Related Experiment Video
Updated: Aug 11, 2026

Protocol for Assessing the Relative Effects of Environment and Genetics on Antler and Body Growth for a Long-lived Cervid
Published on: August 8, 2017
Effects of light environment and population density on growth performance of male turkeys: 2. Physiological changes
1Department of Poultry Science, Virginia Polytechnic Institute and State University, Blacksburg 24061.
Abstract:
This study was designed to determine the effects of intermittent white light [2 h of light (L) followed by 2 h of dark (D) repeated six times per day] vs. diurnal white, blue, and red light (12L:12D), light intensities of 86.1 lx (high) vs. 5.4 lx (low) at high and low population densities, and season of the year on changes in the pineal, pituitary, and adrenal glands and testes of male turkeys. Pineal gland weights were unaffected by any of the factors under study. Pituitary gland weights significantly increased only in 12-wk-old males reared during the fall and winter compared with those reared during the spring and summer, but were unaffected by the imposed light environments or population density. Adrenal glands were significantly larger in males reared under high population density conditions in comparison with those reared under low density housing. The different light environments were ineffective in altering the effects of population density on adrenal response. Intermittent, high intensity light caused precocious sexual development when males were between 12 and 23 wk of age. White light and red-filtered light stimulated testes activity and seminiferous tubule development, whereas blue-filtered light was nonstimulatory.
More Related Videos
05:34Analysis of Arabidopsis thaliana Growth Behavior in Different Light Qualities
Published on: February 2, 2018
06:16An Experimental Approach to Investigating Effects of Artificial Light at Night on Free-Ranging Animals: Implementation, Results, and Directions for Future Research
Published on: February 2, 2022
Related Concept Videos
Nature and Nurture
Population Growth
Background and Environment Affect Phenotype
An example of how genetic background affects phenotype can be seen in horses. The Extension gene in horses is responsible for their coat color. A wild-type gene (EE) produces black pigment in the coat, while a mutant gene (ee) produces red pigment. A...
Testing a Claim about Mean: Known Population SD
Estimating a population mean requires the samples to be distributed normally. The data should be collected from the randomly selected samples having no sampling bias. The sample size needed to be higher than 30, and most importantly, the population standard deviation should be already known.
In most realistic situations, the population standard deviation is often unknown, but in rare circumstances, when it...
Microbial Growth Measurement: Indirect Methods
Rate of Change: Problem Solving