Calving by the Numbers

Updated 11/26/2012
A friend told me the other day that he looked forward to calving season less each year. Mainly it was his having to get up to check on the animals around the clock. This made me think about nature and wonder who gets up to make sure all of the elk and deer are able to have their offspring. In the rare case that one of these females has a problem, nature takes its course, and she does not have a chance to pass those “unsuitable” traits along to any further progeny.


In nature, bugs are the clean-up crew to get rid of the plants that are not fit for consumption. Man comes along and uses chemical warfare agents to keep the bugs from eating the low-nutrient food in his field and then sells that harvested feed to the middleman who advertises it to us as “new and improved.”

What we are doing in our cow herds is no different if we continue to retain animals that can not have offspring on their own. I suggest we go ahead and pull that calf, and when it is time to wean the calf, both mother and offspring should be removed from the herd.

A cow or a heifer should be able to have a calf on her own. If it can happen in nature, it should be our goal to have it take place in our herds. How do we go about selecting for heifers and cows that will calve on their own? The very first place to start is in the shape and width of the rump of the female. A heifer or a cow that has a rump two and one-half inches wider than it is long will rarely have calving issues. If she is wider than this, it only makes calving easier. If her pin bones are spaced wide apart, it is an indication of the width of the pelvic area. Instead of a high tail-head, we are looking for one that rounds down to the rear and off to the sides. This rounding of the rump from hip bones back keeps the calf from having to go as high and making quite as sharp a turn during birth. Both of these traits make calving easier. Another area not to be overlooked is the heart girth. A deep heart girth will give her heart and lungs more room to function and she will be able to handle stress better.

A heifer that has matured in size and glandular function will be able to devote more of her pregnancy to the development of the fetus in the intra-uterine environment and less time completing her own growth. Dr Weston A. Price stated that animals and humans can extract only about 50% of the vitamins and minerals CONTAINED IN their food. At times of stress–pregnancy, fight or flight situations, weather, etc.–we have to double the intake of nutrients to replace those being used by the body.

At two-years old, just at the time a heifer is replacing her teeth, how can we expect her to double her feed intake? Mature cows are able to consume 27 and 50% more alfalfa and brome hay, respectively, per unit of metabolic weight than heifers. If we let that heifer wait until she is three to have her first calf, she will be matured phenotypically, have built up energy stores as back fat, and be able to devote most of her energies to the unborn calf and to nurse that calf until it is 9 to10 months old!

Dr. Edward Howell has been able to show that if we use up our enzymes in a stress-filled life, eating low-quality food, diseases of opportunity will befall us earlier in life. If we want that cow to stay in our herd until she is 12 to15 years old, we have to be good herdsmen, making sure she is looked after in a manner that reduces the stress and increases the nutrition she receives, along with maintaining the economic feasibility of the ranch, the farm and ourselves.

High-quality nutrition is vitally important not only to the cow, but also to her calf. At a minimum this high-quality food needs to be in the bull’s and cow’s system for at least 120 days before calving. The reason 120 days is a “magic” number is that that is how long it takes to change out all of the red blood cells in an animal’s body. The quality of sperm cells from the bull and egg cells from the cow have certain genetic potentials, which can only be passed along in their purest form if we nourish our animals well enough to do so.

The highest-quality feed on our farms starts when the grass greens up and begins growing in the spring. If that is May first in your locale, 120 days later will be approximately September first. Breeding on this date will give us a calf in June. On June 10, there is more potassium in the grass. Potassium helps to prevent dystocia. During the calf’s first 12 days of life, many cells needed later in life are laid down. That first meal (colostrum) is filled with all of the antibodies and bacteria the calf needs to populate his/her gut. Any stress at this time can delay or stop the process. Do we need added weather stressors when so much is on the line in those first 12 days? According to Dick Diven, a cow that calves closer to the longest day of the year breeds earliest and heifers born closer to the longest day of the year will commence cycling at a younger age than those born closer to the shortest day of the year.

We can’t leave that cow without determining her ideal adult size. Every environment is different; however, one thing that can be said is that the smaller a cow is, up to a point, the more efficient she is. A frame 3.5 cow that weighs 950 pounds in Nevada may weigh as much as 1150 pounds in irrigated pastures in California or Virginia. Ease of grazing will vastly change the “fighting weight” of any cow. What we are looking for here is a cow that weans a higher percentage of her body weight, each and every year, with the least input cost. One hundred 1000 pound cows will wean more total pounds than seventy-two 1400 pound cows. The reason is that as a cow goes up in weight, the percentage of the weight she weans every year decreases.

