Influence of piglet birth weight on postnatal growth performance, tissue lipogenic capacity and muscle histological traits at market weight

High fecundity of sows induces a large within-litter variation in piglet birth weight. This study aimed to determine whether piglet birth weight influenced growth performance, tissue lipogenic capacity and muscle characteristics at slaughter. A total of 1 9 piglets were assigned to either light birth weight group (LBW: 0.80-1.10 kg, n=9) or heavy birth weight group (HBW: 1.75-2.05 kg, n=10). Light birth weight was associated significantly with reduced average daily gain during suckling and post-weaning periods only. At slaughter (102 +/- 0.6 kg), LBW pigs were 12 days older than HBW littermates (P < 0.01). Plasma IGF-1 concentration was reduced by 24% (P < 0.05) in LBW pigs compared to HBW pigs. Subcutaneous fat depth, tissue lipid content and lipogenic capacity did not differ between groups. Fiber mean cross-sectional area was increased by 14% in semitendinosus, and by 20% in longissimus and rhomboideus muscles, respectively (P < 0.05), in LBW pigs compared with HBW pigs. Total fiber number was reduced in both semitendinosus (-13%) and rhomboideus muscles (-20%, P < 0.10) of LBW pigs compared with HBW pigs. Whether such histological modifications influence the sensory quality of pork remains to be established. (c) 2004 Elsevier B.V. All rights reserved.