By the year 2050, the global human population is projected to reach approximately 9.5 billion, necessitating a corresponding 70% increase in demand for animal-based food production, such as milk and meat (1). The primary livestock categories include pigs, with a production of 112.33 million metric tons (MT); poultry, with 109.02 million MT; and cattle (including beef and buffalo meat), with 67.99 million MT, collectively representing 91.80% of global meat production (2). As the most populous country globally, China has a significant demand for livestock products, particularly those derived from ruminant animals. Consequently, this surge in demand for animal-derived products may escalate the need for livestock feed (3). Providing sufficient feed for livestock is anticipated to encounter challenges as available land for cultivating feed resources diminishes. Intensive livestock production systems heavily depend on soybean meal (SBM) as a primary source of protein and essential amino acids (4). Nevertheless, its extensive use raises concerns regarding environmental sustainability and its competition with human nutrition (5).

Insects represent promising and innovative feed ingredients due to their valuable chemical composition. They are notably rich in proteins and contain significant amounts of lipids, making them suitable as protein and energy sources in animal dietary formulations (6). Insects have been incorporated as a feed ingredient in various animal species, including broiler chickens (7), laying hens (8), turkey (9), ducks (10), quail (11), rabbit (12), swine (13), companion animals (14), and aquatic species (15, 16). Despite their widespread use across these species, the utilization of insects in ruminant diets has been relatively limited. The limited adoption of insects in ruminant diets may be attributed to concerns regarding the potential risk of transmitting bovine spongiform encephalopathy (mad cow disease) despite the absence of evidence supporting such a linkage to date (17). While ruminants primarily consume grasses, legumes, and agricultural by-products, they frequently require protein supplements to enhance their production efficiency (18).

Moreover, feed expenses represent a significant constraint on advancing the livestock production industry. Feed costs typically constitute around 50–70% of the total budget, with protein requirements alone accounting for more than 15% of the overall feed expenditure (19). Hence, to address the rising demand for animal products in the coming years, there is an urgent need for innovative solutions and sustainable alternatives to traditional protein sources in animal diets, aiming to minimize environmental impact. The utilization of insects as animal feed offers substantial environmental benefits compared to conventional sources. Insects play a key role in bioconverting waste materials, require less water and land for cultivation, and contribute to lower greenhouse gas (GHG) emissions (5). Therefore, this development has prompted policymakers in the European Union to approve the use of insects as feed for pigs and poultry in April 2021, in addition to their existing approval for aquaculture since July 2017 (20). Currently, there is limited available data on the utilization and effects of insects as alternative feed for ruminants. Therefore, further scientific research is needed to raise awareness of this topic among policymakers in Europe, China, and globally and to assist in establishing a regulatory framework for licensing insects as ruminant feed (21).

The utilization of insects as feed for monogastric animals has been extensively reviewed (22). However, there remains a gap in applying insects as feed for ruminants. In Asia, Africa, Oceania, and South America, insects have historically served as traditional food sources within these regions. They have recently garnered interest as alternative protein sources in additional regions, including Europe and North America (23). In the United States, the black soldier fly (Hermetia illucens) is utilized exclusively in aquaculture. In Canada, the use of Hermetia illucens larvae is approved for both aquaculture and poultry production. Brazil currently lacks specific legislation addressing this matter, with insects permitted only for feeding non-ruminant animals (24). In countries like China and South Korea, this matter has no restrictions or limitations (25).

