Iron supplement type may boost piglet organ weight, blood parameters

The type of iron supplement used in the diet of pregnant pigs may improve blood parameters, organ weight and iron nutritional status for piglets, say researchers.

A team of researchers from the Lethbridge Research Centre in Canada and Shandong Agricultural University in China examined the use of different sources and amounts of supplemental iron in sow diets to see the influence on piglets. The goal was to find a way to address iron deficiency in piglets.

“This study aimed to determine the reasonable addition of organic or inorganic iron in sow diets by investigating the effects of maternal dietary supplementing with varying levels of Fe-Gly [ferrous glycine chelate] and FeSO4·H2O [ferrous sulfate monohydrate] from d 86 of gestation to d 21 of lactation on the iron nutritional status of neonatal pigs,”​ the researchers said.

The team found that different forms of iron supplementation in sow diets generate improved results for piglets. Piglets from sows getting levels of Fe-Gly had higher organ weights and showed increased iron levels in the liver, spleen, kidney and femur.

“These findings suggest that Fe-Gly supplemented at the level of 110 mg/kg in the diet of sows in this experiment is superior to other forms of supplementation, based on HGB [hemoglobin] concentration, the relative organ weight, tissue iron contents and blood biochemical indices of piglets.”​

The group published its work in the journal Animal Science​​​.

Why examine iron use in sow diets?​

Iron is an important trace element needed for animal growth and health, said the researchers. However, iron deficiency anemia is common in piglets as their iron stores are low at birth and there tends to be little iron in sows’ milk.

Without iron supplementation, piglets could have reduced feed intake, lowered growth rate, increased risk of iron deficiency anemia and diarrhea, they said. Dietary additions of inorganic iron for pregnant and lactating sows is common.

“However, the absorption and activity of inorganic iron are impaired by the antagonism among trace elements and macroelements (Umbreit, 2005),”​ they said. “Studies suggested that amino acid chelated irons had the advantages of stability, high biological efficacy, nutritional benefits, anti-stress effects, and reducing excretion compared with inorganic iron.”​

Chelated or protein-based sources of iron could provide improved biological efficiency compared to the use of ferrous sulfate (FeSO4), they said. Ferrous glycine chelate (Fe-Gly) is an iron supplement used in human and infant food, which has been linked to improved iron absorption compared with the use of FeSO4-H20.

However, there is minimal information regarding the use of differing levels of Fe-Gly and ferrous sulfate monohydrate (FeSO4-H2O) to improve the iron nutritional status of newborn piglets, the researchers said.

Methods and materials​

In the feeding trial, 45 sows were given one of nine diets for a 28d period starting at day 86 of gestation through day 21 of lactation, the researchers said. The diets included a control with no supplemental iron, that diet with 50, 80, 110, or 140 mg Fe/kg using Fe-Gly or with those same levels of supplementation using FeSo4-H2O.

The control diet was corn-wheat-soybean meal-based and was designed to meet or exceed the NRC nutritional requirements for pregnant and nursing sows, they said. The iron supplements were mixed with corn and added as a premix.

Piglets were weighed at birth, and a sample was collected at that time for analysis of heart, liver, spleen, femur and kidneys, they said.

Relative organ weight was established and blood samples were taken at birth and on day 21 to check for red blood cells (RBC), hemoglobin (HGB) concentration and hematocrit (HCT), they said. Serum iron (SI) and total iron binding capacity (TIBC) also were checked as was serum ferritin (Fn).

Results​

Overall, piglets from sows getting the Fe-Gly supplement outperformed piglets from the control group or those getting the alternative supplement, the researchers said. However, more work is needed to establish the appropriate amount of FeSo4-H2O to add to sow diets and meet the nutritional needs of neonatal piglets.

“According to the HGB concentration of piglets, and taking relative organ weight, tissue iron contents and blood biochemical indices into consideration, the appropriate dosage of Fe-Gly in the diet of sows was 110 mg/kg in the present study,”​ they said. “As iron anemia is a common and detrimental problem for piglets, these findings can be used for improving management practices in the swine industry.”​

Compared to the control, piglets from sows that received the Fe-Gly supplement showed increased weights for the spleen and kidneys at birth, the researchers said. Piglets also had higher organ weight than those from sows getting the FeSO4-H2O supplement.

Organ weights increased linearly as additional Fe-Gly was added to the sow diets, except for those with the highest levels of supplementation, they said.  

When compared to the control group or piglets getting the FeSo4-H20 supplement, piglets reflected linearly increasing amounts of iron in the liver, spleen, kidneys and femur as sows had more Fe-Gly added to their diets, the researchers said. There was no major difference between the amounts of iron found in organs for piglets on the control or getting the FeSO4-H2O additive.

“Increasing the supplement amount of Fe-Gly in the diet of sows enhanced the heart, liver, spleen, kidneys and femur iron content of piglets linearly,”​ they said. “No significant difference could be found between 110 mg/kg Fe-Gly and 140 mg/kg Fe-Gly groups.”​

Piglets from sows getting the Fe-Gly supplement had higher RBC, HGB concentration and HTC, they said. The piglets also had more RBC and higher HGB levels than piglets from sows getting the alternative iron supplement.

As amounts of Fe-Gly in the sow diets increased, piglets showed a linear and quadratic increase in RBC, HGB concentration and HTC, they said.

When compared to the control, piglets had more serum Fn and SI and a drop in TIBC when sows were given Fe-Gly, said the researchers. At both day 1 and day 21, there was a linear increase in serum Fn, Si and a linear decrease in TIBC for the piglets as sows had more supplement added to their diet, although results for those receiving the 110 and 140mg/kg supplement amounts were similar.

“In the FeSO4·H2O groups, there was a linear increase in the Fn of piglets (d 21) and a linear decrease in serum TIBC on d 1 and 21 of piglets,” ​they said.

Source: Animal Nutrition​

Authors: Y Li, W Yang, D Dong, S Jiang, Z Yang, Y Wang