ABSTRACT: Ninety-six crossbred intact male pigs
(34.5 ± 3.5 kg BW) were allocated by weight and vocal-
ization score to a 2 × 2 × 2 dynamic experimental design
including two stocking densities (1 or 2 m2
/pig), two
temperatures (22°C and 30°C), and two short groupings
of unfamiliar cohorts (six pigs as one pig per group, and
six pigs per group). The study was conducted over 8
wk, and live weight gain (WTG) and feed intake (FI;
as-fed basis) were measured weekly. During the first
week, pigs were housed in individual pens from four
independent rooms. To group pigs, pen partitions were
removed. Pigs were grouped in Rooms 2 and 3 from wk
2 to 4, and in Rooms 1 and 4 during wk 7. Temperature
was increased from 22°Cto30°C in Rooms 1 and 2
during wk 4 and 7. Pen partitions were replaced in
Rooms 2 and 3 at the end of wk 4 and in Rooms 1 and
4 at the end of wk 7 to return pigs to their individual
pens. Grouping pigs decreased FI during wk 3 (15.08
± 0.43 vs. 14.03 ± 0.41 kg P < 0.10), and during wk 7
(17.42 ± 0.46 vs. 14.24 ± 0.41 kg; P < 0.01). In addition,
grouping had a negative effect (P < 0.001) on WTG at
wk 3 (7.38 ± 0.28 vs. 5.71 ± 0.28 kg) and at wk 7 (6.70
± 0.26 vs. 2.99 ± 0.26 kg). For grouped pigs, raising the
temperature decreased (P < 0.01) WTG (7.49 ± 0.29 vs.
6.41 ± 0.29 kg during wk 4, and 3.37 ± 0.38 vs. 2.62 ±
0.38 kg during wk 7). Mean FI was decreased (P < 0.01)
with the 30°C treatment during wk 7 only (15.49 ± 0.33
kg at 22°C compared with 12.99 ± 0.33 kg at 30°C).
Compensatory feed intake was evident after the treat-
ments had ceased at wk 6, whereby previously heat-
treated grouped pigs had a higher FI (17.97 ± 0.45 kg)
than the animals individually housed at 22°C (12.99 ±
0.33 kg). Stocking density effects were noted after the
grouping and high temperature treatments had ceased.
For instance, during wk 5, low-density-housed pigs
grew faster (P < 0.001) than their high-density counter-
parts (9.04 ± 0.38 vs. 7.49 ± 0.29 kg). In conclusion,
under the conditions of this study, the grouping of unfa-
miliar cohorts and high ambient temperature treat-
ments had a detrimental effect on pig performance, and
these effects were reversible.
ABSTRACT: Ninety-six crossbred intact male pigs(34.5 ± 3.5 kg BW) were allocated by weight and vocal-ization score to a 2 × 2 × 2 dynamic experimental designincluding two stocking densities (1 or 2 m2/pig), twotemperatures (22°C and 30°C), and two short groupingsof unfamiliar cohorts (six pigs as one pig per group, andsix pigs per group). The study was conducted over 8wk, and live weight gain (WTG) and feed intake (FI;as-fed basis) were measured weekly. During the firstweek, pigs were housed in individual pens from fourindependent rooms. To group pigs, pen partitions wereremoved. Pigs were grouped in Rooms 2 and 3 from wk2 to 4, and in Rooms 1 and 4 during wk 7. Temperaturewas increased from 22°Cto30°C in Rooms 1 and 2during wk 4 and 7. Pen partitions were replaced inRooms 2 and 3 at the end of wk 4 and in Rooms 1 and4 at the end of wk 7 to return pigs to their individualpens. Grouping pigs decreased FI during wk 3 (15.08± 0.43 vs. 14.03 ± 0.41 kg P < 0.10), and during wk 7(17.42 ± 0.46 vs. 14.24 ± 0.41 kg; P < 0.01). In addition,grouping had a negative effect (P < 0.001) on WTG atwk 3 (7.38 ± 0.28 vs. 5.71 ± 0.28 kg) and at wk 7 (6.70± 0.26 vs. 2.99 ± 0.26 kg). For grouped pigs, raising thetemperature decreased (P < 0.01) WTG (7.49 ± 0.29 vs.6.41 ± 0.29 kg during wk 4, and 3.37 ± 0.38 vs. 2.62 ±0.38 kg during wk 7). Mean FI was decreased (P < 0.01)with the 30°C treatment during wk 7 only (15.49 ± 0.33kg at 22°C compared with 12.99 ± 0.33 kg at 30°C).Compensatory feed intake was evident after the treat-ments had ceased at wk 6, whereby previously heat-treated grouped pigs had a higher FI (17.97 ± 0.45 kg)than the animals individually housed at 22°C (12.99 ±0.33 kg). Stocking density effects were noted after thegrouping and high temperature treatments had ceased.For instance, during wk 5, low-density-housed pigsgrew faster (P < 0.001) than their high-density counter-parts (9.04 ± 0.38 vs. 7.49 ± 0.29 kg). In conclusion,under the conditions of this study, the grouping of unfa-miliar cohorts and high ambient temperature treat-ments had a detrimental effect on pig performance, andthese effects were reversible.
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