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A total of 336 newborn pigs (DNA 241 × 600, initially 1.75 ± 0.05 kg bodyweight [BW]) from 28 litters were used in a 63-d study evaluating the effects of increasing injectable Fe dose on suckling and subsequent nursery pig performance and blood Fe status. GleptoForte (Ceva Animal Health, LLC, Lenexa, KS) contains gleptoferron which is an Fe macromolecule complex that is commercially used as an injectable Fe source for suckling piglets. On the day of processing (day 3 after birth), all piglets were weighed and 6 barrows and 6 gilts per litter were allotted within sex to 1 of 6 treatments in a completely randomized design. Treatments consisted of a negative control receiving no Fe injection and increasing injectable Fe to achieve either 50, 100, 150, 200 mg, or 200 mg plus a 100 mg injection on day 11 after birth. Pigs were weaned (~21 d of age) and allotted to nursery pens based on BW and corresponding treatment in a completely randomized design. During lactation, increasing injectable Fe up to 100 mg improved (quadratic; P < 0.05) average daily gain (ADG) and day 21 BW with no further improvement thereafter. There was no evidence of differences (P > 0.10) observed between the 200 mg and 200 mg + 100 mg treatments for growth. For the nursery period, increasing Fe dosage increased (linear; P < 0.05) ADG, average daily feed intake, and day 42 BW. There was no evidence of differences (P > 0.10) between the 200 mg and 200 mg + 100 mg treatments for nursery growth. For blood criteria, significant treatment × day interactions (P = 0.001) were observed for hemoglobin (Hb) and hematocrit (Hct). The interactions occurred because pigs that had <150 mg of injectable Fe had decreased values to day 21 and then increased to day 63 while pigs with 150 or 200 mg of injectable Fe had increased values to day 21 then stayed relatively constant to day 63. In summary, piglet performance during lactation was maximized at 100 mg while nursery growth performance and blood Fe status were maximized with a 200 mg Fe injection at processing. Providing an additional 100 mg of Fe on day 11 of age increased Hb, and Hct values at weaning and 14 d into the nursery but did not provide a growth performance benefit in lactation or nursery. These results indicate that providing 200 mg of injectable Fe provided from GleptoForte is sufficient to optimize lactation and subsequent nursery growth performance and blood Fe status., (© The Author(s) 2020. Published by Oxford University Press on behalf of the American Society of Animal Science. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

The relationship of injected Fe doses on blood hematology and pig growth performance during both preweaning and postweaning periods was studied. In Exp. 1, the effect of BW of 347 pigs injected with 200 mg of Fe (dextran) intramuscularly (i.m.) at birth on hemoglobin (Hb) and percent hematocrit (Hct) at weaning was assessed. As BW increased there was a decline (P < 0.01) in Hb and Hct. In Exp. 2, Fe injection doses and timing of injected Fe on blood hematology and pig growth were evaluated. Injections were as follows: 1) 200 mg of Fe at birth; 2) 300 mg of Fe at birth; or 3) 200 mg of Fe at birth + 100 mg of Fe at d 10. A total of 269 pigs were allotted within litter to 3 treatments. The 2 greater quantities of injected Fe (i.e., 300 or 200 + 100 mg of Fe) had similar but greater (P < 0.05) Hb and Hct values than pigs receiving 200 mg of Fe, but growth rates were similar at weaning. The effects of injecting 200 mg of Fe at birth and either saline or 100 mg of Fe at 10 d of age were investigated in Exp. 3. Weaned pigs of each group were fed diets with 0, 80, or 160 mg/kg of added Fe for 35 d as a 2 × 3 factorial arrangement with 12 replicates (n = 360 pigs) in a randomized complete block design (RCB). The innate Fe contents of diets averaged 200 mg/kg. The greater Fe injection group (200 + 100 mg) had greater (P < 0.01) Hb and Hct values through 14 d postweaning (P < 0.05) and greater (P < 0.01) Hct values through 21 d postweaning. As dietary Fe increased, Hb was greater only at d 14 (P < 0.05 4), whereas Hct increased linearly to d 35 (P < 0.01) postweaning. Dietary Fe resulted in linear increases (P < 0.01) in ADG from d 21 to 35 and d 0 to 35. In Exp. 4, 3 dietary Fe (80, 160, and 240 mg/kg of diet), 2 injected Fe treatments (200 or 300 mg of Fe) at birth, and birth BW (<1.5 or ≥1.5 kg) were evaluated as a 2 × 2 × 3 factorial arrangement of treatments in a RCB design with 6 replicates (n = 280 pigs). The 300 mg of Fe injection group had lighter BW in both birth BW groups, with a birth BW × injected Fe interaction (P < 0.01). This resulted in the lighter birth BW pigs receiving 200 mg of Fe having greater BW gains to 240 mg/kg of dietary Fe, whereas light birth BW pigs injected with 300 mg of Fe plateaued at 160 mg/kg of Fe. Pigs in the heavy birth BW group injected with 200 or 300 mg of Fe at birth responded similarly to dietary Fe postweaning. These results indicate that blood Hb and Hct were affected by pig BW at weaning, but the additional 100 mg of Fe i.m. at 10 d of age increased blood hematology and that Fe injected preweaning affected initial postweaning performance.

