# Effects of Early Lactation Milking Frequency in an Automated Milking System on Cow Performance

## TL;DR

This study examines how milking frequency in automated systems affects milk production and metabolism in dairy cows during early lactation.

## Contribution

The study reveals that higher milking frequency in automated systems improves milk fat production but increases metabolic stress in mature cows.

## Key findings

- Cows milked six times daily produced more milk fat and had higher milk yield during the carryover phase.
- Six milkings per day altered milk fatty acid composition and increased metabolic stress indicators in mature cows.
- Mature cows milked more frequently showed signs of greater nutrient deficit and metabolic risk.

## Abstract

The increasing use of automated milking systems (AMS) in the dairy industry has led to the necessity for changes in management practices implemented by producers. This study investigated the productive and metabolic impact of three versus six milkings per day (MPD) during early lactation on multiparous Holstein cows managed in an AMS. Mature cows (third and greater parity) with six MPD had greater milk fat production during the experimental phase (4 to 29 days in milk; DIM) and milk production during the carryover phase (30 to 90 DIM) than mature three MPD cows. The composition of milk fatty acids differed between MPD groups with cows, with three MPD having greater short-, medium-, odd- and branched-chain fatty acids during the experimental phase compared to cows with six MPD. Based on greater blood fatty acid and β-hydroxybutyrate concentrations, the mature six MPD cows may have been in a greater postpartum nutrient deficit and at greater risk of metabolic illness. Our findings suggest a need to strategically manage the MPD or nutrition of mature, early lactation dairy cows in an AMS.

Automated milking systems (AMS) are increasingly adopted for dairy cow production, promoting individualized cow management dependent on factors like lactation stage, age, and productivity. The study objective was to investigate the effects of early lactation milking frequency on cows milked via AMS. Multiparous Holstein cows blocked by parity and due date were randomly assigned to treatments (n = 8 per treatment): three (3X) or six (6X) milkings per day (MPD). The experimental phase (EXP) was defined as 4 to 29 days in milk (DIM). The AMS settings were programed so 3X cows were limited to three MPD while 6X cows were allowed six MPD. Afterwards was the carry over phase (CO) ranging from 30 to 90 DIM; all cows were allowed up to six MPD. Measurements by the AMS included bodyweight, milk yield (MY), and pellet intake. Weekly composite milk samples were analyzed for macronutrient composition and fatty acid (FA) profile. Coccygeal blood was sampled at 3, 8 ± 1, and 13 ± 1 DIM; concentrations of blood plasma analytes were quantified. Greater MPD was achieved for 6X cows versus 3X cows during EXP, but similar during the CO. Daily MY was non-separable during the EXP while 6X cows in their third or greater lactation group (3 + LG) had greater MY than 3X cows of the same LG during the CO. Milk fat content and 4% fat-corrected MY were both greater for 6X, 3 + LG cows during the EXP compared to 3X, 3 + LG cows. Milk FA methyl esters (FAME) proportions were different between MPD groups, with 6X, 3 + LG cows having the lowest short, even-chain FA from de novo or post-absorptive origin. Differences in analytes indicated that 6X, 3 + LG cows experienced metabolic stress and incorporated greater FA from adipose tissue. Greater early lactation MPD in AMS may shift cow nutrient partitioning to support greater production in 3+ parity cows.