Effect of Fasting on Hormones and Metabolites in Plasma of Fast-growing, Lean and Slow-growing Obese Pigs

Abstract

Plasma concentrations of glucose, free fatty acids (FFA), insulin and growth hormone (GH) were determined immediately after food removal and then hourly for 24 hours. Blood was sampled from six lean and six obese pigs at 10 weeks of age via indwelling catheters. Plasma glucose decreased but was similar in both pig strains shortly after feed removal; at the end of the 24-hr fast, plasma glucose was higher (P less than .01) in lean pigs. Plasma FFA concentrations were similar in lean and obese pigs and increased five-fold within 24 hr of fasting. Plasma insulin was higher (P less than .05) in obese pigs than in lean pigs immediately after food removal only (21.4 +/- 3.0 vs 9.8 +/- 2.4 microU/ml). Pattern of GH secretion over 24 hr was episodic; average plasma GH was lower in obese pigs than in lean pigs (2.8 +/- .7 vs 9.4 +/- 1.9 ng/ml). In summary, FFA mobilization was similar in lean and obese pigs, GH concentrations were lower in plasma of obese pigs and relative differences in plasma glucose and insulin between pig strains were influenced by time after feed removal.

Feeding motivation in swine: Relation with insulin, glucose and free fatty acids in portal and jugular blood, and involvement of cholecystokinin

“…Lower insulin concentrations after a fast were also previously observed (Ozawa et al 1996;Wangsness et al 1981;Buonomo and Baile 1991;Fernandez et al 1995) and were thought to act as a mechanism preventing fasting-induced hypoglycemia (Fernandez et al 1995). This would maintain peripheral glucose concentrations and partly explain present and published results that short-term feed deprivation does not reduce peripheral glucose concentrations in growing swine (Wangsness et al 1981;Buonomo and Baile 1991;Fernandez et al 1995).…”

“…This would maintain peripheral glucose concentrations and partly explain present and published results that short-term feed deprivation does not reduce peripheral glucose concentrations in growing swine (Wangsness et al 1981;Buonomo and Baile 1991;Fernandez et al 1995). Yet, FFA and glucose concentrations in jugular and portal blood were differently affected by fasting.…”

“…Furthermore, as reported in gilts (Barb et al 1997), growing pigs (Wangsness et al 1981;Ozawa et al 1996) and piglets (Fernandez et al 1995), fasting increased FFA concentrations in jugular blood. Rapid mobilization of FFA as alternative energy stores may have maintained peripheral glucose levels during fasting (Barb et al 1997) since raising plasma FFA concentrations inhibits glucose utilization and stimulates gluconeogenesis (Randle 1998).…”

Serum profile of metabolites and hormones in obese (Iberian) and lean (Landrace) growing gilts fed balanced or lysine deficient diets

“…Furthermore, IGF-1 is expressed in most tissues and can act via an autocrine/paracrine fashion. GH clearly differed when extreme breeds were compared and was mainly lower when a reduced growth rate coincides with high daily deposition of fat (Althen and Gerrits, 1976;Kasser et al, 1981;Wangness et al, 1981). Others found no plasma GH differences among pigs with divergent genetic merit for postweaning ADG (Clutter et al, 1995).…”

Effects of water supplementation with tryptophan and vitamin B6 or feeding hydrogenated fat on reducing hunger-induced drinking pre-slaughter in pigs

“…The use of body energy reserves to maintain physiological function during a 24-h feed deprivation is characterized by higher muscular and plasma free fatty acids concentrations (Wangsness et al 1981;Fernandez et al 1995), greater salivary cortisol levels (Parrott and Misson 1989), reduced plasma glucose and liver glycogen content (Wangsness et al 1981;Warriss and Brown 1983). Furthermore, pre-slaughter fasting may result in liveweight losses as high as 5% (Warriss 1985).…”