Anaemia in the sow: a cohort study to assess factors with an impact on haemoglobin concentration, and the influence of haemoglobin concentration on the reproductive performance

Effects of dietary iron supplementation on reproductive performance of sows and growth performance of piglets

This experiment aimed to investigate the effects of dietary iron supplementation from different sources on the reproductive performance of sows and the growth performance of piglets. A total of 87 sows with similar farrowing time were blocked by body weight at day 85 of gestation, and assigned to one of three dietary treatments (n = 29 per treatment): basal diet, basal diet supplemented with 0.2% ferrous sulfate (FeSO4), and basal diet supplemented with 0.2% iron sucrose, respectively, with 30% iron in both FeSO4 and iron sucrose. Compared with the control (CON) group, iron sucrose supplementation reduced the rate of stillbirth and invalid of neonatal piglets (P < 0.05), and the number of mummified fetuses was 0. Moreover, it also improved the coat color of newborn piglets (P < 0.05). At the same time, the iron sucrose could also achieve 100% estrus rate of sows. Compared with the CON group, FeSO4 and iron sucrose supplementation increased the serum iron content of weaned piglets (P < 0.05). In addition, iron sucrose increased serum transferrin level of weaned piglets (P < 0.05) and the survival rate of piglets (P < 0.05). In general, both iron sucrose and FeSO4 could affect the blood iron status of weaned piglets, while iron sucrose also had a positive effect on the healthy development of newborn and weaned piglets, and was more effective than FeSO4 in improving the performance of sows and piglets.

Evaluation of the potential benefits of iron supplementation in organic pig farming

Background: Iron from the stock acquired during foetal life and the ingestion of milk is not sufficient to cover the needs of the piglets during their first weeks of life. In organic farming, systematic supplementation with iron is problematic due to a strong limitation in pharmaceutic treatments. Methods: Erythroid parameters around weaning were measured in piglets from organic outdoor and indoor farms, and related to indicators of the inflammatory status. Blood samples were collected from 28.9±2.6 piglets/herd at 42.0±3.2 days of age and 11.9±3.0 kg live weight (mean ± SD) in 21 farms from the west part of France. Among the 11 outdoor farms, only one had supplemented piglets with 200 mg iron while among the 10 indoor farms, only one had not supplemented piglets, one had supplemented them with 100 mg, 8 with 200 mg and one with 400 mg. Results: Compared to outdoor piglets without supplementation, piglets kept indoors and receiving 200 mg iron had lower haemoglobin concentration (105 vs 118±2 g/l, mean ± SE) and red blood cell volume (56 vs 60±1 fl) (P<0.005). The reduction in haemoglobin concentration and red blood cell volume was more pronounced in indoor piglets supplemented with 100 mg of iron and even more when they had not received iron. The plasma concentration of haptoglobin was lower in outdoor than in indoor piglets (0.51±0.06 vs 0.78±0.09 g/l) whereas no effect of housing was observed for markers of oxidative stress (dROM, BAP). In the 14 farms where sow parity was known, the haemoglobin concentration was lower in piglets from primiparous than from multiparous sows (109 versus 114±2 g/l, P < 0.001). Conclusion: With the exception of soils where the content of bioavailable iron is very low, piglets from outdoor farms do not require iron supplementation, unlike those raised indoors.

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.

Effects of Dietary Modified Bazhen on Reproductive Performance, Immunity, Breast Milk Microbes, and Metabolome Characterization of Sows

Bazhen is a classic prescription used for the prevention of qi and blood deficiency. The present study aimed to investigate the effects of dietary supplementation with modified Bazhen powder (MBP) on sows during lactation. Forty pure-bred Yorkshire sows on day 100 of gestation were randomly fed a standard diet supplemented with 20 g MBP per sow per day (MBP group) or without (control group) during -14 to 7 days relative to parturition. Results showed that the serum levels of interleukin 2 (IL-2), immunoglobulin A (IgA), and IgG were higher, whereas IL-10 level was lower in sows fed with MBP diet than in controls on day 7 postpartum. A significantly elevated proportion of serum CD4⁺ T cells and a slight increase in the ratio of CD4⁺ to CD8⁺ T cells in the MBP group were also observed. Furthermore, MBP supplementation improved gastrointestinal function of postpartum sows, evidenced by increased levels of motilin, gastrin, and nitric oxide. Ultra high-performance liquid chromatography combined with a quadrupole time of flight and tandem mass spectrometer identified a total of 21 absorbed milk components. 16S rRNA gene amplicon sequencing data revealed that the microbiota diversity of the colostrum and transitional milk in the MBP group was increased. At the genus level, relative abundances of Enterococcus and Anaerostipes were significantly lower in the MBP group on day 0 of lactation. Metabolomic analysis showed that 38 metabolites were upregulated, and 41 metabolites were downregulated in the transitional milk; 31 metabolites were upregulated and 8 metabolites were downregulated in the colostrum in response to MBP. Metabolic pathways, protein digestion and absorption, and biosynthesis of amino acids were enriched in the colostrum and transitional milk. Our findings provide new insights into the beneficial effects of MBP, highlighted by the changes to the microbiota and metabolomic profile of breast milk from sows fed with an MBP-supplemented diet. Thus, MBP should be considered as a potential dietary supplement for lactating sows in pork production.

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.

Haematological reference intervals of sows at end gestation in ten French herds, the impact of parity on haematological parameters and the consequences on reproductive performance

BACKGROUND

Changes in haematological values occur during the reproductive cycle. In veterinary swine practice, haematological reference intervals for this period are scarce. Over past decades, there has been a remarkable increase in reproductive prolificacy, possibly making previously established haematological reference intervals for sows outdated.

