The serum leptin concentration and condition of gilts and sows

Leptin is the hormone produced in the adipocytes of white adipose tissue. Concentration of leptin in blood serum is correlated with thickness of backfat. It was confirmed that sows with higher leptin concentration show heat faster after weaning. To properly choose sows for mating, it is necessary to determine their body condition. It could be done using BCS (subjective method) or USG (objective method). In the literature breeding condition is described as not too thin and not too fat. It is expected that sows in poorer condition after weaning should have lower concentration of leptin what is undesirable because low concentration of leptin decrease AI efficiency. The aim of the study was to compare results of objective and subjective body condition estimation with leptin concentration on AI day.

The study was carried out on 180 sows (29 gilts and 151 multiparous) in industrial farm. Animals were estimated on insemination day - BCS and backfat fat at P2 point, 30 minutes before AI blood samples were collected to measure leptin concentration.

Sows and gilts were assigned to three groups, depending on backfat thickness at P2: Gilts group I (n=10) < 16 mm, group II (n=5) between 17-20 mm and group III (n=2)> 20 mm; Sows group I (n=14) < 18 mm, group II (n=15)19-22 mm, group III (n=10) > 22mm. Reproduction performance was estimated basis on: insemination efficiency, no of piglets born (alive, stillborn, mummies). Statistical analysis were made by the use of Anova, differences between analyzed groups were determined by Duncan test.

According to the USG measurement gilts were divided into 3 groups while using BCS, only to 2 groups. Gilts from I and II group according to USG were chosen to one group in BCS scale and it was also confirmed by concentration of leptin. Leptin concentration increases in the successive experimental groups with increasing of backfat. The highest concentration was in Gilts group III and this is the only case when the concentration of leptin in gilts was higher than in sows. Unexpectedly the highest concentration of leptin was observed in the group I of sows. In this case (the thinnest sows) it could be explained as a result of using flushing after weaning.

Enhancement of energy level prior to estrus in flush fed sows increases ovulation rate what was confirm in this study. BCS seems to be more reliable in field conditions than instrumental estimation what could be additionally confirmed by presented changes of leptin concentration. Flushing through the short period after weaning didn't increase backfat but change the fat metabolism and reproductive performance.

Disclosure of Interest: None Declared.