Scope for earlier removal of clusters?

Milking is the main chore on dairy farms and typically consumes over 30% of total labour input. With high labour costs and problems accessing skilled labour, the recent trend has been to install milking parlours, with a greater number of clusters to be handled by one operator.

Automatic cluster removers (ACRs) are a useful automation to facilitate single-operator management of a greater number of milking clusters. They also offer consistency around the endpoint of milking and can eliminate over-milking of cows.

Over-milking should be avoided to keep teats in good condition and to maintain cow comfort during milking. Much work has already been conducted to provide strong support for significant reduction in milking duration without impact on milk yield through increasing the flow-rate at which the ACRs detach the milking cluster (ACR threshold). However, in practice, many farms have not adopted this labour-saving technology on the basis that it may increase milk somatic cell count (SCC – an indicator of udder health).

Removing clusters earlier

Researchers at Teagasc Moorepark have tested the effect of removing milking clusters earlier than normal to examine the effects on milk yield and SCC. John Upton, a Senior Research Officer in the Livestock Systems Department, explains:

“Typically, the ACR threshold is set at a flowrate of 0.2kg/min, i.e. completely milking the cow out. The objective of this study was to increase the ACR threshold from 0.2kg/min to 0.8kg/min in steps of 0.2kg/min and document the effects on milk yield, milking duration, average milk flowrate, strip milk — milk left behind after cluster removal — and SCC over a 31-week period.”

Increasing ACR thresholds

Four treatments were deployed over 31 weeks to cows at the Moorepark research centre. The treatments consisted of ACR thresholds increasing from 0.2kg/min to 0.8kg/min in steps of 0.2kg/min (ACR0.2 ACR0.4, ACR0.6, ACR0.8). A mid-line 30-unit Dairymaster herringbone, swing-over milking system was used for twice-daily milking of the cows on the study.

John further explains the methodology: “The milking system utilised simultaneous pulsation (i.e. 4x0 pulsation) and was fitted with ACRs and Weigh-All milk meters. The standard farm ACR threshold was 0.2kg/min. The milking parlour software was modified to apply a pre-defined ACR threshold to a specific cow regardless of when she presented for milking. Cows were managed in a pasture-based system and were milked twice per day with a 16:8h milking interval. Each experimental group had 27 cows at the beginning of the study.

“Strip milk was recorded on four separate occasions over the course of the study,” says John. “This was carried out by reattaching the cluster to the cow after it had been removed by the ACR, adding a 2.5kg weight to the cluster, and removing the unit once milk flow had ceased. The strip milk yield was then recorded from the milk meter. The strip milk data of 64 randomly selected cows spread evenly across all four treatments were collected.”

Milking duration, yield and SCC

The milking duration for ACR0.8 was significantly shorter than ACR0.2, by 95s (14%). Similarly, the average flow rate for ACR0.8 was significantly larger than ACR0.2, by 0.26kg/min (16%). There was no treatment effect on milk yield or strip milk — i.e. increasing the ACR threshold did not affect the milk yields of the cows, or the amount of milk left behind in the udder after milking.

There was no significant effect of treatment on SCC. The SCC values were 71,700, 67,000, 69,900 and 67,700 cells per ml for the ACR0.2, ACR0.4, ACR0.6 and ACR0.8 treatments respectively. The researchers found a significant effect of week on milk SCC, whereby the SCC of the cows on the experiment increased as lactation progressed in a similar way across all treatments.

There were 10 cases of clinical mastitis among the cows on the study. There were two cases on ACR0.2, one case on ACR0.4, four cases on ACR0.6 and three cases on ACR0.8. Strep. uberis was identified in four cases, Staph. aureus was identified in three cases and in three cases no bacteria was identified.

Overall, results are positive, suggesting that milking duration can be reduced without significant effect on milk yield and SCC. John concludes: “We did not find a significant effect of increasing the ACR threshold from 0.2 to 0.8kg/min on milk SCC in this long-term study. We found a significant effect of week on milk SCC, whereby the SCC of the cows on the experiment increased as lactation progressed. We can also conclude that increasing the ACR threshold from 0.2kg/min to 0.8kg/min reduced daily milking duration by 14% without any significant reductions in milk production or significant increase in strip milk in this study.” 

This article first appear in the Spring Edition of TResearch. Access the full publication here

Funding

The VistaMilk Research Centre was funded by Science Foundation Ireland (SFI) and the Department of Agriculture, Food and the Marine (DAFM) on behalf of the Government of Ireland under Grant Number [16/RC/3835]. Further financial and technical support was provided by Dairymaster.

Contributors

• John Upton, Senior Research Officer, Livestock Systems Department, Teagasc Moorepark. upton@teagasc.ie
• Martin Browne, Milking Efficiency Technologist, VistaMilk SFI Research Centre, Teagasc Moorepark.
• Pablo Silva Boloña, Research Officer, Animal Bioscience Department, Teagasc Moorepark.

This article first appear in the Spring Edition of TResearch. Access the full publication here