Iron treatment of pregnant sows in a Danish herd without iron deficiency anemia did not improve sow and piglet hematology or stillbirth rate

Iron Supplementation of Pregnant Sows to Prevent Iron Deficiency Anemia in Piglets: A Procedure of Questionable Effectiveness

In pigs, iron deficiency anemia (IDA) is a common disorder that occurs during the early postnatal period, leading to the stunted growth and increased mortality of piglets. The main cause of IDA is low iron stores in the liver of newborn piglets; these stores constitute the main source of iron needed to satisfy the erythropoietic requirements of the piglets in their first weeks of life. Insufficient iron stores in piglets are usually due to the inadequate placental iron transfer from the sow to the fetuses. Therefore, iron supplementation in pregnant sows has been implemented to enhance placental iron transfer and increase iron accumulation in the liver of the fetuses. Over the years, several oral and parenteral approaches have been attempted to supplement sows with various iron preparations, and consequently, to improve piglets' red blood cell indices. However, there is debate with regard to the effectiveness of iron supplementation in pregnant sows for preventing IDA in newborn piglets. Importantly, this procedure should be carried out with caution to avoid iron over-supplementation, which can lead to iron toxicity. This article aims to critically review and evaluate the use of iron supplementation in pregnant sows as a procedure for preventing IDA in piglets.

Sow hematological parameters in late pregnancy and an investigation as to whether these parameters are predictors of stillbirths in a Canadian sow herd

Animal and objective

The objectives of this study were to produce hematological reference intervals for late-pregnancy sows and to assess whether there were associations between sow hematological end points and the number of stillborn pigs.

Procedure

Whole blood was collected from 272 healthy pregnant sows ~1 wk before farrowing, and complete blood (cell) counts and hemoglobin determinations were obtained. Sows were monitored during farrowing, and litter characteristics, including number of stillborn piglets, were recorded.

Results and conclusion

Values for red blood cells, hemoglobin, mean corpuscular volume, mean corpuscular hemoglobin, mean corpuscular concentration, platelets, and white blood cells were significantly higher in Parity 1 sows compared to older sows. The mean (± SD) litter size was 14.5 ± 3.4 pigs, with 1.5 ± 2.0 stillborn pigs per litter. There was no significant association between any hematological end point (except white blood cell counts) and the likelihood of a stillborn piglet in a litter. There was a relationship between parity and stillbirth (P < 0.05), with higher-parity sows being more likely than younger sows to produce a stillborn piglet. Although it had been reported that anemic sows were more likely to have stillbirths, perhaps the relatively high mean hemoglobin concentration of sows in this study resulted in the lack of a relationship.

Genetic polymorphisms in ESR and FSHβ genes and their association with litter traits in Large White pigs

The estrogen receptor (ESR) gene and follicle-stimulating hormone β (FSHβ) gene are responsible for litter traits. The present study aimed to verify the polymorphisms of ESR and FSHβ and assess their effects on the litter traits in 201 Large White pigs. Four SNPs (g.C669T, g.A1296G, g.C1665T and g.A1755G) were found in ESR. The TT genotype at g.C1665T locus and AA genotype at g.A1755G locus could significantly increase the total litter size of the first litter of American Large White pigs (p < 0.05). Eight SNPs were found in exon 3 of FSHβ. The AA genotype at g.A511G locus, AA and AG genotypes at g.A617G locus, CC and CT genotypes at g.C630T locus, CT and TT genotypes at g.C652T locus, CT and TT genotypes at g.C735T locus, AA and AG genotypes at g.A746G, AA and AG genotypes at g.A921G and CT genotype at g.C678T could significantly increase the litter size of different strains of Large White pigs (p < 0.05). Our study revealed that the genetic variations of ESR and FSHβ were closely related to the litter trait of Large White pigs. Therefore, ESR and FSHβ genes could be used as molecular markers for the genetic selection of Large White pigs.

