Effect on type dietary protein and form of iron in creep feed diets on utilization of iron by nursing pigs

In two experiments nursing piglets (142 Duroc x Yorkshire x Duroc pigs from the October 1977 farrowing and 160 Duroc x Yorkshire X Duroc pigs from the January 1978 farrowing), respectively, were utilized to determine the effect of type of dietary protein and form of iron in creep feed diets on utilization of iron by nursing pigs. The litters were randomly allotted to one of four treatment rations. In experiment one the treatment rations consisted of corn + soybean meal + ferrous sulfate (control ration) (1); corn + soybean meal + ferric citrate (2); corn + soybean meal + dried whey product + ferrous sulfate (3); corn + soybean meal + dried whey product + ferric citrate (4). In experiment two the treatment rations (1) and (2) were the same as in experiment one. Treatment ration (5) consisted of corn + dried skim milk + ferrous sulfate, and (6) consisted of corn + dried skim milk + ferric citrate. One-half the piglets in each litter were injected with 100 mg of iron from iron dextran intramuscularly at three days of age.

In experiment one the pigs were weighed and bled at 3, 4, and 5 weeks and in experiment two at 5, 6, and 7 weeks. At 10 days of age feeding of the experimental rations was initiated, and throughout the trial creep feed consumption was recorded. At each bleeding various hematological analyses were performed on each blood sample.

The results of this study indicate that source of protein and form of iron can affect iron utilization in the nursing pig. In experiment one pigs receiving soybean meal protein had greater hemoglobin and hematocrit values, serum iron concentrations, and total iron binding capacities. In experiment one hematocrit values were higher for those pigs receiving ferric citrate, but hemoglobin, serum iron and total iron binding capacity values were less at each of the three bleeding periods.

There was no significant difference on average pig weight due to source of protein or form of iron at any of the three weigh periods. Pigs receiving dried whey product and those receiving ferric citrate consumed less total creep feed per pig weaned than those receiving soybean meal or ferrous sulfate.

In experiment two hemoglobin and hematocrit values, serum iron, total iron binding capacity and percent saturation of transferrin values of pigs receiving soybean meal as a source of protein were higher at each of the three bleeding periods. Those pigs receiving ferrous sulfate had higher hematocrit, hemoglobin, serum iron and total iron binding capacity values at all three time periods. The hemoglobin, hematocrit and serum iron concentrations were significantly higher by the seventh week.

The average weekly weights were significantly greater for pigs receiving dried skim milk as the major source of dietary protein. Form of iron had no significant effect; however, pigs receiving ferric citrate were heavier.

Pigs receiving dried skim milk in the diet consumed more total creep feed per pig weaned than did pigs receiving soybean protein. In both experiment one and two, pigs receiving ferric citrate consumed less total creep feed per pig weaned than pigs receiving ferrous sulfate.