Lau Calvin Ho-Fung, Capitani Sabrina, Tien Yuan-Ching, Verellen Lou Ann, Kithama Munene, Kang Hellen, Kiarie Elijah G, Topp Edward, Diarra Moussa S, Fruci Michael
Ottawa Laboratory (Carling), Canadian Food Inspection Agency, Ottawa, ON, Canada.
London Research and Development Centre, Agriculture and Agri-Food Canada, London, ON, Canada.
Anim Microbiome. 2024 Feb 15;6(1):6. doi: 10.1186/s42523-024-00293-9.
We had earlier described the growth-promoting and -depressive effects of replacing soybean meal (SBM) with low (12.5% and 25%) and high (50% and 100%) inclusion levels of black soldier fly larvae meal (BSFLM), respectively, in Ross x Ross 708 broiler chicken diets. Herein, using 16S rRNA gene amplicon sequencing, we investigated the effects of replacing SBM with increasing inclusion levels (0-100%) of BSFLM in broiler diets on the cecal bacterial community composition at each growth phase compared to broilers fed a basal corn-SBM diet with or without the in-feed antibiotic, bacitracin methylene disalicylate (BMD). We also evaluated the impact of low (12.5% and 25%) inclusion levels of BSFLM (LIL-BSFLM) on the prevalence of selected antimicrobial resistance genes (ARGs) in litter and cecal samples from 35-day-old birds.
Compared to a conventional SBM-based broiler chicken diet, high (50 to100%) inclusion levels of BSFLM (HIL-BSFLM) significantly altered the cecal bacterial composition and structure, whereas LIL-BSFLM had a minimal effect. Differential abundance analysis further revealed that the ceca of birds fed 100% BSFLM consistently harbored a ~ 3 log-fold higher abundance of Romboutsia and a ~ 2 log-fold lower abundance of Shuttleworthia relative to those fed a BMD-supplemented control diet at all growth phases. Transient changes in the abundance of several potentially significant bacterial genera, primarily belonging to the class Clostridia, were also observed for birds fed HIL-BSFLM. At the finisher phase, Enterococci bacteria were enriched in the ceca of chickens raised without antibiotic, regardless of the level of dietary BSFLM. Additionally, bacitracin (bcrR) and macrolide (ermB) resistance genes were found to be less abundant in the ceca of chickens fed antibiotic-free diets, including either a corn-SBM or LIL-BSFLM diet.
Chickens fed a HIL-BSFLM presented with an imbalanced gut bacterial microbiota profile, which may be linked to the previously reported growth-depressing effects of a BSFLM diet. In contrast, LIL-BSFLM had a minimal effect on the composition of the cecal bacterial microbiota and did not enrich for selected ARGs. Thus, substitution of SBM with low levels of BSFLM in broiler diets could be a promising alternative to the antibiotic growth promoter, BMD, with the added-value of not enriching for bacitracin- and macrolide-associated ARGs.
我们之前曾描述过，在罗斯×罗斯708肉鸡日粮中，分别用低（12.5%和25%）和高（50%和100%）添加水平的黑水虻幼虫粉（BSFLM）替代豆粕（SBM）时，所产生的促生长和抑生长作用。在此，我们使用16S rRNA基因扩增子测序技术，研究了在肉鸡日粮中用不断增加添加水平（0 - 100%）的BSFLM替代SBM，对各生长阶段盲肠细菌群落组成的影响，并与饲喂基础玉米 - SBM日粮且添加或不添加饲料用抗生素杆菌肽亚甲基二水杨酸酯（BMD）的肉鸡进行比较。我们还评估了低添加水平（12.5%和25%）的BSFLM（LIL - BSFLM）对35日龄鸡的垫料和盲肠样本中选定抗菌抗性基因（ARGs）流行率的影响。
与传统的基于SBM的肉鸡日粮相比，高添加水平（50%至100%）的BSFLM（HIL - BSFLM）显著改变了盲肠细菌的组成和结构，而LIL - BSFLM的影响最小。差异丰度分析进一步表明，在所有生长阶段，与饲喂添加BMD的对照日粮的鸡相比，饲喂100% BSFLM的鸡的盲肠中，罗姆布茨菌的丰度始终高约3个对数级，而沙氏菌的丰度低约2个对数级。对于饲喂HIL - BSFLM的鸡，还观察到几个潜在重要细菌属的丰度出现短暂变化，这些细菌主要属于梭菌纲。在育肥阶段，无论日粮中BSFLM的水平如何，未添加抗生素饲养的鸡的盲肠中肠球菌都有所富集。此外，在饲喂不含抗生素日粮（包括玉米 - SBM或LIL - BSFLM日粮）的鸡的盲肠中，发现杆菌肽（bcrR）和大环内酯（ermB）抗性基因的丰度较低。
饲喂HIL - BSFLM的鸡呈现出肠道细菌微生物群谱失衡的情况，这可能与之前报道的BSFLM日粮的生长抑制作用有关。相比之下，LIL - BSFLM对盲肠细菌微生物群的组成影响最小，并且不会使选定的ARGs富集。因此，在肉鸡日粮中用低水平的BSFLM替代SBM可能是抗生素生长促进剂BMD的一个有前景的替代品，其附加值在于不会使与杆菌肽和大环内酯相关的ARGs富集。
