Effects of including white clover and plantain species in perennial ryegrass pastures on qualitative indicators and metabolome of milk

Background Cows can typically utilise only 10?30% of dietary nitrogen, with the rest excreted in urine and faeces, contributing to nitrate leaching and ammonia volatilisation. There is increasing desire to incorporate multispecies sward pastures into dairy systems to improve diversity and sustainability of primary production and to improve N use efficiency. Aim The objective of this study was to explore the effects of including white clover (WC) and plantain grass species with perennial ryegrass (PRG) pasture systems on milk composition and quality. Methods Nine rumen-cannulated cows were randomly allocated to one of three dietary treatments in a Latin square design. The dietary treatments consisted of PRG only receiving 50?kg of inorganic N/ha (GO), a combination of PRG and WC receiving 25?kg of inorganic N/ha (GC), and a combination of GC and plantain receiving 25?kg of inorganic N/ha (GCP). Milk samples were collected and analysed for milk composition, milk metabolomics, fatty acids and techno-functional properties, including rennet gelation and heat stability. Major Findings The inclusion of plantain or WC grass species had a significant effect on milk composition, particularly for nonprotein nitrogen (NPN) and fat content, both of which were present in higher concentration in milk of cows fed GO compared with GCP. Of the 42 metabolites and 22 FA identified, three metabolites and seven FA were significantly influenced by dietary treatments according to the mixed effect model. Furthermore, receiver operating characteristics analysis highlighted three metabolites and eight FA as potential biomarkers to distinguish between dietary treatments [area under curve (AUC) value >0.7]. Dietary treatment did not have a significant effect on the functional properties of milk. Scientific and Industrial Implications The inclusion of these pastures did not appear to have any negative effects on milk composition or functionality, offering confidence for their further adoption in the future.