There is a growing awareness that fostering the transition toward plant-based diets with reduced meat consumption levels is essential to alleviating the detrimental impacts of the food system on the planet and to improving human health and animal welfare. The reduction in average meat intake may be reached via many possible ways, one possibility being the increased consumption of plant-based meat alternatives (PBMAs). For this reason, in recent years, hundreds of products have been launched on the market with sensory attributes (i.e., taste, texture, appearance, and smell) similar to their animal counterparts; however, these products have often a long list of ingredients and their nutritional values are very different from animal meat. The present review aims to highlight the main opportunities and challenges related to the production and consumption of PBMAs through an interdisciplinary approach. Aspects related to the production technology, nutritional profiles, potential impacts on health and the environment, and the current market and consumer acceptance of PBMAs are discussed. Focusing on the growing literature on this topic, this review will also highlight research gaps related to PBMAs that should be considered in the future, possibly through the collaboration of different stakeholders that can support the transition toward sustainable plant-based diets.

The utilization of animal donors of rumen fluid for laboratory experiments can raise ethical concerns, and alternatives to the collection of rumen fluids from live animals are urgently requested. The aim of this study was to compare the fresh rumen fluid (collected at slaughter, W) with that obtained from a continuous fermenter (RCF) and three methods of rumen fluid preservation (refrigeration, R, chilling, C, and freeze-drying, FD). The fermentability of different inoculum was evaluated by three in vitro tests (neutral detergent fiber (NDF) and crude protein (CP) degradability and gas production, NDFd, RDP and GP, respectively) using six feeds as substrates. Despite the two types of inoculum differed in terms of metabolites and microbiota concentration, the differences in vitro fermentability between the two liquids were less pronounced than expected (−15 and 20% for NDFd and GP when the liquid of fermenter was used and no differences for RDP). Within each in vitro test, the data obtained from rumen and from fermenter liquids were highly correlated for the six feeds, as well as between W and R (r: 0.837–0.985; p < 0.01). The low fermentative capacity was found for C and, particularly, FD for liquids. RCF could be used to generate inoculum for in vitro purposes and short-term refrigeration is a valuable practice to manage inoculum.

The environmental impacts of the dairy industry, particularly global warming, are heavily influenced by milk production. Thus, there is an urgent need for farm-level actions and opportunities for improvement, implying mitigation strategies. The aim of this paper is to investigate five possible mitigation actions at the dairy farm and which one the farmers were willing to adopt: management and distribution of livestock manure and fertilizers, anaerobic manure treatment, optimization of the herd composition, feed quality, and heat recovery. A life cycle assessment was conducted on 63 farms using the product environmental footprint approach. The latter was divided into four quartiles, from which four representative farms were selected. For each farm, three scenarios have been analyzed considering the reference impact (reference scenario), the application of the mitigation actions (best-case scenario), and what farmers would implement (realistic scenario). Overall, the most effective mitigation actions in the best-case scenario were anaerobic manure treatment and the management and distribution of livestock manure and fertilizers, showing a potential reduction in total environmental impacts of 7–9% and 6–7%, respectively. Farmers’ responses indicated a willingness to implement the latter mitigation strategy better. The optimization of the herd composition, feed quality, and heat recovery reported a range impact reduction between 0.01–5%.

An estimate of the environmental impact of dairy farms in Northern Italy producing milk for hard cheese (protected designation of origin) has been obtained through a comprehensive life cycle assessment. The estimate focused on climate change (CC) and photochemical ozone creation potential (POCP) indicators, which were evaluated according to the Intergovernmental Panel on Climate Change (IPCC) guidelines and interpreted with the aid of the feeds’ composition evaluated using near-infrared reflectance spectroscopy (Foss NIR-System 5000) as well as with a diet evaluation according to the NRC (National Research Council) or the CNCPS (Cornell Net Carbohydrate and Protein System) nutrient requirement modeling. Herds were classified into high-, mid-, and low-performing based on the daily milk yield per cow. A lower impact on indicators was observed as herd performance increased. The high-performing herds had a lower contribution from enteric fermentation (6.30 × 10⁻¹ kgCO₂-eq), and the more milk that they produced allowed for a differentiation of CC from land use and transformation (2.39 × 10⁻¹ kgCO₂-eq), compared to low-performing herds (3.66 × 10⁻¹ kgCO₂-eq). Compared to the IPCC approach, the CC and POCP indicator estimates were reduced when addressing the feed’s quality, particularly in mid- and high-performing herds. The results could be helpful in the dairy sector as they provide an insight into how diet quality affects the environmental impact of milk.

