RELATIONSHIPS AMONG MATERNAL BACKFAT DEPTH, PLASMA ADIPOKINES AND THE BIRTHWEIGHT OF PIGLETS

Adipose tissue produces hormones, such as leptin and adiponectin, that are key factors in energy metabolism. The aim of this study was to assess the endocrine role of the adipose tissue in controlling intrauterine growth, so we evaluated the relationships among maternal adiposity, leptin and adiponectin-pregnancy trends and foetal growth in 48 Large White x Landrace crossbreed sows. Two groups of sows were designated based on backfat (BF) depth at the end of the lactation phase: a Low Fat group (LF, 11.60 mm; n = 24) and a High Fat group (HF, 18.20 mm; n = 24). During the subsequent pregnancies, the same level of feed was provided to both groups. The BF values of the sows were recorded, and blood samples were collected to assess the concentrations of leptin and adiponectin at mating and during gestation. The weights and temperatures of piglets were recorded at farrowing and after 24 h, and their body mass index and ponderal index values were calculated at farrowing. Before the piglets suckled colostrum, blood samples were collected, and the leptin, adiponectin and IGF-1 plasma levels were analysed. The observed differences in backfat depth between the LF and HF groups at mating persisted during pregnancy, and a decrease in adiponectin and an increase in leptin plasma levels were observed throughout gestation in both groups. Plasma adiponectin was lower in the HF group than in the LF group, but plasma leptin did not differ significantly. Compared to HF sows, LF sows gave birth to lighter piglets (P = 0.014). In addition, the weights of 27% of the piglets in the LF group and 14% in the HF group fell within the first 25th percentile (weight ≤ 1 kg). A positive correlation between offspring weight and maternal adiposity at mating (r = 0.149; P = 0.020) and a negative correlation between offspring weight and adiponectin-leptin ratio at mating (r = −0.198; P = 0.022) were observed. The morphometric parameters (body mass index, ponderal index) and thermoregulatory abilities of the piglets were unaffected by maternal adiposity. In terms of haematology, differences were found in the IGF-1 level, which was lower in piglets born from LF than HF sows (P < 0.001). The knowledge gained from this study suggested that differences in maternal adiposity, which were due to individual variability and not feeding strategies, influence the plasma concentration of adipokines, thus affecting offspring weight.