A fresh look at the benefits of lowering BMSCC

A fresh look at the benefits of lowering BMSCC
By John Penry, Anexa FVC Veterinarian and Researcher Morrinsville

Farms have been receiving a bulk milk somatic cell count (BMSCC) measurement with each vat pickup for many years now, and it is easy to lose sight of its value to a farm business because it such a commonplace part of the daily routine.

As everyone knows, the BMSCC measures the number of white blood cells in the vat milk in cells/ml. It gives each farm an accurate estimate of the degree of subclinical mastitis infection in the herd on a daily basis. In very general terms, for each 100,000 increase in BMCSS, there is around a 10% increase in the number of sub-clinically infected cows in the herd. It is a rough “rule of thumb” but a useful one. What is also seen is an increase in variability of BMCSS, with an increased average; the cell count “bounces around more” with an increasing average. In addition to this, the risk of clinical mastitis cases as the BMCSS average rises.

As a herd progresses from the start of the season through to the end, it is not only the proportion of sub-clinically infected mastitis cows that is important, but the rate of new sub-clinical infections as well. The key question here is, how many uninfected cows become new infections per month or over the lactation? It make sense that having this as low as possible benefits the herd.
Cows that are sub-clinically infected have been shown, through various studies, to have reduced milk production across the lactation. It is around a 2% decrease compared to an uninfected herd mate. Now this does not sound like much, but it is worth chasing as the 2% reflects the drop in production despite the same per cow inputs when compared to an un-infected cow. This 2% drives straight into the profitability of each cow.

Research work in both New Zealand and Australia has quantified the average decreased dollar turnover per cow per year associated with an increase in average BMCSS. The New Zealand based work is summarised in the diagram (for an approximate $6.50 kg MS payment).
Irrespective of any reduction in clinical cases in the herd per year, there is a well-defined milk production benefit from lowering the annual average BMCSS and this has attached to it an increase in turnover per cow. While not shown on the diagram, this benefit continues down to an average BMCSS of 50,000. Irrespective of the milk quality pricing structure of your processor, there is money on the table around a lower cell count.

It is also important to note, the per cow benefits are cumulative. For example: If your herd’s BMSCC moves from 350,000 to 250,000 you can expect a $11+$14=$25/cow/year benefit or shifting BMSCC from 300,000 to 150,000 results in a $14+$16+$20=$50/cow/year benefit.

If you are interested in gaining this financial advantage through better milk quality, the next steps are straight forward:
  • What is the level of new infections based on either herd test or clinical case records (particularly for the heifer group in the herd)?
  • What are the common mastitis causing bacteria in the herd based on any previous, or current, milk culture results?
  • What are the likely mechanisms for new infection spread specific to your herd?
Armed with this knowledge, progress can be made! Our veterinary team is highly experienced in this type of work and is able to help with an assessment and an action plan. Give your local Anexa FVC clinic a call and ask to be put in touch with one of our Vets that focus on milk quality - we’re here to help.

Date Added: Tuesday, 3rd October 2017