# Herd Dominance Influences Dairy Cows’ Use of Heat Abatement Resources in a Silvopastoral System

## TL;DR

This study shows that dominant dairy cows use shade more often, while subordinate cows rely more on water to cope with heat, highlighting the need for varied heat abatement resources.

## Contribution

The study reveals how social hierarchy affects cows' use of heat abatement resources in a silvopastoral system.

## Key findings

- Dominant cows used shaded areas more frequently than subordinate and intermediate cows.
- Subordinate and intermediate cows visited water troughs more often, especially during peak heat.
- Social rank and time of day influenced behaviors in shaded areas, with dominant cows more likely to lie down.

## Abstract

In this study, we investigated how the social category of cows within a herd can influence their use of shade and water, two important resources for coping with heat. We observed 39 Jersey cows in a pasture-based system with access to natural shade and water. Dominant cows used the shaded areas more often, while subordinate and intermediate cows visited the water trough more frequently. These findings suggest that social relationships among animals directly affect their thermal comfort, especially during hot periods. This study highlights the importance of providing ad libitum access to heat abatement resources to improve the thermal comfort of the herd. These results can encourage farmers to adopt more effective management practices that promote animal welfare in different production systems.

The social category of dairy cows within a herd may influence their access to essential heat abatement resources. We evaluated how dominant, intermediate, and subordinate cows used shade and water in a silvopastoral system. Thirty-nine lactating Jersey cows were observed in a replicated study. Cows had unrestricted access to natural shade and a water trough. Microclimatic conditions and cow behaviors were recorded, and social rank was determined. Sunny areas promoted potential thermal discomfort for the cows, with higher heat load (on average 580.7 W/m2) than shaded areas (on average 438.6 W/m2). Intermediate (IRR: 2.07) and subordinate (IRR: 1.63) cows were more likely (p < 0.001) to visit the water trough than dominant cows. The odds of drinking water decreased by 13% (p < 0.001) for each hour that passed throughout the day. In contrast, the odds of using shaded areas increased by 7% (p < 0.001) for each increase in hour unit. Although all cows used the shaded areas at some point, they generally spent more time standing than lying down in the shade. Social category and hour influenced (p < 0.001) the behaviors in the shaded areas, with dominant cows more likely to engage in lying behaviors such as idling and rumination. In conclusion, our study demonstrated that cows’ social category and thermal environment influenced the use of shade and drinking water. Although the overall pattern of resource use increased with rising thermal load, the proportion of use varied according to social category. Ensuring multiple or alternative resources may help meet the needs of cows across social ranks and improve thermal comfort during heat stress periods.