Presently, there is a lack of statistical data regarding the commercial rearing of insects. However, numerous countries have begun farming insects like crickets for the feed market. Annual insect meal production is anticipated to increase to 1.2 million tons by 2025 (26). Cricket presents promising potential as an alternative feed resource for animals. Figure 1 illustrates the detailed life cycle of selected insect species in this context. Typically, crickets are reared for approximately 5–6 reproductive cycles before being discarded due to diminished productivity. These discarded crickets can subsequently be utilized as animal feed (27). The black soldier fly (Hermetia illucens) exhibits a life cycle lasting approximately 40–43 days (28). Research interest in using edible insects as alternative feed has surged recently. As Hanönü et al. (29) reported, insect farming emerges as a more cost-effective option when evaluating land allocation for forage crop cultivation and their associated water requirements. Insects exhibit efficient feed conversion rates and rapid growth rates. It is estimated that approximately 2 kg of organic waste and 1 m² of space could yield 1 kg of insect protein. In particular, Hermetia illucens has gained increasing commercial utilization in animal feed due to its ease of rearing, high productivity, rich nutritional content, and efficient organic waste utilization. Hermetia illucens larvae have demonstrated the capacity to consume substrate ranging from 25 mg to 500 mg of fresh matter per larva per day, achieving a body length of approximately 27 mm, width of 6 mm, and weight of 220 mg by 14 days of age (30).

Moreover, Indonesia, characterized by its archipelagic geography and tropical climate, offers favorable conditions for Hermetia illucens production. Data from the Indonesian Ministry of Fisheries in 2021 indicate the presence of over 175 Hermetia illucens farmers spanning from the Sumatra Island (western) to the Papua Island (eastern) regions, with an average production rate of 100 kg per day (2). One challenge associated with small-scale production is the cost factor. Implementing good manufacturing practices could help mitigate the production costs of insects. Numerous insect species have undergone evaluation as potential components of ruminant diets, with notable candidates including the larvae of the mealworm beetle (Tenebrio molitor), pupae of the silkworm (Bombyx mori), larvae of the black soldier fly (Hermetia illucens), and adult two-spotted cricket (Gryllus bimaculatus) (Figure 2). However, research into consumer and stakeholder perspectives regarding the use of insects in farm animal diets remains limited. The chemical composition and average nutritional values of commonly studied insects used in ruminant nutrition research, such as Gryllus bimaculatus adults, Tenebrio molitor larvae, Hermetia illucens larvae, and Bombyx mori pupae are fully described in Table 1.

Consequently, this article is structured as follows: following the introduction, the second section discusses insects’ effects on in vitro ruminal fermentation characteristics, mainly focusing on ruminal digestibility and gas production in vitro. The third section is centered on the evidence of in vivo studies investigating insects on ruminants, including the impacts on ruminal fermentation, productive performance, and health. The fourth section presents an economic evaluation of insect protein compared to alternative protein sources. The fifth section then thoroughly examines the legislative framework necessary for introducing a novel protein source into the specific sector of ruminant nutrition, specifically scrutinizing the governmental regulations governing insect utilization in the European Union. The sixth section delves into ethical considerations surrounding the use of insects. The seventh section summarizes the current research gaps and outlines future directions for applying insects in ruminant nutrition. Subsequently, the eighth section (Supplementary material 1) offers insights into statistical modeling and prediction of the optimal inclusion level of insects in the ruminants’ diet based on in vitro and in vivo studies, focusing on crucial aspects of ruminal fermentation driven by data availability. Finally, the conclusion will recapitulate the existing challenges and propose avenues for future research in this domain.

Supplementary Table S8 (Supplementary material 2) presents descriptive statistics for the variables used in assessing the impact of Hermetia illucens, Tenebrio molitor, Bombyx mori, and Vespa orientalis on blood biochemical parameters. Astuti et al. (36) documented that incorporating cricket meal at a concentration of 30% within the concentrate for post-weaning Etawah crossbred goats resulted in physiological responses (rectal temperature, heart rates, and respiration rate) that fell within normal ranges. However, the experimental group exhibited 182% significantly higher crude fat intake compared to the control group. Importantly, no adverse effects on ruminal fermentation profiles were observed, and the goats in the experimental group performed comparably to those on the control ration. These findings are consistent with earlier observations indicating that incorporating 15% cricket meal (replacing 100% soybean meal) as a protein source in lamb rations does not adversely affect palatability, performance, digestibility of DM and crude protein, feed efficiency, or blood metabolite profiles (including glucose, triglycerides, and total protein).

