来源：Pig Progress
Oxidative stress is one of the processes happening inside a pig’s gut during and after weaning. Feeding trials in both China and Germany have demonstrated that high quality proteins may limit the impact of post-weaning stress syndrome.
氧化应激是断奶期间和之后猪肠内发生的一种。中国和德国的喂养试验表明，高质量的蛋白质可能会减轻断奶后应激综合症的影响。
More than 25 years of studies and practical experience on farms have demonstrated that the use of highly digestible protein in piglet starter feed results in improved weight gain, a better feed conversion rate and less diarrhoea during the critical weaning phase. While it is well known that this performance improvement is partly due to the piglets’ immature gut, which requires easily digestible nutrients, other biological processes have been less well understood.
超过25年的农场研究和实践经验表明，在断奶这个关键阶段，在仔猪饲料中添加高度可消化的蛋白质可以增加仔猪体重，提高饲料转化率，并减少腹泻率。众所周知，这种性能改善，部分是由于仔猪肠道尚未成熟，因此需要易消化的营养素，至于其他生物过程，则一直不太清楚。
This is starting to change. Within the past year, scientists have found strong indications of the missing link between feed proteins and piglet performance. The answer, they believe, lies with oxidative stress and related inflammatory processes.
不过情况开始在变化。过去一年中，科学家们已经发现了强有力的迹象，表明饲料蛋白与仔猪性能之间曾经缺失的关联。他们认为，答案在于氧化应激和相关的炎症过程。
Findings from recent studies in China and Germany suggest that, when piglets are given starter feeds containing a high quality, easily digestible soy protein, their oxidative stress level is lower – hinting at the possibility to reduce vitamin E addition in piglet diets. The German study also reports an improved inflammatory status. And, as documented in previous studies, piglet growth is improved.
近期中国和德国的研究结果表明，给仔猪喂食含有高质量、易消化的大豆蛋白的饲料时，其氧化应激水平较低 – 这暗示了可以减少仔猪日粮维生素E添加量的可能性。这项德国研究还表明炎症状态有所改善，并且，正如先前研究中所记录的，仔猪生长性能得到了改善。
The health impact of weaning
断奶对健康的影响
Oxidative stress is a consequence of all kinds of dietary, social and environmental stress during the life of a high-performing animal. In piglets, it is especially noticeable during the weaning phase, when young animals tend to put on less weight and are more susceptible to disease – a phenomenon known as post-weaning stress syndrome.
氧化应激是高性能动物一生中各种饮食、社群和环境压力共同作用的结果。在仔猪中，在断奶期尤其明显，这个阶段往往体重减轻、易患病 - 这种现象称为断奶后应激综合症。
Social and environmental stress are difficult to avoid, but possibilities do exist to reduce dietary stress, which is typically caused by a poor-quality feed. Although such feed is typically high in protein, much of the protein content is impossible for the young animals to digest and may contain anti-nutritional factors (ANFs), such as soy antigens – factors that can trigger inflammation in the gut. The first symptoms of oxidative stress are decreased immunity, muscle degeneration, loss of appetite, diarrhoea, liver damage and apoptosis (cell death).
社群和环境压力难以避免，但降低饮食压力的可能性确实存在，这通常是由劣质饲料引起的。虽然这种饲料通常蛋白质含量很高，但是大部分蛋白质对于幼崽来说是不可能消化的，并且可能含有抗营养因子（ANF），例如大豆抗原 - 可以引发肠道炎症的因素。氧化应激的最初症状是免疫力下降、肌肉退化、食欲不振、腹泻、肝损伤和细胞凋亡（细胞死亡）。
An opportunity to reduce vitamin E?
维生素E添加量可减少？
When gut inflammation occurs, the piglets’ own radical defence system responds by attacking the cause of the problem. However, if oxidative stress persists, prolonged activation of the radical defence system backfires, causing further gut inflammation or cell death due to the formation of free radicals.
肠道发炎时，仔猪自身的自由基防御系统通过攻击病原做出反应。然而，如果氧化应激持续存在，则自由基防御系统的长时间活跃会产生反作用，自由基的形成导致肠道炎症加剧或细胞死亡。
<Figure 1 – Trial to investigate the oxidative status of piglets fed a starter feed containing a specialty soy protein*. Oxidative stress was measured by testing gluthathion peroxidase (GPX) and superoxide dismutase activity (SOD). On day 28, the diets including enzymatically treated soybean meal (ESBM)* had higher (P<0.05) concentrations of sod and gsh-px.>
<图1 - 研究饲喂添加了特种大豆蛋白*的初乳饲料的仔猪的氧化状态的试验。通过测试谷胱甘肽过氧化物酶（GPX）和超氧化物歧化酶活性（SOD）来测量氧化应激。第28天，添加酶处理大豆粉（ESBM）*的配方具有更高（P <0.05）的sod和gsh-px浓度。>
Vitamin E, in the form of alpha tocopherol, is a known natural antioxidant in the radical defence system. This is why many starter feeds contain an extra dose of vitamin E and other additives to support piglet growth and performance during the stressful weaning period. What the Chinese and German feeding trials suggest is that, if piglets are given feed containing a source of high quality protein, the addition of antioxidant additives may be reduced.
