Design of algorithms for evaluating the efficiency of labour and variability of some group milking parlour parameters

The first objective of this paper was to develop a series of algorithms for sizing group milking parlours (herringbone and parallel) that guarantee the best approximation to maximum efficiency and allow the variability of some important design parameters to be considered. The maximum efficiency was defined as that achieved when the total milking time worked by milkers was minimised given recommended milking duration. The main parameters considered were milking routine time, milk extraction time and milking duration. The second aim was to study the effect of variations in these parameters on parlour efficiency. To this end, the number of milking units and milkers required was determined for various combinations of cow number (40-240), milking routine times (30-100 s) and milk extraction times (250-600 s), considering the effects of each option on the duration of milking and total time worked. The results showed that the achieved efficiency varies as a function of the different combinations of values tested, and that using these algorithms, it is possible to establish an approximation for maximum efficiency for each combination. The best approximations are obtained when the milking duration is lower. Our study of the influence of parameter variability on efficiency found two models of farms: the first model combined a slow routine, low production and high inter-cow variability in production, and the second model combined a quick routine, high production and low variability. In the first model, the efficiency of labour is very close to maximum; even when using a large parlour or more workers, the performance in cows per hour will remain relatively stable, and no improvement is observed compared with using smaller parlours or fewer workers. For this reason, the increase in parlour performance can only be obtained by improving farm management, including milking routine times or grouping cows. In the second model, an increase in the number of milkers and milking units usually leads to a decrease in milking duration, but this comes at the cost of substantially increasing the total time worked; this case needs a detailed study to achieve the best efficiency. These results show that optimisation of parlour performance and approximation to maximum labour efficiency should be addressed differently depending on the characteristics of the farm; in some cases, an improvement in management activities is necessary. In others, a detailed study of the number of milkers and milking units is needed.