULTS

The impact of molt on gene expression and gene transcript usage appeared to vary substantially across tissues types in terms of histological entities or physiological functions particularly related to nervous system. Blood was the tissue most affected by molt in terms of differentially expressed genes in both sexes, closely followed by meninges, bone marrow and heart. The effect of molt in blood appeared to differ between males and females, with a more than fivefold difference in the number of down-regulated genes between both sexes. The blueprint of molt in roosters appeared to be specific to tissues or group of tissues, with relatively few genes replicating extensively across tissues, excepted for the spliceosome genes (U1, U4) and the ribosomal proteins (RPL21, RPL23). By integrating miRNA and mRNA data, when chickens molt, potential roles of miRNA were discovered such as regulation of neurogenesis, regulation of immunity and development of various organs. Furthermore, reliable candidate biomarkers of molt were found, which are related to cell dynamics, nervous system or immunity, processes or functions that have been shown to be extensively modulated in response to molt.

CONCLUSIONS

Our results provide a comprehensive description at the scale of the whole organism deciphering the effects of molt on the transcriptome in chicken. Also, the conclusion of this study can be used as a valuable resource in transcriptome analyses of chicken in the future and provide new insights related to molt.

Long noncoding RNAs profiling in ovary during laying and nesting in Muscovy ducks (Cairina moschata)

There are recent reports of the important functions of long noncoding RNAs (lncRNAs) in female reproductive and ovarian development. Studies in which there was characterization of lncRNAs in the ovaries of laying compared with nesting poultry, however, are limited. In this study, RNA libraries were constructed by obtaining sequencing data of ovarian tissues from laying and nesting Muscovy ducks. In the ovarian tissues of Muscovy ducks, a total of 334 differentially abundant mRNA transcripts (DEGs) and 36 differentially abundant lncRNA transcripts were identified in the nesting period, when compared with during the laying period. These results were subsequently validated by qRT-PCR using nine randomly-selected lncRNAs and six randomly-selected DAMTs. Furthermore, the cis- and trans-regulatory target genes of differentially abundant lncRNA transcripts were identified, and lncRNA-gene interaction networks of 34 differentially abundant lncRNAs and 263 DEGs were constructed. A total of 7601 lncRNAs neighboring 10,542 protein-coding genes were identified and found to be enriched in the Wnt signaling pathway and oocyte meiosis pathways associated with follicular development. Overall, only 11 cis-targets and 57 mRNA-mRNA except trans-targets were involved in the lncRNA-gene interaction networks. Based on the interaction networks, nine DEGs were trans-regulated by differentially abundant lncRNAs and 20 differentially abundant lncRNAs were hypothesized to have important functions in the regulation of broodiness in Muscovy ducks. In this study, a predicted interaction network of differentially abundant lncRNAs and DEGs in Muscovy ducks was constructed for the first time leading to an enhanced understanding of lncRNA and gene interactions regulating broodiness.

Effects of photoperiod on performance, ovarian morphology, reproductive hormone level, and hormone receptor mRNA expression in laying ducks

