Effects of the plane of nutrition during the latter grower and entire finisher phases on grow-finish pig performance in summer

The present study was undertaken to investigate the effects of the plane of nutrition (PN) for growing-finishing pigs on growth performance and meat quality in summer. One hundred and two barrows and 102 gilts weighing approximately 44 kg were placed on a high-, medium-, or low-plane grower diet (HPG, MPG, or LPG) with ME and lysine concentrations ranging from 3.33 to 3.40 Mcal/kg and 0.93% to 1.15%, respectively, for 29 days in 6 replicates (pens) in total. Pigs from each grower pen were divided into two finisher pens and provided with a high-plane finisher diet (HPF) containing 3.40 Mcal ME and 9.5 g lysine/kg and a low-plane finisher diet (LPF; 3.25 Mcal ME and 8 g lysine/kg), respectively, up to approximately 110 kg, and slaughtered. Growth performance of the pigs, including average daily gain (ADG), average daily feed intake (ADFI), and gain:feed ratio, was not influenced by the grower-phase PN during any of the grower phase, a 31-d finisher phase I, and ensuing phase II. However, both the ADG and gain:feed ratio were greater (p < 0.05) for the HPF group than for the LPF group during the finisher phase I (748 vs. 653 g with SEM = 13 g and 0.333 vs. 0.299 with SEM = 0.008, respectively). The ADG, but not gain:feed ratio, was greater for the HPF group vs. LPF during the finisher phase II (673 vs. 623 g with SEM = 15 g for ADG and 0.322 vs. 0.323 with SEM = 0.005 for the gain:feed ratio). The carcass backfat thickness (BFT) was greater for the LPF group vs. HPF within the pigs which had been placed on LPG during the grower phase, but not within the pigs from the HPG or MPG group. Physicochemical characteristics of the longissimus dorsi muscle (LM) and sensory quality attributes of fresh and cooked LM were not influenced by either the grower-phase or finisher-phase PN. In conclusion, high PN is necessary for finishing pigs during the hot season to minimize the reduced rate of weight gain and also to prevent the increase of BFT that could result from low PN.