Relationship between lactose concentration and rumination quality in early-lactation dairy cows

In cows, lactose is the primary solid component of milk and is routinely measured in lactating cows worldwide as part of standard evaluation systems. Over recent decades, likely due to the growing availability of milk data from innovative technologies, lactose has been increasingly incorporated into scientific studies, alongside traditional traits like milk yield, fat, and protein concentrations. The goal of this study was to determine the connection between in-line lactose concentration and rumination quality. Research was conducted on a Lithuanian farm in 2023. A total of 502 cows were selected for the study. According to the literature (1) they were divided into two groups: A (lactose concentration < 4.7%) and B (lactose concentration ≥ 4.7%). The average milk yield was 12,500 kg per lactation. Milk lactose concentration was recorded continuously during each milking by the “BROLIS HERDLINE (Vilnius, Lithuania)” in-line milk analyzer, which was integrated into a milking robot. Rumination quality was monitored using the RumiWatch sensor (Itin + Hoch GmbH, Liestal, Switzerland). Jaw movements during rumination showed a significantly higher number of rumination chews (p < 0.01), with a 13.84% increase in Group B (ML ≥ 4.70%) compared to Group A (ML < 4.70%). The average number of rumination chews in Group B was 1280.80 chews per hour (±52.28), while in Group A, it was 1103.58 chews per hour (±23.37). Additionally, the results showed a significant increase (p < 0.001) of 16.70% in the number of cuds in Group B (ML ≥ 4.70%) compared to Group A (ML < 4.70%). The average number of cuds in Group B was 22.69 per hour (±0.92), while in Group A, it was 18.90 per hour (±0.38). Our study has shown that lactose concentration has a strong relation with rumination quality and may provide insight into cattle health status.