We investigated the effect of photoperiod on performance, ovarian morphology, reproductive hormones levels, and their receptors mRNA expressions in laying ducks. After adaption, 300 252-day-old Jinding laying ducks were randomly allocated to 5 groups, receiving 12L:12D, 14L:10D, 16L:8D, 18L:6D, or 20L:4D, respectively. Each treatment had 6 replicates of 10 birds each. The feeding trial lasted 8 wk. Egg production, egg mass, and ADFI increased linearly and quadratically with increasing photoperiods (P < 0.05), and the higher values of them occurred in photoperiods ≥ 16 h, compared with 12L:12D (P > 0.05). Initial and bare stroma weight increased quadratically, while total large white follicle (LWF) number and weight increased linearly and quadratically, with increasing photoperiods (P < 0.05). The higher values of them occurred in 16L:8D and 18L:6D treatments as well as the higher total LWF weight also occurred in 20L:4D, compared with 12L:12D (P > 0.05). Besides, 16.93 and 16.93 h were the optimal photoperiods for bare stroma (follicles ≥ 2 mm in diameter removed) weight and total LWF weight, respectively, calculated from reliable regression equations (R² ≥ 0.5071). Compared with 12L:12D, the higher levels of estradiol, progesterone, follicle-stimulating hormone (FSH) as well as the higher expressions of estrogen, luteinizing hormone (LH) and progesterone receptors were observed in ≥16 h photoperiods (P < 0.05), while the higher LH level and FSH receptor expression only occurred in 16L:8D and 18L:6D (P < 0.05). In the hypothalamus, higher mRNA expression of gonadotropin-releasing hormone occurred in 16L:8D and 18L:6D groups (P < 0.05). Meanwhile, gonadotropin-inhibitory hormone and prolactin increased in 20-hour photoperiod (P < 0.05), and the latter may be due to theup-regulation of vasoactive intestinal peptide expression (P < 0.05). To sum up, an appropriate photoperiod could improve the performance and reproductive organ and ovarian follicles development through reproductive hormones and their receptors, and 16.56 to 10.93 h is an adequate photoperiod for laying ducks.

The effect of parachlorophenylalanine treatment on the activity of gonadal and lactotrophic axes in native Polish crested chickens stimulated to broodiness

Brooding behavior, a common characteristic of native breeds of the domestic chicken, is marked by elevated prolactin (PRL) levels, which is necessary for incubation and connected with changes in hypothalamic–pituitary–gonadal axis activity. Evidence indicates the serotoninergic system is a potent modulator of PRL secretion. The objective of this study is to investigate whether blocking serotonin synthesis with parachlorophenylalanine (PCPA) prevents incubation behavior in native Polish crested chickens. In addition, we examined the effect of PCPA on the gene expression of the gonadal and lactotrophic axes. Birds were stimulated to broodiness by artificial eggs in nests. At 34 wk of age (April: spring period), the hens were divided into 2 groups (14 hens in each group): control and PCPA-treated (50 mg/kg BW) group. After 5 wk of treatment, the artificial eggs were removed from the nests. Egg production, incubation activity, and levels of plasma ovarian steroids progesterone (P4), testosterone (T), estradiol (E2), and PRL were examined. At the end of the experiment (45 wk of age, June: summer period), ovarian characteristics and mRNA gene expression of gonadal (gonadotropin-releasing hormone [GnRH] I, luteinizing hormone [LH] ß, follicle-stimulating hormone [FSH] ß) and lactotrophic (vasoactive intestinal peptide [VIP], PRL) axes were measured by quantitative real-time PCR. Incubation activity was observed in the hens of both groups but with lower frequency in PCPA-treated birds. Moreover, the PCPA group had a higher cumulative egg production than the controls. During the first six and 8 wk of the experiment, levels of P4 and E2, respectively, were similar in both groups, but all concentrations increased in the PCPA-treated hens after this period. In addition, increased GnRH-I, LHß, and FSHß and decreased VIP mRNA expression was observed in the PCPA group compared with the controls. There were no differences in PRL mRNA expression, the PRL level, and ovarian morphometry between the 2 groups. These results indicate that blockage of serotonin synthesis by PCPA does not effectively prevent incubation in native Polish crested chickens. However, treatment with PCPA increased gonadal axis activity and improved reproductive performance.

Differential gene expression profiling of the goose pineal gland

1. The present study was conducted to obtain a better understanding of the molecular mechanisms underlying broodiness in a commercial breed, Tianfu geese, as little is known about the role of the pineal gland in this period. The aim was to identify genes which are differentially expressed in the pineal gland between the laying and broodiness periods by performing a transcriptome screen.2. After sequencing cDNA derived from the pineal gland and annotation of the results, a sequencing depth of 14.82 and 18.17 million mapped tags was obtained during the laying and broodiness periods, respectively, and a total of 120 differentially expressed genes were identified. Of these, 32 genes showing up-regulated expression and 88 genes showing down-regulated expression were identified in broodiness period vs. laying period libraries.3. Gene ontology (GO) analyses showed that these genes were related to the visual process, phototransduction, and lipoprotein metabolism. Kyoto Encyclopaedia of Genes and Genome (KEGG) analyses showed that phototransduction and tryptophan metabolism pathways exhibited the largest enrichment factors. The reliability of the RNA sequence data was confirmed by quantitative real-time PCR analysis of five genes, and the results were mostly consistent with those from the high-throughput RNA sequencing.4. The goose transcriptome and the identification of differentially expressed genes provided comprehensive gene expression information that enables a better understanding of the molecular mechanisms underlying the broodiness period of geese.

