Abstract: The experiment was conducted to investigate the relationships between changes in body weight and backfat thickness, body protein and fat, serum hormones concentration and metabolites which are involved in the regulation of appetite and energy metabolism at weaning in 24 sec parity crossbreed sows (Landrace x Large White; LxLW). Samples were collected and divided into three groups: 48 h before Weaning (W-48 h), at Weaning (W), 48 h post-weaning (W+48 h). Leptin, ghrelin, cortisol, estradiol-17β, protein, lactic acid and glucose were determined in blood serum of sows. In addition, sow body chemical composition were estimated using two different equations. Using regression analysis association between leptin and ghrelin levels at W-48 h, W and W+48 h were estimated. The 4 weeks of lactation induced significant changes in decrease of Body Weight (BW) and Backfat Thickness (BFT) as well as in loss of body fat and protein. Both BW and BFT loss were strong positive correlated with the Weaning to Estrus Interval (WEI) with exception of evaluated sow body chemical composition which had non-significant relationships with WEI. Mean concentration of glucose, estradiol-17β, leptin and ghrelin did not differ between investigated groups. High level of cortisol is mostly related to the stress at weaning caused by piglet removal. In sow, no antagonistic relationships between leptin and ghrelin level were observed. Moreover, concentration of serum leptin, ghrelin and cortisol had no significant correlation with the changes in calculated sow body protein and fat and with reproductive performance after Weaning (WEI). In conclusion, this study suggest strong evidence that it is not likely direct one to one relationship between those hormones and changes in crossbreed (LxLW) sow body weight, fat, protein and backfat thickness.
Nina Batorek, Marija Vogrin Bracic and Dejan Skorjanc, 2013. Serum Concentrations of Leptin, Ghrelin and Cortisol are not Direct Related to the Loss of Backfat Thickness, Body Weight, Protein and Fat at Weaning of Second Parity of Crossbreed Sows (Landrace x Large White). Journal of Animal and Veterinary Advances, 12: 766-774.