A situation like the new coronavirus pandemic makes clear the connectedness of our global food supply. Much of the agriculture industry relies heavily on national supply chains and export markets to function. The dairy supply chain has been very susceptible to global shutdowns.

At some point, many farmers have had to dump a tank of surplus milk. However, the ongoing pandemic has raised uncertainty about how long such practices may be necessary and prompted questions from farmers about best management practices for dumping milk. Dumped milk does not have to be money down the drain. Milk can be used as a feed, though typically only on the farm where it was produced because local regulations and/or cooperative contracts may prevent the sale of a “raw” milk product. Milk can also be applied to land as a fertilizer. A typical farm is likely to have more milk than can be feasibly used solely as a feed source. Whether land-applied as a nutrient source or disposed of through the waste management system, the milk should be handled according to your Certified Animal Waste Management Plan (CAWMP). See Guidance on Land Application of Discarded Milk for more information. Also, consult the N.C. Department of Environmental Quality (NCDEQ) or the regulatory agency in your state.

As a Waste Product

• Transporting large volumes of milk, either as feed or fertilizer, from the tank to the field or feed bunk will require some ingenuity. Any equipment used to move the milk will need to be cleaned regularly. If you have innovative ways to achieve this, reach out to NC State Dairy Extension with details (ncdairyextension@ncsu.edu).
• Milk can also be disposed of in the waste lagoon. It is important to flush behind to reduce any odors or insects associated with spoiled milk.

Besides complying with your basic CAWMP, you may need to address other challenges if milk is to be land-applied or stored in the waste management system. If you run out of space for application, you need to update your CAWMP to reflect any additional land application sites using a temporary amendment. A temporary amendment (contact NCDEQ for more information) is required whether producers apply the milk or whether the producers pay someone else to apply it to fields they are currently farming. If a third-party hauler is receiving the milk for land application to fields not farmed by a producer, the export should be documented using NCDEQ’s Animal Waste Transfer Record (TRAN-1).

It is strongly advised that you talk to your neighbors prior to dumping milk. Direct land application or storing milk in the waste management system is highly likely to generate odors. Select areas on the farm that are as far away from neighbors as possible, keeping in mind common wind directions. Identify neighbors who might be affected and discuss, in advance, the situation. This could prevent potential disputes and complaints. Clearly explain the situation and list all mitigation strategies that will be implemented to reduce odor.

As a Fertilizer

Because milk is much higher in nitrogen (N) than manure, land application rates to meet agronomic nitrogen requirements will be lower. While application rates of manure may be reported in acre-inches, application rates of discarded milk will be in the amount of several thousand gallons (for example, 4,000 gallons of milk will provide about 200 lb of nitrogen). In addition to N, availability of nutrients such as phosphorus (P) and potassium (K) is also much greater in milk than manure. Make sure you have a plan to apply appropriately low application rates if spreading milk directly onto pasture or cropland. It is recommended that you make several small applications rather than a large one. This will prevent ponding on the soil surface, reducing the chance for runoff and odors. A fatty film can accumulate on hoses and nozzles, creating clogs, so be sure to clean equipment well after use. If you plan to cultivate the soil for corn planting, consider applying milk prior to those activities; incorporating the milk into the soil will greatly reduce the potential for runoff and odors.

Finally, if you use an anaerobic digester, consult the manufacturer before adding any milk to your waste management system. Digesters require certain microbial communities to remain functional, and the addition of milk or any new feedstock could affect these microbes and reduce the efficiency of your digester.

If you have any questions about fertilizer or waste systems, please contact Steph Kulesza at sbkulesz@ncsu.edu.

• One limitation to using whole milk as a feed is the potential for spreading diseases. Johne’s disease, Mycoplasma, and bovine leukemia virus (BLV) are some diseases that can be spread through unpasteurized milk. Thus, knowing the health status of your herd is essential. If possible, pasteurize the milk before feeding it. Typically, milk for calves is vat-pasteurized for a minimum of 60 minutes at 140ºF. Milk that is successfully pasteurized should have a Standard Plate Count (SPC) of < 20,000 CFU/mL.
• Though milk can be a great source of protein, fat, and minerals, it is more than 85% water, so controlling the dry matter of the ration or TMR is very important. See the Feeding Milk Nutrient Calculator for calculating milk nutrients on a dry matter basis.

Lactating Cow Rations

Before you pour milk on your ration, call your nutritionist. While milk can be an excellent source of protein in particular, milk is also full of fat, lactose, and minerals. It is not recommended to feed milk to close up dry cows or transition cows, as it can be difficult to produce a consistent ration and consistent mineral concentrations for those groups of cows.

Maintaining ration dry matter (%) is necessary for success. A TMR (total mixed ration) should be 45% to 50% dry matter. Since milk is >85% water, using milk as feed is essentially like using water to reduce dry matter of your ration (while adding some nutrients). For example, if a cow is eating 100 lb per day as fed TMR, adding milk at a rate of 10% to 15% of the diet dry matter would be adding 10 to 15 lb of milk or 1.5 to 2.25 lb of total milk solids (based on 85% water and 15% solids), keeping total diet dry matter at 50%. That translates to 0.52 lb of protein, 0.60 lb of fat, and 0.74 lb of lactose (based on 15 lb as fed milk at 3.5% protein, 4% fat, and 5% lactose).

To maintain rumen microbial health and to reduce heat load in hotter weather, total fat (% diet dry matter) should be 6% or less. In the previous example, feeding 15 lb per day as fed milk (at 4% fat) adds about 1% total fat to the ration. It is very important that you work closely with your nutritionist to monitor feed mixing, intake, and cow performance if you choose to feed dump milk.

Pre-weaned Heifers and Bull Calves

Typically, in a high milk price market, milk replacer is fed even though it costs slightly more than feeding waste bulk milk (based on $18/cwt or greater mailbox price); the higher costs are often outweighed by the benefits—consistent nutrient supply; reduction of disease transfer; and better storage, feeding, and labor time management. However, when milk prices are low or if you find yourself with a few thousand extra pounds of nonsalable milk, using dump or waste milk for feeding calves makes sense practically and economically.

For reference, our recommendations for milk feeding for calves in a milk replacer program are:

• 1.5 lb powder per day (minimum 15% solids) fed at least twice per day
• 26% to 28% protein
• 20% to 22% fat

To meet these same requirements using whole milk (nonsalable), whole milk is >85% water, making that milk approximately 15% solids. In that instance, feeding 1.5 to 2 gallons per day (over two feedings) could provide adequate nutrition for calves, depending on fat and protein concentrations. Table 1 shows a comparison of a standard milk replacer (28CP/20Fat) to bulk tank milk at 3.5% CP and 4% fat.

Note that total solids of whole milk can range from 10% to 15%, and nutrient composition of whole milk is not consistent from day to day or even between milkings. If you plan to feed your bulk milk to calves, send a sample to a commercial feed lab for analysis. At the very least, you can use your DHI (or other milk system) test results to estimate nutrient concentrations.

When feeding nonsalable milk, it is imperative to maintain clean conditions. Pasteurize the milk if possible, keep all feeding and mixing utensils clean, and feed the milk at a warm temperature to reduce disease and ensure consumption by the calves.