g., Ayliffe et al., 2004, Bahar et al., 2005, Harrison et al., 2011 and West et al., 2004). Specifically in poultry, stable isotopic composition has been used to determine turnover time in tissues (Cruz et al., 2005 and Hobson and Clark, 1992); nutrient routing (Cruz et al., 2004); to track the presence of animal protein in commercial poultry rations (Carrijo et al., 2006, Denadai et al., 2008 and Mori et al., 2007),
to detect the presence of corn in poultry diet (Rhodes et al., 2010), and to differentiate eggs laid by hens under different growth systems (Rogers, 2009). The latter was the only study designed to investigate differences between barn-raised and free-range chickens, and it was specifically
designed for eggs and not for meat. Therefore, there is a need for studies that aim to investigate whether it is possible to differentiate barn-raised from free-range Navitoclax nmr chickens by the use of stable isotopes. This is especially important because free-range chickens usually have a higher price than barn-raised chickens. The main objective of this study was to investigate temporal changes in the isotopic composition of chickens grown under learn more controlled conditions receiving two different diets. One diet was a conventional grain-based ration used in commercial barn-raised chicken plants, and the other diet was typical of free-range MycoClean Mycoplasma Removal Kit chickens in Brazil, which is a mixture of corn, grass and earthworms
from the soil. We further compared the stable isotopic composition of barn-raised chickens bought in grocery stores, produced by 15 different companies, with 27 homegrown free-range chickens obtained from local households. The Caipirinha is a slow-growing chicken developed by the Genetic Department of the Escola Superior de Agricultura “Luiz de Queiroz” (ESALQ) and its main characteristics are its resilience and adaptability as a free-range bird, especially developed for homegrown conditions. Seventy-five Caipirinha broilers received the same corn and soybean starter feed ad libitum for the first 28 days ( Table 1). After this period, broilers were divided into three groups of 25 birds each and were fed ad libitum with three different diets. One group continued receiving a final corn and soy-based feed (Caipirinha-barn-raised corn–soybean-fed; Table 1), a second group was allowed free access to grass pasture areas and also received milled corn (Caipirinha-free-range), and, finally, a third cohort received only milled corn (Caipirinha-barn-raised corn-fed). Individuals for each diet-treatment were kept apart and those allowed to pasture had free access to grass areas. At 28, 60, 90, and 120 days of age, five individuals randomly selected from each treatment were slaughtered and the breast muscle of each bird was analysed for carbon and nitrogen stable isotopes.