Metabolic changes during the transition from the fed to the acute feed-deprived state in prepuberal and mature gilts.

Abstract

The present study compared the metabolic response to acute feed deprivation in ovariectomized prepuberal (P; n = 6), 62 +/- 2 kg BW, and mature (M; n = 6) gilts, 124 +/- 4 kg BW. Blood was collected at 1, 2, 3, 4, 6, 8, 12, 16, 20, 24, 28, 32, 40, and 48 h after initiation of feeding. Samples were quantified for glucose, insulin, free fatty acids (FFA), beta-hydroxybutyrate (HBA), IGF-I, IGF binding proteins (BP)-1 to -4, cortisol, and amino acids (AA). At 24 h, blood samples were collected every 15 min for 8 h and an additional 1 h after i.v. injection of GnRH (.2 microgram/kg BW) and growth hormone-releasing factor (GRF; 1 microgram/kg BW). Samples were assayed for growth hormone (GH) and LH. Serum insulin concentrations were lower (P < .05) in P gilts. Plasma glucose concentrations were similar. Serum FFA concentrations were greater (P < .05) in P gilts. Serum concentrations of HBA were greater (P < .001) in P gilts at 48 h. Serum IGF-I concentrations were lower (P < .05) in P gilts by 16 h. Serum IGFBP-1-4 levels were similar. Serum cortisol concentrations were similar. Serum concentrations of the essential AA, isoleucine, lysine, threonine, valine, and phenylalanine were greater (P < .05) in P gilts at 40 h. Serum LH concentrations and response to GnRH were similar. Basal serum GH concentrations and peak response to GRF were greater (P < .05) in P than in M gilts. The transition from fed to unfed state occurs more rapidly in P than in M gilts.

GH and IGF-I binding sites in adipose tissue, liver, skeletal muscle and ovaries of feed-restricted gilts

“…However, the present study failed to show a significant difference in IGFBP levels between restricted and well-fed gilts. This finding was in agreement with the lack of effect of a 48 h food deprivation in prepubertal and mature gilts [1]. This suggests that the sensitivity of plasma IGFBPs to feed restriction differs between pubertal and younger animals.…”

“…has also been described by Mao et al [18]. The finding of a lower plasma IGF-I concentration in feed-restricted gilts is consistent with the response to feed deprivation or restriction previously reported in young growing pigs [5,8,9], prepubertal and mature gilts [1,6] and lactating sows [18,27]. Because the liver is considered as one of the major sites of IGF-I production, it has often been indicated that the low concentration of IGF-I results from a decrease in GH binding.…”

Dietary protein restriction during lactation in primiparous sows with different live weights at farrowing: II. Consequences on reproductive performance and interactions with metabolic status

“…Moreover, several AA share a common AA transporter with large neutral AA (LNAA), and their uptake into the brain depends on the LNAA concentrations [28]. In pigs, brain serotonin concentrations are increased dose-dependently by dietary supplementation of tryptophan to a deficient ration [29], but it is decreased by additional crude protein or additional LNAA [29,30] Barb et al [31] reported that 48-h fasting reduced the tyrosine/LNAA ratio in the plasma of prepuberal gilts. These gilts exhibited an alteration in GH secretion but not in LH secretion.…”

Insulin-stimulating diets during the weaning-to-estrus interval do not improve fetal and placental development and uniformity in high-prolific multiparous sows

“…probably resulted in short-term increases in plasma free fatty acid levels before morning feeding (Barb et al, 1997;Inoue et al, 2005), which in turn can stimulate glucose-stimulated insulin secretion (Haber et al, 2003;Itoh et al, 2003). As insulin responses differ between morning and afternoon feedings, studies investigating effects of insulin on, for example, follicle development should consider both insulin responses.…”