ORIGINAL ARTICLE Effects of caponization on fat metabolism–related biochemical characteristics of broilers G. K. Symeon 1 , M. Charismiadou 1 , F. Mantis 2 , I. Bizelis 1 , A. Kominakis 1 and E. Rogdakis 1 1 Department of Animal Science and Aquaculture, Faculty of Animal Breeding and Husbandry, Agricultural University of Athens, Athens, Greece, and 2 Department of Food Technology, Laboratory of Meat & Meat Products Technology and Quality Control, Technological Educational Institution (T. E. I.) of Athens, Athens, Greece Introduction The liver is the primary site for the de novo synthesis of fatty acids in birds (Pearce, 1977). Fatty acid syn- thesis depends on the availability of plasma triglyce- rides (TG), and it is mediated through a complex enzymatic system which includes, among others, fatty acid synthase, ATP-citric lyase and NADP- malate dehydrogenase (MDH). MDH (EC 1.1.1.40) is responsible for the predominant amount of NADPH that is necessary for de novo synthesis of fatty acids (Shapira et al., 1978). Newly produced fatty acids are incorporated into triglycerides which in the form of lipoproteins [mainly very low density lipoproteins (VLDL)] are secreted from the liver and through blood circulation are moved throughout the body. Triglycerides are deposited within adipocytes where several small droplets form before becoming an expansive lipid droplet as a distinguishing character- istic of the cell type (Cartwright, 1991). The main fat depot in the body of chickens is the abdominal adi- pose tissue and can make up approximately 30% of the mass of major fat depots (Nir et al., 1988). Caponization is an ancient practice used for the production of special quality chicken meat. The sur- gical removal of the testes results in androgen defi- ciency and consequently the secondary male sexual characteristics such as the comb, the wattle, fighting behaviour and vocalization degenerate (Chen et al., 2005). Caponization also results in increased overall fatness in terms of abdominal, subcutaneous and intramuscular fat as well as increased liver weight (Symeon et al., 2010). Caponization’s induced fat accumulation should be also reflected at the biochemical level. There is some evidence that capons display increased serum Keywords caponization, fat deposition, NADP dehydrogenases, serum lipoproteins Correspondence I. Bizelis 75, Iera odos, 11855 Athens, Greece. Tel: +302105294452; Fax: +302105294442; E-mail: jmpiz@aua.gr Received: 24 June 2011; accepted: 11 October 2011 Summary A two-trial experiment was conducted to evaluate the effects of capon- ization on fat metabolism-related biochemical characteristics of broilers. Male Redbro broilers were purchased, caponized at 3 weeks and reared until either the 18th (Trial 1) or the 24th (Trial 2) week. In Trial 1, five slaughters were performed at 6, 9, 12, 15 and 18 weeks of age while in Trial 2 one slaughter at the end of the experiment (24 weeks). In each slaughter, the abdominal adipose tissue cellularity, the NADP dehydro- genase activity in the liver and some serum lipoproteins concentrations were assessed. Caponization had a marked effect on the adipocyte vol- ume and NADP-malate dehydrogenase activity in the liver at 24 weeks but it did not affect adipocyte number or the activity of NADP-isocitrate dehydrogenase activity at any age (p < 0.05). Regarding the lipoproteins, cholesterol and HDL-cholesterol were elevated in capon serum at 18 weeks of age while no difference was detected in the triglyceride concentration at any age. In conclusion, a relationship between fat deposition at the phenotypic level and the level of lipogenic enzymes and lipoproteins capons was established but not as pronounced as expected as some parameters displayed a constant increasing pattern while others did not. DOI: 10.1111/j.1439-0396.2011.01254.x 162 Journal of Animal Physiology and Animal Nutrition 97 (2013) 162–169 ª 2011 Blackwell Verlag GmbH