Slow-growing pigs negatively affect production efficiency in conventional pig farms by increasing the occupation time of the facilities and being a limiting factor for the All-In/All-Out swine production systems. This subset of pigs is usually managed with the rest of the pigs, and their nutrient requirements may not be fulfilled. The purpose of the present study was to compare the productive performance of slow- and fast-growing pigs to different standardized ileal digestible (SID) amino acids (AA) dietary levels at late grower–finisher stage. A total of 84 pigs were weighed, tagged, and classified as slow-growing (SG; n = 48; 24.1 ± 1.38 kg) or fast-growing pigs (FG; n = 36; 42.7 ± 1.63 kg) at 11 weeks of age. Pigs were housed in mixed sex pens (n = 8 SG+6 FG/pen) equipped with feeding stations to record daily feed intake per individual pig. Pigs were assigned to three dietary treatments resulting in a 2 × 3 factorial arrangement at 15 weeks of age. Isoenergetic diets were formulated by increasing the ideal protein profile based on the following SID lysine (Lys) levels: 0.92%, 1.18% and 1.45%. Pigs were weighed bi-weekly until 21 weeks of age. Fast-growing pigs were 33.7 kg heavier, gained 255 g/day and consumed 625.5 g/day more than SG pigs (p < 0.001). No interaction or diet effects were observed for final body weight, average daily gain and average daily feed intake (p > 0.05). However, feed conversion ratio was 0.3 lower for SG pigs fed 1.45% SID Lys/AA compared to SG pigs fed 0.92% SID Lys/AA (p = 0.002). Feed conversion ratio was not different within the FG pigs’ dietary treatments (p > 0.05). The efficiency of SG pigs may be improved when dietary SID AA levels are increased from 0.92 up to 1.45% SID Lys/AA. Thus, nutrient requirements may vary depending on growth rate at the same age, and SG pigs may require higher dietary SID AA levels than FG pigs to achieve similar productive performance.

中文翻译：

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高水平的标准化回肠可消化氨基酸可提高生长肥育后期生长缓慢的猪的饲料效率

生长缓慢的猪通过增加设施的占用时间和成为全进/全出养猪系统的限制因素，对传统养猪场的生产效率产生负面影响。这部分猪通常与其他猪一起管理，它们的营养需求可能无法满足。本研究的目的是比较生长迟缓和快速生长猪与不同标准化回肠可消化 (SID) 氨基酸 (AA) 日粮水平在生长后期 - 育肥阶段的生产性能。 在 11 周龄时，共有 84 头猪被称重、标记并分类为生长缓慢（SG；n  = 48；24.1 ± 1.38 kg）或快速生长猪（FG；n = 36；42.7 ± 1.63 kg） . 猪被圈养在混合性别的围栏中（n = 8 SG+6 FG/栏）配备饲喂站以记录每头猪的每日采食量。猪被分配到三种日粮处理中，导致 15 周龄时的因子排列为 2×3。通过根据以下 SID 赖氨酸 (Lys) 水平增加理想的蛋白质组成来配制等能饮食：0.92%、1.18% 和 1.45%。猪每两周称重一次，直到 21 周龄。与 SG 猪相比，快速生长的猪体重增加了 33.7 公斤，体重增加了 255 克/天，消耗了 625.5 克/天（p  < 0.001）。最终体重、平均日增重和平均日采食量未观察到交互作用或日粮效应（p  > 0.05）。然而，与饲喂 0.92% SID Lys/AA 的 SG 猪相比，饲喂 1.45% SID Lys/AA 的 SG 猪的饲料转化率低 0.3（p = 0.002)。饲料转化率在 FG 猪的日粮处理中没有差异 ( p  > 0.05)。当日粮 SID AA 水平从 0.92 增加到 1.45% SID Lys/AA 时，SG 猪的效率可能会提高。因此，营养需求可能因同一年龄的生长速度而异，而 SG 猪可能需要比 FG 猪更高的日粮 SID AA 水平才能达到相似的生产性能。