Ideally, we need cows of such a structure that their body condition score (BCS) is still adequate after 10 months of lactation. The cow that is put together, with a good escutcheon to boot, and can nourish her calf for 10 months will contribute to the development of that calf’s rumen to its fullest potential. The only reason to wean a calf, in my estimation, is to allow time for the cow to achieve the proper BCS prior to calving. If the cow is not calving in sync with nature, we have to feed very expensive stored forage and supplements to maintain her. Dick Diven says, “When day length is short, a cow must have a much higher BCS (for rebreeding) than when the day is long…. Further, even when calving on a day of long photoperiod, the farther south the ranch is located, the higher the BCS must be.” If this is true, and I have no reason to doubt it, we will be weaning her calf earlier to keep the cow in a higher BCS and feeding costly inputs to do so. We are losing on both ends of the stick. Using a few weeks of your highest-quality grass forage in the spring to achieve the proper BCS makes it much less expensive.

What should genetic potential look like phenotypically when we are selecting a bull? Wide shoulders on bulls put wide rumps on females. Remember, the wider the rump is on the female, the easier time she will have at calving. At a minimum, the shoulders of the bull should be 2 inches wider than the rump length. If we choose masculine, prepotent bulls, our calves will be born closer to their father’s birth weight and length of gestation . A crossbred or out-crossed bull will not have offspring as consistent in size, quality and gestation as a line-bred bull.

Pedigree and the uniformity of the breeder’s herd will be two of the main indicators to use to find a prepotent bull. High-breeding is sometimes used synonymously with close-breeding, but it more properly signifies a rigorous selection of breeding stock with reference to a definite standard and within the limits of a particular family. We can not let those be our only ruler. The size of the “factory” is of utmost importance. James Drayson, in his book Herd Bull Fertility, says you can somewhat know how long your breeding season is going to take by measuring the bull’s testicles, starting as early as 7 ½ months of age. The charts in his book show how fertile a bull is by measuring scrotal circumference and length. Length is just as important as the circumference because the combination of the two measurements will give us the total size of the “factory.” Very few bulls born in America today fit into his optimal category.

Now that we have a well nourished “factory,” what can we expect? Bulls collected in New Zealand off a diet comprised exclusively of forage always have higher live sperm counts and lower abnorms than grain-fed bulls or, worse yet, those fed fermented feedstuffs. Cows that are well nourished and cycling close to the fall equinox are the most fertile. A higher percentage of our females should get pregnant within a shorter breeding season under these two conditions. Culling open cows that have had a 45-day exposure to bulls rapidly increases herd fertility. A shorter calving season would, in and of itself, make my friend happier, let alone the thought of not having to pull as many calves.

What goal do we have in mind for the finished product of our cow’s offspring? Are we looking for an animal that will produce gourmet grass-finished beef? If we are, we need to be selecting for quality and quantity indicators in the bulls and females we put into our herd. A cow having an unusually small front cannon bone, both in length and diameter; a pointed poll; a clean hock; an adrenal hair whorl placed in her shoulder area or forward; a uniform, shiny hair-coat; a gentle disposition; and an escutcheon that indicates a lot of butterfat will provide us with gourmet beef. Speaking of butterfat and milk, A2 milk is natures natural feed for all young mammalian offspring. Of all the mammals that have been tested for A2 milk–sheep, goat, camel, yak, water buffalo, bovines and humans–bovines are the only mammals that don’t always test positive for A2 milk. Breeds of cattle that have not been “messed with” will have a much higher probability of testing positive. Holsteins will probably have the smallest percentage, as they have been bred for quantity instead of quality for a long time. Have you ever heard that goat milk is easier for humans to digest than cow’s milk? I speculate that, everything else being equal, it is the A2 qualities of the milk that makes this difference.

Volume of meat in this gourmet animal will be influenced by rump length, rump width and heart girth. For every inch the animal’s girth exceeds his top line measurement, we add thirty-seven pounds of red meat to his carcass. (For more information on this subject go to )

Well, this may not have been algebra or trigonometry, but a close look at the numbers by which we select, run and breed or animals will allow us to begin to make the kind of changes which will make calving season more enjoyable and profitable. When a person starts to think about all of the blessings that come with calving in sync with nature, it becomes obvious why the wild animals have few problems.

1 Milch Cows, Guenon, Orange Judd Company, 1913