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.

Association between sow and piglet blood hemoglobin concentrations and stillbirth risk.

Previous studies have indicated that high piglet blood hemoglobin concentration (HbC) at birth lead to better performance later in life. The primary objective of this study was to investigate the association between sow and piglet blood HbC at farrowing. A secondary objective was to investigate the relationship between sow HbC and probability of stillbirths. Farrowings were observed in 22 sows in a Danish commercial herd. Maternal blood HbC was measured 1-3 days before farrowing using a HemoCue 201 + Hb device. Similarly, HbC was measured from 144 offspring piglets before colostrum intake. Total number of born piglets per litter and parity of the sow were recorded and stillborn piglets were identified using a lung flotation technique. The association between HbC in sows and piglets was determined using a linear mixed model. The relationship between sow HbC and probability of stillbirths was determined using a generalized linear model. The mean HbC of the sows and piglets were 106.9 ± 12.2 and 124.4 ± 19.9 g/L, respectively. A tendency towards a positive association between HbC of the piglets and HbC of the sow around farrowing was found (P = 0.058). Additionally, the probability of stillbirths was negatively associated with the sow HbC (P = 0.021). These results indicate that HbC in newborn piglets may be increased by increasing the sow HbC. Furthermore, stillbirth rates might be reduced by increasing the HbC of the sow.

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

BACKGROUND: Anemia characterized by low hemoglobin concentration (HbC) is common in indoor housed pregnant sows. Iron is essential for hemoglobin synthesis and a number of metabolic processes including DNA synthesis and regulation of enzyme systems. In sows, anemia has been linked to lower HbC in piglets and increased occurrence of stillbirths. Therefore, the main objective of this study was to evaluate the effect of iron injection on hematology of pregnant sows and their offspring. Other objectives were to evaluate the effect of this injection on the probability of stillbirths and to study the tolerability of injected iron. RESULTS: A sow herd with bi-weekly batch farrowing was selected for the study and 100 sows at mid-gestation were randomly assigned to either a treatment (FeT) or a control (FeC) group. At the time of recruitment to the study (baseline), 46% of the sows in the herd were anemic with a HbC less than 103 g/L. However, none of the anemic sows had iron deficiency anemia on erythrocyte characterization. HbC decreased numerically during gestation in both the FeT (- 2.48 g/L) and FeC (- 2.99 g/L) groups but the decrease was insignificant between the groups (P = 0.79). Likewise, the change from baseline to farrowing and from baseline to post-farrowing in other hematologic variables was similar for both groups. The percentage of transferrin saturation was not statistically different between groups (P = 0.14). There was a batch effect (week of breeding) in most of the hematologic variables. The probability of stillbirth in the two groups did not differ (P = 0.94). None of the hematologic variables in piglets was significantly different between the two groups. The sows tolerated the iron injection well. CONCLUSIONS: Intramuscular injection of two doses of 2500 mg iron 2 weeks apart at mid-gestation did neither change hematologic variables in sows nor in the piglets at farrowing. Similarly, iron treatment did not reduce the probability of stillbirths among the offspring. The sows recruited in this study tolerated the iron injections well. Further characterization of erythrocytes did not support that sows had iron deficiency anemia at baseline. Therefore, further studies on animals with well-defined anemia and with focus on the iron regulating hormone hepcidin are recommended.

Hematologic reference intervals of Danish sows at mid-gestation.

Hematologic reference intervals are useful tools for interpretation of laboratory results in swine practice and research. Until now, there were no hematologic reference intervals established for gestating Danish sows and those established in other countries are either out-dated, produced using very few sows or incomplete with few variables. In the past few decades there have been significant increases in litter size due to breeding, as well as the development of new analytical procedures for hematology and statistical procedures for calculating reference intervals. Therefore, hematologic reference intervals representing current pig production and technology are greatly needed. The main objective of this study was to provide updated and complete hematologic reference intervals for Danish sows at mid-gestation. Blood samples were collected at mid-gestation from 248 sows belonging to five commercial herds in Denmark and the samples were analysed for several hematologic variables using the Advia 2120i Hematology System. The reference intervals were calculated according to the guidelines of American Society for Veterinary Clinical Pathology. The reference interval for hemoglobin concentration was 103.1-145.0 g/L. For red blood cells, hematocrit and mean corpuscular volume, the 95% reference intervals were 4.98-7.50 × 1012/L, 0.32-0.47 L/L, 57.0-69.3 fL, respectively. The reference intervals established in this study are different from those previously reported in the literature. These reference intervals add to the current knowledge and will be useful in the prevention, diagnosis and treatment of several disease conditions in gestating sow populations.