Hematological indexes and iron status in pregnant mares

During pregnancy, iron requirements are increased to meet optimal placental and fetal growth and the expansion of the maternal red-cell mass and to prevent complications related to the mother's iron deficiency anemia. Red-cell parameters and iron status provide consistent additional information for diagnosis of iron deficiency conditions. The aim of this study was to evaluate the serum iron status and its relation to hematological indexes in pregnant mares. Blood samples were taken from 31 Spanish Purebred mares over 11 months of pregnancy. Concentrations of iron (Fe), ferritin (Ferr), transferrin (T), and total iron-binding capacity (TIBC) increased significantly and unsaturated iron-binding capacity (UIBC) decreased as the pregnancy progressed without changes in red blood cell (RBC) count, hemoglobin (HB) concentration, packed cell volume (PCV), and transferrin saturation (TSAT). Fe and Ferr were positively correlated (r = 0.21 ). Fe and T (r = 0.69 ) and Fe and TSAT (r = 0.94 ) were positively correlated, and Fe and UIBC were negatively correlated (r = - 0.69 ). T and TIBC were positively correlated (r = 1.00 ). Pregnancy in the Spanish Purebred mare is characterized by a progressive increase in Fe, Ferr, T, and TIBC and a decrease in UIBC without modification in hematological indexes. Hematological parameters and iron status seem to indicate a sufficiency for Fe transport and its related mobilization and utilization during gestation in Spanish Purebred mares.

Effects of Different Iron Supplements on Reproductive Performance and Antioxidant Capacity of Pregnant Sows as Well as Iron Content and Antioxidant Gene Expression in Newborn Piglets

To improve the reproductive performance of sows and the iron nutrition of newborn piglets, we studied the effects of dietary iron on reproductive performance in pregnant sows as well as antioxidant capacity and the visceral iron content of sows and newborn piglets. Forty pregnant sows were divided into four groups, the iron deficiency group (Id group) was fed a basic diet while sows in the treatment groups were fed diets supplemented with 200 mg/kg lactoferrin (LF group), 0.8% heme-iron (Heme-Fe group), or 500 mg/kg iron-glycine complex (Fe-Gly group). The results indicated that (1) different sources of iron had no significant effect on litter size, live litter size, and litter weight of sows; (2) the three additives improved iron nutrition in newborn piglets, with LF and Heme-Fe having better improvement effects; and (3) the addition of different iron sources improved the level of serum antioxidant biochemical indexes of sows and newborn piglets, and it can have an effect on gene level, among which lactoferrin has the best effect. Thus, adding LF, Heme-iron, or Fe-Gly to the diet of sows during the second and third trimester of gestation can improve the antioxidant capacity of the sows. The supplementation of LF in pregnant sow diets can also improve the antioxidant capacity and the iron nutrition of newborn piglets, with better additive effects than in Heme-Fe and Fe-Gly.

Effects of dietary iron sources on growth performance, iron status, Fe-containing enzyme activity and gene expression related to iron homeostasis in tissues of weaned pigs

The aim of this study is to evaluate the effects of dietary iron sources on growth performance, iron status and activities of Fe-containing enzymes and gene expression related to iron homeostasis in tissues of weaned pigs. A total of 480 piglets at d 28 (Duroc X Landrace) were allotted to four groups as a factorial arrangement of treatments with 30 pigs/pen (male: female = 1:1) and 4 replicate pens/treatment. The treatments for iron in the diets were: control basal diet (Con); Con + 150 mg Fe/kg as inorganic Fe (iFe); Con + 75 mg Fe/kg as inorganic Fe + 75 mg Fe/kg as organic Fe-peptide complex (iFe+oFe) and Con + 150 mg of Fe/kg as organic Fe-peptide complex (oFe). The feeding trial lasted for 36 days. There were no significant differences in final body weight, ADG, ADFI, and G/F as well as blood hemoglobin and MCHC contents between piglets fed the control and iron-supplemented groups (P > 0.05). The iron supplemented groups exhibited increased iron content in the liver, kidney and spleen as well as the CAT and SDH activities in liver compared to the control group (P < 0.05), while piglets in oFe group experienced greater Fe accumulation and activities of CAT and SDH in the liver than piglets in the iFe group. Compared with the control group, dietary supplementation of iron increased the NCOA4 mRNA expression and decreased the TfR1 mRNA expression in liver of piglets. The TfR1, NCOA4 and Ferritin mRNA expressions of bone marrow in both iFe and iFe+oFe groups were greater than both in the Con and oFe groups. These results suggest that dietary supplementation of iron does not influence the growth performance and hematological parameters in weaned pigs fed a corn-soybean meal basal diet (75.8 mg/kg) from d 28 to d 70, but increased tissue iron status and activities of Fe-containing enzymes at d 70. The addition of organic Fe-peptide complexes presents greater beneficial effects on enhancing tissue Fe accumulation and Fe-containing enzyme activities, which may be involved in different gene expression patterns related to iron intake and transport in tissues of weaned pigs.

