本试验旨在研究围产期低能饲粮添加过瘤胃赖氨酸（RPL）对初乳质量、断奶前犊牛生长性能和瘤胃发酵的影响。试验采用2×2析因试验设计，即能量（产奶净能）水平设为6.40、5.73 MJ/kg DM和RPL添加水平设为0、40 g/（d·头）。选取体况和预产期相近的52头第3胎荷斯坦奶牛，分为4组，分别为基础饲粮（B）组、低能饲粮（L）组、基础饲粮+RPL（BL）组和低能饲粮+RPL（LL）组，每组13头牛。试验从预产期前21天至产后犊牛断奶结束。奶牛产后第1次泌乳时采集初乳，测定初乳中总固形物、蛋白质、脂肪和乳糖、免疫球蛋白（Ig）G、IgM和IgA含量；犊牛出生当天（1日龄）、60日龄测定体重和体尺；犊牛60日龄采集瘤胃液，测定pH、氨态氮（NH₃-N）和挥发性脂肪酸（VFA）浓度。结果表明：1）围产期低能饲粮显著降低了初乳总固形物、乳糖和IgM含量（P<0.05）；围产母牛饲粮添加RPL对初乳乳糖含量有提高的趋势（P=0.068 2），对其他初乳指标无显著影响（P>0.05）。2）围产期低能饲粮显著降低了母犊60日龄体重、体高、体斜长和胸围（P<0.05），显著降低了公犊60日龄体斜长和初生胸围（P<0.05）。围产母牛饲粮添加RPL有降低公犊60日龄体重的趋势（P=0.073 0）。3）围产期低能饲粮显著降低了母犊初生体躯指数（P<0.05），对母犊60日龄体躯指数有升高的趋势（P=0.059 6），对公犊初生体躯指数有降低的趋势（P=0.099 1），提高了公犊60日龄体躯指数（P<0.05），降低了公犊60日龄体长指数（P<0.05）。围产母牛饲粮添加RPL对公、母犊体尺指数没有显著影响（P>0.05）。4）围产期低能饲粮显著降低了犊牛瘤胃液中总挥发性脂肪酸、乙酸、丙酸、异丁酸、丁酸、异戊酸和戊酸浓度（P<0.05）。围产母牛饲粮添加RPL对犊牛瘤胃发酵指标无显著影响（P>0.05）。5）围产母牛饲粮能量水平与添加RPL对奶牛初乳质量指标、断奶前犊牛体重、体尺指标、体尺指数和瘤胃发酵指标均不存在交互作用（P>0.05）。综上所述，围产期低能饲粮降低了奶牛初乳质量、断奶前犊牛体重、体尺及体尺指数和瘤胃发酵指标；围产期母牛饲粮添加RPL对奶牛初乳质量和断奶前犊牛体重、体尺及体尺指数和瘤胃发酵无不利影响；围产期低能饲粮中添加RPL并不能替代正常标准能量水平饲粮。

This experiment was conducted to investigate the effects of diets with low energy level and rumen-protected lysine (RPL) for perinatal period on colostrum quality of cows, growth performance and rumen fermentation of pre-weaning calves. This experiment was used a 2×2 factorial design, including net energy for lactating cow (NEL, 6.40 and 5.73 MJ/kg DM) and RPL (0 and 40 g/d per head). Fifty-two Holstein cows in 3 parities were blocked by body score and predicted calving date and randomly assigned to 1 of 4 groups. Cows were fed in the four groups including a basal diet (B), a low energy diet (L), the basal diet supplemented with RPL (BL) and the low energy diet supplemented with RPL (LL), respectively. The experiment was lasted from day 21 before expected date of calving of cows to weaning of calves after calving. The colostrum was collected during the first milking time after giving birth, and the contents of total solids, protein, fat and lactose, immunoglobulin (Ig) G, IgM and IgA were measured. Body weight and body side were measured on birth (1 days of age) and 60 days of age. Rumen liquid was collected on 60 days of age to measure pH, ammonia nitrogen (NH₃-N) and volatile fatty acid (VFA) concentrations. The results showed as follows:1) diets with low energy level for perinatal period significantly decreased total solid, lactose and IgM contents in the colostrum (P<0.05); RPL supplementation in diets for perinatal period had an increasing trend on lactose content in the colostrum (P=0.068 2) and had no significant effects on others (P>0.05). 2) Diets with low energy level for perinatal period significantly decreased body weight, body height, body length and chest girth of female calves at 60 days of age (P<0.05), and significantly increased body weight of male calves at 60 days of age and chest girth of male calves at birth (P<0.05). RPL supplementation in diets for perinatal period had a decreasing trend on body weight of male calves at 60 days of age (P=0.073 0). 3) Diets with low energy level for perinatal period significantly decreased body structure index of female calves at birth (P<0.05), had an increasing trend on body structure index of female calves at 60 days of age (P=0.059 6), had a decreasing trend on body structure index of male calves at birth (P=0.099 1), significantly increased body structure index of male calves at 60 days of age (P<0.05), and significantly decreased body length index of male calves at 60 days of age (P<0.05); RPL supplementation in diets for perinatal period had no significant effects on body structure index, body length index and chest girth index of female calves and body side index of calves (P>0.05). 4) Diets with low energy level for perinatal period significantly decreased total volatile fatty acids, acetic acid, propionic acid, isobutyric acid, butyric acid, isovaleric acid and valeric acid concentrations in the rumen liquid of calves (P<0.05); RPL supplementation in diets for perinatal period had no significant effects on rumen fermentation indexes of calves (P>0.05). 5) No interaction was observed between dietary energy level and RPL supplementation on colostrum quality of cows, body weight and body side, body side indexes and rumen fermentation indexes of pre-weaning calves (P>0.05). In conclusion, diets with low energy level for perinatal period decreases the colostrum quality of cows, body weight and body side, body side indexes and rumen fermentation of pre-weaning calves; RPL supplementation in diets for perinatal period has no harmful effect on the colostrum quality of cows, body weight and body side, body side indexes and rumen fermentation of pre-weaning calves; diets with low energy level and RPL supplementation for perinatal period cannot instead of basal diets with normal standardized energy level.