DAIRY PRODUCTION, CARBON FOOTPRINTS, AND ANTIBIOTICS
(A) Introduction
No two dairy farms are the same, but the general methods of conventional milk production are comparable across U.S. and western Europe. Although all dairy cows are slaughtered for beef at some point in their lives, dairy cattle are bred almost exclusively for high milk production, meaning a farm relying mostly on milk sales will use different breeds than those relying on sales of beef. Most all dairy cows are fed a high-energy diet in addition to forage (grass and hay), and are milked twice or more each day in a parlor using automatic milking machines. For those unfamiliar with dairy production, this lecture will take them on a virtual tour of the dairy farm at Oklahoma State University, which is a decent representation of most dairy farms in the U.S.
On this tour we will start with a recently born calf and discuss how its life changes as it ages, allowing us to learn how dairy cows are fed, housed, bred, and milked. While on this tour, we will discuss the carbon footprint of milk and antibiotic use on the farm.
(B) Birth
Figure 1—A heifer is born
Figure 2—Taken from its mother
The calf is separated from its mother shortly after birth to make sure the calf receives adequate nutrition. When a mammal gives birth its milk will initially contain high levels of colostrum, a fluid containing antibodies that help boost the calves’ immune system. It is imperative that the calf receive quality colostrum in its first few days. The quality of the colostrum varies across cattle, so rather than hoping the mother has good colostrum, the calf is separated and fed colostrum from another cow whose colostrum level has been tested and proven to be high in antibodies. The mother is milked by humans and her colostrum tested for antibodies. If the colostrum is of high quality it will be frozen so that it can be fed to other calves in the future.
Figure 3—The heifer’s first taste of [formula] milk
The calves remain separated from their mothers because the mother’milk is reserved for human consumption. Don’t worry, the calf will receive plenty of nourishment from a milk made from formula, much like the formula milk my mother fed me (as breastfeeding was not popular in 1974). The formula milk fed to the calf will be made from a variety of ingredients, like a number of different grains, minerals, vitamins, and molasses. As the calf ages the formula milk will be supplemented with grain and hay, and at weaning it will no longer receive the milk formula. The amount and type of feed is scientifically designed to meet the calf's precise nutrition requirements, given its breed and age. Trust me, if you give just half the thought to what you feed your child as dairy farmers do for their calves, your children will be healthy and strong!
(C) From birth till weaning
You’ll notice the calf has its own little housing unit, separate from other calves. Calves are vulnerable to disease at this age, and keeping them separated from other calves reduces the spread of sickness. This also makes it easier to monitor exactly how much each calf is eating to ensure the calf is healthy. Because they do not nurse from their mothers the calves are confused about where milk comes from. Walk up to any dairy calf and extend your hand and it will try to nurse from it (really, you can do this, it doesn’hurt). If you place the calf in a group with others they will try to nurse from one another, also. Of course, they won’t find any milk, and this frustrates them, so they to butt the udders of their peers, causing injury and perhaps even knocking each other down. In general, whenever you see livestock producers separate animals into individual pens, whether it be cows, pigs, or chickens, it is usually to prevent them from hurting one another.
Figure 4—Dinner time!
When born the calves will be fed only formula milk twice a day (3:00 AM and 3:00 PM), and after three weeks grain and forage will be added to the diet. At eight weeks of age they will receive formula milk only once a day, and when they turn nine weeks old they are weaned completely. Shortly after weaning they can be placed in groups with other calves and consume only grain and forage.
If you look closely on the heads of most breeds of dairy calves you will find the beginning of horns. Yet, in all the Chick-fil-A commercials you’ve seen the black and white calves (Holsteins, they are called) don’t have horns. What gives? To keep the cows from hurting farmers and each other their horns are removed at an early age.
If you feel around the top of the calves’s heads you can find the roots of budding horns. By burning these roots with an electric dehorning iron or rubbing a special paste on the roots these roots can be removed and horns will not grow. It is painful, for sure, but if performed at an early age the pain is only temporary is less painful than being stabbed in the side by another cows’s horns. These calves have the fortune of being part of university research involving animal scientists and veterinarians in how to minimize the pain from dehorning, so not only will they feel less pain than other calves, but are helping us learn how to improve welfare throughout all dairy and beef cattle production.
The females, called heifers, will stay here on the farm for milk production. After weaning at about nine weeks of age the heifers will be placed into small groups of similar-aged calves and fed a high-energy, high-nutrient diet, supplemented by all the forage they wish to eat.
You’ll notice that every cow we will see, from the calf to her milking mother, is provided shelter with dry bedding for their comfort.
7-9 weeks of age
At about seven to nine weeks of age (differs across farms) the calves will be weaned and transferred to group pens, lots, or pastures, where they will be cared for until they are ready for breeding.
