Change in body condition score (BCS) during lactation in Simmental cows.

Body condition scores (BCS) at approximately three-month intervals were taken during over 2 years on 920 Simmental cows housed in 36 farms, with the purpose of studying the temporal trend of body reserves and some factors affecting the change of body score during lactation. Cows were allotted in 2 parity groups and 3 yielding ability classes according to mature equivalent milk yield. Data were analyzed using ANOVA according to a time-dependent model based on days in milk, which accounted for 64% of the variation of test-day BCS. Condition score appeared closely related to the stage of lactation. Body reserves decreased from calving until 100 days in milk and were restored in mid and late lactation. The duration and the amount of body fat mobilisation increased with the increase of yielding ability of cows, and the highest yielding cows exhibited a loss of condition score since calving twice as high as the lowest yielding cows (-0.34 vs -0.14 units, respectively). However, apart from their yielding ability, cows were able to restore body reserves during mid and late lactation, and BCS at 305 days in milk was on average similar to that exhibited at calving. Conversely, parity did not significantly affect the pattern of change of body condition score. Equations provided can be used as guidelines of BCS change during lactation for Simmental cows and allow to compute the predicted change in BCS since calving for cows differing in dairy merit