本研究旨在探讨断奶日龄、断奶体重及饲喂方式对断奶后仔猪生产性能的影响。重点放在体重较轻的仔猪上，因为他们可能需要较长的日龄或提供一种特殊的饲喂管理方式才能更好地断奶。从110头母猪分娩的2周龄以上仔猪中选择试验对象（n = 1448），分别称重，并在出生时进行形态测量。
仔猪在同一天断奶，但由于出生日期的不同导致断奶日龄的不同（平均日龄34.1d，SD = 2.5）。最年轻的50%在断奶时被归类为Y组，最年长的50%被归类为O组；在一个年龄组中，体重最轻的50%被归类为L类，体重最重的50%被归类为H类，并被相应地放置。分别在断奶时、断奶后第7周和第15周称重。断奶时，Y组比O组猪小6 d，轻1.4kg，L比H猪轻3.2kg。猪被随机分配到三阶段优级保育管理组（SUP）或对照保育管理（CON）组中，与CON相比，SUP组第一和第二阶段饲料的供应量（以kg/猪为基础）高出65%。
试验数据表明，Y组从断奶～断奶后7周仔猪死亡率高于O组（9.14%和4.98%，P = 0.046）。与预期一样，断奶日龄和体重显著（P < 0.001）影响了断奶后7周和15周的仔猪生产性能：在15周时，Y组断奶的猪只比O组轻5.5kg； L类猪只体重比H类轻9.0kg。据估计，与O组L类断奶仔猪相比，YL断奶仔猪要达到60kg体重需要多4d的时间（P = 0.018）。采食量没有受到管理方式、日龄和体重、以及他们相互作用的影响。生长性能没有受到管理方式的影响（P > 0.05），但是断奶后7周仔猪生长性能是受体重×管理方式双因素影响的（P = 0.044）：L组SUP猪只比CON重1.2kg，但H组的猪只情况并非如此。YL猪和OL猪在断奶后7周内的生产性能与出生重、颅围比和断奶重呈正相关（P < 0.05），对于后者，额外的性能预测因子是断奶日龄（P= 0.044）和饲喂方式（P = 0.027）。L组猪只断奶后7周内的生长可通过增加保育日粮获得改善。然而，较晚断奶能够促进L类仔猪的生长性能达到正常的体重，这表明这可能是一种更长久更有效益的策略。
Weaning age and post-weaning nursery feeding regime are important in improving the performance of lightweight pigs
The aim was to investigate the effect of weaning age, weaning weight, and nursery feeding regime on post-weaning performance. The focus was on pigs weaned light, as they may be better off when weaned at a later age and/or offered a specialist nursery feeding regime. Piglets (n = 1,448) from one farrowing batch of 110 sows that farrowed over 2 wk were individually weighed and their morphometric measurements were taken at birth. Pigs were weaned on the same day, but variation in birth date resulted in variable weaning ages (mean age day 34.1, SD = 2.5). The youngest 50% at weaning were classified Y and the oldest 50% as O; within an age class, the lightest 50% were classified L, the heaviest 50% as H, and housed accordingly. Pigs were individually weighed at weaning, 7 and 15 wk post-weaning. At weaning, Y were 6 d younger and 1.4 kg lighter than O pigs, whereas L were 3.2 kg lighter than H pigs. Pigs were randomly allocated to a 3-stage superior (SUP) or control (CON) nursery feeding regime, with SUP pigs having a 65% greater allowance (on a kg/pig basis) of the first and second stage feeds than the CON. Pigs weaned Y had a higher mortality rate from weaning to 7 wk post-weaning than pigs weaned O (9.14% vs. 4.98%; P = 0.046). As expected, age and weight significantly (P < 0.001) affected performance to both 7 and 15 wk post-weaning: at 15-wk pigs weaned Y were 5.5 kg lighter than pigs weaned O; pigs weaned L were 9.0 kg lighter than H pigs. It was estimated that pigs weaned YL needed ~4 d more (P = 0.018) to reach 60 kg BW than pigs weaned OL. Feed intake was not affected by feeding regime, age and weight, or their interactions. Performance was not affected by feeding regime (P > 0.05), but was affected by the weight × feeding regime interaction (P = 0.044) to 7 wk post-weaning: L pigs on SUP were 1.2 kg heavier than L pigs on the CON regime; this was not the case for the H pigs. Performance up to 7 wk post-weaning was positively associated with birth weight to cranial circumference ratio and weaning weight (P < 0.05) for both YL and OL pigs; for the latter, additional performance predictors were weaning age (P = 0.044) and feeding (P = 0.027). Improved growth for L pigs up to 7 wk post-weaning could be obtained by a greater allowance of the nursery diets. However, weaning at a later age benefitted the performance of L pigs to a common BW, suggesting that this might be a strategy with longer term benefits.