In vivo assessment of body composition and growth potential of modern broiler using dual-energy X-ray absorptiometry

Context: Genetic improvements in modern strains have led to continuous increments in broiler growth rates, which, as a consequence, have resulted in higher economic returns for broiler producers over the last decades. Aim: The present study was conducted to characterise the potential growth of the body and feathers of Cobb 500, Hubbard Flex and Ross 308 male and female broilers, as well as to assess the changes in chemical composition that occur up to 16 weeks of age. Methods: Birds were fed isoenergetic diets divided in four phases and formulated to marginally exceed the nutritional requirements of the strains throughout the growing period. They were maintained in a controlled environment so as not to limit growth. A dual energy X-ray absorptiometry (DXA) scanner was used to follow the in vivo body composition of 12 broilers of each strain and sex (total of 72 broilers), and the feather weight and composition was determined in four birds of each strain and sex selected at intervals during the growing period (total of 288 broilers) through comparative slaughter with later chemical analysis. Key results: Parameters of Gompertz growth curve to describe the strains were estimated for body and feather weight as well as for the growth of their chemical components. Conclusion: Differences in the growth rates between strains were evident, indicating the possible differences in selection methods used by geneticists in the different breeding companies. These genetic parameters would explain part of the variation on broileŕs performance which impacts on the way they should be fed and housed during growth. Implications: The accurate description of genetic growth potential is useful information to be associated with factorial models that predict nutritional and feed intake requirements of birds. The main advantage of DXA technology is to decrease the variation of body deposition on the Gompertz model, resulting from the use of the same bird throughout its life. Despite the speed of obtaining chemical values of the body, the method is unsuitable for measuring the growth of feathers, which is also important data to be collected and related to the broiler strains.