Economics, disease and the environment must be considered when deciding whether to feed “waste” milk to your dairy calves. Adding the benefits and risks of all these factors will yield a different answer for every farm, says Tom Anderson, Shawano County dairy and livestock agent.
“It’s nice to have people advise you and give you a black-and-white, yes-or-no answer,” Anderson explained. “This is an issue you can’t do that with. This is an issue that can vary with every dairy operation.”
One question to consider is economics, Anderson said. According to AgSource, approximately 2-3 percent of all milk produced is not marketed. While a small portion of that “waste” milk is unwholesome due to severe clotting or blood in the milk, a larger share can come close to meeting the liquid feed needs for calves. There are approximately 125-175 pounds of colostrum and transitional milk per freshening.
Cost estimate of feeding milk replacer to eight weeks of age is about $40-$45 per calf, Anderson said. Feeding waste milk will reduce those costs.
Anderson reminds farmers that any costs required for special milk handling, storage and feeding equipment must be considered when comparing economic factors.
Colostrum and transitional milk (first four or five milkings) are different than normal milk obtained two to three weeks after calving, Anderson explains. (See Table 1.) The most striking difference is the high protein content of colostrum, in part due to the large amounts of gamma globulins which contain the antibodies.
| Table 1. Milk Composition | ||||
|---|---|---|---|---|
| Component | Colostrum | Transitional Milk | Mastitic Milk | Normal Milk |
| Total solids (%) | 23.9 | 14.1 | 12.7 | 12.9 |
| Fat (%) | 6.7 | 3.9 | 3.8 | 4.0 |
| Protein (%) | 14.0 | 5.1 | 3.1 | 3.1 |
| Lactose (%) | 2.7 | 4.4 | 4.5 | 5.0 |
| Minerals (%) | 1.11 | .87 | .85 | .74 |
| Milk from a typical Holstein Cow
Source:Tom Anderson, Shawano County dairy and livestock agent |
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Another difference between colostrum and normal milk is a lower level of lactose, or milk sugar. Lactose is a scouring agent in calves, and the low level of lactose in colostrum is built-in protection to reduce scours in newborn calves.
Mastitic milk that is not visibly foul or irregular is only slightly different in composition from normal milk. Mastitic milk may contain up to 10 percent less milk sugar and may have some high quality protein, casein, converted to lower-quality protein, whey. There may also be a slight decrease in butterfat content.
Studies have shown that these changes in composition have little impact on calf performance, Anderson said.
Research in the 1940s found that calves fed mastitic milk had a higher incidence of Streptococcus agalctiea mastitis infections when grown. However, Anderson notes, calves in the study were fed mastitic milk until seven months of age, and heifer calves were mingled, allowing them to suckle on each other.
That study’s conclusion is less relevant today because calf management systems have changed, Anderson said. Studies in California and Oklahoma, comparing groups of calves fed normal milk and milk containing Staph aureus, found no difference in the number of Staph aureus intramammary infections in the heifers.
A 1994 Washington study, not directly related to the feeding of mastitic milk, has implications as to mastitis sources, Anderson said. In the study, waste milk, including mastitic milk, was fed to heifer calves in seven herds. A total of 700 body sites on the test heifers were sampled for Staph aureus from preweaning to freshening. None of the heifers that had Staph aureus on a body site prior to weaning freshened with Staph aureus mastitis.
“When they tried to link together calves fed Staph aureus milk, and those having Staph aureus on their bodies, they could not find a relationship between that and the incidence of Staph aureus in first-calf heifers,” Anderson said. He concludes that the more recent research shows there is not a great risk to feeding calves mastitic milk under modern management practices.
What about feeding milk withheld from the market because the cow was treated with antibiotics? Anderson says there are some risks, although small.
“I would avoid feeding antibiotic-treated milk to bull calves,” Anderson warned. “That bull calf that you think for sure is going into the veal crate might not make it there. It might go to the terminal market. Guess what’s going to happen then? You’ve got antibiotics in the body of that calf. The first you know, it’s going to get flagged, and it’s going to come back around to you.”
Anderson said some Russian research has turned up stomach ulcers in young calves fed antibiotic milk. However, he said, those results have not been found in any other study.
Dairy replacement heifers are routinely fed antibiotic milk, without adverse effects, Anderson said. Some researchers point to the potential problem of scouring in calves fed antibiotic feeds.
Another, longer-term concern is that of developing antibiotic and/or disease resistance. Antibiotic-enriched milk replacers and calf starters raise these same concerns.
“By far the biggest issue related to feeding waste milk to dairy calves is the transmission of communicable diseases,” Anderson said. While both marketed milk and waste milk possess the same potential, marketed milk is pasteurized, eliminating that concern.
Research had pointed to new information that concludes feeding milk directly to calves poses a very real threat of transmitting diseases. Three diseases of special concern are Mycoplasma bovis (M. bovis), Johne’s disease and bovine leukosis virus (BLV). Anderson urged farmers to check with their veterinarians about potential transmission of other diseases, as well.
