The aim of this study was to investigate the effects of different levels of cadmium supplementation (0, 5, 10, 20, 40 and 80 mg/kg) in the diet on performance, egg quality, tibia biomechanical properties and eggshell and bone mineral contents in laying quails. In this 10-week trial, a total of 96 laying quails, aged 21 weeks, were randomly distributed among six experimental groups. Each experimental group contained four replicates of four birds each. The performance parameters were adversely affected quadratically when cadmium was added to the diets in the concentrations of 20 mg/kg and above ( P < 0.01). The specific gravity and eggshell weight were maximal with the addition of 20 mg/kg cadmium to the diet. The biomechanical properties of the tibia were negatively affected by cadmium supplementation in quails ( P < 0.05). The eggshell boron content decreased linearly ( P < 0.001) with cadmium supplementation to the diet. The cadmium content in bone increased when cadmium was added to the diets ( P < 0.001). The bone boron concentration decreased as dietary cadmium supplementation was increased ( P < 0.001).Keywords: cadmium, bone, eggshell, performance, quail Implications Cadmium (Cd) is known as a toxic element for living organisms. However, low levels of Cd added to rations are also reported to have positive effects. In the present study, high levels of added Cd were toxic; however, when added in small amounts, positive effects were observed. There was a negative correlation between Cd and boron concentration in bones.
IntroductionNumerous reports have shown that exposure to cadmium (Cd), which is very toxic and non-essential for poultry, results in limitations on growth, increased mortality and decreased egg production (EP) and eggshell quality (Leach et al., 1979;Nolan and Brown, 2000;Sant'Ana et al., 2005;Rahman et al., 2007). Leach et al. (1979) indicated that the addition of Cd (48 mg/kg) to the diets of laying hen markedly decreased EP and eggshell thickness during a 48-week trial period. Similarly, Rahman et al. (2007) showed that exposure to Cd (0.1 to 10 mg/kg BW injection) decreased EP and eggshell thickness in quails.Bones not only provide structural support for birds but are also an important mineral source for metabolic requirements such as for the formation of the eggshell in female birds. Cd has adverse effects on minerals such as calcium (Ca), which is the main component of bones and the eggshell. It has been reported that exposure to Cd decreased bone resistance and mineral levels in bones in rats (Brzoska and MoniuszkoJakoniuk, 2004;.Cd is known to be toxic for humans and animals (Friberg et al., 1992;Jarup, 2002;Satarug et al., 2003;Jemai et al., 2007), but the results of some studies indicate that it may be useful when low levels are added to diets (Leach et al., 1979;Bokori and Fekete, 1995;Pribilincova and Marettova, 1996;Rahman et al., 2007). Leach et al. (1979) reported a positive effect of Cd supplementation (3 mg/kg) on EP during a 12-week study in laying hens. Pribilincova and Mar...