Evolution of Broilers and Broiler Breeders

Abstract

Selection of meat-type chickens is primarily focused on growth rate and body composition improvement. The negative relationship between growth and reproduction related characteristics makes rearing and breeding applications difficult. Although the studies on chicken breeding have more than 150 years of history, the speed-up have been derived only in last 75 years. While selection breeding birds based on their phenotype for such traits as skeletal integrity, body conformation, condition, morbidity etc. Over the years, progress has been made in terms of number of hatching eggs, egg weight and hatchability at the parent stocks. For the meat-type chickens, the average body weight gain was 8 g per day and feed conversion rate was 5.0 until the age of slaughter in the first quarter of the 20th century, whereas at the beginning of the 21th century, these characteristics reached 66 g and 1.7, respectively. Improvement in body weight and the feed conversion ratio of the genotypes which have been used for broiler production is because of the development in genetics. Besides these developments, some problems have surfaced regarding immune function, skeletal disorders, liability, and in the breeder level reproductive troubles.