Effect of litter size and birth weight on growth, carcass and pork quality, and their relationship to postmortem proteolysis

The objective of the study was to test the hypothesis that birth weight (BtW) influences growth, carcass characteristics, meat quality, and postmortem (pm) proteolysis differently when pigs originate from small (S) or large (L) litters. Swiss Large White barrows (60) used in this study originated from 20 litters with either less than 10 (S) or more than 14 (L) piglets born per litter. Within each of the S and L litters, 3 barrows were selected at birth: the lightest (L-BtW), the heaviest (H-BtW), and the one with a BtW nearest to the average BtW of the litter (M-BtW). The BW and total feed intake of the individually penned pigs were determined weekly. At slaughter, carcass characteristics were assessed. Meat quality traits were determined in the LM and dark portion of semitendinosus muscle. Titin, nebulin, desmin, and integrin proteolysis were evaluated by SDS-PAGE and Western blot technique, and mu - and m-calpain activities were monitored using casein zymography. Litter size affected BtW of L-BtW and M-BtW but not of H-BtW barrows (BtW x litter size interaction; P = 0.07). From weaning to slaughter, L-BtW barrows grew slower (P < 0.01), ingested less feed (P < 0.01), and were less efficient (P < 0.01) than H-BtW and M-BtW barrows. The carcass yields were greater (P < 0.01), and livers and kidneys were lighter (P