M.bovis is not exactly a bacteria, but related to bacteria, Anderson said. It is an uncommon cause of mastitis in dairy herds. The disease is characterized by clotting milk and very high somatic cell counts (10 million to 25 million). Abortion, pneumonia, joint swelling and lameness are common symptoms. Mastitis and lameness are not necessarily seen at the same time in herds infected with M. bovis.
M.bovis is one of the very few mastitis agents that do not necessarily enter the mammary gland by way of the teat canal, Anderson explained. Cows that carry M. bovis may be difficult to identify, but some special bulk tank cultures are reliable.
Intrammary therapy seems to have limited treatment value, and teat dipping and good milking hygiene are important in the disease’s control. Cows infected with M. bovis are strong candidates for culling, Anderson urges.
Milk from M. bovis cows should not be fed to calves. A Michigan study linked M. bovis isolated from a bulk tank in a 600-cow dairy to infections of young calves fed milk from the farm. The disease has proven to cause inner ear infections, sometimes fatal, in young bull calves.
“Let’s not mess around with this one,” Anderson stressed. “If you’ve gotM. bovis in your herd, do not feed the waste milk to calves.”
The Johne’s disease organism, M. paratuberculosis, is taken in by mouth, and has often been associated with ingestion of water or feed sources contaminated by manure.
“We also know now that we have cases where the organism has found its way into milk and colostrum as well,” Anderson said. “We need to be careful with this one. Calves up to six months old are most susceptible to the disease.”
Anderson urged dairymen to test for Johne’s before feeding waste milk.
BLV is a widespread viral disease in the U.S., with highest incidence in Florida. Contrast that to northern Europe, where the disease is virtually nonexistent, Anderson said. It has been long associated with blood, passed from animal to animal during ear-tagging, castration, vaccinations or other management steps associated with blood.
The risk of transmitting BLV through waste milk is probably not very high, Anderson said.
“Some research done at Penn State shows pretty clearly that the risk of passing BLV to calves through waste milk is not very great,” Anderson said. “Once the organism is in the cow, she is going to mobilize a lot of antibodies.
As a result, when the calf accepts the milk from the cow, it is also going to accept a heavy dose of antibodies, and probably receiveng more than enough protection.”
On-farm pasteurization has been suggested as one way to kill the disease carriers. However, pasteurization requires supervision, and probably isn’t economical at the farm level, Anderson said. Milk needs to reach 161 degrees Fahrenheit and be maintained at that temperature for 15 seconds for flash pasteurization. An alternative process requires the milk be heated to 145 degrees F and maintained for 30 minutes.
Proper pasteurization stops the growth of E. coli, Salmonella and Staph aureus, eliminates M. bovis and controls BLV. However, it’s very unlikely that pasteurization has any affect on M. paratuberculosis, the agent that causes Johne’s disease.
Heating colostrum coagulates and clots the feed, inactivating the vital gamma globulins the calf needs for immunity. Heating also causes cleaning and sanitizing problems.
“Pasteurization probably works four days out of five,” Anderson said. “It works a lot better in principle than it does in practice.”
Sanitation remains the most important factor when considering feeding waste milk, Anderson said. Liquid feeds present the perfect host for microorganism growth. Feeding immediately after milking or cooling the milk to reduce spoilage are recommended.
California veterinarian Walter Guterbock recommends larger dairies pay special attention to sanitizing waste milk handling equipment. Waste milk held without cooling presents a significant risk for bacterial growth.
Custom heifer growers can successfully feed waste milk by dedicating a used bulk tank to receive and store it. The milk should be free of the disease carriers, listed above. The cool milk can be reconstituted with hot water and milk replacer to make a suitable liquid feed.
Avoid mingling successive milkings in holding tanks, Guterbock recommends. Completely remove the milk from the holding tank and sanitize it to avoid bacterial growth.
Waste milk has extremely high biochemical oxygen demand (BOD) and can pose a significant environmental challenge (see Table 2), Anderson said. Dairy farmers who have liquid manure storage can use the system to hold waste milk and later dispose of it on fields.
| Table 2. Components of Waste | |||
|---|---|---|---|
| Household Wastewater | Milkhouse Wastewater | Waste Milk (estimated) | |
| Suspended Solids (mg/L) | 290 | 996 | 65,138 |
| Total solids (mg/L) | 1,000 | 3,506 | 227,890 |
| Oil & grease (mg/L) | 150 | 300 | 19,260 |
| Biochemical Oxygen Demand (mg/L) | 400 | 1,530 | 100,000 |
| Source:Tom Anderson, Shawano County dairy and livestock agent | |||
However, the waste milk will impact the manure handling system, preventing crust build up, which leads to more odor problems. If you’re already running into trouble with your nonfarm neighbors over manure storage odor problems, Anderson recommends not putting the waste milk into a manure storage system.
If you don’t have a liquid manure storage system, don’t depend on the milk house wastewater system to dispose of the waste milk.
“(Waste milk) will defeat any milk house wastewater system,” Anderson said. “It’s so high in biochemical activity that the system can’t deal with it. For years we’ve said that milk house wastewater was hard to deal with. (Compared to milk house wastewater), waste milk is off the scale.”
Admits Anderson, “I don’t know how to get rid of it.”
Reprinted with permission by AGRI-VIEW, January 15, 1998