Growing–finishing pigs do not need additional zinc in a phytase-supplemented wheat–barley–soybean meal-based diet

Focus remains on reducing the excretion of surplus zinc (Zn) from pigs through manure due to environmental and public health concerns. Growing–finishing pigs may need less dietary Zn than current EU legislation allows and what is typically applied on farms. The aim of this study was to evaluate the effect of three dietary Zn levels on productivity, Zn homeostasis, and health status in growing pigs fed a grain and soybean meal-based diet with a high inclusion of phytase (1000 phytase units). Ninety pigs were offered a diet with 1431 and 83 ppm total Zn from weeks 0–2 and 2–6 post-weaning, respectively, followed by one of three dietary Zn levels (31 (unsupplemented), 69, or 102 ppm total Zn, n = 30/Zn level) from weeks 6–16 post-weaning (30–110 kg). Productivity and health were unaffected by dietary Zn level. Despite differences in serum Zn according to dietary Zn level in week 10, serum Zn remained above the assumed sufficient level following all dietary Zn levels through the experiment. No signs of parakeratosis were observed, and we conclude that growing–finishing pigs produce and stay healthy without added Zn to a phytase supplemented grain–soybean meal-based diet when optimal dietary Zn levels are applied up to 30 kg.