Effects of an additional iron injection on growth and humoral immunity of weanling pigs

In a 5-week study, 120 crossbred weaning pigs (age 4 weeks) were used to examine the effects of an additional Fe-injection and immunization moment on the growth and humoral immune response. Pigs were allotted to one of eight treatments based on body weight and litter origin. Factors included: (1) single intramuscular injection (day 3 after birth) vs. double intramuscular injection (days 3 and 21 after birth) of 200 mg Fe; (2) antigen challenge (Keyhole limpet hemocyanin (KLH) and ovalbumin (OA) vs. placebo); and (3) immunization moment (day 2 1 vs. 1 after weaning). All pigs had free 21 access to prestarter diets supplemented with 80 mg kg Fe as FeSO ? 7H O. Pigs were housed in a room consisting of 12 4 2 pens (ten pigs per pen). During the experiment, blood hemoglobin (Hb) levels and body weight were determined weekly and total Ig, IgG and IgM titers to KLH and OA twice a week. At day 6 after weaning, the blood Hb levels of double injected pigs were higher (P , 0.01) than the blood Hb-levels of the pigs that had received a single Fe-injection. Prior to day 6 and thereafter, blood Hb levels were similar both for single and double injected groups. Throughout the experiment, the additional Fe-injection, and immunization moment had no effect (P . 0.1) on growth and total Ig response to KLH and OA. But the genotype of the pigs affected (P , 0.05) the kinetics of the total Ig response to KLH and OA. In conclusion, an additional injection of Fe one week prior to weaning does not affect body growth, and does not enhance or support the humoral immunity to a T-cell dependent antigen. Furthermore, the suppressing effect of weaning on humoral immunity was not affected by additional Fe.  2000 Elsevier Science B.V. All rights reserved.