Objective   Effects of a forage with reduced protein and a supplement of essential amino acids, glutamate, and arginine on the growth, diarrhea rate, and serum indicators of weaned piglets were studied.

  Method  One-hundred-ninety-two healthy (26±2)-day-old crossbred piglets (Duroc × Landrace ×Large White) were randomly divided into a control and 3 treatment groups. Each group comprised 6 replicates of 8 piglets. They were fed for 16 days with the following forages containing 21.16% crude protein (CP) as control (Group 1), low-protein of 15.97% CP supplemented with the essential amino acids including L-Lys, DL-Met, L-Thr, L-Thr, L-Val, and L-Ile (Group 2), 15.93% CP with the same added essential amino acid plus 1.5% glutamate (Group 3), and 15.95% CP with the added essential amino acids plus 1.5% glutamate and 1.0% arginine (Group 4). At end of the feeding, body weight, forage consumption, number of days with diarrhea, and blood samples of the piglets were collected for daily gain, feed to weight ratio, diarrhea rate, and plasma biochemicals and hormones determinations.

  Result  The average daily weight gain (ADG) of the piglets in Group 2 was significantly lower than those in other groups (P＜0.05). There were no significant ADG differences among those 3 groups, nor the average daily feed intake (ADFI) among all groups (P＞0.05). The feed/gain (F/G) of Group 2 was significant higher than other groups (P＜0.05). The diarrhea rate of Group 2 piglets was significantly lower than that of Group 1; Group 3 and Group 4 extremely significantly lower than that of Group 1; and Group 3 and Group 4 significantly lower than that of Group 2 (P＜0.05). The activities of serum LDH, ALP, GPT, and GOT among the 4 groups did not differ significantly (P＞0.05). The DAO of Group 2 animals was significantly higher than that of Group 1; Group 3 and Group 4 significantly lower than Group 2; while Group 3 and Group 4 not significant differed from Group 1 (P＞0.05). The PUN of Group 2 was significantly lower than the other 3 groups (P＜0.05). The CCK of Group 3 and Group 4 were significantly higher than those of Group 1 and Group 2 (P＜0.05). No significant differences on IGF-1 were found among piglets of Group 1, Group 2, and Group 3, but that of Group 4 higher than those of Group 1 and Group 2 (P＜0.05).

  Conclusion   The reduction of CP to 15.97% in forage could adversely affect the growth as well as the intestinal barrier permeability to varying degrees of the weaned piglets. However, it also reduced the diarrhea rate and plasma PUN of the weaned piglets. Since the addition of glutamate in diet restored the growth and improved the levels of gastrointestinal hormones of piglets, feeding piglets an essential amino acid-balanced, low-protein diet with the supplementation of glutamate could be a plausible strategy to mitigate the occurrences of diarrhea and interference on the intestinal mucosal barrier permeability in the animals after weaning.