Figure 5—Weaned onto hay and grain
Figure 6—Between weaning and first breeding
(D) Artificial insemination at 15 months of age
15 months of age
Now the heifer is ready to be bred, but you won’t find a bull on this farm. Instead, she will be bred using artificial insemination. For those interested in how artificial insemination works, please see the following video created by the agricultural college here by Dr. Stein at the Department of Animal Science at Oklahoma State University.
Figure 7—Artificially insemination
(E) Brief detour: the carbon footprint of dairy production
Artificial insemination allows bulls with superior genetics to have far more offspring than would be possible using natural breeding. These superior genetics have led to an astonishing rise in cow productivity in the last century. While the number of dairy cows in the U.S. has fallen from around 17 million to 9 million since 1960, total milk production has rise 40%. How? Because each cow is producing more milk. A lot more! 1960 the average cow produced about 755 gallons (or 6,493 lbs) of milk per year, while today she will produce over 2,326 gallons (or 20,000 lbs).(G1,N1)
Figure 8—U.S. dairy production over time
This is a picture of what it takes to produce one gallon of milk today: 2 gallons of water and roughly 10 lbs of feed (that feed consists of Alfalfa hay, bermudagrass hay, cotton seeds, corn, soybean meal, and various vitamins and minerals).(C1,D2)
Figure 9—What the cow needs to make one gallong of milk today
In 1945 it would have taken five times the amount of feed and water to produce that same gallon of milk—a remarkable improvement in productivity, which both reduces the price of milk and lowers the carbon footprint associated with one gallon of milk (if fewer inputs are needed to produce one gallon of milk, that corresponds to fewer carbon emissions). In fact, the carbon footprint of a gallon of milk in 1945 was almost three times greater than the footprint today!(C1) (Note that “carbon” refers to carbon-equivalent emissions. For instance, methane is a greenhouse gas that creates 21 times the warming of the same amount of carbon, but instead of saying “one ton of methane” I say “21 tons of carbon”.)
That does not mean that the total carbon emissions from dairy production has fallen, as more milk is produced in the U.S.. than in 1945. Let X be the total carbon emissions from dairy production in 1945. If the same amount of milk were produced today the new level of emissions would be (1/3)X. However, milk production has risen 68% since 1945, and so the new level of carbon emissions from all the milk produced in the U.S. is (1.68)(1/3)X = 0.56X. Consequently, a rough calculation suggests dairy production today leads to about half the total carbon emissions compared to dairy production in 1945, despite producing much more milk.
Cows are producers of methane, a greenhouse gas, and they expel methane as they burp, which can be as often as once a minute. So being able to get more milk out of a single cow is like getting more milk for each lb of methane emitted, allowing us to consume foods we enjoy while benefiting the environment at the same time.
Of that surge in productivity in the last fifty years, 2/3 is due to better genetics, and 1/3 is due to better management and feed.(D1)
Figure 10—What the cow needs to make one gallon of milk in 1945
This attention paid to genetics is a rather recent part of running a dairy farm, when viewed from the long timeline of agriculture.
(F) Brief detour: selective breeding in dairy cattle
Up until around the time of Henry VIII in England, little care was given to what cows would be bred with another. In another lecture I talked about how King Henry enclosed the commons and converted it to private property, giving big landowners the monetary incentive to increase productivity. At the time, cattle were better described as different races in each region as opposed to different breeds. Each region had its own particular genetics, and people were not eager to import the genetics of other regions.(F1)
The black and white cows you see here—and in every Chick-fil-A commercial—are referred to as Holsteins in the U.S. and Friesians elsewhere. Every now and then a recessive gene will cause them to be red and white. They are called Holsteins or Friesians because this line of cattle was developed in both the Friesland of the Netherlands and the Holstein region of Germany. These cattle were imported to the U.S. at different periods, but most of today’s U.S. Holstein cattle can trace their ancestors back to the imports arriving between 1877 and 1905,(D1) and are the most popular dairy breed because of their superior milk production.
Figure 11—Origin of the Holstein breed
Figure 12—Holstein breed
The smaller brown cows are Jersey cattle, which originated from the Isle of Jersey in the English Channel. Although a single Jersey produces less milk than a Holstein, Jerseys convert feed to milk more efficiently (Holsteins therefore produce more because they eat more). This farm had only a few Jerseys until the price of corn rose to historical levels, at which point they integrated more Jerseys for their more efficient conversion of feed to corn. Milk from Jersey cows are also higher in butterfat, and if butterfat is scarce relative to fluid milk, the output of Jersey cows can elicit a higher price than their Holstein counterparts. For these reasons Jerseys can be more or less profitable than Holsteins, based on the price of feed and consumer demand for milk, cheese, and butter. (G1)
Figure 13—Origin of Jersey breed
Figure 14—Jersey breed
Interestingly, while the Jersey cows are gentle and have an gregarious personality, the meanest animal I have ever seen in my life was a Jersey bull. I hear Holstein bulls are no better.
