Comb size and estrogen levels toward the onset of lay in broiler and layer strain females under ad libitum and restricted feeding

Eitan, Y.; Soller, M.; Rozenboim, Israel

doi:10.1093/ps/77.11.1593

Cited by 25 publications

(22 citation statements)

References 14 publications

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“…In leghorns, early-maturing hens began laying at a similar body weight to that of hens that matured later, indicating that there is a relation between body weight of birds and initiation of lay (Dunnington and Siegel, 1984). Eitan et al (1998) found that restricted feeding slightly, albeit not significantly, delayed the onset of lay in layers, suggesting that birds had met their threshold body weight to initiate lay. Interactions between body weight, fat deposition, and sexual maturation following photostimulation have also been reported in broiler breeders (Pishnamazi et al, 2014).…”

Section: Discussionmentioning

confidence: 89%

Evaluation of the Impact of Light Source on Reproductive Parameters in Laying Hens Housed in Individual Cages

Baxter

Bédécarrats

2019

J. Poult. Sci.

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Higher light wavelengths have been shown to stimulate extra-retinal photoreceptors more efficiently than lower wavelengths to promote reproduction in poultry. We developed a light emitting diode (LED) bulb that emits 60% of its light in the red spectrum (LED-R), and evaluated the effects of different light sources on growth and reproduction in commercial layer hens. Three rooms equipped with either 100 W incandescent, 15 W compact fluorescent (CFL), or 10 W LED-R bulbs were populated with 96 Lohmann LSL-Lite layers housed in individual cages from 14 to 69 weeks of age (woa). Pullets were initially maintained on a 10-h photoperiod, then photostimulated at 18 woa. Surprisingly, regardless of the light source, plasma levels of estradiol peaked at 16 woa, 2 weeks before photostimulation, and egg-laying was initiated at 19 woa. As a direct correlation between age at first egg and body weight was identified, metabolic cues most likely served as a primary trigger to initiate sexual maturation prior to photostimulation. Overall egg production and cumulative egg numbers were similar among treatments. Interestingly, a second increase in estradiol was observed at 52 woa under all treatments, suggesting an additional ovarian stimulation, possibly associated with an additional follicular recruitment at that age. Overall, changes in estradiol concentrations were more pronounced in hens maintained under LED-R light than in hens exposed to incandescent and CFL, especially for the second increase, suggesting that a higher amount of red light leads to stronger ovarian activity. Maintaining hens under LED-R bulbs also resulted in lower feed consumption, which combined with the lower energy consumption of LED-bulbs (LED-R: 306 kW; incandescent: 2,514 kW; CFL: 422 kW) could reduce the production cost.

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Section: Discussionmentioning

confidence: 89%

Evaluation of the Impact of Light Source on Reproductive Parameters in Laying Hens Housed in Individual Cages

Baxter

Bédécarrats

2019

J. Poult. Sci.

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“…For female chickens, as the pullets advance into sexual maturity, the comb begins to get larger, and plasma estrogen level increases [ 8 ]. After sexual maturation, the comb will be fully developed by sex hormones, such as androgen, estrogen and testosterone [ 33 ]. While hens are laying, the comb begins to redden and with loss of comb redness ovarian regression occurs [ 67 ].…”

Section: Discussionmentioning

confidence: 99%

“…The CL and CH were measured to the nearest 0.01 mm with a Vernier caliper. CL and CH were measured in accordance with the study by Eitan [ 33 ]. The CW was measured to the nearest 0.1 g on an electronic balance.…”

