Chapter 8
Breeding
If you intend to breed your cow, it’s important to be able to detect when she’s in heat. Ideally, you’ll begin to notice the cycles, and mark them on your calendar, and be able to call for artificial insemination in time for the technician to arrive before the heat has passed.
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Detecting Heat
At any time from one week after calving onward it is possible for your cow to come in heat. This early heat is sometimes called the “calf heat” and may or may not introduce a normal estrus cycle and may appear as early as six months of age. Occasionally the next heat will be delayed for a couple of months, especially in a thin, high-producing cow. The estrus cycle in cattle is twenty-one days, with a normal range of eighteen to twenty-three days. The actual heat period is rather short, especially in winter. A period of from ten to eighteen hours is considered the length of time in which the cow can conceive. The signs of oncoming heat will start before this critical breeding period.
The signs of heat are mooing and bellowing; agitation, tail swishing, and prancing around; clear or stringy mucus on the vulva or tail; swelling and reddening of the vulva; sudden decrease in appetite or milk production; mounting of other cattle; and a bad attitude. A cow kept without any bovine companions may attempt to mount her human friends. If she is this excited, you will know she is in heat, so maybe you shouldn’t turn your back on her that day.
If you have other cattle of either sex, your cow will jump on them and they on her. After a couple of hours of alternate jumping, the one that stands still while being mounted is in heat. This is true even if the other cow appears to be more excited. This “standing heat”—when a cow does not object to holding up another—is the definitive sign of readiness to breed. When you telephone the inseminator, he may ask about your cow’s behavior. If you can tell him she is standing for another animal, he will expect his trip to be worthwhile. If you don’t have other animals, you can compensate for this lack of an indicator by being very observant in the months after calving. A dairy cow is usually a quiet animal. When she goes into a bellowing session, look for other heat symptoms. As noted, milk production will sometimes drop suddenly when a cow is in heat. A difficulty with this symptom is that you might not react to it quickly. The heat period is rather short, especially in winter. A period of from ten to eighteen hours is considered the window in which the cow can conceive. The signs of oncoming heat will start before this critical breeding period, so it is important to become adept at detecting signs of heat early such that you can arrange for the technician to arrive during this time.
One heat detection method is to stand behind the cow and put your weight on her back end. If not in heat, she will find this annoying. If she stands still and seems to like it, you have a useful indicator.
When you observe the first heat period after calving, note the date and mark your calendar three weeks ahead as well. That will remind you to be on the alert for the next heat so you can establish a pattern. Ovulation occurs about twelve hours after the end of standing heat. It takes some hours in the cow’s reproductive tract for the sperm to develop the capacity to fertilize the egg. Breeding should therefore occur toward the end or just after standing heat. Because the length of the cow’s heat may vary and the period of viability of both sperm and egg is also variable, the golden moment is sometimes known only to God and perhaps a bull. Yet artificial insemination works impressively . . . when it works at all.
The period of greatest heat activity is between twelve midnight and six a.m. If she has a bell on, you will hear a great deal of ringing, especially if there is more than one animal. Even alone, a cow is much more active when in heat. The poorest time to make observations is at feeding time. Have one person take responsibility for careful observation (just watching the cow) for at least two ten-minute periods each day, and four if you can manage it. Dairymen often report a dramatic improvement in their herd’s settling rate with this measure alone. Have everyone in the family trained to observe and report immediately any of the signs of heat. Mark suspected heats on a calendar along with the next projected date. Some cows seem to have a “silent heat” with no detectable signs. Experts writing on this subject suggest the main problem is that we neglect to observe carefully enough.
If all this fails, there is a hormone shot that you or your vet can give that will bring on ovulation (Lutalyse; it must be strictly avoided by pregnant women). Insemination then takes place three days later.
If there is a show of blood, heat is over. A breeding that occurred thirty hours earlier would have been ideal, so you can mark this on your calendar, too.