Correlations of gestational hemoglobin level, placental trace elements content, and reproductive performances in pregnant sows

The iron status of sows has a great influence on reproductive performance. Iron deficiency reduces reproductive performance and newborn piglet survival rate of sow. The hemoglobin is a potential predictor for the iron status of sows and is convenient for rapid detection in pig farms. However, the relationship between iron status, hemoglobin, placental trace elements, and reproductive performance remains unclear. In this study, the hemoglobin and reproductive performance of more than 500 sows with first to sixth parities at different gestation stages (25, 55, 75, 95, and 110 d of gestation) in two large-scale sow farms were collected, and the content of placental Fe, Zn, Mn, and Cu was analyzed. The results show that hemoglobin levels of sows during pregnancy (days 75, 95, and 110) decreased significantly (P < 0.001). As the parity increases, the hemoglobin levels of sows at days 25 and 55 of gestation and placental mineral element contents including Fe, Zn, Mn, and Cu at delivery decreased (P < 0.05), while the litter size, birth alive, and litter weights increased gradually (P < 0.001). Furthermore, hemoglobin during pregnancy had a negative linear correlation with litter weight and average weight (P < 0.05), and higher hemoglobin at day 25 of gestation may reduce the number of stillbirths (P = 0.05), but higher hemoglobin at day 110 of gestation may tend to be a benefit for the birth (P = 0.01). And there was a significant positive linear correlation between hemoglobin at day 110 of gestation and placental Fe and Mn levels (P = 0.002, P = 0.013). There was also a significant positive linear correlation among Fe, Zn, Mn, and Cu in the placenta (P < 0.001). The levels of Fe, Zn, and Mn in the placental at delivery were positively related to the average weight of the fetus (P = 0.048, P = 0.027, P = 0.047), and placental Cu was linearly correlated with litter size (P = 0.029). Our research revealed that the requirements for iron during gestation were varied in different gestation periods and parities. The feeds should be adjusted according to the gestation periods, parities, or iron status to meet the iron requirements of sows and fetal pigs.

An Experimental Model for Iron Deficiency Anemia in Sows and Offspring Induced by Blood Removal during Gestation

Anemia is a common condition in sow herds. We aimed to study the effects of severe iron deficiency during gestation on sow and piglet health outcomes with an experimental model for blood-removal-induced iron deficiency anemia. In total, 18 multiparous sows (8 in trial I and 10 in trial II) were allocated to either a blood removal group or a control group. Hematologic parameters were monitored at regular intervals and the tissue iron concentrations were measured for the sows and newborn piglets after farrowing. In trial I, the mean liver iron content was reduced to 46.7 µg/g in the blood removal sows compared to 252.6 µg/g in the controls (p < 0.001). In trial II, sows in the blood removal group had lower iron content in the liver (147.8 µg/g), kidney (46.3 µg/g) and spleen (326.5 µg/g) compared to the control sows (323.2 µg/g, 81.3 µg/g and 728.9 µg/g, respectively; p = 0.009, 0.016, 0.01, respectively). In trial I, piglets from sows in the blood removal group had significantly decreased hematocrit (Hct), red blood cells (RBC) and a tendency for reduced hemoglobin (Hb) compared to the control piglets. We established a blood removal model that resulted in mild- to severe degrees of sow anemia and reduced tissue iron stores at farrowing.

