# Positive Emotional States in Dairy Cows: Reflections in Milk Quality and Udder Health

## TL;DR

Dairy cows in better emotional states produce higher quality milk with better udder health, suggesting emotional well-being affects milk composition.

## Contribution

This study links positive emotional states in dairy cows to specific milk quality and udder health biomarkers using a behavior-based index.

## Key findings

- Higher positive emotional states correlate with lower somatic cell counts, indicating better udder health.
- Positive affect is associated with higher lactose levels and a better fat-to-protein ratio in milk.
- Milk yield tends to increase slightly with positive emotional states, though protein content is slightly diluted.

## Abstract

This study explored how the emotional state of dairy cows relates to milk quality and udder health under real farm conditions. Using a behaviour-based Positive Affect Index (PAI) derived from the Qualitative Behaviour Assessment (QBA), we evaluated 37 commercial dairy herds in Romania. The results showed that herds with more positive emotional states had lower somatic cell counts, indicating better udder health, and higher lactose levels, reflecting stable milk secretion. These herds also tended to produce slightly more milk, with only minor dilution effects on protein content. Overall, the findings suggest that the emotional well-being of cows is biologically reflected in their milk. Integrating QBA-derived indicators with routine milk biomarkers could provide a practical, non-invasive way to monitor and promote positive welfare within precision dairy management systems.

Integrating positive welfare indicators into dairy science is gaining attention, yet the biological correlates of affective states in commercial herds remain poorly understood. This study explored associations between dairy cows’ emotional states quantified through the Positive Affect Index (PAI) derived from the Qualitative Behaviour (QBA) Assessment and milk biomarkers, yield, and udder health indicators across 37 commercial farms. Descriptive statistics, housing-adjusted linear regressions, and partial Spearman correlations were used to explore these relationships. Higher PAI values, indicating more positive herd-level emotional states, were significantly associated with lower SCC (22% reduction, p = 0.016) and lower odds of elevated DSCC (OR = 0.69, p = 0.002), reflecting improved udder health. Positive affect was also linked to a higher lactose concentration (p < 0.001) and an increased fat-to-protein ratio (FPR). A tendency for higher milk yield (+1.07 L per milking, p = 0.077) and slightly lower protein content was observed, consistent with a dilution effect. These associations remained robust after sensitivity analyses and were independent of housing type. The results demonstrate that milk composition and udder health biologically reflect positive emotional states, supporting the integration of behavioural assessments and milk biomarkers as a non-invasive framework for advancing welfare-oriented and precision dairy farming.