Nutritional value of suckler beef from temperate pasture systems

Abstract

The role of beef in human diets has been questioned over the last few decades, due largely to its typically high mass-based carbon footprint. However, recent advancements in sustainability literature challenge this paradigm based on the new theory that climate impacts of food commodities should be measured relative to their overall nutritional value rather than their nominal mass. This shift has opened a new opportunity for the global beef industry, and especially for pasture-based systems that can avoid food-feed competition for land and other resources, as beef is a nutritionally dense food. Nonetheless, the sector’s true capability to supply a wide range of nutrients for humans, consistently across multiple systems under multiple weather patterns, has not been well-documented. Using whole-system datasets from the North Wyke Farm Platform in the South West of England, we investigated the nutritional value of beef produced from the three most common pasture systems in temperate regions: permanent pasture ( PP ), grass and white clover ( GWC ) and a short-term monoculture grass ley ( MG ). Beef produced from these three pasture systems was analysed for key nutrients (fatty acids, minerals and vitamin E) over three production cycles (2015–2017) to determine potential differences between systems. Fatty acid, mineral and vitamin E profiles of the pasture and silage fed to each group were also assessed, with subtle differences between pastures reported. For beef, subtle differences were also observed between systems, with GWC having higher omega-6 polyunsaturated fatty acid ( PUFA ) concentrations than PP and MG. However, the overall nutritional quality of beef was found to be largely comparable across all systems, suggesting that temperate pasture-based beef can be classified as a single commodity in future sustainability assessments, regardless of specific sward types. A 100 g serving of temperate pasture-based beef was found to be a high source (>20% recommended daily intake: RDI ) of protein, monounsaturated fatty acids, saturated fatty acids, vitamins – B2, B3, B12 and minerals – Fe, P, Zn; a good source (10–19% RDI) of vitamin – B6 and mineral – K; and a complementary source (5–9% RDI) of omega-3 PUFA, vitamin – B9 and minerals – Cu, Mg, Se. The nutritional value of a food item should be used in defining its environmental cost (e.g. carbon footprint) to make fair comparisons across different food groups (e.g. protein sources). Here, we showed that pasture-based beef had a nutrient indexed carbon footprint of between 0.19 and 0.23 Kg CO2-eq/1% RDI of key nutrients.

Nutritional Benefits from Fatty Acids in Organic and Grass-Fed Beef

“…This pattern indicates that when cattle are typically fed diets with more n -6 (i.e., intensive growing/finishing feeding systems), there will be a much greater decrease in the n -6: n -3 ratio when switching (or comparing) to pasture-fed beef, thus having more of an impact on the overall ratio consumed and potentially nutritional and health attributes of the meat. Interestingly, there do not appear to be major differences in meat FA profile from cattle grazing different sward types [ 129 ], further demonstrating that the majority of the benefit to meat FA profile comes from the partial or full replacement of grain with fresh, preferably grazed, pasture or forages.…”

Fatty Acid and Antioxidant Profile of Eggs from Pasture-Raised Hens Fed a Corn- and Soy-Free Diet and Supplemented with Grass-Fed Beef Suet and Liver

“…Further, vitamin K1 was only detected in the pasture-raised egg groups. Access to green vegetation, a source of vitamin K1, may contribute to this difference [ 75 ].…”

Protein quality as a complementary functional unit in life cycle assessment (LCA)

“…That said, our virtual experiment used pre-existing DIAAS values summarised by Adhikari et al (2022) and substantial uncertainties remain regarding protein quality adjustment as a useful amendment for nLCA. Further research is required in this area using either, ideally, direct IAA/DIAAS values from a supply-chain under consideration (which is highly difficult to achieve, but ongoing nonetheless, due to existing data limitations despite rapid growth in this area) or more up-to-date values indirectly linked to the food systems being analysed (McAuliffe et al 2020;Lee et al 2021a). Regardless of the approach adopted when using protein as a functional unit, it is worth bearing in mind that protein ratios (e.g., with fat or carbohydrate, respectively) differ greatly depending on Poore and Nemecek (2018a) for most products, the value used for wheat was unidentifiable (cereals were simply reported as 'variable protein'); as a result, we adopted the protein value from the same food commodity used in Table 1 which equated to 11.2% protein (USDA 2019; product code 08,144); however, the GWP value was transformed from bread to wheat and may therefore be slightly misaligned with primary processing into consumable wheat, though the protein content was not sensitive following a check with similar food items in USDA (2019) the cut of meat or section of plant being utilised (Table 3), and average values often do not represent the specific food item under consideration Franco et al 2010;Rice et al 2017.…”

“…It is also important to reflect that amino acids sourced from proteins are only one compilation of vital nutrients contained within these food items (Leroy et al 2022). Ideally, in future nLCAs, a wider nutrient density analysis (e.g., the NRF9.3 scoring system devised by Fulgoni et al 2009) should be performed to more robustly align environmental impact(s) to the wider functionality of foods (i.e., to provide complete nutrition; Lee et al 2021a). Even then, food items are not consumed in isolation but as part of a diet and, perhaps more importantly in the current context, a meal due to reasons outlined in Section 1 (i.e., the rapid uptake and excretion of IAAs/proteins).…”