Telomeres are specialised nucleoprotein end structures of eukaryotic chromosomes and protect and maintain genome integrity from recombination, exonuclease degradation and end-to-end fusion. Because of the end replication problem, telomere length in somatic cells tends to decrease with organismal age. Telomere shortening is known to occur in chicken somatic tissues and correlates with advanced developmental age. However, age is not the only determinant of telomere length in an individual. Several factors at the genetic and epigenetic levels are known to affect telomere length in different ways. Herein, we review several factors that affect telomere length in the chicken. Genetic factors include breed and sex, while the epigenetic factors include environmental and stochastic influences. Age, stocking density and living or housing systems were reviewed as environmental factors pertaining to the habitat of the organism. Factors such as oxidative stress, antioxidants in feed and restriction feeding were the stochastic factors that we reviewed.
