A quantitative case study assessment of the biophysical and economic effects of three different feed management systems in a Northland farmlet trial

A three-year farm-systems trial was conducted in Northland from 2018–2021 with three independent 28-ha farms: 1) PAST: 2.7 cows/ha, no imported feed; 2) PKE: 3.1 cows/ha, palm kernel to meet pasture deficits; 3) PKE-PLUS: 3.1 cows/ha, palm kernel plus other supplementary feeds to meet pasture deficits. On average, cows on the PKE-PLUS farm were fed more supplementary feed and produced more milksolids than cows in the PAST and PKE farms (1328, 916 and 1209 kg MS/ha, respectively). Due to large variability in climate, pasture grown, milk and feed prices, there was no significant difference in mean operating profit ($2,636, $3,053, and $2,939 for the PAST, PKE and PKE-PLUS farms, respectively). The PAST farm had least personnel and machinery hours, and lowest methane emissions per hectare (316, 386 and 412 kg methane/ha, for PAST, PKE and PKE-PLUS, respectively). The low-input system was more affected by climate, whereas supplementary-feed systems were affected by externalities (milk and feed prices). With increasing environmental challenges and the need to ensure appropriate staff, farm systems should be evaluated by considering environmental, personnel and profit, rather than just milk production. Greater production may lead to more hours worked and more methane emissions, without any increase in profit.