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Deciding on Calving Interval
The widely accepted ideal is to have the cow back in calf seventy to ninety days after calving. With a gestation period of approximately 285 days for a Jersey, breeding at eighty days after calving would produce the yearly calving often sought after. It isn’t always possible to be that exact. Yearly calving makes possible the highest milk yields and is a pattern that gives the cow a reasonable balance of milking and recuperating time in relation to the length of the gestation period. You may have a reason to lengthen a lactation so as to be in the dry period at a time when you wish to be away from home. Or if you have more than one cow, you may wish to spread calving around the year. You can also shorten the period between calvings by a month if your cow is young and healthy. Assuming you plan to breed for annual calving, the ideal situation for breeding is to observe one or two heats in a regular pattern and then breed your cow on the next heat that falls nearest ninety days after calving. If you don’t observe any signs of heat until eighty days, go ahead and have her inseminated on that heat. See also the section on infertility in chapter 16, “Diseases and Disorders.”
There isn’t any law that says you must get your cow bred back. You may just keep on milking her through a second year if you wish. Production will decline but will be boosted up again by spring grass. For this to work, great attention to stripping at each milking is required. See chapter 3, “Milking Your Cow.”
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Artificial Insemination
To arrange for breeding your cow, contact the artificial insemination service in your area, but don’t wait until your cow is in heat to locate the service. There are artificial insemination (AI) technicians within a few miles of most places where there are dairies. Consult a veterinarian or a local dairyman about an AI service. There is widespread sharing of semen from proven bulls among the services. Some larger cattle farms do their own insemination, but they’ll have a liquid-nitrogen freezing tank for the storage of semen. Sometimes a dairy will permit semen you have ordered to be stored in their tank and even assist with insemination.
Nathan Cossaboom, Artificial Insemination Technician.
Photograph courtesy of Joann S. Grohman
After you locate an insemination service, it is a good idea to talk to the technician in advance of the time you want your cow bred. Be sure he knows exactly where you live. You can discuss the cost of the service and the bulls he has available. You may ask for literature on the bulls his service offers. The cost of AI varies and generally includes a separate charge for the service and for the semen. There are various arrangements for repeat services if the insemination is not successful. A conception rate of just over 50 percent on the first service is common, so don’t be overly concerned if the first attempt is not successful. One of the many advantages of a flesh-and-blood bull over frozen semen is that the bull tries and tries again, and he’s there when needed. Furthermore, the AI service semen is greatly diluted. With an inseminator you may need to call by eight a.m. to get service the same day. You may observe your cow in heat at noon and not be able to get an inseminator until late the following day. This could be too late. My experience, however, is that the technicians do the best they can to arrive when needed.
If you want specific characteristics in your calf, such as high butterfat or A2 genetics (see the discussion of genetics here), you can arrange for semen to be pre-ordered and sent to either the AI technician or anyone nearby with a tank. This may add a couple of hundred dollars to the cost of insemination.
Many breeding difficulties (failure to come into heat especially) are reduced when a bull is kept. (The presence of the bull appears to induce heat.) If you have encountered breeding problems in the past and have a bull calf, you may be tempted to rear it to breeding age. I don’t advise it. A dairy bull turns dangerous at somewhere around fifteen months of age, and it isn’t worth the risk. If you have the space and good fences, a beef bull is safer. The resulting calves will make good beef, and a beef heifer may even be a fair milker. Sometimes there is a bull of a beef breed in the neighborhood where you can take your cow. In point of fact, if he is close enough to hear her bellowing, they are likely to find a way to meet. Then you won’t be able to separate them until heat is past. You may miss a milking, always a bad thing, but in this case it can’t be helped.
Unless you have been studying breeding records for some time, you won’t have much to go on in choosing an AI bull as a mate for your cow. You can tell the technician you want a bull that produces medium-size rather than large calves or one that has a high first-service conception rate or a record of milk or butterfat increase in succeeding generations. But all the technician’s bulls will be proven, so if you don’t have specific breeding goals, you can safely just ask for the cheapest.
After calling the technician to arrange for insemination, keep your cow in her stall so that no time is lost when he arrives. A big chase is not the best way to get the cow in condition for conception or to make a friend of your technician. A stanchion is an ideal place for insemination. If you don’t have one, your cow can be tied in a corner of her box stall. The inseminator puts on a plastic glove and sleeve. He reaches in the anus with one hand, removing the dung as he does so. With the other hand, he inserts a long plastic tube in the vagina, guiding it with the gloved hand (which is on the other side of the vaginal wall) into the cervix. If your cow is properly in heat this will not be difficult. When the end of the tube is in place, the technician pushes a plunger on the stainless-steel holder to eject the semen from a plastic capsule that has been placed inside the end of the long plastic tube.
