过量赖氨酸对断奶仔猪及其肠道上皮细胞的影响

旨在从体内与体外探究过量赖氨酸对断奶仔猪的影响。本试验选用144头杜×长×大三元杂交断奶仔猪，随机分为4组，每组6个重复，每个重复6头仔猪（3头阉公猪和3头母猪），各组在日粮中分别添加1.3%、2.6%、3.9%和5.2%的回肠标准可消化赖氨酸（standardized ileal digestibility lysine，SID Lys），观察其对于仔猪生长性能、器官指数以及生理生化等指标的影响。以IPEC-J2为体外模型，根据培养基与营养需要中氨基酸的种类与比例，添加赖氨酸及其他氨基酸，测定IPEC-J2细胞的增殖情况，并试图通过平衡氨基酸手段降低因过量添加赖氨酸造成的不利影响。结果显示，随着日粮SID Lys添加量的增加，断奶仔猪的生长性能显著下降（P<0.05），血浆平均红细胞血红蛋白含量（mean corpuscular hemoglobin，MCH）、部分血清游离氨基酸含量和肠道形态受到影响。当在培养基中添加2.0 mmol·L^-1赖氨酸时，IPEC-J2细胞活力显著下降（P<0.05），培养基中原赖氨酸浓度（0.5 mmol·L^-1）是IPEC-J2生长的最适浓度。当按照培养基中氨基酸平衡比例补充其他必需氨基酸时，细胞活力有一定程度的改善；当按照猪碱性氨基酸的最适比例补充相应浓度的精氨酸与组氨酸时，细胞活力随处理时间的变化而变化。综上所述，单独添加过多的赖氨酸对断奶仔猪的生长会产生负面作用，在生产实际应用中应充分考虑氨基酸之间的平衡。

Effects of Excessive Lysine on Weaned Piglets and Their Intestinal Epithelial Cells

The aim of this study was to investigate the effects of excess lysine on weaned piglets in vivo and in vitro. A total of 144 weaned piglets (Duroc×Landrace×Yorkshire) were randomly divided into 4 groups, 6 replicates for each group, 6 piglets for each replicate (3 barrows and 3 sows). The pigs in different groups were fed with excessive standardized ileal digestibility lysine (SID Lys) of 1.3%, 2.6%, 3.9% and 5.2%, respectively in the diet to observe its effects on growth performance, visceral indexes and physiological and biochemical indicators. Using IPEC-J2 as an in vitro model, the proliferation of IPEC-J2 cells was measured by adding lysine and other amino acids according to the type and ratio of amino acids in the culture medium and nutritional requirements, and attempting to reduce the adverse effects of excessive addition of lysine by balancing other amino acids. The results showed that, with the increase of the amount of SID Lys in the diets, the growth performance of weaned piglets significantly decreased (P<0.05), the mean corpuscular hemoglobin (MCH), some serum free amino acids and intestinal morphology were affected. When lysine was 2.0 mmol·L^-1in culture medium, the viability of IPEC-J2 cells significantly decreased(P<0.05), with the original lysine concentration in the medium (0.5 mmol·L^-1) being the optimum concentration for IPEC-J2 growth. Cell viability was improved to some extent when other essential amino acids were supplemented according to the balanced ratio of amino acids in the medium; Cell viability varied with treatment time when the corresponding concentrations of arginine and histidine were supplemented according to the optimum ratio of porcine basic amino acids. The study demonstrated that the addition of excessive lysine has negative effect on the growth of weaned piglets. The balance of amino acids should be fully considered in practical applications.