Selection of copper and zinc dosages in pig diets based on the mutual benefit of animal growth and environmental protection

Dietary copper and zinc additives facilitate the growth and development of animals, but heavy metal in feces threatens the ecological environment, and balance is the key to solving the problem. In this study, a trial of 2000 pigs (early nursery, 9–15 kg; late nursery, 15–25 kg; grower: 25–60 kg) was conducted to analyze the effects of different diets (gradient dosage of copper and zinc additives) on growth performance, antioxidant performance, immune function, and fecal heavy metal excretion of piglets and growing pigs. Although no significant differences were observed in average daily gain (ADG) and average daily feed intake (ADFI) between treatments during the entire nursery-grower period, the addition of appropriate high doses of copper and zinc to the diet had a beneficial effect on the antioxidant status and immune function of weaned piglets. Especially at early nursery, compared with the low-copper group (5 mg/kg Cu), the high-copper group (120 mg/kg Cu) could significantly increase the peroxidase (POD), glutathione peroxidase (GSH-PX), total antioxidant capacity (T-AOC), catalase (CAT) and copper/zinc superoxide dismutase (Cu/Zn-SOD), cortisol in the serum. Moreover, the addition of zinc and copper in the diet not only increased the concentration of corresponding trace elements in the serum, but also affected the concentration of other trace elements in the serum. The reduction of copper and zinc content in the diet contributed to reducing the copper and zinc content in feces. In conclusion, we have formulated the mutual benefit dosages of copper and zinc (9–15 kg: 5 mg/kg Cu and 50 mg/kg Zn; 15–25 kg: 4 mg/kg Cu and 50 mg/kg Zn; 25–60 kg: 4 mg/kg Cu and 10 mg/kg Zn) for weaning piglets and growing pigs, which would help ensure the healthy growth of animals and reduce environmental heavy metal residues. This study developed a mutually beneficial dose of copper and zinc in pig diets, which promotes animal growth and protects the environment. [Display omitted] •The effect of gradient copper and zinc additives on the growth performance of piglets were determined.•The copper and zinc in the diet would change the serum trace element content.•Appropriate diets high in copper and zinc could help pigs resist oxidation and improve immunity.•The copper and zinc in the diet would directly affect the fecal copper and zinc content.•The use of copper and zinc feed additives in Chinese pig breeding should be reasonably reduced.