Section: Methodsmentioning

confidence: 99%

Genome-Wide Association Studies for Comb Traits in Chickens

Shen

et al. 2016

PLoS ONE

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The comb, as a secondary sexual character, is an important trait in chicken. Indicators of comb length (CL), comb height (CH), and comb weight (CW) are often selected in production. DNA-based marker-assisted selection could help chicken breeders to accelerate genetic improvement for comb or related economic characters by early selection. Although a number of quantitative trait loci (QTL) and candidate genes have been identified with advances in molecular genetics, candidate genes underlying comb traits are limited. The aim of the study was to use genome-wide association (GWA) studies by 600 K Affymetrix chicken SNP arrays to detect genes that are related to comb, using an F2 resource population. For all comb characters, comb exhibited high SNP-based heritability estimates (0.61–0.69). Chromosome 1 explained 20.80% genetic variance, while chromosome 4 explained 6.89%. Independent univariate genome-wide screens for each character identified 127, 197, and 268 novel significant SNPs with CL, CH, and CW, respectively. Three candidate genes, VPS36, AR, and WNT11B, were determined to have a plausible function in all comb characters. These genes are important to the initiation of follicle development, gonadal growth, and dermal development, respectively. The current study provides the first GWA analysis for comb traits. Identification of the genetic basis as well as promising candidate genes will help us understand the underlying genetic architecture of comb development and has practical significance in breeding programs for the selection of comb as an index for sexual maturity or reproduction.

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“…Follett (1991) suggested that 2 months of short days would dissipate photorefractoriness (sic, when birds are fed ad libitum), but it is possible that more than 2 months is required to obtain photosensitivity in feed-restricted birds. Eitan et al (1998) and Eitan and Soller (2001) suggested that feed restriction per se decreases photoperiod responsiveness, putting forward two alternative explanations for the effect: (a) sexual maturation is delayed endo-physiologically during feed control in anticipation of better breeding conditions, or (b) that a simple nutritional imbalance is created by the feed restriction. A further possibility is that at 10 weeks of age the hypothalamic-pituitary axis of feed-restricted birds is still insufficiently developed to permit a photosexually induced increase in follicle stimulating hormone (FSH) release.…”

Section: Current Datamentioning

confidence: 99%

Photorefractoriness in broiler breeders: Sexual maturity and egg production evidence

Ciacciariello

Gous

2003

British Poultry Science

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1. Photorefractoriness was assessed in two lines of broiler breeders. In one trial, male-line and female-line pullets were reared on the floor and transferred to individual cages at 15 weeks. Birds were either maintained on 8-, 11- or 16-h photoperiods or transferred from 8- to 16-h photoperiods at 67 or 124 d. In the second trial, female-line pullets were concurrently housed in the same rearing facilities as trial 1 and transferred to adult floor-pens at 12 weeks. These birds were either maintained on 11- or 16-h photoperiods or transferred from 8- to 11-h or from 8- to 16-h photoperiods at 140 d. 2. In the cages, male-line and female-line birds responded similarly to the lighting treatments, but with the male-line maturing 1 to 2 weeks later than the female-line in each case. Birds on constant 11-h photoperiods matured 3 to 8 d earlier than constant 8-h birds, but 3 weeks earlier than constant 16-h birds. Birds photostimulated at 67 d matured at a similar time to constant 16-h birds, but almost 7 weeks later than those transferred from 8 to 16 h at 124 d. In the floor facilities, constant 11-h birds matured 3 weeks earlier than constant 16-h birds, but almost 2 weeks later than either of the photostimulated groups. Birds transferred from 8 to 16 h matured 4d earlier than those transferred from 8 to 11 h. 3. Caged birds maintained on 16 h or transferred from 8 to 16 h at 67 d laid at least 24 fewer eggs, and had more hens not laying at 58 weeks, than birds maintained on 11-h days or those transferred from 8 to 16 h at 124 d. In the floor-pens, constant 11-h and both photostimulated groups produced about 20 more eggs to 56 weeks of age than the constant 16-h controls. 4. Collectively, these findings indicate that conventionally managed broiler breeders exhibit photorefractoriness. Additionally, a combination of photorefractoriness and controlled feeding appears to prevent broiler breeders from being photoresponsive until at least 10 weeks of age, and to cause some individuals still to be photoperiodically non-responsive at 18 weeks.

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Comb size and estrogen levels toward the onset of lay in broiler and layer strain females under ad libitum and restricted feeding

Cited by 25 publications

References 14 publications

Evaluation of the Impact of Light Source on Reproductive Parameters in Laying Hens Housed in Individual Cages

Evaluation of the Impact of Light Source on Reproductive Parameters in Laying Hens Housed in Individual Cages

Genome-Wide Association Studies for Comb Traits in Chickens

Photorefractoriness in broiler breeders: Sexual maturity and egg production evidence

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