Numerous studies have focused on the beneficial effects of probiotics in animals. Even so, additional information should be obtained about the mechanisms by which a useful probiotic strain successfully exerts such beneficial effects. In this study, we evaluated the effect of the dietary supplementation of both live and disrupted Lactobacillus johnsonii (LJ) strain BS15 in broilers at different ages. Specifically, growth performance, lipid metabolism, gut microbiota, intestinal development, and digestive ability of the broilers were assessed. A total of 180 1-day-old Cobb 500 chicks were randomly distributed into three groups. These chicks were fed diets supplemented with 1 × 106 colony-forming units (cfu) LJ per gram of feed (LJ group); 1 × 106 cfu disrupted LJ per gram of feed (D-LJ group); and de Man, Rogosa, and Sharpe liquid medium (control group), respectively, throughout a 42-day experimental period. The results demonstrated that LJ supplementation of feed had a positive effect on the average daily gain and starter feed conversion ratio. In addition, LJ supplementation of feed decreased serum triglyceride and low-density lipid cholesterol levels, as well as abdominal fat deposition. LJ also reduced the mRNA levels of lipoprotein lipase in adipose tissue and stearoyl-CoA desaturase-1 in the liver. LJ diminished the mRNA quantities of the sterol regulatory element binding protein-1c and fatty acid synthase, as well as increased the level of serum high-density lipid cholesterol. LJ increased the mRNA quantities of peroxisome proliferator-activated receptor α, acyl-CoA oxidase in the liver, and carnitine palmitoyltransferase-1. LJ also improved the intestinal development and digestive ability mainly by increasing the villus height/crypt depth ratio in the ileum. The probiotic increased the levels of epidermal growth factor and insulin-like growth factor-1, as well as the activities of trypsin and lipase in the jejunum and ileum. LJ exerted beneficial effects on the intestinal flora. Specifically, LJ markedly enhanced the population of Bacteroidetes and Lactobacillus spp. Moreover, the probiotic reduced the population of Enterobacteriaceae and the Firmicutes/Bacteroidetes ratio. Slight changes caused by disrupted LJ were detected. These findings indicated that live LJ supplementation may promote growth performance and lower fat deposition in broilers.

中文翻译：

---

活的约翰逊乳杆菌BS15通过改善肉鸡的脂质代谢，肠道发育和肠道菌群来促进生长性能并降低脂肪沉积。

大量研究集中于益生菌对动物的有益作用。即使这样，仍应获得有关有用的益生菌菌株成功发挥这种有益作用的机制的其他信息。在这项研究中，我们评估了日粮中添加活的和破坏的约翰逊乳杆菌（LJ）菌株BS15在不同年龄的肉鸡中的效果。具体而言，评估了肉鸡的生长性能，脂质代谢，肠道菌群，肠道发育和消化能力。总共180只1天大的Cobb 500小鸡被随机分为三组。给这些小鸡饲喂每克饲料添加1×106个菌落形成单位（cfu）LJ的日粮（LJ组）；每克饲料1×106 cfu破坏LJ（D-LJ组）; 和德曼，罗戈萨，和Sharpe液体培养基（对照组）分别在整个42天的实验期内。结果表明，补充LJ饲料对平均日增重和起始饲料转化率有积极影响。此外，LJ饲料的添加降低了血清甘油三酸酯和低密度脂质胆固醇水平，以及腹部脂肪沉积。LJ还降低了脂肪组织中脂蛋白脂肪酶和肝脏中硬脂酰-CoA去饱和酶-1的mRNA水平。LJ减少了固醇调节元件结合蛋白-1c和脂肪酸合酶的mRNA数量，并增加了血清高密度脂质胆固醇的水平。LJ增加了过氧化物酶体增殖物激活受体α，肝脏中的酰基辅酶A氧化酶和肉碱棕榈酰转移酶-1的mRNA量。LJ还主要通过提高回肠中的绒毛高度/隐窝深度比来改善肠道发育和消化能力。益生菌增加了空肠和回肠中表皮生长因子和胰岛素样生长因子-1的水平，以及胰蛋白酶和脂肪酶的活性。LJ对肠道菌群产生有益作用。具体而言，LJ显着增加了拟杆菌和乳酸杆菌属的种群。此外，益生菌减少了肠杆菌科的菌群和Firmicutes / Bacteroidetes比率。检测到由LJ破坏引起的轻微变化。这些发现表明，实时补充LJ可以促进肉鸡的生长性能和降低脂肪沉积。益生菌增加了空肠和回肠中表皮生长因子和胰岛素样生长因子-1的水平，以及胰蛋白酶和脂肪酶的活性。LJ对肠道菌群产生有益作用。具体而言，LJ显着增加了拟杆菌和乳酸杆菌属的种群。此外，益生菌减少了肠杆菌科的菌群和Firmicutes / Bacteroidetes比率。检测到由LJ破坏引起的轻微变化。这些发现表明，实时补充LJ可以促进肉鸡的生长性能和降低脂肪沉积。益生菌增加了空肠和回肠中表皮生长因子和胰岛素样生长因子-1的水平，以及胰蛋白酶和脂肪酶的活性。LJ对肠道菌群产生有益作用。具体而言，LJ显着增加了拟杆菌和乳酸杆菌属的种群。此外，益生菌减少了肠杆菌科的菌群和Firmicutes / Bacteroidetes比率。检测到由LJ破坏引起的轻微变化。这些发现表明，实时补充LJ可以促进肉鸡的生长性能和降低脂肪沉积。LJ显着增加了拟杆菌和乳酸杆菌的数量。此外，益生菌减少了肠杆菌科的菌群，并且减少了Firmicutes / Bacteroidetes的比例。检测到由LJ破坏引起的轻微变化。这些发现表明，实时补充LJ可以促进肉鸡的生长性能和降低脂肪沉积。LJ显着增加了拟杆菌和乳酸杆菌的数量。此外，益生菌减少了肠杆菌科的菌群和Firmicutes / Bacteroidetes比率。检测到由LJ破坏引起的轻微变化。这些发现表明，实时补充LJ可以促进肉鸡的生长性能和降低脂肪沉积。