Comparison of the broody behavior characteristics of different breeds of geese

A low laying performance in goose is one of the key factors preventing the industrial development, and the laying performance is related to broody behavior. However, the characteristics of broody behavior in geese remain unclear. In this study, the total 144 geese (300 day old), including Zhedong geese (Anser cygnoides), Sichuan geese (Anser cygnoides), and Carlos geese (Anser anser) were selected and assigned to 1 of 3 groups/breed (including 4♂+12♀). Laying and broody behaviors were recorded using the infrared video cameras from 2016 November 11 to 2017 June 15. The broody behavior was detected in 19.4% of Carlos geese, 33.3% of Sichuan geese, and 100% of Zhedong geese. Different goose breeds showed similar behavior characteristics. The low frequency of feeding, drinking, and low body weight were observed in the middle of broodiness. As the brooding progressed, the body temperature showed a downward trend and then recovered, whereas no difference was observed in Carlos goose. In addition, the plasma hormone concentration from different breeds and stages of broodiness were compared. The contents of FSH (follicle-stimulating hormone) and LH (luteinizing hormone) in geese were greater in the laying stage than that in the broody stage. Fewer FSH and LH were detected in Zhedong geese and Carlos geese, more in Sichuan geese. In broody goose, the PRL (prolactin) concentrations of the 3 goose breeds peaked in the middle of broodiness, and greater PRL was detected in Sichuan geese than those in Carlos geese and Zhedong geese. Finally, we compared egg production between the broody and non-broody geese in the observation period. The egg production of broody Carlos geese was 27, which was significantly higher than non-broody geese (14 eggs), while in Sichuan geese there was no significant difference between broody (24 eggs) and non-broody geese (26 eggs). Finally, the higher egg production was found with the more broody times in Zhedong geese. Taken together, although the different goose breeds showed similar broody behavior characteristics, the broody rate and hormone secretion were dissimilar, and the Zhedong geese exhibited strong broody feature.

Intermittent lighting regime as a tool to enhance egg production and eggshell thickness in Rhode Island Red laying hens

Influences of intermittent light regime as a tool to enhance egg production, egg quality, and blood parameters of laying hens were investigated. A total of 270 hens of Rhode Island Red (during 20 to 36 wk of age) were used to investigate the effects of intermittent light regime in completely randomized design. The birds were divided into 3 equal groups (6 replicates of 15 birds each) and housed in floor pens. The first group was served as non-treated control (C) and was exposed to continuous and constant light for 16 h light/day throughout the experimental period. Whereas, birds of the other groups were exposed to intermittent lights for 20 min/h + 40 min of constant light (T1; FLASH20) and 40 min/h + 20 min of constant light (T2; FLASH40) during the 16 h of light period. Hens of T1 group showed significantly (P ≤ 0.05) the highest concentration of total antioxidant capacity and the lowest one of malondialdehyde in comparison with the other groups. Hens of T1 group had significantly (P ≤ 0.05) the greatest egg laying rate and egg mass in comparison with the other counterparts. Feed consumption was similar in the groups under study. Hens exposed to FLASH20 had the lowest (P ≤ 0.05) FCR when compared with the other treatments. Eggs produced from hens exposed to FLASH20 had the highest value of shell thickness followed by the control and then that of those exposed to FLASH40. There were insignificant differences among the treatments in body weight of hens and all of other egg quality and egg problem traits. In conclusion, intermittent light regime of 20 min/h was the most efficient in comparison with the other ones. Finally, intermittent light regime of 20 min/h during laying period (during 20 to 36 wk of age) is highly recommended.