Furthermore, utilizing 7.5% cricket meal in lamb rations has been shown to reduce CH₄ production, as reported by the authors significantly. Therefore, replacing soybean meal with 7.5% cricket meal may be more advantageous, considering the positive impact on CH₄ reduction (37). Another example of this is the study carried out by Phesatcha et al. (4), which demonstrated that incorporating adult cricket meal (Gryllus bimaculatus) at 8% of the ration resulted in a significant linear increase of 25.6% in average daily gain and 7.46% in apparent digestibility of crude protein in Thai native male beef cattle. This increase was accompanied by linearly significant rises in rumen ammonia-nitrogen (26.5%) and blood urea nitrogen (6.4%). Furthermore, total volatile fatty acids (TVFA) were linearly increased by 26.5%, predominantly due to a 4.2% higher propionic acid level compared to the control group when cricket meal was included at 12% of the ration. Their study highlighted that cricket meal had a CP content of 62.4%, higher than soybean meal (SBM), influencing the alteration in TVFA.

Consequently, the C₂:C₃ ratio was significantly reduced. Moreover, estimated CH₄ emissions decreased by 20.9%, partially explained by a 35.9% decrease in protozoa when cricket meal completely replaced SBM in the ration. These findings suggest the potential benefits of cricket meal in improving cattle performance and reducing CH₄ emissions in feed formulations. Moreover, several research studies have recently investigated the use of defatted silkworm pupae meal in ruminant nutrition. Rashmi et al. (38) conducted a study that concluded that defatted silkworm pupae meal could be safely included at a level of 4.1% in cattle concentrate mixtures (substituting soybean meal up to 30%) without adverse effects on health or performance. This finding suggests that defatted silkworm pupae meal is a promising alternative to traditional protein sources for cattle, offering both nutritional benefits and cost advantages. A notable aspect of their study is the cost-effectiveness of defatted silkworm pupae meal compared to soybean meal. The price of defatted silkworm pupae meal was found to be 51.2% lower than soybean meal when calculated on per kilogram of crude protein basis. This cost advantage further enhances the appeal of defatted silkworm pupae meals as a viable protein source for cattle feed formulations. A notable finding from the earlier-reported results highlights the effective use of silkworm pupae oil to enhance ether extract digestibility by approximately 10% and reduce enteric CH₄ emissions by 17.5%–20.5%. These improvements were achieved without compromising nutrient intake or digestibility when oil supplementation was administered continuously (daily) or intermittently (alternate week) at a consistent level of 2% of the diet.

Furthermore, the observed reduction in CH₄ emissions is attributed to a decrease in protozoa population. Expressly, significant decreases were noted in total protozoa (39.8%–42%) and Isotrichidae (40.3%–41.8%) (39). These findings align with a meta-analysis by Dai et al. (40), which demonstrated that CH₄ emissions correlate positively with total rumen protozoa and Isotrichidae but not with Ophyroscolecidae. In summary, using silkworm pupae oil as a supplement in livestock diets shows promise for improving nutrient digestibility and reducing CH₄ emissions through targeted modulation of rumen microbial populations. Further research could contribute valuable insights into sustainable livestock production practices.

Only one study has explored the effects of Oriental Hornet meal on lamb nutrition (41). The findings from this study revealed significant improvements in the digestibility of DM, organic matter (OM), crude protein, and ether extract when Oriental Hornet meal was included at a level of 3.42% of the ration. Specifically, digestibility increased by 2.32, 2.99, 9.74, and 1.93%, respectively. Moreover, including Oriental Hornet meal at this level led to notable enhancements in average body weight gain (30.9%) and growth rate (30.7%) compared to the control group. This improvement can be attributed to the higher total digestible nutrients and digestible crude protein content in the experimental ration, which were 1.56 and 1.43% higher than the control group, respectively, due to the substitution of Oriental Hornet meal for SBM. An intriguing finding was the significantly increased economic efficiency of 19.1% observed in the experimental group compared to the control group. This higher economic efficiency suggests a higher net return from using Oriental Hornet meal, making it potentially well-suited for the Egyptian market. In summary, the limited study on Oriental Hornet meal in lamb nutrition demonstrated promising effects on digestibility, growth performance, and economic efficiency. Further research could provide valuable insights into the potential utilization of Oriental Hornet meals as a cost-effective and beneficial protein source for ruminants, particularly in specific regional markets like Egypt (41).