维生素E以α生育酚的形式存在，是自由基防御系统中已知的天然抗氧化剂。这就是为什么许多起仔猪饲料需要额外剂量的维生素E和其他添加剂，来维持仔猪在断奶应激期间的生长和性能。中国和德国的饲养试验表明，如果给仔猪喂食含有高质量蛋白质的饲料，抗氧化剂可以减少。
Evaluating soy proteins in starter feed
评估仔猪饲料中的大豆蛋白质
Both studies tested a highly digestible, speciality soy protein with a low ANF content (HP 300, Hamlet Protein) against soybean meal products with a higher content of the antigen beta-conglycinin. The trial conducted at the China Agricultural University in Beijing also evaluated the performance of fishmeal.
两项研究都测试了一种高消化率的特种大豆蛋白，其抗营养因子含量低（HP 300，哈姆雷特蛋白），而豆粕产品含有较多的抗原β-伴大豆球蛋白。在中国农业大学进行的试验也评估了鱼粉的性能。
The purpose was to investigate the oxidative status of piglets fed a starter feed containing HP 300 or another protein source. Oxidative status was measured by testing gluthathion peroxidase (GPX) and superoxide dismutase activity (SOD), which are indicators of antioxidative capacity. These enzymes are considered main components of the endogenous radical defence system. In this case, the greater the enzyme activity, the higher the antioxidative capacity – and the better the oxidative status.
目的是研究给仔猪饲喂含有HP 300或其他蛋白质来源的饲料时，仔猪的氧化状态。通过测试谷胱甘肽过氧化物酶（GPX）和超氧化物歧化酶活性（SOD）来测量氧化状态，这是抗氧化能力的指标。这些酶被认为是内源性自由基防御系统的主要成分。在这种情况下，酶活性越大，抗氧化能力越高 - 氧化状态越好。
The studies also measured the malonyldialdehyde (MDA) level, which is a strong indicator of lipid peroxidation, and advanced oxidised protein products (AOPP), which indicate protein damage. Both reflect the level of cell damage by free radicals.
研究还测定了丙二醛（MDA）水平——脂质过氧化的指标，以及高级氧化蛋白产品（AOPP）——表明蛋白质受损。两者都反映了自由基对细胞的损伤程度。
Best oxidative status
最佳氧化状态
Piglets fed the speciality soy protein had the best score on all counts compared to other soy proteins, indicating the best oxidative status, and performed on a similar level to fish meal. Another important finding was that the speciality soy protein gave the best growth performance and lowest incidence of diarrhoea of all the soy protein sources in the study.
与其他大豆蛋白相比，喂食特种大豆蛋白的仔猪在所有指标上都获得了最高分，表明其具有最佳的氧化状态，并且与鱼粉对照组水平相当。另一项重要发现是，该研究中所有大豆蛋白质来源的特种大豆蛋白质都能带来最佳的生长性能和最低的腹泻发生率。
<Figure 2 – Effect of protein source on haptoglobin levels in piglets. The significantly lower haptoglobin level in the specialty soy protein group indicates an improved inflammatory status.>
<图2 - 蛋白质来源对仔猪触珠蛋白水平的影响。 特种大豆蛋白组中，触珠蛋白水平显着降低，表明炎症状态改善。>
Analyses of piglet blood samples in the German study proved the close relation between oxidative stress and inflammatory processes. While oxidative status was best in piglets fed the speciality soy protein, they also showed the lowest haptoglobin values, an indicator of inflammatory status. At the same time, the level of vitamin E in the blood was higher.
德国研究对仔猪血液样本的分析证明了氧化应激与炎症过程之间的密切关系。饲喂特种大豆蛋白的仔猪的氧化状态最好，同时它们也检测出最低的触珠蛋白值——炎症状态的指标。与此同时，血液中的维生素E水平也更高。
This suggests that piglet immune systems are less challenged when the speciality soy protein is used in starter diets. In this way, more protein and energy are available to promote piglet growth. It is also a strong indication that the use of a high quality protein with a low ANF content may reduce the need for an extra dose of vitamin E and other feed additives with anti-oxidative properties in starter feed.
这表明，当特种大豆蛋白用于仔猪日粮时，仔猪免疫系统面临的挑战较小。通过这种方式，更多的蛋白质和能量可被仔猪利用，从而促进仔猪生长发育。这也强有力地表明，使用低ANF含量的高质量蛋白质，可以减少在仔猪饲料中额外添加维生素E和其他抗氧化剂。
Together, these studies provide the first evidence that the choice of protein in piglet diets does have an influence on gut inflammation and oxidative status. Many studies have already documented the benefits of low-ANF soy proteins for piglet growth and performance. Further studies are now in the pipeline to confirm the indications: that the biological explanation behind these benefits is reduced oxidative stress.
总之，这些研究第一次提供了证据，即仔猪日粮中蛋白质的选择确实会对肠道炎症和氧化状态产生影响。许多研究已经证明了低ANF大豆蛋白对仔猪生长和性能的益处。目前正在进行进一步的研究加以证明，即这些益处背后的生物学解释是氧化应激减少了。
（文/爱猪网记者刘坤颖编译，爱猪网原创请勿转载）
