In vitro evaluation of graded level of Silkworm pupae (Bombyx mori) oil on methane production, fermentation characteristics, and protozoal populations

Abstract

<jats:p>Aim: The present study was undertaken to evaluate the effect of variable levels of silkworm pupae oil and roughage: concentrate ratio on in vitro methane production, fermentation characteristics, and rumen protozoa population. Materials and Methods: In vitro gas production study (24 h) was performed with graded levels of silkworm pupae oil, namely, 0.5, 1, 2, 4, and 5% of the basal diet and four variable dietary regimes consisting roughage and concentrate in different proportions (70:30, 60:40, 50:50, and 40:60). At the end of incubation, gas samples were analyzed for methane, while fermented rumen liquor was used for protozoa enumeration. A separate set of incubations was carried out for the determination of in vitro dry matter digestibility. Results: Results from the in vitro studies revealed no adverse impact of the silkworm pupae oil supplementation up to 2% level on total gas production. However, supplementation beyond 2% has shown a reduction in total gas production. Incubation with variable levels (0.5-5%) of silkworm pupae oil with different dietary regimes indicated negligible (3-5%) to a substantial reduction (25-30%) on methane production. A graded decrement in methane production was recorded with increasing levels of silkworm pupae oil. Similarly, the protozoal populations were decreased from 10 to 51.5% with graded levels of silkworm pupae oil in different dietary regimes as studies did not reveal any significant (p&gt;0.05) variation between 2 and 4% of oil supplementation. Conclusion: The silkworm pupae oil supplementation at 2% level decreases methane production by 12-15% without any adverse impact on feed fermentation. Oil supplementation may have a more pronounced effect on methane reduction if added to high roughage diet at in vitro conditions. However, in vivo, studies in ruminants are warranted to confirm the methane reduction with silkworm pupae oil supplementation.</jats:p>

Are insects a solution for feeding ruminants? Legislation, scientific evidence, and future challenges

“…Despite an unexpected increase in ammonia concentration and protozoa population counts in rumen fluid, H. illucens oil decreased methanogenesis in a dose-dependent manner, with significant effects with inclusion levels equal or higher than 4%. The same general trend was also reported by Thirumalaisamy et al (2020) , using increasing levels of B. mori oil (0.5–5% diet), and in a previous study by Jayanegara et al (2020) , who tested the in vitro effects of the addition of 5% of insect oils with different unsaturation degree (species of origin are reported in Table 1 ). Interestingly, Thirumalaisamy et al (2020) showed stronger antimethanogenic effects in high-forage substrates, whereas Jayanegara et al (2020) reported no interaction between effect of insect oil and basal diet composition (70:30 or 30:70 F:C ratio) on enteric methane production.…”

“…The same general trend was also reported by Thirumalaisamy et al (2020) , using increasing levels of B. mori oil (0.5–5% diet), and in a previous study by Jayanegara et al (2020) , who tested the in vitro effects of the addition of 5% of insect oils with different unsaturation degree (species of origin are reported in Table 1 ). Interestingly, Thirumalaisamy et al (2020) showed stronger antimethanogenic effects in high-forage substrates, whereas Jayanegara et al (2020) reported no interaction between effect of insect oil and basal diet composition (70:30 or 30:70 F:C ratio) on enteric methane production. Overall, these studies suggest a promising potential to alleviate this energy loss and decrease the environmental impact of livestock.…”