Detection of ghrelin, obestatin and nesfatin-1 in sheep milk: Three-way evaluation in ewe plasma, milk and lamb plasma

Ghrelin, obestatin, and nesfatin-1 peptides are regarded as the primary regulators of the body’s appetite and energy balance. However, few studies have explored the roles of these peptides in milk and in metabolic adaptation in sheep. The presence of these peptides was investigated in blood samples from sheep and lambs and in milk samples from sheep during the early lactation phase in the current study. Thirty healthy ewes along with their single lambs were followed through their 3 rd to 5 th week after giving birth. Blood samples from ewes and lambs, and matched milk samples, were collected and analyzed by using enzyme-linked immunosorbent assay (ELISA) kits. Sampling was conducted over three weeks, and differences among time periods were compared. A significant increase was recorded for ghrelin and obestatin levels in plasma, whereas nesfatin-1 levels were decreased to a considerable extent. The milk samples followed a similar pattern with ghrelin and obestatin levels increased, whereas nesfatin-1 levels decreased. Nevertheless, a similar pattern was recorded for plasma samples. This study detected obestatin and nesfatin-1 peptides from the sheep milk for the first time. It is thought that coordinated action of these peptides affects the body, milking and offspring of sheep during early lactation phase. The increased ghrelin and obestatin levels along with decreased level of nesfatin-1 decreases work in coordination to fulfill energy needs of sheep. The detection of these peptides in milk samples warrants that energy balance of offsprings can be altered by maternal metabolism. This study provides first evidence for the presence of these peptides in the milk samples and confirms that these peptides can alter feeding behavior and energy regulation in lambs.