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 co ws milked per hour and the amount of milk harvested per shift. Modeled parlors operated using a task-oriented milking routine. The simulatio n also modeled milking personnel, milking system vacuum pressure and p ulsation ratio, and milk yield per cow per milking. The probability di stributions of the model components that were used for validation were fitted from data collected from four dairies with the following parlo rs: double-16 herringbone, double-20 herringbone, double-35 parallel, and double-40 parallel. All fitted distributions were continuous, nonn egative, and skewed to the right. The mean number of cows milked per h our (simulated and observed, respectively) was 1) double-16 herringbon e; 164.8 and 164.6; 2) double-20 herringbone, 207.6 and 206.6; 3) doub le-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 herringb one, 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 paralle l, 27,100 and 26,974 kg, for simulated and observed yields, respective ly. Differences between simulated and observed means for either variab le were not significant.