Until 1750 very little attention was given to the bull that would be used, when today that is the most important choice a farmer can make. This might be because they had no system for collecting data and so no good system for designating which bulls were superior. The quality signals they relied on were flawed. When a farmer in the Elizabethan Age set about trying to determine whether a cow would produce a lot of milk they might look at the direction of its hairs on the rear part of an udder, a custom which had about as much validity as the many superstitions that existed at the time.(F1)
Today, milk production is a highly advanced science, and an enormous data collection program has been established, allowing dairy producers to use statistics—not myths or tradition—to identify the best genetics.
So if the carbon footprint of your milk is a major concern for you, then nothing is more important that the semen the farmer buys to impregnate the heifer. The good news is you don’t need to worry about whether the farmer is reducing the carbon footprint of milk. The farmer has even more incentive than you to get more milk with fewer inputs, and so this increase in productivity and reduction in carbon footprint over the last century came about by farmers doing what they do best: increasing the productivity of their animals. It came about out of the farmers’ self-interested pursuit of profits, not concern for the environment, as global warming did not exist as an issue in 1945.
The same thing goes for better nutrition, the second most important reason for higher dairy productivity. Before the 16th century a lot of farmers would slaughter much of their livestock in the fall because they couldn’t produce enough feed to carry them through the winter. This first changed once they learned to grow turnips for a winter feed. Over the next few centuries small advancements in nutrition were made, but still, even in 1900, the science of nutrition was hardly a science at all.(A1,M1)
Now, more thought is given into what these cows eat than what we feed our pets—or even ourselves. Today, computer programs are used to determine exactly what cows will be fed, and this program is used to deliver exactly what the cow needs at each stage in its life at the least cost. Farmers can purchase some of these programs themselves to determine their feed formulations, use free programs provided by university scientists (like the Spartan 3 program by Dr. Hutjens at the University of Illinois), or hire consultants to design feed formulations for them. Whatever strategy is taken, the feed will be determined based on the the size of the cow, whether the cow is lactating, an enormous amount of data on nutrition requirements and milk prices, and a computer optimization routine to make sense of it all. This is one reason why students in agricultural economics and animal science learn mathematical optimization algorithms in college. Since roughly half of the dairy farm’s cost is feed,(D1) and since small deficiencies in nutrition can cause considerable shortfalls in milk production, a farmer can thrive or go bankrupt based on her feeding strategy.
Figure 15—Computer program to formulate dairy cattle feed
(Accessed January 6, 2013 at http://www.youtube.com/watch?v=37bHvCG92zc)
Two years of age
Gestation (the time between conception and birth) for a cow is about nine months, so if she is bred at fifteen months she will give birth when she is two years old. During gestation dairy farmers will keep heifers in an outdoor lot, barn, or pasture. Wherever they are located they will be provide ample space, shelter, comfortable resting areas, and superb nutrition. This farm provides pregnant heifers with pasture with shelter.
At two years of age the heifer is ready to give birth for the first time. Her calf will be removed immediately after birth and for the first three days after birth her milk will be kept from the milk supply because it is high in colostrum. Once she has ceased producing colostrum her milk will be used for human consumption.
Twice, sometimes three, times a day she will be taken to a milking parlor. This is probably a pleasant experience. It give her exercise, variability in her activities, and relieves pressure in her udder, which can become uncomfortable if not milked.
Figure 16—Cow’s view of milking parlor
(G) The milking parlor
All modern dairy farms use automatic milkers, where the udders are cleaned and the milkers are placed on the udders by humans, but a machine does all the sucking, delivering all the milk into a storage tank. Observe what the milkers do for each cow. First they clean the udder, and then they dip it in iodine, to help sanitize it. They will check the udder to make sure the milk looks healthy, after which they will attach the automatic milkers and move to the next cow.
Figure 17—Attaching the automatic milker to the cow’s udder
While this is a typical parlor design, other designs exist. There even now exists a system where animals are led into a stall and milked automatically, with no human labor at all. Search the term “robots in agriculture” at criticalcommons.org to see a video of such a machine.
When the milkers squeeze each teat to inspect the milk they are looking for a bacterial infection called mastitis, where the mammary glands are inflamed, causing the cow pain and clumpy, semi-solid milk.
