Energy utilization of weanling pigs raised under pen conditions

Two comparative slaughter experiments were conducted to evaluate the energy utilization of weanling pigs raised in groups under pen conditions. In Trial 1, 64 weanling pigs were kept in groups of four and fed every 12 h. The pigs were fed either ad libitum during the two daily feedings or 80, 60 or 40% of the intake/kilogram body weight (BW) of the 100% intake group. The efficiency of dietary energy and N utilization for carcass energy and N gains increased quadratically (P less than .01) with increasing feed intake. The daily metabolizable energy (ME) requirement for maintenance (MEm) was calculated to be 115 kcal X d-1 (kg X 75)-1. Above maintenance, the ME of the diet was utilized for carcass energy gain with an efficiency of 50%. Trial 2 was conducted to examine the energy and N utilization of weanling pigs kept either individually in cages or in groups of four under pen conditions. Twelve pigs were allotted to each pen type and fed at levels of 2, 3.5 or 5% of their BW daily. Increasing the level of intake, quadratically increased (P less than .01) the efficiency of ME and digestible N (DN) utilization for carcass energy and N gains. The apparent digestibilities of energy and N decreased linearly (P less than .05) while rate of passage increased linearly (P less than .05) with increasing feed intake. When compared with the individually caged pigs, the grouped pigs showed lower apparent digestibility of energy (P less than .05) but improved efficiency (P less than .05) of ME and DN utilization for carcass energy and N gains.(ABSTRACT TRUNCATED AT 250 WORDS)