Exogenous porcine somatotropin administered to neonatal pigs at high doses can alter lifetime fat but not lean tissue deposition

Abstract

The growth rate of the young pig is generally much less than its potential and may be constrained by endocrine status as well as nutrient intake. The aim of the present study was to determine whether porcine (p) somatotropin (ST) treatment of the sucking pig could alter subsequent body composition. Twelve mixed-parity cross-bred sows with an average litter size of ten piglets were used to nurse pigs for the present study. On day 1 of lactation, the median two male pigs (by weight) from each litter were randomly allocated to one of two doses of pST (0 or 1 mg/kg per d) until weaning on day 21. Pigs were weaned and offered feed ad libitum until slaughter at 134 d of age. Body composition was measured using dual-energy X-ray absorptiometry (DXA) at 21, 49, 77, 105 and 133 d of age. There was no significant difference in growth rates between day 1 and 21 of lactation in pigs injected with either saline (9 g/l NaCl/l) or pST (258 v. 246 g/d for control and pST-treated pigs respectively, P=0·61), and as a consequence there was no significant difference in liveweight at weaning (7·13 v. 6·84 kg, P=0·59). However, fat mass at weaning tended to be decreased (1·18 v. 0·96 kg, P=0·064), while the % fat in the body at weaning was significantly (16·7 v. 13·9 %, P=0·008) decreased by exogenous pST treatment. In the immediate post-weaning period there was a reduction in lean tissue deposition (347 v. 300 g/d, P=0·021) but no effect on fat deposition (35 v. 33 g/d, P=0·72). Over the entire weaning-to-slaughter period, pST treatment of neonatal pigs decreased the rate of fat deposition (130 v. 112 g/d, P=0·033), but had no effect on lean tissue deposition (550 v. 538 g/d, P=0·49). Therefore, treatment of nursing pigs with high doses of pST for a short period before weaning may provide a means of reducing the fat content of pork and pork products.

Slow Growing Pre-Weaning Piglets Have Altered Adipokine Gene Expression

“…Restricted feed intake has been shown to elevate skeletal muscle LPL activity [44]. Slower growing piglets have been reported to have higher rates of lean deposition [12]. Dual x-ray absorptiometry of additional slow and fast growing pairs of pigs from other litters at our laboratory has confirmed that slower growing piglets have higher rates of lean deposition than faster growing piglets [13].…”

“…[23]. Slower growing and subsequently smaller piglets have less fat deposition during the preweaning period [12] [13]. This slower growth rate may be the consequence a difference in relative fetal maturity, health status, nutrition, response to stress or a combination of these factors.…”

“…The rapid rate of preweaning growth results in linear increases in protein and fat deposition that correlates with overall growth rate [12] [13]. However, growth rate between piglets within a litter can significantly diverge [14] and slow growing piglets have been reported to display greater adiposity post-weaning [15].…”

“…The MIF protein has been shown to both impair glucose uptake by the adipocyte and attenuate insulin sensitivity [41]. The consequences of the lower MIF mRNA abundance in the slow growing piglet would imply a paracrine counter regulatory attempt to increase the lower lipid accretion rate of the slow growing pig [12] [13]. However, MIF has numerous other functions that have yet to be evaluated within the context of adipose tissue biology [42].…”

Non-invasive determination of body composition in pigs using a Norland XR-26 bone densitometer

“…In numerous studies the applicability has been proven on pigs and a good precision has been shown (PINTAURO et al, 1996;KOO et al, 2002;CHAUHAN et al, 2003;SUSTER et al, 2003). Dual-energy X-ray absorptiometry has been applied in growth studies with pigs (MITCHELL and SCHOLZ, 1997;DUNSHEA et al, 2003;PURSEL et al, 2004;SUSTER et al, 2006a) and is also able to demonstrate genetic differences (MARCOUX et al, 2005;MITCHELL et al, 1998c). The software of commercially available DXA devices has been generated for the accurate determination of human body composition.…”