In addition, recent research comparing the supplementation of 4% Hermetia illucens oil to sheep ration vs. no supplementation has shown significant increases in both TVFA and total bacteria in the ruminal fluid, with increments of up to 44.8 and 77.1%, respectively (28). The variation in total bacterial population can be attributed to several factors, including differences in rations, types of feed, timing and methods of rumen fluid collection, and feeding frequency. Rations containing easily digestible protein and carbohydrates promote bacterial growth in the rumen. In the study by Ningsih et al. (28), the experimental diets exhibited a total digestible nutrients (TDN) content up to 5% higher than the control meal. This increase likely contributed to the observed rise in the TVFA in the rumen, presumably due to the higher bacterial population resulting from the addition of black soldier fly oil supplementation. Consistent with the findings of this study, previous research has shown that the addition of Hermetia illucens fat at a level of 0.2% in the ration of multiple-breeding black-motley cows resulted in a significant increase in TVFA production in the rumen (42).

Recent investigations have explored the impact of incorporating Hermetia illucens meal into sheep nutrition. Researchers observed that replacing soybean meal with black soldier fly larvae did not negatively affect the performance or hematological profile of the sheep. Notably, body weight gain tended to increase (p = 0.082), and feed conversion ratio tended to decrease (p = 0.089) when Hermetia illucens larvae meal was included at 2.5 and 5% of the ration, respectively. Furthermore, analysis of blood leukocyte differentiation, including lymphocytes, monocytes, neutrophils, eosinophils, and basophils, showed no significant differences, indicating that all animals maintained a healthy status (43). Because lymphocytes play a central role in adaptive immunity, recognizing and targeting specific pathogens. Monocytes can differentiate into macrophages upon entering tissues, where they play a vital role in engulfing and digesting pathogens. Neutrophils, the most abundant white blood cells, act as the body’s primary defense against infections by engulfing and destroying bacteria through phagocytosis. Eosinophils combat parasitic infections and regulate allergic responses by releasing toxic proteins. Basophils release histamine and other chemicals involved in allergic reactions, contributing to the inflammatory response and defense against certain parasites (44).

Moreover, Supplementary Tables S1–S5 (Supplementary material 2) contains a comprehensive list of both in vitro and in vivo experiments discussed in the review, detailing experimental methodologies such as methods used, incubation times or experimental periods, information about animal donors including their status and feeding regimens, specifics of treatments applied, insect species studied, and ethical approvals obtained. Besides, depending on the species, form, and inclusion level of insects, substituting soybean meal can have varying degrees of impact on ruminal fermentation indices and performance, as detailed in Table 2. Moreover, descriptive statistics of the variables in the database used to evaluate the effect of Gryllus bimaculatus, Hermetia illucens, and Bombyx mori on ruminal fermentation parameters in ruminants (in vivo) have been shown in Supplementary Table S9 (Supplementary material 2). Supplementary Table S10 (Supplementary material 2) displays the impact of various insects on ruminal fermentation parameters. The Gryllus bimaculatus treatment yielded a significant increase (p < 0.01) in ruminal pH, rising by 3.76% compared to the control. Vespa Orientalis treatments enhanced the apparent digestibility of DM by 7% (p = 0.003) compared to the control.

Furthermore, the Bombyx mori treatment notably increased the apparent digestibility of acid detergent fiber (ADF) compared to the control treatment (p = 0.007; Supplementary Table S10 in Supplementary material 2). Supplementary Table S11 (Supplementary material 2) illustrates their influence on biochemical parameters in the context of in vivo experiments. None of the dietary insect interventions elicited discernible alterations in the blood biochemical profiles of ruminants compared to the control.

