Manual and thermal induced feed intake restriction on finishing barrows. II: Effects on heat production, activity, and organ weights

A Study was designed to investigate the bioenergetic differences in two typ es of feeding restriction in order to evaluate the additional effects of he at stress beyond a reduction in feed intake. Sixty Large White x Landrace b arrows (65.2 +/- 0.5 kg) were randomly assigned to one of five treatments: control, two levels of heat stress (HS) imposed feeding restriction (13% HS , 26% HS), and two levels of manual feed restriction at thermoneutral (13% TN, 26% TN). Three measurements of heat production and activity (standing, lying, eating) were made during the trial. The pigs were slaughtered at an average treatment weight of 107.5 kg. ALL organs were collected and weighed . Heat production (P < 0.0001) and activity (P < 0.05) were significantly d ifferent for the different treatments. The thermoneutral treatments (contro l, 13% TN, and 26% TN) had the highest heat production values. These treatm ent groups also spent significantly less time lying than the heat stress tr eatment groups (P < 0.05). The 13% TN and 26% TN pigs tended to spend more time standing (P < 0.10) than the respective HS treatments. Although indivi dual organ weights differed among treatment, total metabolically active org an weights were similar between types of restriction, indicating similar ma intenance requirements. It was concluded that activity accounted for most o f the difference between the 13% HS and 13% TN groups, while activity and c omposition accounted for the difference between the 26% HS and 26% TN group s.