Efficiency of Swiss and New Zealand dairy breeds under grazing conditions on commercial dairy farms

The objective of the study was to investigate over three years (2007 – 2009) the attributes of cows adapted to a pasture-based seasonal milk production system (New Zealand Holstein Friesian) under Swiss conditions and to compare them with Swiss breeds. For this purpose, pairs of Swiss (CH) and New Zealand (NZHF) cows were established (100 cows in total) with similar age and calving date on 15 commercial farms. Body weight (BW) in the first and second lactations were higher in CH cows than in NZHF cows (in 2007, 544 vs. 477 kg, P<0.001; in 2008, 578 vs. 517 kg, P<0.001). Milk yield was similar in CH and NZ cows for the initial two years but the milk of NZ cows had higher fat and protein content. The NZ cows produced more energy corrected milk (ECM) in the second lactation than the CH cows (6017 vs. 5470 kg, P< 0.001). As a consequence, the efficiency (ECM per metabolic BW, kg kg-1) was higher in NZ than in CH cows in both years (2007, 49.7 vs. 44.2, P<0.001; 2008, 55.6 vs. 46.6, P