Upcycling post-harvest biomass residues from native European Lupinus species: from straws and pod shells production to nutritive value and alkaloids content for ruminant animals

Lupin Seed Supplementation as a Functional Feed Additive: In Vitro Ruminal Gas, Methane and Carbon Dioxide Production, Fermentation Kinetics, and Nutrient Degradability

The inevitable enteric gas emission from ruminants is considered a modern-day problem from an environmental perspective. Addressing this problem requires nutritional approaches such as the use of phytogenic additives in ruminant diets. In this regard, lupin seed (LS) can be a useful additive due to its phytochemical constituents. Therefore, this study investigated the effects of lupin (Lupinus angustifolius) seed supplementation as a functional and sustainable feed additive in sheep diet (50:50 concentrate-to-forage ratio) on in vitro gas production (GP; mL/g DM), methane (CH4; mL/g DM) and carbon dioxide (CO2; mL/g DM) emissions, fermentation parameters, and nutrient degradability (g/kg DM incubated). Gas production and CH4 were measured per gram of incubated dry matter (DM), degradable DM (dDM), degradable neutral detergent fiber (dNDF), and degradable acid detergent fiber (dADF). Lupin seeds were included at 0 (control), 0.5, 1.0, 1.5, and 2% of the diet. The seeds contained 3.27% essential oils (DM basis), with eucalyptol as the main phytochemical. The highest GP per gram of DM and dDM was observed (p < 0.01) with 2.0% LS supplementation level. While 1.0% LS had the highest GP per gram of dNDF, 0.5% lupin diet had the highest GP per gram of dADF. Asymptotic GP and CH4 emissions linearly and quadratically increased (p < 0.01) with increasing LS level, while lag time decreased. Despite increased CH4 production, the proportion of CH4 in total biogas was lower (p = 0.008) for LS treatments than the control, with the 0.5% LS showing the lowest CH4 proportion. Production of CO2 increased with lupin seed treatments, with 0.5% LS producing the highest proportion (p = 0.027). Degradability of DM, NDF, and ADF was greater (p < 0.01) for the high LS supplementation level, while 0.5% supplementation level decreased ADF degradability. Total short-chain fatty acids, acetic acid, and propionic acid increased (p < 0.05) with LS supplementation level, leading to a reduced acetate:propionate ratio. Rumen pH decreased (p = 0.036) with LS supplementation, while ammonia-N decreased (p = 0.045) and estimated metabolizable energy increased (p < 0.001) linearly. Calculated microbial protein synthesis (p = 0.005) and gas yield (p = 0.047) increased with LS supplementation level. LS supplementation at 2.0% of diet (DM basis) increased GP and CH4 emission (mL/g DM) and enhanced nutrient degradability, suggesting its potential use as a functional feed additive for ruminants when supplemented at a 2.0% level into diet.

Environmental conditions affect the nutritive value and alkaloid profiles of Lupinus forage: Opportunities and threats for sustainable ruminant systems

The identification of crops that simultaneously contribute to the global protein supply and mitigate the effects of climate change is an urgent matter. Lupins are well adapted to nutrient-poor or contaminated soils, tolerate various abiotic stresses, and present relevant traits for acting as ecosystem engineers. Lupins are best studied for their seeds, but their full foraging potential needs further evaluation. This study evaluated the effects of location and sowing date on forage production, proximate composition, and the detailed mineral and alkaloid profiles of three species of Lupinus (L. albus cv. Estoril, L. angustifolius cv. Tango, and L. luteus cv. Cardiga). Sowing date and location and their interaction with the plant species significantly affected the vast majority of measured parameters, emphasizing the effects of climate and soil conditions on these crops. The relatively high crude protein and in vitro digestibility support the potential of the lupin species studied as sustainable forage protein sources in diets for ruminant animals. The content of individual essential macro and trace elements was below the maximum tolerable levels for cattle and sheep. Lupanine, smipine, and sparteine were the most abundant quinolizidine alkaloids in L. albus cv. Estoril, lupanine, and sparteine in L. angustifolius cv. Tango, and lupinine, gramine, ammodendrine, and sparteine in L. luteus cv. Cardiga. Based on the maximum tolerable levels of total quinolizidine alkaloid intake, the dietary inclusion of forages of L. albus cv. Estoril and L. angustifolius cv. Tango does not pose a risk to the animals, but the high alkaloid content of L. luteus cv. Cardiga may compromise its utilization at high levels in the diet. Overall, the results reveal a high potential for lupins as protein forage sources well adapted to temperate regions and soils with lower fertility, with a relevant impact on livestock sustainability in a climate change era.