Effect of live yeast supplementation and feeding frequency in male finishing pigs subjected to heat stress

In growing pigs, reduced growth during heat stress (HS) is mainly related to decreased feed intake. The study aimed to determine whether the reported positive effects of live yeast (LY) supplementation in HS pigs were due to a modified feeding behaviour or energy metabolism, and if these can be replicated by imposing an increased meal frequency. The effect of LY supplementation (0 (NS) v. 100 (LY) g/ton of feed), and of feeding window (FW) (unlimited or Unli, 2FW of 1 h each and 8FW of 15 min each) were measured in entire male finishing pigs (n 36). Ambient temperature was at 22 degrees C during the thermoneutral (TN) period (5 d) and at 28 degrees C during the HS period (5 d). Heat exposure decreased DM intake (DMI) and retained energy (RE) (-627 and -460 kJ center dot kg BW-0 center dot 60 center dot d(-1), respectively; P < 0 center dot 01). During HS, LY supplementation in Unli pigs decreased inter-meal intervals (P = 0 center dot 02) attenuating HS effect on DMI which tended to improve RE (P = 0 center dot 09). NS - 8FW had higher DMI and RE than NS - 2FW (P < 0 center dot 05) but protein deposition (PD) were similar. Supplemented pigs had higher PD during HS regardless of FW (+18 g center dot d(-1); P = 0 center dot 03). Comparing the 2FW groups, improved heat tolerance of LY-supplemented pigs were due to improved insulin sensitivity (P < 0 center dot 05) and latent heat loss capacity after a meal (P < 0 center dot 05) allowing them to increase their DMI (via an increased number of meals) and thus their energy efficiency. Imposing an increased meal frequency improved DMI in HS pigs but did not replicate positive effects of LY on PD.

Automated summary

In growing pigs, reduced growth during heat stress is mainly due to decreased feed intake. The study investigated the positive effects of live yeast supplementation on heat-stressed pigs and whether increasing meal frequency can replicate these effects.