Abstract for: HERDAIRY MODEL: MAPPING DYNAMICS OF DAIRY FARMS TO SUPPORT HERD MANAGEMENT
System Dynamic in dairy farming management might be helpful but scarce application were developed. This work aimed to define the dynamic structure of an intensive dairy herd by mapping the animal stocks and the reproduction, the replacement and the culling flows and to predict milk deliveries over time. A reference farm, intensively managed, over the biggest 1% of Italian herd size (>2500 cattle heads), provided monthly farm records, from Jan 2016 to Dec 2019. Model development included: i) a preliminary farm survey; ii) a Stock&Flow cattle model on Stella® (Isee System) describing aging chains of heifers and cows; iii) the model calibration of technical parameters; iv) the model evaluation of cattle consistency and milk deliveries against farm historical records. The model reproduced with high accuracy the farm dynamics from two main loops: the balancing loop of replacements heifers vs. culled cows and the reinforcing reproduction loop of the cows pushing the milk delivery. The model reproduced the historical oscillation patterns of cattle consistency and the milk deliveries with high accuracy (root mean square prediction error of 2.8% and 5.2% for lactating cows number and milk deliveries, respectively). Further modeling effort for farm production planning of the next 10 years should focus on endogenous and exogenous factors affecting animal intake and reproduction rates.