Effects of an all-herbage versus a concentrate-supplemented ration on productivity, body condition, medical treatments and reproduction in two Holstein cow types under organic conditions

The effects of an all-herbage ration on dairy cows, as compared to a concentrate-supplemented herbage-based ration, were investigated over three years. In total, 138 lactation records of 92 Holstein cows, of which 67 were of Swiss (HCH) and 25 were of New Zealand origin (HNZ), were taken into account. Concurrently, the all-herbage ration (AH) was compared to a treatment in which 750 kg of concentrate (C750) were offered during the first 300 days in milk. During the winter feeding period, hay was fed, and during the grazing season, herbage was grazed. With this concentrate supplementation, dairy cows produced, per standard lactation (305d), more milk, energy-corrected milk (ECM), milk fat, milk protein, lactose, ECM per body weight (BW) and ECM per unit of metabolic body size. In addition, the concentrate-supplemented cows showed slightly higher BW and body condition scores (BCS). The milk content in terms of fat, protein, lactose and urea, as well as the somatic cell counts (SCC), remained unchanged with concentrate supplementation. The HCH produced more milk and lactose. Due to the lower fat, protein and lactose content in the milk of the HCH, no significant differences were found concerning ECM, milk fat and milk protein yield between the two cow types. Because the HCH were heavier, they produced less ECM per BW and unit of metabolic body size than the HNZ. Furthermore, the HCH received lower average BCS ratings than the HNZ. Finally, both cow types showed similar values regarding milk urea content and SCC. No interactions between the concentrate supplementation and cow type factors were found. No significant differences in the number of medical treatments and reproduction traits were noted between the concentrate treatments, except for a trend towards fewer re-calvings after standard lactation with the all-herbage ration. In contrast, differences occurred between the two cow types. The HCH received more medical treatments than the HNZ for fertility issues and in total. Fewer medical treatments were necessary for claw and leg issues for the HCH compared to the HNZ. In contrast, the calving intervals of the HCH were significantly longer, and the intervals between calving and both first service and conception tended to be longer. All-herbage rations remain feasible today, but dairy cows adapted to cope with adversities commonly associated with low-input feeding systems might be advantageous to use.