Skeletal muscle goitrin concentration and organ weights in growing pigs fed diets containing rapeseed meal

In two trials with a total of 120 growing pigs (23–102 kg) the effects of incorporating either of three 00-rapeseed meal levels (00-RSM, 0; 100 and 200 g kg−1) into cereal based diets on the transfer of goitrin into skeletal muscle (n=60) and on weights of thyroid glands (n=96), livers and kidneys (n=120) were investigated. The concentrations of alkenyl-glucosinolates of the RSM batches used in Trial 1 and 2 differed (12.4 and 6.4 μmoles g−1 fat-free dry matter, respectively). The respective progoitrin concentrations were 7.5 and 3.8 μmoles g−1 fat-free dry matter. Corresponding concentrations of indole-glucosinolates were 0.62 and 0.73 μmoles g−1 fat-free dry matter, respectively. Loin muscle goitrin concentrations averaged 8.3 and 3.8 μmoles g−1 in Trial 1 and 2, respectively, and were thus affected by dietary progoitrin concentration (P<0.001). Thyroid gland and liver weights were significantly affected by RSM-level and dietary concentrations of indole-glucosinolates. At the dietary inclusion level of 200 g kg−1 as compared with the control, the weights of thyroid glands were increased on average for Trial 1 and 2 by 1.26 (P<0.001), of livers by 1.10 (P<0.001) and of kidneys by 1.07 (P=0.03). Thus, the responsiveness of organ weights to RSM inclusion decreased in the order thyroid glands, liver and kidneys. It is concluded that at recommended levels of RSM-inclusion the muscle goitrin values observed are acceptable from a human food hygiene point of view.