OBJECTIVES

The aim of this study was to provide updated haematological reference intervals for sows at end-gestation, to study the influence of parity on those haematological parameters and to evaluate the impact of haemoglobin levels on production performance.

METHODS

The data presented in this article were obtained using blood samples from 198 apparently healthy and conventionally managed group-housed sows at end-gestation from ten breeding herds located in France. The samples were analysed for haematological variables using impedance technique on Horiba ABX analyser (Horiba, Kyoto, Japan). The reference intervals were calculated according to the guidelines of The American Society for Veterinary Clinical Pathology using SUMMARY procedure in R Studio. Analysis of variance (ANOVA) models were used to evaluate the influence of parity on each haematological parameter and the impact of haemoglobin values on production performances at farrowing. Differences were considered as significant if p < 0.05.

RESULTS

Reference intervals produced in this study were similar to previously published references but we noticed marked differences in white blood cell values. The study of the impact of parity revealed significant changes for gilts and parity 5 + sows regarding haematological values. Gilts had higher red and white blood cells counts, haemoglobin values and haematocrit values. Regarding haemoglobin values, the higher the number of liveborn and weaned piglets per litter, the lower the haemoglobin value at end-gestation. For sows of fifth or higher gestation, we found that the higher the percentage of stillborn piglets, the lower the haemoglobin value at end-gestation.

CONCLUSIONS

This study provides haematological reference intervals for sows at end-gestation. These will be useful for swine veterinarians and researchers for a better understanding of the influence of parity on haematological parameters and haemoglobin values and their relation to reproductive performance.

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.

Genetic parameters for haemoglobin levels in sows and piglets as well as sow reproductive performance and piglet survival

Genetic parameters were estimated for haemoglobin (Hb) levels in sows and piglets as well as sow reproductive performance and piglet survival. Reproductive traits were available between 2005 and 2014 for 7857 litters from 1029 Large White and 858 Landrace sows. In 2012 and 2013, Hb levels, sow BW and sow back fat depth were measured on 348 sows with 529 litters 5 days prior to farrowing. In addition, Hb levels were available for 1127 one-day-old piglets from 383 litters (a maximum of three piglets per litter) of 277 sows with Hb levels. The average Hb levels in sows (sow Hb), their litters (litter Hb, based on average Hb of three piglets) and individual piglets (piglet Hb) were 112 ± 12.6 g/l, 103 ± 15.3 g/l and 105 ± 21.7 g/l, respectively. Heritabilities for Hb levels were 0.09 ± 0.07 for sow Hb, 0.19 ± 0.11 for litter Hb and 0.08 ± 0.05 for piglet Hb. Estimates for the permanent environment effect of sows were 0.09 ± 0.09 for sow Hb, 0.11 ± 0.12 for litter Hb and 0.12 ± 0.03 for piglet Hb. In comparison, heritabilities for both number of stillborn piglets and pre-weaning survival were lower (0.05 ± 0.01 and 0.04 ± 0.01). Sow BW had no significant heritability, while sow back fat depth was lowly heritable (0.10 ± 0.08). Positive genetic correlations were found between sow Hb and litter Hb (0.64 ± 0.47) and between litter Hb and sow back fat depth (0.71 ± 0.53). Higher litter Hb was genetically associated with lower number of stillborn piglets (-0.78 ± 0.35) and higher pre-weaning survival (0.28 ± 0.33). Negative genetic correlations between sow Hb and average piglet birth weight of the litter (-0.60 ± 0.34) and between piglet Hb and birth weight of individual piglets (-0.37 ± 0.32) indicate that selection for heavier piglets may reduce Hb levels in sows and piglets. Similarly, selection for larger litter size will reduce average piglet birth weight (rg: -0.40 ± 0.12) and pre-weaning survival (-0.57 ± 0.13) and may lead to lower litter Hb (-0.48 ± 0.27). This study shows promising first results for the use of Hb levels as a selection criterion in pig breeding programs, and selection for higher Hb levels may improve piglet survival and limit further reduction in Hb levels in sows and piglets due to selection for larger and heavier litters.

Effects of different iron supply to pregnant sows (Sus scrofa domestica L.) on reproductive performance as well as iron status of new-born piglets

The present study aimed to investigate the effects of different iron (Fe) supply to sows during gestation on their reproductive performance and placental Fe load. Additionally, the Fe status of the corresponding offspring was assessed. Twenty multiparous sows were fed from insemination to farrowing with isoenergetic and isonitrogenic balanced diets differing in Fe content. The diet low in Fe (Group -Fe) was mainly composed of soybean meal and maize meal and had a Fe content of 114 mg/kg DM. For the diet high in Fe (Group +Fe), the diet was supplemented with Fe(II)SO₄ · 7H₂O to a total Fe content of 256 mg/kg. Blood characteristics (haemoglobin, haematocrit, mean corpuscular haem concentration, total Fe-binding capacity, transferrin saturation) of all sows were measured at the beginning and at the end of gestation. Daily Fe retention was calculated at the day of farrowing. After birth, reproductive performance (litter size, piglet weight, litter weight), placental Fe content and Fe blood characteristics of the piglets were determined. Apparent daily Fe retention tended to be greater in Group +Fe (p < 0.1). Blood parameters of the sows did not show any variations between feeding groups, neither at the beginning nor at the end of pregnancy, whereas placental Fe content was lower in Group -Fe (p < 0.05). In addition, Fe supply during gestation improved litter size (p < 0.01) and litter weight (p < 0.05). Although all sows were supplied according to the current Fe recommendations, a significant decline in reproductive performance of Group -Fe was recognised. Therefore, it was concluded that the re-evaluation of the gross Fe requirements of pregnant sows is inevitable to accommodate the current feeding recommendations.