# Evaluating the impact of milk sample-based pregnancy test procedures on milk production and daily time budgets of dairy cows

## TL;DR

Using milk samples for pregnancy testing in cows increases milk production and activity while reducing rest time, potentially improving cow welfare.

## Contribution

This study demonstrates that milk-based pregnancy testing improves productivity and alters cow behavior compared to traditional methods.

## Key findings

- Milk sample-based testing increased daily milk yield by 0.45 kg on testing days.
- Testing procedures led to higher step counts and more frequent lying bouts in cows.
- Lying bout durations were shorter for cows undergoing milk-based testing.

## Abstract

Summary: Milk sample-based pregnancy testing procedures (SBPT) increased daily milk yield and cow activity, as evidenced by greater step counts and more frequent lying bouts. These procedures also reduced lying bout duration, suggesting altered rest behavior. Findings support the utility of milk-based testing procedures in enhancing productivity and cow welfare by reducing cow restraint time. CON = control.

Summary: Milk sample-based pregnancy testing procedures (SBPT) increased daily milk yield and cow activity, as evidenced by greater step counts and more frequent lying bouts. These procedures also reduced lying bout duration, suggesting altered rest behavior. Findings support the utility of milk-based testing procedures in enhancing productivity and cow welfare by reducing cow restraint time. CON = control.

•Milk sample-based pregnancy testing procedures increased daily milk production.•Milk sample-based pregnancy testing procedures increased daily step count and lying bout frequencies.•Milk sample-based pregnancy testing procedures decreased daily lying bout duration.

Milk sample-based pregnancy testing procedures increased daily milk production.

Milk sample-based pregnancy testing procedures increased daily step count and lying bout frequencies.

Milk sample-based pregnancy testing procedures decreased daily lying bout duration.

Prolonged restraint of dairy cows during pregnancy diagnosis in headlocks can elicit stress responses, potentially compromising animal welfare and productivity. Sample-based pregnancy testing (SBPT) utilizing milk samples obtained at the milking parlor eliminates the necessity for prolonged headlock restraint. The objective of this study was to evaluate the effects of implementing SBPT procedures in commercial dairy farms by assessing milk production and daily time budgets of cows compared with traditional pregnancy testing methods. An experiment was conducted at a USDA-certified organic dairy farm using a repeated crossover design with treatment (TRT: SBPT) and control (CON: transrectal ultrasound) groups in 3 pens over 6 periods. Cows in the TRT group were subjected to IDEXX milk SBPT in the milking parlor, whereas those in the CON group underwent transrectal ultrasound in headlocks for pregnancy diagnosis by a trained veterinarian. Daily milk yield from individual cows was recorded by inline milk meters, and lying behaviors and step counts were recorded using leg-based accelerometers. On the day of the pregnancy test, TRT cows exhibited a 0.45 kg higher milk yield compared with CON cows. Milk yield increased by 1.13 kg on the day after testing and by 0.53 kg per day weekly average in TRT cows. The TRT cows displayed higher daily step counts and lying bout frequencies, but shorter lying bout durations on testing days, although total lying time did not differ significantly between groups. These results suggest that SBPT procedures may facilitate reduced restraint time, leading to improved milk production and altered daily time budgets, thereby potentially reducing prolonged headlock-induced stress for a short term.