Background: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. Results: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％). Conclusion: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.

Pablo G.Toral;Gonzalo Hervás;Mariana Gabriela González-Rosales;Alejandro G.Mendoza;Lizbeth E.Robles-Jiménez;Pilar Frutos

Instituto de Ganadería de Monta?a(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

畜牧与生物技术杂志（英文版）

[1]Pablo G.Toral;Gonzalo Hervás;Mariana Gabriela González-Rosales;Alejandro G.Mendoza;Lizbeth E.Robles-Jiménez;Pilar Frutos-.Insects as alternative feed for ruminants:comparison of protein evaluation methods)[J].畜牧与生物技术杂志（英文版）,2022(04):1143-1150

Zophobas,morio,Alphitobius,diaperinus,Acheta,crucibles,feedstuffs

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