Consequences of Improving Growth Rate of Turkeys

Dr. Karl Nestor

            The turkey breeding industry has greatly improved growth rate by selective breeding and utilizing matings designed to obtain the full expression of genetic potential.    In most animals, the individual in the wild has been selected by natural forces to survive under conditions that are sometimes severe.  The turkey is no exception.  The wild turkey survives in sometimes severe weather conditions without adequate feed.  The wild turkey also must adapt to predators including humans.  The wild turkey must be able to walk and run easily and be able to fly into trees for perching during the night.

The commercial turkey is grown primarily for meat and is provided a very pampered environment in comparison to wild turkeys.  They are provided extra heat when they are young and fed the best feed available.  They are housed in buildings with excellent climate control.  They are sometimes vaccinated to prevent serious diseases and are treated by veterinarians if disease conditions are present. 

The large genetic gains in growth rate that have been obtained by commercial breeders have caused numerous problems.  As the turkeys have gotten larger, they have more difficulty walking and leg problems are of major concern.  Birds with bad legs have difficulty standing and walking so getting to the feeders and waterers is a difficult task.  Birds with extremely bad legs sometimes die before market age and in the case of breeder replacements to not survive to breeding age. Breeders have tried to address this problem by selecting to improve the relative amount of leg bones and muscles so that the bird can handle the extra weight. 

Large bodied turkeys are also more susceptible to a number of diseases including fowl cholera, erysipelas, and Newcastle disease.  The selection for increased growth rate has greatly altered the immune system of the bird and the large-bodied bird has reduced capacity to resist exposure to both bacteria and viruses.  In the future, commercial turkey breeders will have to develop methods to improve disease resistance along with increasing growth rate.

Reproduction is also reduced by genetic increases in growth rate in turkeys.  Egg production is reduced and there are problems with fertility of the eggs and hatching of the eggs.  All commercial turkeys are now produced by artificial insemination because the commercial turkeys are too large to mate naturally.  The reduction in egg production limits the number of offspring that can be produced by the breeders and increases the cost of each young turkey, termed poults.