Volume 89, Issue 6, June (2003), pp. 795-801 © The Author 2003
doi:10.1079/BJN2003843

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

Frank. R. Dunshea^1,2,*, Danny Suster¹, Douglas J. Kerton¹ and Brian J. Leury^2
1Victorian Institute of Animal Science, Werribee 3030, Australia
²The University of Melbourne, Melbourne 3010, Australia

 (Received 2 January 2002–Revised 5 January 2003–Accepted 17 January 2003)

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.

Abbreviations: DXA; dual-energy X-ray absorptiometry; IGF; insulin-like growth factor; p; porcine; ST; somatotropin

Keywords:
Lactation, Somatotropin, Growth, Body composition, Neonate, Pig