Comparison of milk production and herd characteristics in New Zealand herds milked once or twice a day

To attract and retain quality staff, dairy farming must be competitive with industries offering conventional work hours. Full-lactation once-a-day (OAD) milking can improve staff working conditions. The aim of the present study was to compare the characteristics of OAD herds relative to a peer group of herds milked twice-a-day (TAD). Data were sourced from the Dairy Industry Good Animal Database, pairing OAD and TAD herds within 25 km, 20% herd size, and 14 days of planned start of calving. Aggregated data from these herds were extracted for the dairy production years 2007-2008 through 2015-2016. In 2015-2016, 9% of all herds tested in New Zealand were milked full-lactation OAD. Results are presented from -4 to 4 years, with 0 as the year of switching to OAD. Results indicated that herds adopting full-lactation OAD milking experienced an 11% decrease in total farm milksolid (MS; fat kg + protein kg) production (kg MS/herd) in Year 0 but, by Year 3, the prior level of production was regained. However, OAD herds remained 11% behind their TAD peer group, due to both OAD and TAD herds increasing production at a rate of 2171 kg MS/year in Years 0-4. The annual herd replacement rate was 20% for both groups. Differences also included a higher 6-week calving rate (82% TAD, 87% OAD), and a divergence in herd breed, with an increase in Jersey and a decrease in Holstein-Friesian genetics for the OAD herds from Year -2. Cows in OAD herds were less likely to be removed due to not being pregnant, but more likely to be removed due to low production or udder health. Milking interval x year interactions were significant for milk volume and liveweight breeding values, with OAD herds having lower values at Year 4. The main conclusion is that to retain an equivalent level of profitability, farm expenditure must be permanently reduced on the adoption of OAD by the initial production decrease multiplied by the long-term milk price. Farmers considering OAD should evaluate the trade-off between the ability to decrease costs to offset any decreased production and impacts on labour and/or lifestyle.