Milk Science

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What is Milk Made Of?

MS 1.07 The Impact of Dairy Farming on the Environment

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Blue-green algae in full bloom

Based on results of a 2008 study, the US dairy industry produces an average of 2.05 kg of CO2 per litre of milk consumed (Thoma et al 2013). Of this, 72% is accrued up to the farm gate. This means that there is much to be done in terms of increasing efficiency at the farm level in the form of biogas digesters and in silage production.

This highlights the significant opportunity for the industry in on-farm improvements, specifically in terms of manure management and controlling enteric methane emissions. These emissions sources, as well as the incoming burden of the feed, are significantly influenced by the on-farm feed conversion efficiency. (i.e. how easily the cow digests the feed supplements). Improving conversion efficiency reduces GHG (greenhouse gas) emissions from all three sources’ (Thoma et al 2013). To put this figure in perspective,  a carbon footprint audit of the Pepsi Cola group’s Tropicana orange juice line revealed a footprint of 899 g of CO2 per litre. This is 57% less than the US dairy output.

Eighty percent of the waste in dairy farming is considered to be recoverable with existing technologies. However, there is a big deficit in the adoption of these sorts of technologies. In 2014, of the 1,496 dairies in the state of California, only 26 farms had biogas technology installed. Of these, 17 had ceased using the equipment. A thesis by Desireé Lee Libarle explores impediments to the adoption of technologies in the dairy industry. Reasons for the low uptake of emission-control technologies in California included  ‘[the] initial costs of implementing combined with low negotiated energy prices and changing emissions regulations’.

The successful adoption of emission-control technology has been seen in the Netherlands, however. There, dairy farmers, aided by considerable investment from the Dutch government, have begun to explore the benefits of biogas technology.

The shift towards intensive dairy farming could account for small farmers’ hesitation in investing more in this technology. Libarle quotes a statistic from the California Department of Food and Agriculture in 2013 which indicates a 70% increase in herd sizes between the years 2000 and 2012, from 696 cows per operation up to 1,186. By way of contrast, Rupert Cyster (the UK dairy farmer we interview in lesson 1.6), is milking only 60 cows per day.

Manure continues to be a key element in agricultural practice, and it is widely collected for processing into fertilizers. Oscar Schoumans of Wageningen University and Research in Holland is working on a project to extract value from manure. ‘We need to see [manure] not as waste but as a source for minerals we need for [agricultural] production,’ he says. This is important because if left untreated, excess nitrates and phosphates in cow manure will leach into waterways, causing algal blooms and pollution in a process known as eutrophication.

Probably a reason for the low uptake of extraction technologies can be explained by the continued low cost for consumers of gas and coal power energy sources in the US. Mass-scale intensive farming could present opportunities for efficiency but, as we have seen in the coffee industry, this can come at the expense of quality.


Your Milk Waste Percentage

In this video we show you a method we use to track, and reduce our milk waste in a commercial setting

A reduction in the waste of milk may be particularly relevant to the carbon-conscious cafe. An audit published in 2013 calculates a 20% wastage quotient. This indicates a huge opportunity to dramatically reduce methane emissions and to offset any increased production costs associated with a move into specialty milks. Try this waste-consciousness building exercise: Collect all the spare milk that you would otherwise discard across an entire work shift to calculate your milk-waste percentage. Simply tally up the total amount of milk bottles you opened across the shift. Work out what proportion your waste milk constitutes of this amount. Home baristas can obtain a less reliable but still helpful figure even from a single pour. A figure below 5% is essential for professional baristas.

We are concerned with more than just the ecological cost of milk waste. Even with a 5% milk-waste percentage, there is a significant financial toll for specialty coffee shops. For example, a good, single-herd specialty milk in the UK will wholesale to a medium-sized cafe for around £0.80 per litre. The average UK cafe produces around 300 drinks per day and of these, 90% are milk drinks. If we estimate that the typical milk drink size requires approximately 150 ml of milk, the average milk bill for a cafe will come in at a little under £11,826 per annum (US$16,067). Even at a 5% milk-waste percentage, you are still pouring almost £600 (US$815) worth of milk down the drain each year.