Antianemic action of the iron (IV) clathrochelate complexes

Anemia is one of the most common non-contagious diseases of pigs. Modern antianemic drugs have several drawbacks, so finding new drugs is a pressing issue. We previously reported the results of preclinical studies of iron in rare high valence IV. This allowed us to determine, supplement, and generalize the data on clinical studies of the new drugs with the active substance iron (IV) clathrochelate. Therefore, we studied its antianemic effect on piglets. Experiments were carried out on piglets-analogues neonates, which were divided into three groups: control and two experimental groups. Piglets were kept with sows on suckling. For the purpose of prevention of iron deficiency anemia, the traditional solution of iron dextran was administered once intramuscularly to piglets of I control group. The aqueous solution of iron (IV) clathrochelate complexes was administered once intramuscularly to piglets of II experimental group. Iron (IV) clathrochelate complexes were dissolved in a solvent of rheopolyglucin and administered once intramuscularly to piglets of III experimental group. 1 mL of test solutions contained 100 mg of active substance. The investigative material were the samples of blood and serum of piglets, their liver and spleen. The experiment lasted during a 30-day period since the birth of the piglets. According to the results of the experiments, iron (IV) clatrochelate complexes which were dissolved in water for injection and rheopolyglucin had higher antianemic activity compared to the control. This is evidenced by the dynamics of probable changes in the number of erythrocytes, hemoglobin content and hematocrit, iron content in serum and its mass fraction in the blood, liver and spleen of piglets. The effectiveness of the action of iron (IV) clatrochelate complexes is demonstrated by the full supply of piglets with iron and its higher bioavailability.

Effect of Oral Supplementation of Healthy Pregnant Sows with Sucrosomial Ferric Pyrophosphate on Maternal Iron Status and Hepatic Iron Stores in Newborn Piglets

Simple Summary

In most mammals, including humans, the need for iron increases rapidly in the last period of pregnancy. Therefore, in compliance with World Health Organization (WHO) recommendations, iron supplementation has become a standard procedure even in healthy pregnant women although it carries the risk of iron toxicity and dysregulation of systemic iron homeostasis. Due to physiological and genomic similarities between swine and humans, pigs constitute an useful animal model in nutritional studies during pregnancy. Here, healthy pregnant sows were supplemented with sucrosomial ferric pyrophosphate (SFP), a new non-heme iron formulation, to study its effect on their iron metabolism and that of their progeny. In particular, we aimed at verifying whether supplementation of pregnant sows with SFP will increase the level of low hepatic iron stores in newborn piglets. Results of our study show that SFP does not significantly alter neither systemic iron homeostasis in pregnant sows, nor hepatic iron stores in newborn piglets, which can be used during neonatal period for the maintenance of hematological status. We hypothesize that supplemental iron given orally to pregnant sows is poorly transferred across the placenta.

Abstract

Background: The similarities between swine and humans in physiological and genomic patterns, as well as significant correlation in size and anatomy, make pigs an useful animal model in nutritional studies during pregnancy. In humans and pigs iron needs exponentially increase during the last trimester of pregnancy, mainly due to increased red blood cell mass. Insufficient iron supply during gestation may be responsible for the occurrence of maternal iron deficiency anemia and decreased iron status in neonates. On the other hand, preventive iron supplementation of non-anemic mothers may be of potential risk due to iron toxicity. Several different regimens of iron supplementation have been applied during pregnancy. The majority of oral iron supplementations routinely applied to pregnant sows provide inorganic, non-heme iron compounds, which exhibit low bioavailability and intestinal side effects. The aim of this study was to check, using pig as an animal model, the effect of sucrosomial ferric pyrophosphate (SFP), a new non-heme iron formulation on maternal and neonate iron and hematological status, placental transport and pregnancy outcome; Methods: Fifteen non-anemic pregnant sows were recruited to the experiment at day 80 of pregnancy and randomized into the non-supplemented group (control; n = 5) and two groups receiving oral iron supplementation—sows given sucrosomial ferric pyrophosphate, 60 mg Fe/day (SFP; n = 5) (SiderAL^®, Pisa, Italy) and sows given ferrous sulfate 60 mg Fe/day (Gambit, Kutno, Poland) (FeSO₄; n = 5) up to delivery (around day 117). Biological samples were collected from maternal and piglet blood, placenta and piglet tissues. In addition, data on pregnancy outcome were recorded.; Results: Results of our study show that both iron supplements do not alter neither systemic iron homeostasis in pregnant sows nor their hematological status at the end of pregnancy. Moreover, we did not detect any changes of iron content in the milk and colostrum of iron supplemented sows in comparison to controls. Neonatal iron status of piglets from iron supplemented sows was not improved compared with the progeny of control females. No statistically significant differences were found in average piglets weight and number of piglets per litter between animals from experimental groups. The placental expression of iron transporters varied depending on the iron supplement.