Genetic relationship between body reserves mobilisation and feed intake in Holstein cows?

International audience; The dairy cow faces large changes in nutritional requirements after calving. As feed intake adjusts only gradually to the strong increase in nutritional needs due to milk production, body mobilisation cannot be avoided in the beginning of the lactation. Excessive body mobilisation increases the risk of low fertility, of several diseases, and of poorer longevity, decreasing the animal robustness. Although body mobilisation is associated to milk yield, the potential for uncoupling production from body mobilisation remains largely unknown. The aim of this study was to estimate the correlations between feed intake, milk production and body mobilisation trajectories according to body condition score breeding value. This study involved 330 Holstein cows from three experimental facilities. Cows were genotyped and characterised by their direct genomic value for body condition. Their milk production, feed intake and body weight were recorded daily all along their lactation and body condition was scored monthly. Blood metabolites were also measured. Trajectories were found to be dependent on body condition breeding values (BCg). In the beginning of lactation, BCg did not affect feed intake but milk production was lower (-1.5 kg), and body weight and body condition were higher for animal with high BCg (+19.7 kg and +0.2 points per BCg genetic standard deviation, respectively). Contrarily, after 4 months of lactation, cows with high BCg showed more daily feed intake (+4 kg), production (+1.4 kg milk) and less body weight (-13 kg). These trajectories were therefore quite different: low BCg seems to be more favourable short term but at the expense of the mid-term feed intake and persistency. This study is part of the Deffilait project funded by ANR (ANR-15-CE20-0014-03) and ApisGene.