早期断奶应激对仔猪的生长性能和健康产生负面影响，研究表明，乳酸菌发酵酸奶可改善仔猪肠道健康、提高仔猪生产性能。课题组利用分离筛选的三株猪源乳酸菌研发功能性发酵酸奶，前期研究发现该酸奶有利于提高断奶仔猪的生长性能和养分消化率，但其在哺乳仔猪上的应用缺乏效果评价。因此，本论文进一步应用该款酸奶开展饲养试验，旨在研究哺乳期-断奶后补饲发酵酸奶对仔猪生长性能、血清免疫炎症指标及粪菌结构的影响。
本研究选取健康 7 日龄初始体重为 2.85±0.09 kg 的“杜×长×大”仔猪 16 窝，随机
分成对照组（CON组）和发酵酸奶组（FM组），每组 8个重复（窝）。对照组仔猪饲喂教槽料；发酵酸奶组仔猪在饲喂教槽料的基础上每日每窝补饲 2 顿酸奶，对 7-13日龄、14-20 日龄和 21-28 日龄的每窝仔猪每顿分别补饲 150 mL、300 mL 和 450 mL酸奶。试验过程中每周记录每窝仔猪的空腹体重和每窝的投料量、剩料量，观察并详细记录各仔猪腹泻情况。试验第 14 和 21 天，每窝随机采集 1 头仔猪颈静脉血液 5mL。从试验第 11（18 日龄）、18（25 日龄）天起，每天采集 100 g 粪样于新自封袋中并滴加 10 mL10%盐酸以固定氮，连续收集 3天，每天粪样收集后即放入-25℃的冰箱中冷冻保存，采集的粪样用于测定养分表观消化率以及菌群高通量测序分析。试验结果表明，与对照组相比，发酵酸奶组仔猪哺乳期间平均日采食量显著升高（P < 0.05）；在第 21~28日龄时，发酵酸奶组仔猪平均日增重显著提高（P < 0.05），腹泻率显著降低（P < 0.05）。发酵酸奶组与对照组间养分消化率无显著差异（P >0.05）。血清生化检测结果显示，与对照组相比，在第 21 日龄时，补饲发酵酸奶组仔猪的低密度脂蛋白含量有提高的趋势（P = 0.098）；在第 28日龄时，与对照组相比，补饲发酵酸奶组仔猪的球蛋白含量有提高的趋势（P = 0.079）。与对照组相比，补饲发酵酸奶组仔猪在第 21 日龄时 IL-1β 显著升高（P < 0.05）；在第 28 日龄时，补饲发酵酸奶组仔猪 IgG和 IL-10显著升高（P < 0.05），而 IL-6显著下降（P < 0.05）。菌群高通量测序分析结果显示，仔猪在第 21、24、28 日龄时，ACE 指数显著降低（P <0.05），在第 24、28 日龄时 Shannon 指数显著降低（P < 0.05）。在属水平上，与对照组相比，补饲发酵酸奶组仔猪在第 21 日龄时粪便菌群中罗伊氏乳杆菌属和霍尔德曼氏菌属的相对丰度显著提（P<0.05），而 Erysipelotrichaceae UCG-003 属和Intestinimonas 属的相对丰度显著降低；补饲发酵酸奶组仔猪在第 28 日龄时粪便菌群中弯曲杆菌属、梭杆菌属、p-251-o5_norank属的相对丰度显著低于对照组（P <0.05），而巨球形菌属的相对丰度显著高于对照组（P < 0.05）。在第 21 日龄时，仔猪粪便菌群中 Erysipelotrichaceae UCG-003属和Intestinimonas 属的相对丰度与仔猪腹泻率呈显著正相关（P < 0.05）；在第 28 日龄时，仔猪粪便菌群中 p-251-o5_norank 属与腹泻率、IL-6和 TNF-α水平呈显著正相关（P < 0.05），弯曲杆菌属与仔猪 IL-10水平呈显著负
相关（P < 0.05），梭杆菌属与仔猪血清免疫球蛋白 A呈显著负相关（P < 0.05）。以上结果表明，补饲乳酸菌发酵酸奶可以增加哺乳仔猪粪便中罗伊氏乳杆菌属和霍尔德曼氏菌属的等有益菌属的相对丰度，降低Intestinimonas属和Erysipelotrichaceae UCG-003 属等有害菌群的相对丰度，减少断奶仔猪粪便中弯曲杆菌属和梭杆菌属等致病菌的相对丰度。
综上所述，本论文研究表明在哺乳期-断奶后仔猪日粮中补饲发酵酸奶有提高仔猪免疫抵抗能力，提高机体抗炎细胞因子的浓度，缓解仔猪肠道症，激发仔猪生长潜能。

Early weaning stress negatively affects the growth performance and health of piglets, and studies have shown that lactobacillus-fermented yogurt can improve piglet intestinal health and piglet performance. The group used three strains of swine-derived lactic acid bacteria isolated and screened to develop functional fermented yogurt, which was found to be beneficial to improve the growth performance and nutrient digestibility of weaned piglets in the preliminary study, but its application to lactating piglets lacked the evaluation of its effect. Therefore, this thesis further applied the yogurt to carry out feeding trials, aiming to investigate the effects of lactation-post-weaning supplementation with fermented yogurt on growth performance, serum immunoinflammatory indexes and fecal bacterial structure of piglets.

