A network simulation model of large herringbone and parallel milking parlors.

A network simulation model of herringbone and parallel milking parlors was built. Parlor performance was predicted based on the number of cows milked per hour and the amount of milk harvested per shift. Modeled parlors operated using a task-oriented milking routine. The simulation also modeled milking personnel, milking system vacuum pressure and pulsation ratio, and milk yield per cow per milking. The probability distributions of the model components that were used for validation were fitted from data collected from four dairies with the following parlors: double-16 herringbone, double-20 herringbone, double-35 parallel, and double-40 parallel. All fitted distributions were continuous, non-negative, and skewed to the right. The mean number of cows milked per hour (simulated and observed, respectively) was 1) double-16 herringbone, 164.8 and 164.6;2) double-20 herringbone, 207.6 and 206.6; 3) double-35 parallel, 319.2 and 320.2; and 4) double-40 parallel, 361.6 and 362.5. Mean milk yields harvested per shift were 1) double-16 herringbone, 9020 and 9030 kg; 2) double-20 herringbone, 14,800 and 14,746 kg; 3) double-35 parallel, 20,900 and 20,945 kg; and 4) double-40 parallel, 27,100 and 26,974 kg, for simulated and observed yields, respectively. Differences between simulated and observed means for either variable were not significant.