Table 3 demonstrates the economic feasibility of selected insects relative to plant-based protein sources. The current prices of soybean meal, rapeseed meal, and sunflower meal feeds are approximately €0.486, €0.3, and €0.237 per kg, respectively. Meanwhile, the current prices of Hermetia illucens and Tenebrio molitor are approximately €7.25 and €14.5 per kg, respectively. Therefore, for a comprehensive assessment between insects and traditional plant protein sources, it is essential to adjust the nutritional value based on parameters such as crude protein content or essential amino acids profile. This adjustment allows a more accurate comparison of their economic and nutritional merits. The findings indicate that replacing each euro of SBM with Hermetia illucens would cost 16.2 €/kg for protein, 11.9 €/kg for lysine (Lys), and 20 €/kg for methionine (Met) for farmers.

Similarly, replacing each euro of SBM with Tenebrio molitor would lead to costs of 35.2 €/kg for protein, 55.3 €/kg for Lys, and 36.1 €/kg for Met for farmers. The elevated cost of insect meal currently limits its application in ruminant diets. Nevertheless, to be competitive, expanding the scale of insect breeding operations within companies is expected to enhance efficiency and decrease the overall cost of insect protein production over time (45). Achieving mass production remains a distant prospect. While definitive conclusions on cost reduction or profit increase in insect production were not drawn, it has been proposed that greater mechanization could lead to reduced labor costs, and utilizing low-value feed substrates may decrease operational expenses. In terms of farm output sales, commercializing insect frass as fertilizer could offer an additional income stream for insect farmers (46). The potential of insects as a viable alternative feed component is attributed to their short life cycle.

Furthermore, projections from the International Platform of Insects for Food and Feed suggest a significant rise in the utilization of insects for food and feed within the European Union. The insect volume is expected to escalate from 500 tons in 2020 to surpass 1 million tons by 2025, reaching an estimated 3 million tons by 2030, encompassing both larvae and adult forms. This upward trajectory in market demand likely mirrors the lucrative opportunities available to stakeholders engaged in insect production. This growth is anticipated to contribute to heightened consumer awareness regarding the detrimental impacts of conventional animal feed production (45).

Insect meals are categorized as processed animal proteins and are subject to prohibitions on their utilization in numerous high-income nations (e.g., European countries). On the contrary, developing and emerging regions often lack specific legislation. For instance, in Asia, Thailand, a leading producer of crickets, is actively developing the first set of guidelines for insect breeding. In China, insects are widely used as feed and food components in various regions, yet they have not yet been officially recognized under food law (45). In the Americas, there is no specific prohibition or approval concerning the use of insect proteins in the processing, marketing, or incorporation into animal feed within this region. In the recent past, within the European Union, the approval for incorporating insects into farm animal feed was restricted to seven specific insect species, as outlined in Commission Regulation (EU) 2017/893 Commission Regulation-EU (47). These approved species encompassed two mealworm species (Tenebrio molitor, Alphitobius diaperinus), two fly species (Hermetia illucens, Musca domestica), and three cricket species (Acheta domesticus, Gryllodes sigillatus, Gryllus assimilis). Over time, there has been a growing expansion in the utilization of insect species for animal feed. Domestic silkworms, which exclusively consume mulberry leaves, pose no risk of contamination from animal-origin food sources that are not permitted for insect feed. Silkworms (Bombyx mori) have recently been added to the roster of authorized insect species for manufacturing processed animal protein utilized in animal feed, as delineated in Commission Regulation (EU) 2021/1925 (Commission Regulation-EU) (48).

