The nutritional value of meat is an increasingly important factor influencing consumer preferences for poultry, red meat and processed meat products. Intramuscular fat content and composition, in addition to high quality protein, trace minerals and vitamins are important determinants of nutritional value. Fat content of meat at retail has decreased substantially over the past 40 years through advances in animal genetics, nutrition and management and changes in processing techniques. Evidence of the association between diet and the incidence of human non-communicable diseases has driven an interest in developing production systems for lowering total SFA and trans fatty acid (TFA) content and enrichment of n-3 PUFA concentrations in meat and meat products. Typically, poultry and pork has a lower fat content, containing higher PUFA and lower TFA concentrations than lamb or beef. Animal genetics, nutrition and maturity, coupled with their rumen microbiome, are the main factors influencing tissue lipid content and relative proportions of SFA, MUFA and PUFA. Altering the fatty acid (FA) profile of lamb and beef is determined to a large extent by extensive plant and microbial lipolysis and subsequent microbial biohydrogenation of dietary lipid in the rumen, and one of the major reasons explaining the differences in lipid composition of meat from monogastrics and ruminants. Nutritional strategies can be used to align the fat content and FA composition of poultry, pork, lamb and beef with Public Health Guidelines for lowering the social and economic burden of chronic disease.

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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.

Fatty acid (FA) concentration and composition of forage has recently gained interest due to potential opportunities for improving FA profile of ruminant products (meat and milk). Twenty perennial ryegrass genotypes from an experimental breeding population and four genotypes from an experimental mapping population were used to assess (1) genotypic variation, and (2) associations between FAs and other important chemical constituents (i.e., protein, carbohydrate and fibre). Mean total FA (TFA) concentration was 23.8 g kg−1 DM, ranging from 14.5 to 33.8 g kg−1 DM; 89% to 95% of which was comprised of six individual FAs, namely, palmitic acid (C16:0), trans-3-hexadecenoic acid (C16:1Δt3), stearic acid (C18:0), oleic acid (C18:1Δc9), linoleic acid (C18:2Δc9,12) and α-linolenic acid (C18:3Δc9,12,15). Mean crude protein (CP), water-soluble carbohydrate (WSC), neutral detergent fibre (NDF) and acid detergent fibre (ADF) concentrations were: 133, 188, 447 and 240 g kg−1 DM, respectively. Genotypes from the mapping population differed for: WSC (p = 0.015), C16:0 (p = 0.034), C18:0 (p < 0.001), C18:3Δc9,12,15 (p = 0.012) and TFA (p = 0.025). Genotypes from the breeding population differed (p < 0.001) for all measured components except CP (p = 0.078). Higher FA concentration was generally associated with higher CP concentration and lower WSC, NDF and ADF. Selectively breeding for higher FA concentrations may alter the overall feed value of perennial ryegrass, however further investigation is needed to fully understand the relationship between FA concentration and feed value and the possible implications for ruminant nutrition.