The pursuit of alternative ingredients with improved environmental sustainability, nutritive value, and cost efficiency is crucial for modern pork production systems. Replacing soybean meals has the potential to reduce environmental impacts. This study proposes a substitution framework in which alternative ingredients are introduced to replace a growing proportion of soybean meals based on net energy equivalence. Additionally, an optimisation framework has been proposed that simultaneously addresses multiple objectives, including cost, feed weight, environmental impacts, and essential nutritional requirements. Eighteen feed mixes were obtained by introducing alternative ingredients selected from an extensive, if not systematic, literature review. Therefore, black soldier fly meal (BSF), bakery by-product (BP), and pea (P) have been introduced in feed mixes, and feed mixes were evaluated across ten environmental impact categories via a life cycle assessment (LCA) approach (ISO 14040-44), with two different functional units: 1 kg of feed mix and 1 kg of pig meat at the slaughterhouse. To assess the robustness of the optimised feed mixes under uncertainty, a cost and climate change sensitivity analysis was conducted. The results demonstrated that the introduction of BSF increased costs and environmental impacts at the single-score level (by 280% and 118%, respectively), with differences at the single-impact category level. In contrast, BP and P emerged as the most effective solutions in the substitution and optimisation approaches, respectively. BP contributed to a reduction in environmental impacts of up to 9% in optimised diets, while P achieved economic cost savings of up to 28% compared to the original diet. These findings highlighted the need to strike a balance between environmental benefits and financial viability, underscoring the importance of policy support and market incentives to make sustainable practices more accessible.

This study examined the effect of 3-nitrooxypropanol (3-NOP) on enteric GHG emissions, milk production, and the blood metabolic profile of lactating Holstein dairy cows across 2 experiments, one conducted during the summer and the other in fall. Thirty mid lactation multiparous cows, with an average (mean ± SD) of 190 ± 72 DIM and a milk yield of 36.8 ± 7.5 kg/d, were included in the summer experiment. In the fall experiment, cows averaged 158 ± 74 DIM and a milk yield of 36.8 ± 4.6 kg/d. Experiments were structured as longitudinal studies with repeated measurements in a completely randomized design, with an initial 14-d covariate period, a 63-d treatment period, and a 14-d washout period. Cows were randomly assigned to 1 of 2 treatment groups: (i) the control group (CTR), receiving a corn silage-based diet supplemented with a placebo, and (ii) the 3-NOP group, receiving the same diet supplemented with 60 mg/kg DM of 3-NOP. Cows were housed in a freestall barn, with individual monitoring of feed intake, and fed a TMR ad libitum delivered 1 time a day. The enteric CH₄, CO₂, and H₂ emissions were measured using a GreenFeed (C-Lock Inc.) unit. The 3-NOP reduced enteric CH₄ production (46%), yield (46%), and intensity (44%), regardless of the season, but increased H₂ and CO₂ emissions. In the summer, 3-NOP cows reduced DMI (5.7%) and meal size and increased the feed (4.8%) and dairy (4%) efficiencies but not in the fall. Adding 3-NOP increased the apparent OM, CP, and NDF digestibility, independently of the season. There was no effect of 3-NOP on milk yield, although supplementing 3-NOP increased the milk protein and casein and decreased milk urea contents. Saturated fatty acids (FA) increased with 3-NOP, regardless of the phase of the study. In the summer season, 3-NOP supplementation increased de novo FA (7.3%) and decreased mixed FA (6.7%), whereas in the fall, SFA decreased (2.3%) and MUFA increased (6.8%) compared with CTR. Supplementing 3-NOP affected the molar proportions of rumen VFA. Acetate was reduced, whereas butyrate, valerate, isovalerate, and caproate were increased by 3-NOP. Plasma concentrations of urea, nonesterified FA, Zn, and advanced oxidation protein products decreased with 3-NOP, but blood cholesterol and myeloperoxidase increased. In conclusion, including 3-NOP in a high corn-silage and high-starch diet almost halved enteric CH₄ emissions without adversely affecting milk yield and composition.