Although legal regulations regarding the use of insects as feed vary regionally, researchers and feed manufacturers have a notable global interest in promoting innovation and research in this field. In the coming years, this interest may lead to legislative changes similar to those observed for monogastric animals, facilitating broader acceptance and utilization of insects in ruminant feeding practices worldwide. In summary, regarding the current global legislative framework concerning the use of insects as feed for ruminants, both insect oil and meal are explicitly authorized in countries including Mexico, Colombia, Brazil, Morocco, Algeria, Niger, Nigeria, Sudan, South Africa, Namibia, Ethiopia, India, Australia, and New Zealand. Insect oils are authorized but not insect meals in countries such as Russia, Finland, Sweden, Norway, Iceland, the United Kingdom, Denmark, Belarus, Estonia, Ireland, France, Spain, Italy, Romania, Ukraine, and Poland. Some countries like Egypt, Ecuador, Chile, Canada, and Alaska (United States) lack specific insect regulatory frameworks. However, countries such as Argentina, Iran, Japan, North Korea, and Tunisia do not authorize insect oils or meals to be used as feed for ruminants (20). Moreover, a structured compilation of legislative documents from the European Parliament and the Council (EC) concerning insect production for food and feed is presented in Supplementary Table S12 (Supplementary material 2), arranged chronologically.

Insects possess the potential to be incorporated into livestock production systems as a source of feed. However, insects must be cultivated on a large scale within a “mini-livestock” framework to be effective as feed. Because these large-scale rearing systems are relatively novel, formal industry standards and welfare regulations have not been fully established, resulting in unresolved questions related to insect welfare. Considering the significance of consumer attitudes in shaping the social acceptance of insect production, it is essential to analyze consumers’ ethical perspectives on using insects as livestock feed. As per Fukuda et al. (49), sampling involved convenience sampling of 361 adult consumers in the United States. When queried about using insects as livestock feed, 34% of respondents expressed support, 52% remained neutral, and 15% voiced opposition. Among those opposed, 58% cited ethical concerns as their rationale for opposition. Among respondents who expressed support or neutrality regarding using insects as livestock feed, 29% identified concerns related to livestock welfare, while 26% identified concerns related to insect welfare as perceived risks. These observations suggest that insect producers have an incentive to implement best practices that are perceived as fostering high-welfare conditions for their “mini-livestock” when used for livestock feed. Moreover, the findings indicate that, although the existing research on consumer acceptance is limited, it is unlikely to impede the development of the insect protein industry for feed. Nonetheless, additional research is needed to investigate consumer willingness to pay for animal products derived from animals fed with insects and assess whether insects contribute to improved acceptability, both in terms of general perception and sensory appeal, compared to conventional products (50).

