Effect of altering milking interval when milking 3 times in 2 days on milk and component yields in pasture-based dairy systems

Dairy farmers face challenges attracting and retaining staff, partly due to the difficulty meeting the desires of the modern workforce. These include flexible work hours and regular time off. The task of milking fundamentally affects the ability of dairy farmers to meet these desires. Milking contributes to a large proportion of the hours spent working on dairy farms. The number of milkings (milking frequency) and their timing (milking interval) within a day influence the number of hours spent milking and what time in the day they occur. Milking 3 times in 2 d (3-in-2) reduces the amount of time spent milking compared with milking twice a day (TAD), without reducing milk yield as much as milking once a day (OAD). However, long intervals between 3-in-2 milkings can still lead to a long workday if farmers are expected to work between milkings. The objective of this study was to determine the effect of milking interval within a 3-in-2 milking frequency on milk yield and composition at 2 stages of lactation and compare these with OAD and TAD milking. Cows (n = 200) were milked in 5 groups of 40 at 3 intervals of 3-in-2: 8-20-20 h, 10-19-19 h, and 12-18-18 h, along with 24 h (OAD), and 10 and 14 h (TAD), for 6 wk at early lactation (mean 24 d in milk ± 7 d, SD) and again at mid lactation (mean 136 d in milk ± 18 d). Milk yields were recorded at each milking and milk samples collected weekly to determine composition. At both early and mid lactation there were no significant differences in milk, fat, protein, or lactose yields between the three 3-in-2 intervals. Cows milked 3-in-2 produced 8% less milk than cows milked TAD and 14% more than cows milked OAD, with smaller differences observed at mid lactation between TAD and 3-in-2. For a 3-in-2 milking frequency, a shorter milking interval can be implemented on the days when cows are milked twice. This may allow farmers to shorten the working day when using 3-in-2, without compromising milk or component yields.

Improving parlor efficiency in block calving pasture-based dairy systems through the application of a fixed milking time determined by daily milk yield and milking frequency

Adjusting end-of-milking criteria, in particular applying a maximum milking time determined by expected milk yield at an individual milking session, is one strategy to optimize parlor efficiency. However, this strategy can be difficult to apply practically on farm due to large differences in session milk yield, driven by milking interval, which affects milking routines and can be limited by in-parlor technology. The objective of this study was to test the hypothesis that a single fixed milking time (duration) could be applied at all milking sessions without compromising milk production or udder health for a range of milking intervals. To test the hypothesis, 4 experimental herds were established: (1) herd milked twice a day (TAD) using a 10- and 14-h interval, (2) herd milked TAD using an 8- and 16-h interval, (3) herd milked 3 times in 2 d using a 10-19-19-h interval, and (4) herd milked once a day (OAD). Herds consisted of 40 cows each, and were established for two 6-wk experimental periods, one in peak lactation and the other in mid-late lactation. Within each herd, half the cows had an end-of-milking criterion of 0.35 kg/min (Flow), and the other half had milking ended after a fixed period of time (FixedT) based on the average milking session yield, the daily milk yield divided by average number of milkings per day, irrespective of milking interval. We found no differences in daily milk yield between end-of-milking criteria due to residual milk from one milking likely increasing the proportion of milk in the udder cistern at the next milking session for the FixedT treatment. However, fat yield was compromised when the percentage of the herd with a truncated milking exceeded an estimated 33% at a milking session, which occurred in the TAD 8-16 herd due to the divergence from the average milking interval (in the case of TAD, 12-12 h). Applying a fixed milking time had no detrimental effects on udder health, except in the OAD herd in mid-late lactation, which had both a higher cell count and new intramammary infection rate. This warrants further investigation, although the majority of cultured bacteria were coagulase-negative staphylococci (CNS). Consequently, we conclude that, in general, with appropriate monitoring (e.g., weekly inspection) to ensure the proportion of the herd with truncated milkings does not exceed 33%, farmers in pasture-based dairy systems can use a fixed milking time to improve parlor efficiency.