Toral Pablo G, Hervás Gonzalo, González-Rosales Mariana Gabriela, Mendoza Alejandro G, Robles-Jiménez Lizbeth E, Frutos Pilar
Instituto de Ganadería de Montaña (CSIC-University of León), Finca Marzanas s/n, 24346 Grulleros, León, Spain.
Facultad de Medicina Veterinaria y Zootecnia, Universidad Autónoma del Estado de México, No. 100 Instituto Literario 100, Col. Centro, 50000, Toluca, Estado de México, Mexico.
J Anim Sci Biotechnol. 2022 Feb 11;13(1):21. doi: 10.1186/s40104-021-00671-2.
The high dependence of intensive ruminant production on soybean meal and the environmental impact of this crop encourage the search for alternative protein-rich feeds. The use of insects seems promising, but the extent of their ruminal protein degradation is largely unknown. This parameter has major influence not only on N utilization efficiency but also on the environmental burden of ruminant farming. In addition, although assessing ruminal N degradation represents a key first step to examine the potential of new feeds, it is a challenging task due to the lack of a reference method. This study was conducted to investigate the potential of 4 insects (Tenebrio molitor, Zophobas morio, Alphitobius diaperinus and Acheta domesticus) as alternative protein sources for ruminants, using 3 methodologies: 1) a regression technique based on the in vitro relationship between gas production and ammonia-N concentration; 2) a conventional in vitro technique of batch cultures of ruminal microorganisms, based on filtering the incubation residue through sintered glass crucibles; and 3) the in situ nylon bag technique. The in vitro intestinal digestibility of the non-degraded protein in the rumen was also determined. Soybean meal was used as a reference feedstuff.
Comparison of evaluation methods (regression, in vitro and in situ) did not allow to reliably select a single value of ruminal N degradation for the studied substrates, but all techniques seem to establish a similar ranking, with good correlations between methods, particularly between regression and in situ results. Regardless of the methodology, nitrogen from the 4 insects (with contents ranging from 81 to 112 g/kg of dry matter) did not show high ruminal degradation (41-76%), this value being always lower than that of soybean meal. Furthermore, the in vitro intestinal digestibility of non-degraded N was relatively high in all feeds (≥ 64%).
Overall, these results support the potential of the 4 studied insects as alternative feedstuffs for ruminants. Among them, T. molitor showed the lowest and greatest values of ruminal N degradation and intestinal digestibility, respectively, which would place it as probably the best option to replace dietary soybean meal and increase the sustainability of ruminant feeding.
反刍动物集约化生产对豆粕的高度依赖以及这种作物对环境的影响，促使人们寻找富含蛋白质的替代饲料。昆虫的使用似乎很有前景，但它们在瘤胃中的蛋白质降解程度在很大程度上尚不清楚。该参数不仅对氮利用效率有重大影响，而且对反刍动物养殖的环境负担也有重大影响。此外，尽管评估瘤胃氮降解是检验新饲料潜力的关键第一步，但由于缺乏参考方法，这是一项具有挑战性的任务。本研究采用3种方法，研究了4种昆虫（黄粉虫、黑菌虫、赤拟谷盗和家蟋蟀）作为反刍动物替代蛋白质来源的潜力：1）基于产气与氨氮浓度体外关系的回归技术；2）基于通过烧结玻璃坩埚过滤培养残渣的瘤胃微生物分批培养的传统体外技术；3）原位尼龙袋技术。还测定了瘤胃中未降解蛋白质的体外肠道消化率。豆粕用作参考饲料。
评估方法（回归法、体外法和原位法）的比较无法可靠地为所研究的底物选择瘤胃氮降解的单一值，但所有技术似乎都建立了相似的排名，方法之间具有良好的相关性，特别是回归结果和原位结果之间。无论采用何种方法，4种昆虫的氮（干物质含量范围为81至112 g/kg）在瘤胃中的降解率都不高（41%-76%），该值始终低于豆粕。此外，所有饲料中未降解氮的体外肠道消化率相对较高（≥64%）。
总体而言，这些结果支持了所研究的4种昆虫作为反刍动物替代饲料的潜力。其中，黄粉虫的瘤胃氮降解率最低，肠道消化率最高，这可能使其成为替代日粮豆粕和提高反刍动物饲养可持续性的最佳选择。
