Effects of Weekly Administration of Implant-type Recombinant Porcine Somatotropin on the Performance and Carcass Characteristics of Finishing Pigs

The present study was undertaken to investigate the effects of weekly administration of implant type recombinant porcine somatotropin (rpST) on the performance and carcass characteristics in finishing pigs. A total of 120 crossbred (Landrace× Yorkshire×Duroc) pigs were employed for 11 weeks in a growth trial in experiment. A rpST designed to implant every 7 d was used. Forty pigs, each weighing 75 kg, were allocated into three rpST treatments; control (CONT), implant of rpST from 75 kg (TRT1) or 90 kg (TRT2) of body weight. The CONT pig and pigs in TRT2 from 75 kg to 90 kg were treated without rpST but with placebo. In rpST- treated pigs, each 100 mg and 125 mg of the equivalent rpST was implanted from live weight of 75 kg to 90 kg and from 90 kg to market weight, respectively. Half of the pigs from each treatment were marketed at live weight of 110 kg and the rest at 130 kg. All pigs were allowed ad libitum access to a commercial feed containing 0.94% and 0.88% of lysine from 75 to 110 kg, 110 to 130 kg of body weights, respectively. rpST had no effect on daily gain, while feed efficiency was improved by 7 to 13% (p