# NMR Profiling of Milk from Treated Dried off Cows

## TL;DR

This study used NMR to analyze milk metabolites in cows during dry-off and found that physiological stage, not treatment, mainly affects milk composition.

## Contribution

The study demonstrates that physiological changes during dry-off and peripartum periods strongly influence milk metabolite profiles, overshadowing treatment effects.

## Key findings

- Milk metabolite profiles varied significantly between pre-dry-off and post-calving stages.
- Aqueous extracts showed higher choline and branched-chain amino acids pre-dry-off, while post-calving samples had higher saccharides and citrate.
- Organic extracts at pre-dry-off had higher conjugated linoleic acids and caproleic acid.

## Abstract

The milk metabolite profiles of dairy cows during the dry-off and peripartum periods were investigated using 1H NMR combined with chemometric analysis to evaluate the effects of different dry-off management strategies. Milk samples were collected 14 days before dry-off (T0) and 28 days after calving (T1) from cows receiving an internal teat sealant combined with intramammary antibiotics (CTR), an internal teat sealant alone (SIG), or an internal teat sealant associated with dietary supplementation of lyophilized Aloe arborescens (ASIG). Analysis of both aqueous and organic milk extracts revealed no significant metabolite differences among treatment groups. In contrast, a clear discrimination was detected between samples collected at T0 and T1. Aqueous extracts at T0 were characterized by higher levels of choline, butyrate, branched-chain amino acids, and N-acetylated compounds, whereas T1 samples exhibited higher levels of saccharides, citrate, phosphorylcholine, and galactose-1-phosphate. Organic extracts at T0 showed higher concentrations of conjugated linoleic acids (CLAs) and caproleic acid. These findings indicated that the physiological stage of the cows had a more pronounced impact on milk metabolite composition than the dry-off treatments, with no detrimental effects on milk composition or overall metabolite balance.