Although pork producers typically aim to optimize growth rates, occasionally it is necessary to slow growth, such as when harvest facility capacity is limited. In finishing pigs, numerous dietary strategies can be used to slow growth so pigs are at optimal slaughter body weights when harvest facility capacity and/or access is restored. However, the impact of these diets on pork carcass quality is largely unknown. Thus, this study aimed to evaluate the efficacy of dietary strategies to slow growth in late finishing pigs and evaluate their effects on carcass composition and pork quality. Mixed-sex pigs (n = 897; 125 ± 2 kg BW) were randomly allotted across 48 pens and assigned to 1 of 6 dietary treatments (n = 8 pens/treatment): (1) Control diet representative of a typical finisher diet (CON); (2) diet containing 3% calcium chloride (CaCl2); (3) diet containing 97% corn and no soybean meal (Corn); (4) diet deficient in isoleucine (LowIle); (5) diet containing 15% neutral detergent fiber (NDF) from soybean hulls (15% NDF); and (6) diet containing 20% NDF from soybean hulls (20% NDF). Over 42 d, pen body weights and feed disappearance were collected. Pigs were harvested in 3 groups (14, 28, and 42 d on feed) and carcass data collected. From the harvest group, 1 loin was collected from 120 randomly selected carcasses (20 loins/treatment) to evaluate pork quality traits. Overall, ADG was reduced in CaCl2, Corn, and 20% NDF pigs compared with CON pigs (P < 0.001). However, ADFI was only reduced in CaCl2 and 20% NDF pigs compared with CON (P < 0.001). Feed efficiency was reduced in CaCl2 and Corn pigs compared with CON (P < 0.001). Hot carcass weights were reduced in CaCl2 pigs at all harvest dates (P < 0.001) and were reduced in Corn and 20% NDF pigs at days 28 and 42 compared with CON pigs (P < 0.001). In general, CaCl2 and 20% NDF diets resulted in leaner carcasses, whereas the Corn diet increased backfat by 42 d on test (P < 0.05). Loin pH was reduced and star probe increased in CaCl2 pigs compared with CON pigs (P < 0.05); no treatments differed from CON pigs regarding drip loss, cook loss, color, firmness, or marbling (P ≥ 0.117). Overall, these data indicate that several dietary strategies can slow finishing pig growth without evidence of behavioral vices. However, changes to carcass composition and quality were also observed, indicating quality should be taken into consideration when choosing diets to slow growth.

中文翻译：

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减缓后期肥育猪生长的营养方法：对胴体成分和猪肉质量的影响

尽管猪肉生产商通常旨在优化增长率，但有时也有必要放慢增长速度，例如在收获设施容量有限的情况下。在育成猪中，可以使用多种日粮策略来减缓生长速度，以便在收获设施容量和/或通道恢复时，猪处于最佳屠宰体重。然而，这些饮食对猪肉胴体质量的影响在很大程度上是未知的。因此，本研究旨在评估日粮策略减缓后期肥育猪生长的效果，并评估其对胴体成分和猪肉质量的影响。混合性别猪 (n = 897; 125 ± 2 kg BW) 被随机分配到 48 个猪栏，并分配到 6 种日粮处理中的 1 种（n = 8 猪/处理）： (1) 代表典型育肥日粮的对照日粮（反对）；（2）含3%氯化钙（CaCl2）的日粮；（3）含97%玉米且不含豆粕（玉米）的日粮；（4）异亮氨酸（LowIle）缺乏的饮食；(5) 含有 15% 大豆皮中性洗涤纤维 (NDF) (15% NDF) 的日粮；(6) 含有 20% 大豆皮 NDF (20% NDF) 的日粮。超过 42 天，收集栏体重和饲料消失。将猪分 3 组（喂食 14、28 和 42 天）收获并收集胴体数据。从收获组中，从 120 个随机选择的胴体（20 块/处理）中收集 1 块腰肉，以评估猪肉质量性状。总体而言，与 CON 猪相比，CaCl2、玉米和 20% NDF 猪的 ADG 降低（P < 0.001）。然而，与 CON 相比，仅 CaCl2 和 20% NDF 猪的 ADFI 降低（P < 0.001）。与 CON 相比，CaCl2 和玉米猪的饲料效率降低（P < 0.001）。与 CON 猪相比，CaCl2 猪的热胴体重量在所有收获日期都减少了（P < 0.001），并且在第 28 天和第 42 天，玉米和 20% NDF 猪的胴体重量减少了（P < 0.001）。一般来说，CaCl2 和 20% NDF 日粮导致胴体更瘦，而玉米日粮在测试中增加了 42 天的背膘（P < 0.05）。与CON猪相比，CaCl2猪的腰部pH值降低，星形探针增加（P <0.05）；在滴水损失、蒸煮损失、颜色、硬度或大理石花纹方面，没有与 CON 猪不同的处理（P ≥ 0.117）。总体而言，这些数据表明，在没有行为不良证据的情况下，几种饮食策略可以减缓育肥猪的生长。然而，还观察到胴体成分和质量的变化，表明在选择日粮以减缓生长时应考虑质量。