The current study was to determine the effects of growth hormone-releasing peptide
([His1, Lys6]-GHRP) on growth performance and carcass
traits in pigs, and to determine whether the results were
comparable to those of recombinant porcine growth hormone (r-PGH) treatment. Thirty Landrace
and Yorkshire pigs (40–45 kg) were randomly divided into three groups, each group consisted of two
boars, five gilts and three barrows. Peptides were administered daily by intramuscular injection with
the following schemes and dosages: Group A ([His1, Lys6]-GHRP,
200 μg/day in 0·5 ml saline),
Group B (r-PGH, 3 mg/day in 0·6 ml saline), and Group C (sterilized physiological saline,
0·5 ml/day). [His1, Lys6]-GHRP caused significant improvements both in pig growth and carcass
traits. The average daily gain (ADG) and feed efficiency of the [His1, Lys6]-GHRP treated group were
higher than those of the control, but less than with the r-PGH treatment. The net increase in the ADG
by [His1, Lys6]-GHRP was c. 14%, and was 23% by
r-PGH (both P<0·01). The feed efficiency was
improved 17% by [His1, Lys6]-GHRP (P<0·01) and 20%
by r-PGH (P<0·01). On the other hand,
the back-fat thickness in both [His1, Lys6]-GHRP and
r-PGH treated groups (1·76±0·041 cm and
1·72±0·040 cm, respectively) was considerably less
(P<0·05) than that of the control group
(1·81±0·040 cm). In addition, the lean cuts percentage and the
rib longissimus muscle area were
comparable in the [His1, Lys6]-GHRP and r-PGH
treatments (lean cuts percentage: 57±2·0% and
57±1·5%, respectively; rib longissimus muscle area: 32·8±0·91 cm2
and 32·9±1·10 cm2, respectively), and both were significantly (P<0·05)
greater than those of the control group (lean cuts
percentage: 53±1·5%; rib longissimus muscle area: 28·3±1·61 cm2).
In conclusion, [His1, Lys6]-GHRP appeared to be a promising tool for controlling carcass fat in pigs.