Effects of N-methyl-D-aspartate on secretion model and characteristics of growth hormone and somatostatin in pigs.

This experiment was conducted to study the effects of N-methyl-D-aspartate (NMDA) on the secretion model and characteristics of growth hormone (GH) and somatostatin (SS) in pigs. Sixty crossbred (Duroc×Landrace×Yorkshire) pigs with an average initial body weight of (53.0 ±3.6) kg were randomly allotted to 2 treatments with 3 replicates in each treatment and fed diets contained 0 and 100 mg/kg NMDA, respectively. Six pigs per treatment were selected to determine the effects of NMDA on growth performance and to study the dynamic secretion model and characteristics of GH and SS when body weight of pigs reached 90 kg. The results showed that, average daily gain was significantly increased (P0. 05) and feed gain ratio was significantly decreased (P0. 05) in the 100 mg/kg NMDA group; NMDA increased overall level, basal level and peak intensity of GH secretion significantly by 41.01%(P0. 05), 44.70%(P0. 05) and 29. 44% (P0. 05), respectively. There were no significant effects on GH peak frequency and peak duration (P0. 05). For the swine sex, the overall level of secretion of barrows' GH increased by 36.91% (P0. 05), and the basal level increased by 55.69% (P 0. 05). The overall level of gilts' GH secretion increased by 45. 95% (P0. 05), the basal level increased by 50. 10% (P 0. 05). Compared with control group, NMDA group increased SS secretion level of barrows and gilts, but the difference was not significant. In conclusion, 100 mg/kg NMDA could promote the swine growth performance; GH secretion of swine showed strong regular of pulse distribution not only in control group but also in NMDA group; NMDA could improve GH secretion of swine, but secretion model and SS level was not affected by NMDA.