Second-parity sows (n = 7) were fed diets containing organic or inorganic trace minerals, and their progeny (n = 68) were used to determine the Fe status of pigs at birth and nursing and postweaning phases. The experiment comprised 2 parts, in which the first experiment was a 2 x 2 factorial arrangement. Sow trace mineral (organic vs. inorganic) was the first factor evaluated, and the injection of Fe (0 or 200 mg) to neonatal pigs within litter was the second factor. In Exp. 2, half the pigs in each litter from each neonatal Fe injection group were injected with Fe (0 vs. 200 mg) at weaning as an added factor in a 2 x 2 x 2 factorial arrangement in a split-split-plot design. Weanling pigs were fed diets fortified with 90 mg/kg of Fe (sulfate), but the analyzed indigenous and fortified Fe content was 170 mg/kg. Pigs in both experiments were bled at periodic intervals to determine hemoglobin (Hb) concentration, percentage of hematocrit (Hct), and ceruloplasmin oxidase activity. Neonates and d-2 pigs from sows fed organic trace minerals had lower (P < 0.05) Hb concentrations compared with sows fed inorganic trace minerals, but they had similar percentages of Hct values. Blood Hb seemed to remain lower throughout the nursing period when sows were fed organic vs. inorganic Fe. Pigs without Fe injection had decreased ADG (P < 0.05) from 0 to 7 and 7 to 17 d than pigs injected with Fe. Although Hb values increased when neonatal pigs received Fe injection, they were somewhat lower when sows were fed the organic Fe. Ceruloplasmin oxidase activity was low at birth, increased to weaning in each treatment group, and was greater in pigs without Fe injection at d 13 (P < 0.05) and those from sows fed organic minerals at d 17 (P < 0.01). In Exp. 2, when the Fe-fortified diet was fed, BW and ADG responses were both greater (P < 0.01) to 28 d postweaning when neonates had received Fe injections. Neonates not injected with Fe at birth but injected at weaning had greater ADG, Hb, and Hct values, whereas pigs injected with Fe did not respond to Fe injection at weaning, which resulted in interactions (P < 0.05) in those criteria at most measurement periods. The results indicated a reduced Fe bioavailability when sows were fed the organic Fe source, but this may also have been due to the greater Fe need, lowered Fe status, or both, of the sow because of the greater number of pigs farrowed and heavier litter weights at parturition and weaning. The results also indicated that Fe injections at birth may be critical to achieving maximum pig growth response to weaning. There was no apparent advantage to injecting Fe at weaning when neonatal pigs received Fe injections.

The injection of iron-dextran into beef calves at an early age immediately increased values for erythrocyte (RBC) numbers, hemoglobin (Hb) concentration, packed cell volume (PCV), mean corpuscular hemoglobin (MCH) and mean corpuscular volume (MCV), even though the calves were not anemic. There were no significant differences in average daily gain (ADG) from birth through 15 wk between those that were injected and those that were not injected. Hereford calves had lower values for PCV, Hb, MCH and MCV than Angus and crossbred calves, and both Hereford and Angus calves had lesser body weight and slower ADG than crossbred calves. Serum iron (Fe) concentrations were higher in calves born in the spring and pastured in the summer than in calves born in late summer and fall and pastured in the fall. The serum Fe concentration of calves at first sampling (during first week of life) was positively correlated with their weight at that and subsequent times to 15 wk. Mean corpuscular volume and MCH in cows before calving were positively correlated with the MCV and MCH in their calves at first sampling. Serum Fe concentration in cows before calving was negatively correlated with the ADG of their calves through 15 wk.

