Dietary and Animal Strategies to Reduce the Environmental Impact of Pastoral Dairy Systems Result in Altered Nutraceutical Profiles in Milk

Abstract

The objective of this study was to evaluate and provide further insights into how dairy cows genetically divergent for milk urea N breeding values [MUNBV, high (2.21 ± 0.21) vs. low (1.16 ± 0.21); µ ± SEM], consuming either fresh cut Plantain (Plantago lanceolata L., PL) or Ryegrass (Lolium perenne L., RG) herbage, impacted the nutraceutical profile of whole milk by investigating amino and fatty acid composition and applying metabolomic profiling techniques. Both diet and MUNBV, and their interaction term, were found to affect the relative abundance of alanine, glycine, histidine, and phenylalanine in the milk (p < 0.05), but their minor absolute differences (up to ~0.13%) would not be considered biologically relevant. Differences were also detected in the fatty acid profile based on MUNBV and diet (p < 0.05) with low MUNBV cows having a greater content of total unsaturated fatty acids (+16%) compared to high MUNBV cows and cows consuming PL having greater content of polyunsaturated fatty acids (+92%), omega 3 (+101%) and 6 (+113%) compared to RG. Differences in the metabolomic profile of the milk were also detected for both MUNBV and dietary treatments. Low MUNBV cows were found to have greater abundances of choline phosphate, phosphorylethanolamine, N-acetylglucosamine 1-phosphate, and 2-dimethylaminoethanol (p < 0.05). High MUNBV cows had a greater abundance of methionine sulfoxide, malate, 1,5-anhydroglucitol (1,5-AG), glycerate, arabitol/xylitol, 3-hydroxy-3-methylglutarate, 5-hydroxylysine and cystine (p < 0.05). Large differences (p < 0.05) were also detected as a result of diet with PL diets having greater abundances of the phytochemicals 4-acetylcatechol sulfate, 4-methylcatechol sulfate, and p-cresol glucuronide whilst RG diets had greater abundances of 2,6-dihydroxybenzoic acid, 2-acetamidophenol sulfate, and 2-hydroxyhippurate. The results of this study indicate the potential to alter the nutraceutical value of milk from dietary and genetic strategies that have been previously demonstrated to reduce environmental impact.

Implementing plantain (Plantago lanceolata) to mitigate the impact of grazing ruminants on nitrogen losses to the environment: A review

“…There were also small changes in branch‐chain and odd‐number carbon length fatty acids in milk fat reported by Mangwe et al (2018). Similar changes in milk fatty acids in response to feeding PL herbage have been reported by Marshall et al (2022b). Feeding PR‐red clover‐PL silage, with the latter at 35% inclusion in the stack, also resulted in a marked increase in the C18:3 fatty acid content of milk fat (>5‐fold relative to total mixed ration, TMR, Ineichen et al, 2019).…”

“…There was no impact of PL feeding on milk protein content apart from one report of a small increase which was associated with an increase in milk protein yield (Nkomboni et al, 2021). Marshall et al (2022b) also reported changes in multiple minor milk components (mostly intermediary metabolites) from cows fed PL vs. PR herbage.…”

“…Effects on C18:2 were much smaller. Marshall et al (2022b) also studied phytochemical content and noted multiple profile changes in response to feeding PL compared with PR, suggesting the potential for altering the nutraceutical value of milk.…”

Connecting plant, animal, and human health using untargeted metabolomics.

“…The question arises, are there ecological implications and connections between phytochemically diverse swards and the health of humans and soil (Provenza et al, 2019). If so, this expanded pool of nutrients, medicines, and prophylactics, known as plant secondary compounds, must be considered to understand the effects of consuming animal products on human health, as they have been reported to be concentrated in the meat and milk of livestock consuming those plants (Marshall et al, 2022;.…”