Use of Artificial Lighting to Increase Photoperiod Length for Pasture-Raised Laying Hens to Improve Egg Productivity and Quality

Project Overview

Project Type: Graduate Student
Funds awarded in 2014: $10,997.00
Projected End Date: 12/31/2015
Grant Recipient: Texas A&M University-Commerce
Region: Southern
State: Texas
Graduate Student:
Major Professor:
Dr. Jackie Wahrmund
University of Kentucky

Annual Reports


  • Animals: poultry


  • Animal Production: free-range, grazing management, housing, pasture fertility, range improvement
  • Crop Production: food product quality/safety
  • Education and Training: demonstration
  • Farm Business Management: budgets/cost and returns, new enterprise development, whole farm planning
  • Soil Management: organic matter, soil analysis, soil chemistry


    This project investigated the effects of commercial-style photoperiod in a sustainable-style management practice on laying hen deposition rate. Twenty-seven hens were raised in identical conditions.  Three breeds were represented by nine hens each.   Within each breed, three hens were randomly assigned to one of three groups, resulting in three groups of nine hens. Each group was randomly assigned to a coop, and each coop was assigned a management system treatment.  Treatments included: commercial (COM), pasture-raised (PAST) and pasture-raised with an extended, commercial-style photoperiod (PEP). The COM hens were raised indoors with ad libitum feed and a photoperiod of twelve to fourteen hours. This photoperiod became progressively longer as the study progressed. Housing for the PAST hens was identical to that of the COM hens; however, PAST hens had no extended photoperiod and were provided additional access to ten square meters of pasture per hen. Housing for the PEP hens was identical to that of the PAST hens with an additional photoperiod of twelve to fourteen hours. Hen deposition rate was measured once per week over a 56-day period.  Egg quality was measured periodically throughout the experiment.


    The purpose of this project is to investigate a novel method of increasing the productivity of pasture-raised laying hens.  With increasing feed costs, high animal welfare standards preferred by the public, and a movement toward sustainable and natural production practices, poultry scientists and producers are exploring the viability and effectiveness of new production practices.  In the late 1990’s, a directive was introduced to the European Community to ban the use of battery cages for layers by 2012 (Mugnai et al., 2009). Similar legislation has also been passed in the United States such as California’s Prop 2 in 2008, which dramatically increases the minimal amount of square inches per hen in a hen house and also mandates that eggs imported into California from other states meet these same requirements (California Proposition 2, 2008). This law was implemented in 2014. As a result, researchers should investigate alternative and cost-effective egg production practices outside of the usual commercial practices.

    Raising hens on pasture is a popular alternative for many small poultry producers; however, egg production is generally lower in this management system.  Researchers have demonstrated that hens raised on pasture can maintain similar deposition rates as commercial hens in the spring when pastures are generally high in nutrients and daylight hours are long. However, they struggle to maintain the same deposition rate in late summer, autumn and winter (Van Elswyk, 1997; Bubier, 1998; Mugnai et al., 2009; Castellini et al., 2012; Mugnai et al., 2012).  Researchers have also demonstrated that egg quality and nutrient levels are improved when hens are raised on pasture (Mugnai et al., 2009; Mugnai et al., 2012).  Sustainable egg producers will find benefit in maintaining high deposition rates throughout the year while also maintaining high egg quality standards. In addition, the alternative production systems, including pasture production systems, are widely considered to be more humane than caged and free range production systems (Appleby and Hughes, 1991).

    Photoperiod is the length of time within a day that a hen is exposed to sunlight or a broad-spectrum light source. Hens perform at peak production during times of a lengthening or long photoperiod (Sharp, 1993). Commercially-raised hens are commonly kept indoors under artificial lighting for fourteen to sixteen hours per day.  As pasture-raised hens do not have a controlled photoperiod, egg deposition declines during times of the year when day length or photoperiod is short.  It is hypothesized that egg deposition rate will increase in pasture-raised hens if artificial light is added to coops to mimic long days during periods of decreasing day light.

    Costs of egg production can be reduced in a pasture management system because hens may obtain nutrients from natural sources such as forage and arthropods that crawl or fly into hens’ designated pasture area. These hens require fewer nutrient inputs in the form of commercially available feed (Buchanan et al., 2007).  Additionally, the hens will return nutrients to the pasture via waste products (Moore et al., 1995).  Therefore, a pasture-raised hen can contribute to the overall sustainability of poultry production by recycling nutrients between the animal itself and its surrounding ecosystem.  It is hypothesized that the nutrient profile of the pastures where hens are housed will be more desirable for producers. Furthermore, the hens’ outputs, in the form of eggs, will be more desirable for consumers.

    Raising hens on pasture enhances sustainability of agriculture by directly linking the hens to the environment in which they live.  This link is achieved through nutrient exchange from the hen to the soil and then back to the hen again.  However, there are environmental aspects in this management system which cannot be controlled. These include diet, light, temperature, and other weather factors.  This is in great contrast to the housing conditions of commercially-raised laying hens.  The environment for commercially-raised hens is completely controlled, from the room temperature to the lighting and the feed.  It is well-recognized among agriculturalists that providing a consistent, safe environment results in profitable production.  However, commercial systems are not considered to be sustainable as every nutrient input must be obtained and delivered, and every nutrient output must be handled and removed appropriately.  There is no direct link between the animal and its surrounding environment.

    Eggs from pasture-raised hens are a popular sustainable alternative to commercially-produced eggs.  However, certain environmental aspects, such as short day length in the fall and winter, may depress overall productivity and profitability.  One way to control the hens’ environment without removing the hens from their ecosystem is to provide additional lighting (Lewis et al., 1997).  It is hypothesized that this will essentially “trick” the hens’ systems into believing they are in a perpetual spring, when egg production is at its peak. Timed lights are a simple addition to any coop. Therefore, producers may find much benefit in including this artificial environmental stimulus.  Any practice that increases the efficiency of pasture-raised hens at minimal cost will encourage agriculturalists to produce a sustainable, humane product without limiting output.  This will increase the quantity not only of sustainable egg products available for consumers but also of sustainable agricultural practices for producers.  The increased quantity should have a favorable effect on the price for consumers and producers, thereby making the sustainable option a more popular choice.

    Project objectives:

    The experiment has been completed.  This is the Final Report.

    Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.