Effects of weaning weight, co-mingling, group size and room temperature on pig performance.

Four experiments involving 3- to 4-wk-old, ad libitum-fed weanling pigs (n = 809) were conducted to determine the effects of initial pig weight, co-mingling of litters, numbers of pigs/pen and room temperature on pig performance in a conventionally equipped nursery. Pigs that were largest at birth were largest (P less than .01) at weaning (r = .66) and also at 28 d postweaning (r = .62). Light-weight pigs (3.8 kg) at weaning gained more slowly (P less than .05) for 4 wk postweaning than heavy weight pigs (6.5 kg). Growth curves for the light and heavy groups of pigs remained parallel throughout the 4-wk nursery period, indicating that small pigs were not making compensatory gains. Growth rates of average-weight pigs (5.2 kg) were intermediate to and not different (P greater than .05) from light- and heavy-weight pigs. Penning 8, 16 or 24 pigs together while maintaining constant flooring area and feeder and waterer space/pig did not reduce (P greater than .05) intakes, gains or feed:gain ratios. Co-mingled litters grew comparably (P greater than .05) to pigs reared as littermates. In temperature studies, pigs were reared either in a room maintained at 29 +/- 2.8 C throughout the 28-d trials or at 29 +/- 2.8 C the first week postweaning and 24 +/- 2.8 C thereafter. Reducing the nursery temperature to 24 +/- 2.8 C after 1 wk depressed (P less than .05) intakes, gains and feed efficiencies as compared with the warmer temperature regimen.