Influence of individual birth weight and litter size on survival rate, postnatal growth, slaughter performance and meat quality in pigs

Survival rate, growth performance, and carcass and muscle characteristics at slaughter were studied on 1 289 piglets, according to litter size and birth body weight. More than 55% of the litters had at least 12 piglets born alive, 20% of them exhibited more than 15 piglets. Proportions of piglets weighing less than 1.2 kg or more than 1.6 kg at birth were 20% and 37%, respectively. As litter size increased, number of piglets weighing between 1.0 and 1.6 kg increased. For piglets weighing less than 1.0 kg at birth, survival rate was 30% from birth to slaughter, and 67% of them died during the nursing period. Slaughter weight and warm carcass weight were 9.7 kg and 5.6 kg higher for the heaviest pigs at birth. These pigs were also younger (-7.3 days) at slaughter compared to lighter pigs at birth. Carcass composition was not affected by pig birth weight. At similar slaughter weight, pigs exhibiting a low birth weight (0.8-1.1 kg) displayed a reduced plasma concentration in IGF-I (-24%), compared to heavier pigs at birth. For a similar muscle mass at slaughter, mean myofiber size was increased (13 to 21% higher) and total fiber number was proportionally decreased in the lighter compared to the heavier pigs. Intramuscular fat content, pH1 and pHu were not affected by birth weight