本试验旨在研究断奶日龄对五指山仔猪生长性能和血清生化指标的影响。选取日龄相近（±1 d）、体重[（0.56±0.07） kg]相近的五指山仔猪96头，随机分成4组，每组设4个重复，每个重复6头猪。4组仔猪分别在21、28、35和42日龄断奶。试验从8日龄开始，至56日龄结束，试验期间定期测定体重、采食量和血清生化指标。结果表明:各组仔猪断奶后平均日增重（ADG）出现不同程度的下降，且断奶日龄越早，ADG下降幅度越大；35日龄断奶组和42日龄断奶组21~28日龄、28~35日龄、35~42日龄、49~56日龄阶段的ADG显著高于21日龄断奶组（P<0.05）。各组仔猪断奶后平均日采食量（ADFI）显著增加（P<0.05），42日龄以后，各组ADFI无显著差异（P>0.05）。21日龄断奶组、28日龄断奶组、35日龄断奶组血清总蛋白（TP）、白蛋白（ALB）、免疫球蛋白G（IgG）、免疫球蛋白M（IgM）含量以及谷丙转氨酶（ALT）、谷草转氨酶（AST）、乳酸脱氢酶（LDH）活性在断奶后7 d均发生显著变化（P<0.05），并以21日龄断奶组波动最大；与35日龄断奶组和42日龄断奶组相比，21日龄断奶组28、35日龄时血清TP、ALB、IgG、IgM含量显著降低（P<0.05），ALT、AST、LDH活性显著提高（P<0.05），到56日龄时，血清TP、IgG、IgM含量仍显著低于35日龄断奶组和42日龄断奶组（P<0.05）。21日龄断奶组血清甘油三酯（TG）、胆固醇（CHOL）含量在28~56日龄间存在显著变化（P<0.05），35日龄断奶组和42日龄断奶组血清TG、CHOL含量在整个试验期内均无显著变化（P>0.05）。35日龄断奶组血清TP、ALB、IgG、IgM含量以及ALT、AST、LDH活性除在42日龄时与42日龄断奶组存在显著差异（P<0.05）外，其余时间点与42日龄断奶组均无显著差异（P>0.05）。由此得出，35或42日龄断奶的五指山仔猪在生长性能、血清生化指标及免疫机能方面优于21日龄断奶的五指山仔猪。

This experiment was conducted to study the effects of weaning age on growth performance and serum biochemical indices of Wuzhishan piglets. A total of 96 Wuzhishan piglets with the similar age (±1 day) and the average body weight of (0.56±0.07) kg were randomly divided into 4 groups with 4 replicates per group and 6 piglets per replicate. Piglets in those 4 groups were weaned at the age of 21, 28, 35 and 42 days, respectively. The experiment was carried out from 8 to 56 days of age, and body weight, feed intake and serum biochemical indices were regularly determined. The results showed that the average daily gain (ADG) of piglets in the four groups was decreased to varying degrees after weaning. The earlier the weaning age, the more decrease of ADG. The ADG in 35-day-old and 42-day-old weaned groups was significantly higher than that of 21-day-old weaned group at the age of 21 to 28 days, 28 to 35 days, 35 to 42 days and 49 to 56 days (P<0.05). Weaning could significantly increase the average daily feed intake (ADFI) of piglets in the four groups, and the ADFI of piglets had no significant difference among the four groups at 42 days of age (P>0.05). The contents of total protein (TP), albumin (ALB), immunoglobulin G (IgG), immunoglobulin M (IgM), and the activities of glutamic oxalacetic transaminase (AST), alanine aminotransferase (ALT) and lactate dehydrogenase (LDH) in serum in 21-day-old, 28-day-old and 35-day-old weaned groups were significantly changed at 7 days post-weaning (P<0.05), and the largest fluctuation was observed in 21-day-old weaned group. Compared with the 35-day-old and 42-day-old weaned groups, the serum TP, ALB, IgG and IgM contents were significantly decreased (P<0.05), and the serum ALT, AST and LDH activities were significantly increased in 21-day-old weaned group (P<0.05). The serum TP, IgG and IgM contents were still lower in 21-day-old weaned group than 35-day-old and 42-day-old weaned groups at 56 days of age (P<0.05). The serum triglyceride (TG) and cholesterol contents (CHOL) contents in 21-day-old weaned group were significantly changed during 28 to 56 days of age (P<0.05), while these had no significant difference during whole experimental period in the 35-day-old and 42-day-old weaned groups (P>0.05). In addition to significant differences existed at the age of 42 days (P<0.05), there were no significant difference in serum TP, ALB, IgG and IgM contents, and AST, ALT and LDH activities between the 35-day-old and 42-day-old weaned groups (P>0.05). It is suggested that Wuzhishan piglets weaned at 35 or 42 days of age are better than those weaned at 21 days of age in growth performance, serum biochemical indices and immune function.