Methods for estimating milk production of dairy cows with full cow-calf contact.

Dairy cows with full cow-calf contact can nurse their calves and perform maternal behaviors without hindrance. Owing to the unrestricted suckling, the total milk production of the suckled cows (i.e., machine milk yield [MMY] and milk consumed by the calf) is unknown, albeit required for performance testing and sustainability analyses of prolonged cow-calf contact. This study aimed to estimate the daily milk production of dairy cows with full cow-calf contact spanning the whole day using 2 methods. First, individual milk production was estimated using the daily energy intake during the preweaning suckling period and the ratio of MMY to the previous day's energy intake, calculated for the 8-wk postsuckling period. Second, individual milk production was estimated using the daily MMY during the suckling period and adding the estimated calf milk consumption based on their body weight, growth, and energy intake from concentrates. This was done for conventionally managed cows with no contact with their calves beyond 13.5 h after birth (NC; n = 20) and for cows with full contact with their calves until gradual weaning at 13.0 ± 1.1 wk of age (FC; n = 18). Using the first method based on energy intake of the cow, milk production of NC cows was estimated at 33.33 ± 1.40 kg/d and their milk yield to the automatic milking unit averaged 37.73 ± 1.40 kg/d during the first 12 wk of lactation. This discrepancy might be because cows likely experienced a negative energy balance during the preweaning period, which was not accounted for in the estimation. For FC cows, average milk production was estimated at 35.30 ± 1.40 kg/d and their milk yield to the milking unit averaged 24.74 ± 1.60 kg/d during the suckling period of the first 12 wk of lactation. Using the second method based on the estimated milk consumption of FC calves (14.91 ± 2.9 kg/d; mean ± SD), milk production of FC cows during the suckling period was estimated at 37.94 ± 1.80 kg/d. In conclusion, both methods evaluated could estimate milk production of suckled FC cows. In the first method, milk production was underestimated when using ME intake and milk yield during the nonsuckling period, possibly due to not accounting for body reserve mobilization. In the second method, milk production of suckled cows estimated using calf growth aligned with the recorded MMY of nonsuckled cows. The ∼15 kg/d estimated milk consumption of FC calves during the first 13 wk of life corresponded to the recorded milk yield difference between FC and NC cows. Methods evaluated in this study can be applied for performance testing and sustainability analyses of cow-calf contact systems.