Transcriptome analysis revealed the possible regulatory pathways initiating female geese broodiness within the hypothalamic-pituitary-gonadal axis

Geese have the strongest tendency toward broodiness among all poultry. The mechanisms initiating broodiness within the goose hypothalamic-pituitary-gonadal axis (HPGA) are still unclear. Here, we reported the transcriptome differences between laying and initial nesting within the HPGA tissues of geese. We constructed a unigene database based on HPGA tissues and identified 128,148 unigenes, 100% of which have been annotated. By using Digital Gene Expression (DGE) sequencing, we screened 19, 110, 289, and 211 differentially expressed genes (DEGs) in the hypothalamus, pituitary gland, stroma ovarii, and follicles, respectively, between laying and nesting geese. Expression changes of hypocretin (HCRT) and pro-opiomelanocortin (POMC) in the hypothalamus of nesting geese may cause appetite reduction, which is possibly the first step and a prerequisite to initiate broodiness. In addition to prolactin (PRL), follicle-stimulating hormone (FSH) and luteinizing hormone (LH), genes including oxytocin-neurophysin (OXT), chordin-like protein 1 (CHRDL1) and growth hormone (GH), expressed in the pituitary gland, are new candidate molecules that may be involved in broodiness in geese. Heme oxygenase 1 (HMOX1) in the pituitary gland, the proto-oncogene c-Fos (FOS), heat shock protein 90-alpha (HSP90AA), and cyclin-dependent kinase 1 (CDK1) in the ovary that may consolidate and transduce signals regulating the HPGA during broodiness in geese.

Transcriptome analysis of follicles reveals the importance of autophagy and hormones in regulating broodiness of Zhedong white goose

Broodiness, a maternal behavior and instinct for natural breeding in poultry, inhibits egg production and affects the poultry industry. Phenotypic and physiological factors influencing broodiness in poultry have been extensively studied, but the molecular regulation mechanism of broodiness remains unclear. Effective research strategies focusing on broodiness are hindered by limited understanding of goose developmental biology. Here we established the transcriptomes of goose follicles at egg-laying and broody stages by Illumina HiSeq platform and compared the sequenced transcriptomes of three types of follicles (small white, large white and small yellow). It was found that there were 92 up-regulated and 84 down-regulated transcription factors and 101 up-regulated and 51 down-regulated hormone-related genes. Many of these genes code for proteins involved in hormone response, follicular development, autophagy, and oxidation. Moreover, the contents of progesterone and estradiol in follicles were altered, and the autophagy levels of follicles were enhanced during the broody stage. These results suggest that hormone- and autophagy-signaling pathways are critical for controlling broodiness in the goose. We demonstrated that transcriptome analysis of egg-laying and broody Zhedong white goose follicles provided novel insights into broodiness in birds.

Goose broodiness is involved in granulosa cell autophagy and homeostatic imbalance of follicular hormones

Broodiness is observed in most domestic fowls and influences egg production. The goose is one of the most important waterfowls, having strong broody behavior. However, whether autophagy and follicular internal environment play a role in the broodiness behavior of goose is unknown. In this report, we analyzed the follicular internal environment and granulosa cell autophagy of goose follicles. The results show that the contents of hormones, including prolactin (PRL), progesterone (P4), and estradiol (E2), increased in broody goose follicles. Most importantly, the level of granulosa cell autophagy in broody goose follicles was elevated, detected by electron microscopy and western blotting. Also, the expressions of positive regulators of autophagy, including miR-7, miR-29, miR-100, miR-181, PRLR, LC3, p53,Beclin1, Atg9, and Atg12, were up-regulated and the expressions of negative regulators of autophagy, including miR-34b and miR-34c, were down-regulated in broody goose follicles. Our results suggest that goose broodiness is involved in increased granulosa cell autophagy and homeostasis imbalance of internal environment in the follicles. This work contributes to our knowledge of goose broodiness and may influence egg production.