When he is finished, the technician will write out a breeding receipt, which will include the identification number and name of the bull used. If your cow is registered, he will need to see the registration certificate in order to make out a receipt that will be acceptable in registering a calf resulting from the insemination. The technician will need water to wash, and he will wash his boots in disinfectant. This is a valuable precaution to avoid carrying diseases from one place to another.
It’s a good idea to keep your cow in for a while after the inseminator leaves. Evidence indicates that conception is more likely if she remains quiet. Insemination technicians vary in what they tell you about the condition of the reproductive system. Certainly while they have their arm in the cow they have the opportunity to feel the cervix, uterus, and ovaries. Since a technician is not usually a veterinarian, he doesn’t offer medical advice, but I have found that an experienced technician can tell me if my cow is well and truly in heat. If she is not, I am onto the wrong twenty-one-day period, and that is useful to know. If the technician should notice something amiss in the reproductive system (such as an enlarged uterus or a cyst), he may suggest veterinary attention.
You might think your cow would object to all this internal probing. She may, but if she is in heat, she will offer little resistance. (Our technician in England, however, was laid up for three months while his arm healed after an irate cow laid it open with a horn.)
A technician is accustomed to serving a cow without aid when necessary, as long as there is an adequate enclosure and the cow requiring his attention is identified (in case there is more than one cow on the place). If you cannot be present for his visit, leave a big note on the barn with your cow’s ID number, along with her registration papers if she has them. That is where he will look, and he may not bother to come to the house.
Note the date of the insemination on your calendar and also mark the date three weeks ahead. Watch for signs of heat when this date arrives; if you don’t see any, your cow is likely to have conceived. Another sign of successful conception is a sudden drop in milk production after insemination. With good feeding and scrupulous stripping, much of this drop in production can be regained during her pregnancy.
When two twenty-one-day periods following insemination have passed without signs of heat, it is reasonably certain that your cow is in calf. If you want to be sure, wait until eight weeks after service and have a veterinarian do a pregnancy check. A vet does this by reaching into the anus and feeling the size of the uterus. Some authorities say this check can be made after six weeks. Often it can, but it is an annoying waste of a vet call to be told, “I think she’s in calf. I’ll be able to tell better later.” BioTracking (a blood test for pregnancy) is easily possible and can be done earlier if you really need to know. (See the resources at the end of this book.)
If your cow does not come in heat, or if she comes into heat but does not conceive even though inseminated four or more times, read the sections on vaginal discharges and infertility, and consult your veterinarian. If a cow is very thin she may be unable to conceive. Get some fat on her bones.
If there is a special problem in cow keeping that goes with having one cow, it is this matter of heat detection. Sometimes the only practical answer is to forget about calf quality and find a bull. There are always a few cows that consistently fail to “take” with AI but can conceive by natural insemination.
I have known several people who have taken training classes in insemination and learned to do it themselves. This was necessary because they lived in very isolated areas.
A1 and A2 Genetics
For much of the following information I am indebted to Devil in the Milk by Keith Woodford (Chelsea Green Publishing, 2010).
It has long been known that casein, an important milk protein, exists in varying forms known as alpha, beta, and kappa. All of these forms are present in the milk of any cow. However, there are a few slightly different forms of beta-casein, with the most important being those known as A1 and A2 beta-casein. In 1993 a researcher in New Zealand, a major dairying country, made the observation that the incidence of type 1 diabetes among Samoan children living in New Zealand was tenfold higher than among children in Samoa. Researchers realized that the major difference between the two populations was the amount of milk in their diet. Subsequently researchers found that the rates of heart disease and diabetes were many times higher in countries where the majority of cows express beta-casein in the A1 form. Active research soon followed, with an emphasis on patenting a reliable test to identify the genes for A1 and A2.
Beta-casein is formed from a chain of 209 amino acids. A1 and A2 differ by only one amino acid. In the A1 sequence, histidine is found in position 67, immediately following isoleucine at position 66; the chemical bond between these two amino acids is weak. In the A2 sequence, proline is found in position 67, and it makes a strong bond with the neighboring isoleucine. The A1 form is believed to be aberrant, having resulted from a mutation around eight thousand years ago.
