Responses of Nordic Red and Holstein dairy cows to reduced concentrate feed input on a grass silage-based diet

• Nordic Red and Holstein cows were used in a whole lactation milk production experiment • The grass silage-based diet had a high (47%) or low (22%) concentrate proportion • Cows of two genotypes responded to changed concentrate proportion in a similar manner • Reduced concentrate proportion decreased milk production, but cow health was not affected • Based on current feed prices, a high concentrate proportion was economically most viable Low concentrate input systems can potentially solve some of the environmental and societal challenges of the current high concentrate input dairy production. This study compared a typical high concentrate proportion (47% on dry matter basis) used in intensive Northern European dairy cow feeding with a low concentrate proportion (22%) on a grass silage-based diet. The study lasted over the whole lactation period and used Holstein (n=32) and Nordic Red (n=14) dairy cows. A high concentrate proportion significantly increased feed and nutrient intake, while the breed of the cows did not affect nutrient intake and no concentrate proportion × breed interactions were detected. Increased feed intake was reflected in significant increases in daily milk, energy corrected milk, fat, protein, and lactose production. A high concentrate proportion did not alleviate the negative energy balance in the beginning of lactation. No negative effects on cow health were observed related to the low concentrate proportion and both breeds seemed to adapt equally well to the low concentrate proportion. Based on current feed prices in Finland, a high concentrate proportion was economically more viable.