Effect of setting a maximum milking time, from peak lactation, on production, milking time and udder health

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.

Principles for maximising operator efficiency and return on investment in rotary dairies

This study quantified the effect of rotary size, platform speed, cluster attachment time, milk yield and end-of-milking criteria on cow throughput, operator efficiency and return on investment. A model was developed to predict the mean and standard deviation of cow milking duration for a given milk yield using milking data collected from commercial dairy farms in New Zealand. After accounting for the effect of end-of-milking criteria, this estimate was used to calculate the expected cow throughput and operator efficiency for a given platform speed, rotary size and cluster attachment time. The economic return of investing in rotaries of 44–80 bails, relative to a 40-bail rotary, was evaluated using a 25-year internal rate of return. The economic return of installing automatic cluster removers (ACR) was also examined. Estimated cow throughput increased with increasing platform speed and ACR threshold for a 50-bail rotary (a common rotary size) and the largest single gain in cow throughput came from changing the ACR threshold from 0.2 to 0.4 kg/min. Further increases had less impact, especially at lower platform speeds. However, for larger rotaries, maximum operator efficiency could be achieved using a variety of platform speeds and end-of-milking criteria. A larger rotary was required to achieve maximum potential operator efficiency, for a given cluster attachment time, as milk yield was increased. Increasing the minimum cluster attachment time decreased maximum potential operator efficiency. Consequently, operator ability and anticipated milk yield are key parameters when selecting the number of bails in a new-build rotary. Seventy- and 80-bail rotaries were generally not more operator efficient than 60-bail rotaries. Economically, the 50-bail rotary allowed the greatest labour saving per dollar invested for a typical farm conversion in Canterbury, New Zealand, although the ultimate choice of rotary size depends on the individual farm situation. The internal rate of return for installing ACR decreased with increasing rotary size, but was always positive. Farmers should carefully evaluate their options before investing in a new rotary.

Milking efficiency of swingover herringbone parlours in pasture-based dairy systems

The objective of this study was to collect and analyse milking data from a sample of commercial farms with swingover herringbone parlours to evaluate milking efficiency over a range of parlour sizes (12–32 milking units). Data were collected from 19 farms around the Republic of Ireland equipped with electronic milk metres and herd management software that recorded data at individual milking sessions. The herd management software on each farm was programmed to record similar data for each milking plant type. Variables recorded included cow identification, milking date, identification time, cluster-attachment time, cluster/unit number, milk yield, milking duration, and average milk flow rate. Calculations were performed to identify efficiency benchmarks such as cow throughput (cows milked per h), milk harvesting efficiency (kg of milk harvested per h) and operator efficiency (cows milked per operator per h). Additionally, the work routine was investigated and used to explain differences in the benchmark values. Data were analysed using a linear mixed model that included the fixed effects of season-session (e.g. spring-AM), parlour size and their interaction, and the random effect of farm. Additionally, a mathematical model was developed to illustrate the potential efficiency gains that could be achieved by implementing a maximum milking time (i.e. removing the clusters at a pre-set time regardless of whether the cow had finished milking or not). Cow throughput and milk harvesting efficiency increased with increasing parlour size (12 to 32 units), with throughput ranging from 42 to 129 cows/h and milk harvesting efficiency from 497 to 1430 kg/h (1–2 operators). Greater throughput in larger parlours was associated with a decrease in operator idle time. Operator efficiency was variable across farms and probably dependent on milking routines in use. Both of these require consideration when sizing parlours so high levels of operator efficiency as well as cow throughput can be achieved simultaneously. The mathematical model indicated that application of a maximum milking time within the milking process could improve cow throughput (66% increase in an 18-unit parlour when truncating the milking time of 20% of cows). This could allow current herd milking durations to be maintained as herd size increases.

Comparing somatic cell counts, production and milking durations of dairy cows when milked at two automatic cup-removal flow-rate thresholds

The present study evaluated the effect of two automatic cup remover (ACR) flow-rate threshold settings (0.2 and 0.4 kg/min) on somatic cell count (SCC), clinical mastitis (CM), milk production and milking duration for cows milked twice daily. In a crossover design, 161 cows were assigned to one of two groups and milked with an ACR set at either 0.2 kg/min (Group 1, n = 81) or 0.4 kg/min (Group 2, n = 80) for a 3-week period from peak lactation. Following a 1-week transition period at a milk-flow threshold setting of 0.3 kg/min for both groups, there was a further 3-week treatment period where Group 1 was milked with an ACR set at 0.4 kg/min and Group 2 set at 0.2 kg/min. The milk-flow threshold setting did not affect SCC (P > 0.05). Clinical mastitis was detected in 3% of cows, and was not more prevalent when cows were milked to a flow rate of 0.4 kg/min. Post-milking strip yields were larger when thresholds were set at 0.4 kg/min than those with 0.2 kg/min (P < 0.05). Average fat yield was not affected by treatment (P > 0.05), but average daily milk, MS and protein yields were lower (P < 0.05) for the 0.4 kg/min setting, equating to a 1% difference in production. Milking duration was reduced by 11% (P < 0.001) when cups were removed at flow rates of 0.4 kg/min, compared with 0.2 kg/min. Increasing the milk flow-rate threshold for cluster removal can reduce milking time without affecting milk quality, but may result in a minor reduction in MS production.