Effectiveness of zinc acetate injection in alleviating postweaning performance lag in pigs

Four trials were conducted using crossbred pigs (n = 308) to determine the effects of Zn acetate injection near weaning on serum Zn concentrations and performance. In Trial 1, 78 pigs (BW of 5.1 kg and age of 18 d) were injected i.m. 3 d before weaning with either 3 mg of Zn from Zn acetate (in saline) per kilogram of BW or saline. Serum Zn concentrations were higher (P < .05) for Zn-injected pigs at 1 wk postweaning than for controls. In Trial 2, 96 pigs (BW of 7.2 kg and age of 26 d) were used to compare time of i.p. injection of Zn (weaning or 12 h postweaning) and amount of Zn injected (0, 3, or 4 mg of Zn/kg of BW). Serum Zn concentrations were higher (P < .01) in Zn-injected pigs 1 d after injections and remained higher than those in controls until after wk 2. In Trial 3 (n = 30, BW of 6.9 kg and 24 d of age), pigs that were injected with 3 mg of Zn/kg BW i.p. 3 d postweaning had lower (P < .05) ADG and ADFI and lower (P < .01) gain/feed from d 4 to d 7 postweaning than controls. Zinc-injected pigs had higher (P < .05) serum Zn concentrations at d 7. In Trial 4, 104 pigs (BW of 6.4 kg) were used in a 2 x 2 x 2 factorial arrangement of treatments: 1) regrouped 3 d before weaning or not regrouped, 2) Zn injections (3 mg i.p.) or placebo, and 3) time of injection, 2 d before or 1 d after weaning. All pigs were weaned at 23 d of age.(ABSTRACT TRUNCATED AT 250 WORDS)