Twenty-eight 4-d-old nursing pigs were used in two trials to evaluate the effects of im injection of iron (Fe) from Fe-dextran upon subsequent serum mineral concentrations. An im injection of 150 mg of Fe from Fe-dextran was given to all pigs (n = 17) in trial 1. Serum Fe concentration increased rapidly from an initial mean of 65 to 3,466 micrograms/dl at 6 h postinjection (PI), 5,712 micrograms/dl at 24 h PI, then fell to 317 micrograms/dl at 4 d PI, 143 micrograms/dl at 7 d PI and remained about 100 micrograms/dl at 14, 21 and 28 d PI. Concentrations of other serum minerals did not appear to be influenced by the Fe-dextran injection. Treatments of Pigs (n = 11) in trial 2 were no injection, injection of dextran only, injection of 100 mg Fe from Fe-dextran and injection of 200 mg Fe from Fe-dextran. Serum Fe concentration increased rapidly after Fe-dextran injection, rising to a peak of 11,028 micrograms/dl at 6 h PI from the 100-mg Fe injection and 17,012 micrograms/dl at 6 h PI from the 200-mg Fe injection. Serum Fe concentration dropped steadily in pigs that were given no injection or injected with dextran only. Seven days after trial 2 started, all pigs that had received no injection or dextran only were injected with 100 mg Fe from Fe-dextran.(ABSTRACT TRUNCATED AT 250 WORDS)

An experiment using 32 pigs in a 2(3) factorial arrangement of treatments was used to determine the effects on the (1) level of iron dextran supplementation, (2) iv infusion of an Escherichia coli 263 culture filtrate and (3) presence of E. coli 263 in a ligated intestinal segment, on the ability of the young pig to limit systemic Fe availability. Iron dextran was administered im 3 d postpartum. Culture filtrate was infused iv, E. coli were injected into ligated intestines and blood sampling was started at 14 d postpartum. Blood was taken every 2 h for 22 h, after which pigs were euthanized and livers, spleens and kidneys were removed. Pigs receiving 400 mg of iron dextran (HiFe) exhibited greater serum Fe (SFe) and lower total Fe-binding capacity (TIBC) than pigs injected with 100 mg Fe (LoFe). The effects of the E. coli culture filtrate infusion appeared to be associated with endotoxin-induced circulatory shock. The presence of E. coli in the intestine increased TIBC in LoFe pigs, but not in HiFe pigs. The increase in TIBC coincided with the time of maximal fluid secretion into the intestine. Intestinal E. coli also caused an increase in liver Fe content, particularly in HiFe pigs. These data suggest that intestinal E. coli can cause a shift of Fe from the plasma to the reticuloendothelial system, and pigs receiving high supplemental dosages of Fe are less able to limit the availability of Fe to microorganisms.

Serum ferritin concentration of 40 nursing piglets was measured by a two-site immuno-radiometric assay to assess relationships of serum ferritin to Fe-related blood characteristics and nonheme Fe concentration of the liver. Hemoglobin concentration rapidly decreased after nursing to 55% of the birth level at 2 to 4 wk of age when the piglets exhibited severe symptoms of Fe deficiency. However, an im injection of 1 ml of iron-dextran (100 mg Fe) at 3 d of age restored the hemoglobin level to near the concentration of 10 g/100 ml by 2 wk of age. Serum ferritin concentration was low at birth and 1 d of age, but increased by 3 d of age. From 1 wk of age onward, serum ferritin level of the unsupplemented animals decreased linearly and declined to the lowest level at 3 wk of age. With iron-dextran injection, however, systemic concentration of ferritin peaked at 1 wk of age and decreased linearly to 3 wk of age. Serum ferritin of both groups was almost depleted at 3 to 4 wk of age. Although a single injection of 100 mg Fe from iron-dextran is adequate to maximize weight gain and to maintain normal hemoglobin level, serum ferritin concentration was almost exhausted after 2 wk of age. Serum ferritin concentration of both groups increased gradually from 4 wk of age, followed by a quadratic rise to 8 wk of age. The elevation of serum ferritin of the unsupplemented group after 4 wk of age almost paralleled that of hemoglobin concentration.(ABSTRACT TRUNCATED AT 250 WORDS)