The following issues warrant attention: (1) Nutrient requirements and digestibility—research gap: limited comprehensive studies on the specific nutrient requirements of ruminants when fed insect-based diets, especially the insects’ CP conventional factor for proximate analysis not unified yet. Because a portion of the nitrogen is contained within chitin, it is also extracted during protein analysis using the traditional Kjeldahl method, resulting in overestimating the actual CP content. Future direction: to standardize the conventional factor for CP content in potential insect feeds for ruminants across various species and morphological stages of the insects. (2) Feed formulation optimization—research gap: insufficient knowledge about optimal feed formulations incorporating insect meals for different classes of ruminants (e.g., lactating cows, growing calves). Future direction: explore novel feed formulation strategies that maximize the nutritional value of insect-based feeds while ensuring balanced diets for ruminant health and performance. Investigate the synergistic effects of combining insects with other feed ingredients. (3) Long-term effects on animal health and performance—research gap: limited understanding of the long-term impact of insect-based diets on ruminant health, productivity, and reproductive performance. Future direction: conduct longitudinal studies to assess the effects of sustained insect feeding on rumen health, metabolic function, immunity, and overall animal performance over extended periods. Investigate potential benefits or challenges associated with prolonged insect-based feeding. More studies are required to understand the impact of insect-based diets on ruminal fermentation dynamics, microbial populations, and metabolite production. Investigating potential health risks or safety concerns associated with feeding insects to ruminants is essential. Studies should focus on assessing antinutritional factors, toxins, or allergens in insect-based feeds. (4) Environmental impact and sustainability—research gap: incomplete evaluation of the environmental sustainability aspects of using insects as feed in dairy production systems. Future direction: quantify greenhouse gas emissions, resource utilization, and ecological footprints associated with insect farming and incorporation into ruminant diets. Explore integrated systems that leverage insect farming for waste management and circular economy principles. (5) Consumer acceptance and market dynamics—research gap: limited understanding of consumer perceptions and acceptance of dairy products derived from ruminants-fed insect-based diets. Future direction: investigate consumer attitudes toward insect-fed dairy products, addressing concerns related to food safety, quality, and ethical considerations. Develop strategies to enhance market acceptance and promote the adoption of insect-derived feed in dairy production systems. (6) Regulatory framework and policy development—research gap: inadequate regulatory guidelines and policy frameworks governing the use of insects in ruminant nutrition. Future direction: collaborate with regulatory bodies to establish evidence-based standards for insect-derived feed safety and quality assurance. Advocate for policy changes that support the sustainable integration of insects into ruminant diets. (7) Innovative approaches and technology—research gap: limited exploration of innovative technologies and processing methods for optimizing insect-derived feed production and utilization in dairy systems. Future direction: explore novel approaches such as precision feeding, genetic selection for enhanced utilization of insect proteins, and advanced processing techniques to improve the efficiency and efficacy of insect-based ruminant nutrition. Research should explore different insect species and their processing methods to optimize nutrient bioavailability and ensure feed safety. Comparative studies between fresh, dried, and processed insects can provide valuable insights. Addressing these research gaps and advancing future directions will facilitate the broader adoption of insect-derived feed in ruminant nutrition, promoting sustainability, efficiency, and resilience in dairy production systems; especially for neonatal calves, particularly those with underdeveloped rumens, the abomasum assumes paramount importance. The abomasum comprises 60–70% of the calf’s stomach capacity and secretes gastric juices rich in hydrochloric acid and digestive enzymes. These enzymes facilitate the breakdown of proteins, fats, and carbohydrates in the ingested feed, whether insects or other nutrients, into simpler forms readily absorbed by the calf’s body.

Recent data confirm the feasibility of integrating insects into ruminant diets, showing predominantly positive effects on growth performance, ruminal fermentation indices, and methane mitigation. However, the absence of global uniformity in insect products highlights the need for attention and standardization. To optimize the efficiency of insect and ruminant production, comprehensive assessments of economically viable insect species should be prioritized in future studies. Moreover, (1) environmental sustainability: using insects as feed aligns with sustainability goals by reducing reliance on conventional protein sources like soybean meal, which are resource-intensive and contribute to environmental degradation. Insects have a lower ecological footprint and can be produced using organic waste streams. (2) Improved feed efficiency: Insect-derived feeds offer opportunities to optimize feed efficiency in ruminants, potentially enhancing animal performance and productivity; nevertheless, the expenses associated with feed must be tackled. (3) Consumer acceptance and market trends: despite initial consumer reservations, there is growing interest in insect-fed dairy products due to their sustainability credentials and nutritional benefits. Dairy producers can leverage this trend to diversify product offerings and capture niche markets. (4) Research and development: continued research is needed to address knowledge gaps related to nutrient requirements, feed formulation, long-term health effects, and market dynamics surrounding insect-based ruminant nutrition. (5) Policy and regulatory considerations: policymakers and industry stakeholders should collaborate to establish clear guidelines and regulations governing the use of insects in ruminant diets, ensuring food safety and quality standards are met. Adopting insect-based feed strategies holds significant promise for enhancing ruminant nutrition and advancing environmental sustainability in dairy production. Dairy producers can benefit from diversifying feed sources, reducing reliance on traditional protein sources, and improving overall feed efficiency. Researchers should prioritize studies to optimize insect-derived feed formulations and assess their long-term impacts on ruminant health and performance. Policymakers and industry stakeholders play a crucial role in facilitating the adoption of insect-based feed by establishing supportive regulatory frameworks and promoting consumer acceptance. By embracing insect-based nutrition, the dairy industry can contribute to a more sustainable and resilient agricultural future.