In this study, 16 litters of " Duroc×Landrace×Large white" piglets with an initial weight of 2.85±0.09 kg at 7 days of age in close physiological condition were selected and randomly divided into a control group (CON group) and a fermented yogurt group (FM group), with 8 replicates (litters) in each group. Piglets （CON group） were given  chow meal; piglets （FM group）were given chow meal and two daily yogurt supplements per litter, 150 mL, 300 mL and 450 mL of yogurt were given to piglets in each litter from 7 to 13 days old, from 14 to 20 days old and from 21 to 28 days old, respectively. During the test, the piglets were weighed on an empty stomach, and the empty stomach weight of each litter and the amount of feed and leftover feed per litter per week were recorded, and the diarrhea of each litter was observed and recorded in detail. On the 14th and 21st days of the experiment, 5 mL of jugular blood was randomly collected from one piglet in each litter. 100 g of fecal samples were collected in a new self-sealing bag and 10 mL of 10% hydrochloric acid was added to fix the nitrogen for 3 consecutive days starting from the 11th (18 days old) and 18th (25 days old) days of the experiment. digestibility and high throughput sequencing analysis of the flora.

The test results showed that the average daily feed intake of piglets during lactation was significantly higher (P < 0.05) in the yogurt group compared with the control group; at the 21st to 28th day of age, the average daily weight gain of piglets in the yogurt group was significantly higher (P < 0.05), and the rate of diarrhea was significantly lower (P < 0.05). There was no significant difference (P > 0.05) in digestibility between the fermented yogurt supplementation group and the control group. The results of serum biochemical tests showed that compared with the control group, the LDL content of piglets in the fermented yogurt supplementation group tended to increase at the 21st day of age (P = 0.098), and the globulin content of piglets in the supplemented yogurt supplementation group tended to increase at the 28th day of age compared with the control group (P = 0.079).  Compared with the control group, the IL-1β of piglets in the supplemented yogurt supplementation group significantly increased at the 21st day of age compared with that of the control group. (P < 0.05) at the 21st day of age; at the 28th day of age, IgG and IL-10 were significantly higher in the fermented yogurt supplemented group (P < 0.05) and IL-6 was significantly higher in the control group (P < 0.05). The results of high throughput sequencing analysis of the flora showed that the ACE index of the piglets was significantly reduced at the 21st, 24th and 28th day of age (P < 0.05), and the Shannon index was significantly reduced at the 24th and 28th day of age (P < 0.05). At the genus level, the relative abundance of Lactobacillus and Hordeumannia in the fecal flora of piglets in the fermented yogurt supplementation group was significantly higher (P < 0.05) and the relative abundance of Erysipelotrichaceae UCG-003 and Intestinimonas in the fecal flora was significantly lower (P < 0.05) at the 21st day of age compared to that of the control group, and the relative abundance of Lactobacillus and Hordeumannia in the fecal flora of piglets in the fermented yogurt supplementation group. The relative abundance of Campylobacter, Clostridium and p-251-o5_norank in the fecal flora of piglets in the fermented yogurt supplementation group was markedly lower at the 28th day of age (P < 0.05), whereas the relative abundance of Macrocystis was significantly higher than that of the control group (P < 0.05).The relative abundance of Erysipelotrichaceae UCG-003 and Intestinimonas in the fecal flora of piglets was significantly positively correlated with the diarrhea rate of piglets at the 21st day of age (P < 0.05), and the relative abundance of p-251-o5_norank in the fecal flora of piglets was significantly positively (P < 0.05) correlated with the diarrhea rate of piglets at the 28th day of age and with the levels of IL-6 and TNF-α levels, Campylobacter showed a significant positive correlation (P < 0.05), Campylobacter showed a significant negative correlation (P < 0.05) with IL-10 levels in piglets, and Clostridium showed a significant negative correlation (P < 0.05) with serum immunoglobulin A in piglets. The above results indicated that supplemental feeding of lactobacillus fermented yogurt could build up beneficial bacteria Hordmannia and Lactobacillus in the feces of lactating piglets, decrease the relative abundance of harmful bacteria such as Intestinimonas and Erysipelotrichaceae UCG-003 and build up pathogenic bacteria Campylobacter and Clostridium in the feces of weaned piglets. relative abundance of pathogenic bacteria.

In conclusion, the present study demonstrated that supplementation of fermented yogurt in the diets of lactating and weaned piglets has the ability to improve the immune resistance of piglets, raise the concentration of anti-inflammatory factors, reduce the incidence of gastrointestinal lesions, and stimulate the growth potential of piglets.

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