Figure 18—Checking for mastitis
When I milked cows about 20 years ago we didn’t check cows daily for mastitis like they do today. We would wait until a cow looked sick before we checked. This changed once U.S. producers realized European dairy farmers were producing higher quality milk, with lower somatic counts in the milk. Somatic counts are the number of cells per milliliter of milk. These cells are usually white blood cells produced by the cows’ immune system. Cows with mastitis will thus produce milk with more white blood cells. Milk processors today encourage farmers to produce milk with low somatic cell counts, as it indicates higher quality milk and allows them to produce more cheese from every gallon of milk. Most dairies, including this one, receive a higher price for its milk the lower its somatic cell count.
(H) Milk and antibiotics
Farmers will usually prescribe antibiotics in response to a mastitis-infected cow, and we should pause here to say something about antibiotic residues in milk. Cows receiving any antibiotic for any reason are separated from the herd and their milk is not sold for human consumption. If not separated from the herd, the animals identification number will be recorded and the milkers will be told to milk the cow but to not allow the milk to enter the tank with all the other milk.(R1) Milk is heavily regulated and there is zero tolerance for antibiotic residues in milk, meaning milk must have absolutely zero antibiotic residues for it to be sold. When scientists inspect milk sold in stores they find this zero threshold is only rarely violated.
Sometimes people are not just concerned about antibiotic residues in milk, but that the persistent use of antibiotics in livestock will lead to bacterial resistance, and the possibility that some human health problems currently treatable with antibiotics, will no longer be so.
Dairy calves used to receive small doses of antibiotics in their feed from weaning until their first calf was born, regardless of whether the animal was sick, but it is my understanding that this is no longer the case. These regular, low doses helped the animal remain healthy and grow fast, but it could also lead to bacterial infections that are resistant to antibiotics, infections that could harm both cow and human. The OSU farm only provides antibiotics when cows are sick. Instead, the farm manager says that from weaning until their first calf, heifers are given ionophores, which livestock industries often describe as a feed additive, not an antibiotic. Yet when Tyson Foods attempted to sell chicken meat labeled as “raised without antibiotics” they were prevented from doing so because they used ionophores,(M2) and the Illinois Agricultural Association has stated that, “One-third of all antibiotics used in livestock production are ionophores, which are never used in human medicine.”(I1). Are ionophores antibiotics? They probably are, but because there are no ionophores used to treat human infections, that places them in a class apart from what we usually consider to be antibiotics. If the dairy industry continues to use ionophores and bacteria become resistant to it, there would be little chance of that negatively affecting human health. So yes, ionophores are antibiotics, just not the kind we typically talk about, and not the kind that is at the heart of the controversy on antibiotic use in agriculture.
Video 1—Learn more about mastitis from the Dairy Coach Tom Wall
(I) The rest of a cow’s life
While the cow is producing milk she will be kept in a lot close to the milking parlor. She will be provided shelter with comfortable bedding (on this farm, sand), generous portions of food, and sometimes outdoor access with pasture.
Figure 19—Resting areas
Remember that the cow is about 2 years old the first time she is milked, and 2 months after that she will be bred for a second time.
Then when the cow is 2 years and 7 months old she will be removed from the milking heard and sent to a “dry lot” where she will have access to pasture (during the growing season), other food, shelter, and the like. After two months in the dry lot she will be ready to give birth again, and then return to the milking herd.
Figure 19—Resting areas
Once the cow has given birth about three times, and has been through the milking cycle three times, she will be “culled” from the herd and slaughtered for beef. It varies across cattle though, depending on how much milk the cow is producing and whether she conceives quickly. Cattle with low milk production numbers and experience difficulty conceiving will be removed from the herd earlier than other more productive cows.
What about the male calves?
The discussion thus far concerned only heifers retained by the farm for milking. What about the males, or the females that are not retained for milking? They will be sold when they are only a few days old, which is fairly typical for dairies. Dairy farmers wish to specialize in milk production, and there are other farmers who specialize in raising dairy cattle for meat. According to my sources, about 70% of male dairy calves will be raised for beef and 30% raised for veal (and by the way, veal is produced much differently than you probably think). Some farms now used sex semen, where the ratio of female to male calves born is higher than one-to-one.(N1)
Figure 20—Dr. Norwood feeding a calf
Figures
(1-6) Original photos
(7) Screenshot from Sunup video, accessed March 21, 2014 at http://www.youtube.com/watch?v=stvnGYcKz60&list=PLAF52949131FFB501
(8) Original figure. Sources: G1 and N1.
(9-10) Original figure. Sources: D2, and G2
(11) Maps taken from Wikimedia Commons (source is in the picture)
(12) DASNR Kitchen Sink
(13) Maps taken from Wikimedia Commons (source is in the picture)
(14) DASNR Kitchen Sink
(15) Screenshot from YouTube.com
(16-20) Original photos
