Effects Of Maternal Low Protein Dietary On Iron Metabolism In Male Preweaning Piglets

As an essential nutrient element, iron participates in many biological processes including oxygen transport, energy production and DNA synthesis, especially during the rapid growth and development which occurs after parturition. The main processes of iron metabolism are intestinal absorption, blood transportation, and storage in liver. Furthermore iron homeostasis is regulated systemically and may affect the normal physiological processes, further affecting the normal growth and development, breast milk contains small amounts of iron, piglets can get 1 mg iron from breast milk every day, pig iron stored in the body consumed quickly, but the wild pig can obtain iron through the soil, intensive breeding pigs are not contact with the soil, only get by injection without breast milk. Farmed pigs can not get iron from the soil, so iron of newborn and preweaning piglet was from maternal placenta and breast milk respectively, and maternal nutrition levels directly affect iron levels in piglets. However, most studies focus on the effect of iron content in maternal diets on offspring iron absorption, little information is available on the effect of maternal low protein diet during pregnancy on iron absorption. Therefore, the purpose of this study was to investigate the effect of low protein diet in sows on iron metabolism in male preweaning piglets and explore its underlying mechanisms.1 Effects of maternal low protein diet during pregnancy on iron concentration of serum in male newborn and preweaning pigletsThe animal experiment was conducted in the Shanghai Dafeng ShenHe, Yanchen, Jiangsu Province, P. R. China. Twenty Landrace X large white dual swine were assigned randomly into standard (SP) and low (LP) protein groups. The SP sows were fed on diets containing 15% crude protein during gestation, and those in LP group were fed diets containing 7.5% crude protein. The dietary treatment began one month before artificial insemination at the first observation of estrus. Sows were fed thrice daily with 1.2,1.8 and 2.4 kg/day during the three phases of gestation respectively. The birth weight of piglets was documented after birth. The remaining newborn piglets were fed with diets containing 18% crude protein (SP) and 9% crude protein standard protein (LP) lasting for 28 days from lactation, One male piglet of the mean body weight (±10%) was selected from all male preweaning piglets of each litter, then decapitated to collect samples.There was no significant difference in iron concentration of diets between two groups. Maternal LP diet did not change unsaturated iron binding capacity, total iron binding capacity, transferrin saturation and ferritin (P> 0.05) in sows. However, serum iron concentration (P= 0.09) in sows was tended to be lower. Maternal LP diet did not affect birth weight in newborn, and serum calcium concentration and phosphorus concentration (P > 0.1) in preweaning. Serum irons in male preweaning piglets (P< 0.05) were significantly reduced. Indicators in serum iron metabolism suggested that maternal LP diet did not alter unsaturated iron-binding capacity, total iron binding capacity, and transferrin saturation (P > 0.1), but a lower tendency of serum ferritin (P= 0.08).2 Effects of maternal low protein diet during pregnancy on iron absorption of Duodenal in male preweaning pigletsMaternal LP diet reduced serum iron of male preweaning piglets significantly (P <0.05). In order to investigate whether the dietary protein level influenced iron metabolism in male preweaning piglets, duodenal iron absorption, blood and liver iron regulation of iron transport were studied. The results showed that LP diet had no obvious effect on mRNA level of genes related to duodenal iron absorption, but significantly reduced the transport-related protein levels such as divalent metal ion transporter 1 (DMT1) and ferroportin (FPN) (P<0.05). Hepatic transferrin (TF) and transferrin receptor 1 (TfR1), play vital role in iron transportation, mRNA levels were significantly decreased (P<0.05); As a key factor in regulating iron metabolism, hepcidin did not change in serum, but a higher tendency in liver (P=0.09); BMP-SMAD and STAT are two key signaling pathways involved in the process of hepcidin regulation,and the expression of mRNA did not alter.In conclusion, the results indicated that sows low protein diet in gestation and lactation reduce transport protein expression on duodenal iron absorption and affected transferrin mRNA expression, Interfere with the transport of iron cycle, further disturbing iron metabolism in preweaning piglet.