Abstract

The production of a dairy herd was simulated at two different stocking rates (3.4 cows/ha and 4.0 cows/ha) and two seasonal conditions (an average and a dry Waikato summer). Cows were milked twice-daily (TDM) for varying periods, before being switched to once-daily milking (ODM) for the remainder of the lactation. Switching from TDM to ODM during the milking season reduced the total production of the herd. With 3.4 cows/ha in an average summer, at a break-even value of labour of $100 /milking ($200 /milking) the optimum switch-over date was January 13 (October 21); a dry season brought forward this date by approximately two weeks. Increasing payout increased the break-even value of labour at a given switch-over date. Under a commonly used farmer industry guideline, break-even labour values under average (dry) conditions were $53.47 /milking ($61.47) for 3.4 cows/ha and $36.07 /milking ($33.98) at 4.0 cows/ha. A stocking rate of 4.0 cows/ha switching to ODM after peak production had a lower cash surplus than a 3.4 cows/ha stocking rate with TDM due to additional ($30,000) feed costs with the higher stocking rate. These results suggest a formal approach could be used to complement industry guidelines in deciding when to switch from TDM to ODM.

VCF, Westbrooke, AE Dooley, and I Vetharaniam

Proceedings of the New Zealand Society of Animal Production, Volume 63, Queenstown, 133-137, 2003