During digestion, enzymes readily break apart the weak histidine-isoleucine bond in A1 beta-casein, releasing a peptide (protein fragment) called beta-casomorphin-7 (BCM7). BCM7 is an opioid, a member of the morphine family, and is well recognized to have narcotic properties. It is not released during digestion of A2 milk. In susceptible individuals BCM7 is capable of causing a wide range of intolerance symptoms, including bloating, constipation, and nausea. All of these are believed to arise from BCM7 attaching to receptors in the intestines that control the peristaltic movement of food through the intestines.. This is also a well-known effect of some other opioids such as codeine, so it should come as no surprise.
What is even more problematic is that, in the condition known as leaky gut, BCM7 may enter the bloodstream. Leaky gut, more formally known as permeable intestine, is a chronic condition in some people and an intermittent condition in others. The gut of newborn mammals, including humans, is always leaky until a sufficient amount of colostrum has been ingested. The gut of those suffering from Crohn’s disease is chronically leaky. During a severe bout of diarrhea anyone’s gut may become temporarily permeable. Once in the bloodstream, BCM7 has been shown in rodent studies to attach to opioid receptors, where it causes psychological symptoms similar to autism and schizophrenia. The symptoms are reversed in the presence of naloxone, a well-known morphine antagonist, thus proving the presence of an opioid.
Opioids have been known for a hundred years to affect immune function, possibly explaining the association of BCM7 with numerous autoimmune diseases. BCM7 is an oxidant. It oxidizes LDL cholesterol, a factor in heart disease. Wherever it attaches, BCM7 leads to inflammation, which may explain its association with type 1 diabetes, supposing that it reaches sites in the pancreas. Inflammation is thought to be the initial agent in a great many diseases and disorders and has many causes besides BCM7 from A1 milk. Nonetheless, the evidence against A1 milk is increasingly robust.
Where A2 milk is so labeled, as is the case for some milk in Australia and New Zealand, purchasers often express their gratitude for being able to drink this milk without distress. The issue with A1 milk is entirely distinct from lactose intolerance or classic food allergy. Many people who believe themselves to be lactose intolerant find that they can drink A2 milk. It turns out that the real culprit behind their intolerance of milk may have been not lactose but A1 beta-casein. Alternatively, it may have been due to the BCM7 from the A1 beta-casein slowing down the passage of food in the intestines, and hence giving more time for lactose fermentation.
No genetic engineering or gene splicing would be required to eliminate the A1 variant (or allele) from the national herd. Simple old-fashioned selective breeding would do it. Cows are either homozygous (pure A1 or pure A2) or heterozygous (carrying genes for both forms, in which case their milk is a mixture of A1 and A2). Nearly all Guernsey cows are A2, and many Jerseys are A2; black-and-white cattle are often A1. However, there are too many exceptions for cow color to be of predictive value. All Asian and African cattle that have not interbred with northern European breeds give A2 milk, as do all goats, sheep, yaks, camels, buffalo, and also humans. Three or four generation of using only A2 bulls would virtually eliminate A1 cows. (If you’re interested in finding out what type your own cow is, a number of laboratories will test bovine DNA to find out whether it is A1, A2, or a mix of the two. The UC Davis Veterinary Genetics Laboratory in Davis, California, is one such lab; contact them at 530-752-2211 or via their website at http://www.vgl.ucdavis.edu/.)
Milk is a uniquely valuable food. For millions of people milk is the most consistently available high-quality protein food. Although most people, thanks to a healthy digestive system, are probably unaffected by A1 milk, for some it would appear to be a problem of no small significance. Since breeding away from A1 cows is a straightforward matter, why not do it? After initial enthusiasm for pursuit of research on the A1/A2 factor, which has the potential to greatly expand its consumer base, the dairy industry has chosen to dismiss discussion. Keith Woodford informs us that in New Zealand, which is the world’s largest trader in dairy products, herds are quietly being bred away from A1 cows. In Australia, “A2 milk” (i.e., milk in which all the beta-casein is of the A2 form) is now available in all major supermarkets across the nation. A2 milk is also now available in Britain.
Further discussion of these and other issues surrounding A1 and A2 milk may be found in Keith Woodford’s book Devil in the Milk.