Abstract

Extended lactations (EL) can potentially improve labour efficiency, reduce numbers of non-replacement calves, and reduce cow attrition. A 2023-24 farmlet study compared an EL system whereby half of the cows calved each spring with approximately 24-month calving intervals versus a Control system where all cows calved each spring with approximately 12-month intervals. The EL system produced more milksolids (MS) than Control (1,231 versus 1,182 kg/ha, respectively) from more days in milk (average of 308 across the two herds versus 251 days per cow, respectively) while consuming more supplementary feed (818 versus 621 kg DM/cow, respectively). Cows in EL produced on average 370 kg MS/cow over 304 days of lactation during the season, from a total of 855 kg MS/cow produced over a 600-day lactation. This study has shown the potential viability of this EL system and the data can be used to evaluate impacts on profitability and the environment.

Farrell, L.J., Edwards J.P., Glassey C.B., Lopez-Moreno Y., Rauhala E, and Burke C.R.

Hamilton, Volume 85, Hamilton, 9-12, 2025