# Temporal Distribution of Milking Events in a Dairy Herd with an Automatic Milking System

## TL;DR

This study examines how dairy cows using automatic milking systems choose when to be milked, finding consistent patterns influenced by lactation stage, age, and milk yield.

## Contribution

The study provides detailed insights into how individual and seasonal factors affect milking behavior in automatic milking systems.

## Key findings

- Milking frequency peaks in the early morning and afternoon, with variations based on lactation stage and milk yield.
- Primiparous and high-yielding cows show higher milking frequency and extended activity into the night.
- Seasonal and individual factors influence milking frequency but not the overall daily pattern.

## Abstract

Automatic milking systems (AMSs) give cows the freedom to choose when to be milked, but their milking behavior often follows consistent patterns influenced by biological and management factors. In this study, we analyzed over 94,000 milking events from 130 cows over one year on a Brazilian dairy farm using AMSs. Milking frequency (MF) followed a clear daily pattern, with most milkings occurring in the early morning (4:00 to 11:00 a.m.) and afternoon (2:00 to 6:00 p.m.). Although this pattern remained consistent, its intensity varied according to individual and seasonal factors. Cows in early lactation (<106 days in milk) showed higher MF throughout the day, including during nighttime hours, averaging 3.00 milkings/day. Primiparous cows had the highest MF (2.84 milkings/day), with earlier morning activity compared to older cows. High-producing cows (≥45 L/day) maintained elevated MF from afternoon to night (2:00 p.m. up to 2:00 a.m.), averaging 3.09 milkings/day. These findings highlight that, while AMS offers voluntary access, cow behavior is still influenced by lactation stage, parity, and milk yield. Recognizing these patterns can help farmers optimize cow traffic, feeding strategies, and robot efficiency in AMS-managed herds.

This study aimed to evaluate daily patterns of hourly milking frequency (MF) in dairy cows milked with an automatic milking system (AMSs), considering the effects of season, parity order (PO), days in milk (DIM), and milk yield (MY). A retrospective longitudinal study was conducted on a commercial dairy farm in southern Brazil over one year using data from 130 Holstein cows and 94,611 milking events. MF data were analyzed using general linear models. Overall, hourly MF followed a consistent daily pattern, with peaks between 4:00 and 11:00 a.m. and between 2:00 and 6:00 p.m., regardless of season, PO, DIM, or MY category. MF was higher in primiparous (2.84/day, p = 0.0013), early-lactation (<106 DIM; 3.00/day, p < 0.0001), and high-yielding cows (≥45 L/day; 3.09/day, p < 0.0001). High-yielding cows also showed sustained milking activity into the late nighttime. Although seasonal and individual factors significantly affected MF, they had limited influence on the overall daily distribution of milkings. These results suggest stable behavioral patterns within the specific AMS management conditions observed in this study and suggest that adjusting milking permissions and feeding strategies based on cow characteristics may improve system efficiency.