Effects of exogenous ghrelin on feed intake, weight gain, behavior, and endocrine responses in weanling pigs1

Abstract

The objectives were to determine relative ADG, ADFI, behavior, and endocrine responses in weaned pigs receiving exogenous ghrelin. Twenty-four barrows weaned at 18 d of age (d 0 of the experiment) were catheterized via the jugular vein, weighed, and assigned to either a ghrelin (n = 12) or saline (control; n = 12) infusion group. Initial pig BW did not differ between treatments (7.87+/-0.39 vs. 7.92+/-0.35 kg for ghrelin and control treatments, respectively). Pig BW and feed intakes were measured once daily throughout the experiment. Starting on d 1, the ghrelin pigs were intravenously infused three times daily for 5 d with 2 microg/kg BW of human ghrelin, and the control pigs were similarly infused with saline. Activity observations and blood samples were taken at -15, 0, 15, 30, 60, 90, 120, 240, and 480 min relative to the first infusion and then three times daily (0800, 1600, and 2400) for 8 d. Weight gain during the 5-d infusion period was greater by the ghrelin than by control pigs (0.57+/-0.10 vs. 0.21+/-0.13 kg, respectively; P < 0.04); however, there was no increase in feed intake. During two behavioral observation periods, more pigs in the ghrelin treatment were observed eating compared with control pigs (P < 0.05). The initial infusion of exogenous ghrelin increased serum ghrelin, GH, insulin, and cortisol concentrations (P < 0.05). Endogenous serum ghrelin increased from d 1 to 8 of the experiment in control animals (P < 0.05). Serum IGF-I initially fell in both treatment groups from d 1 to 2 (P < 0.05) but then increased from d 5 to 8 (P < 0.05). Peripheral concentrations of glucose in the ghrelin pigs were greater on d 2, 3, 7, and 8 than on d 1 (P < or = 0.05). In both treatment groups, peripheral concentrations of leptin increased from d 7 to 8, and cortisol decreased from d 1 to 5 of the experiment. These observations provide evidence that ghrelin may positively influence weight gain and concomitantly increase GH, insulin, and cortisol secretion in weaned pigs.

New polymorphisms and expression of the porcine ghrelin (<i>GHRL</i>) gene in different pig breeds

“…The ghrelin protein level was about 50 pg/ml and it was accordance with literature data (Salfen et al, 2004). Our results showed that polymorphism located in promoter region (c.-93A>G) affected expression level of GHRL gene.…”

“…However, the most important factor which regulates the expression and release of ghrelin is feed intake (fasted or fed). Starvation increases ghrelin expression in the gastric fundus and ghrelin peptide content in blood (Salfen et al, 2004). Some reports showed that in pig, nutrient content of the diet regulates ghrelin expression at the post-transcriptional level Yin et al, 2009).…”

Ghrelin in the gastrointestinal tract and blood circulation of perinatal low and normal weight piglets

“…Weaning is considered one of the most stressful periods that has a negative impact on feed intake and BW control, hence influencing ghrelin secretion (Salfen et al, 2004). Our results did not show an effect at 28 days of age (age of weaning) on the amount of gastric GCs nor total ghrelin serum concentrations.…”

“…However, research of Du et al (2007) indicates that changes only appear 10 days after weaning. Interestingly, exogenous ghrelin induces weight gain in weaning piglets (Salfen et al, 2004). Therefore, further research is needed on GC development and ghrelin secretion in piglets within the weaning period.…”

Estimation of the tryptophan requirement in piglets by meta-analysis

“…The effect of Trp on feed intake may also be caused by its effect on gastric emptying (Sè ve, 1999) or on ghrelin (Zhang et al, 2007). Ghrelin is a peptide hormone secreted by the stomach and the duodenum, and is involved in the regulation of feed intake and in the signalling between the digestive system and the brain (Inui et al, 2004;Salfen et al, 2004).…”