Breeding the next generation cattle is always a combining of the females we have in our herds with the breed leading sires to obtain even more profitable herd in the future. How big our Holstein cattle need to be and how their bodies function are important matters that future focused discerning breeders are asking about and discussing with fellow breeders.
How Do You Measure Size?
Many different yardsticks exist in dairy cattle to measure size. It can start at the muzzle and goes all the way to the pins. For some breeders, it starts at the ground and goes to the top of the cow. In the perfect cow it a combination of everything – front to back and top to bottom. However, are all areas that measure capacity of equal importance? Alternatively, are there some areas that are more important than others?
Type classification programs and the show ring deal with many areas relative to width, depth and total mass. There are many areas, but I seldom hear reference made to the lung capacity that an animal has. Sometimes we hear mention of width of heart, as a measure for the size of the lungs. However, do we know, for sure, if animals that have more width of chest and heart actually have a greater lung capacity?
Do You Consider Lung Capacity?
We know that in humans the ability to take in air and add oxygen to our systems is essential for every person especially physical workers, mountain climbers or Olympic athletes. Do cattle breeders consider the capacity of their animals’ lungs? If they do, how do they know if animals have more or less lung capacity? As in human environments, dairy cattle are subjected to high altitudes, high temperatures and airborne diseases and our cattle are expected to perform no matter what. Every breeder knows that calves that have had severe pneumonia will not reach their genetic potential to produce milk. So less lung capacity due to loss definitely has an effect on performance. In cows, the more milk produced, the more blood that must flow to the udder. Every drop of blood requires oxygen. Larger lungs facilitate the addition of more oxygen to the blood.
Measuring Lung Capacity
One question that remains unanswered for me is this: “By breeding taller and taller Holsteins with narrow and narrower width between their front legs and also less width side to side in the heart region, have we decreased the lung capacity of our breed?”
I know from hands on experience that cows in hot climates differ in their ability to cope with sweltering weather. Especially when the temperature does not drop during the night. It’s hot sometimes for weeks on end. I have seen, in such an environment, wide chested cows able to produce 100 pounds (45 kgs) of milk in 113F (45C) temperature days. Moreover, in the same herds small heart and narrow chested cows have froth dropping to the ground from their mouths. They are panting, and even when cold mist is sprayed on their backs they can barely produce 80 pounds (36 kgs). In large herds, the managers do not often choose to take the steps necessary for the narrow cows to be comfortable. It’s a matter of economics not animal treatment. Trained staff are often not available on the farm. The narrow cows self eliminate from the herd.
During physical exams, people often blow into a device to measure their lung capacity. It’s not so easy to get a measure of an animals’ lung capacity. Somehow we need to know more about lung capacity and its impact the productive ability of our dairy cattle.
More Thoughts on Lung Capacity
There may be a way to physically measure lung capacity in dairy cattle but then to collect enough data to do genetic evaluations is a very costly task. Could an animal appraisal be done on heifers at weaning for a number of traits? Besides lung capacity, additional traits could include weight, feet, height, vigour and rumen function. After all, we need the type of weanling that will grow into heifers able to calve at 20 months and then quickly become productive and profitable member of the milking cow herd. Herd replacements are the third biggest cost item on dairy farms yet we often do not track and manage the heifer herds as well as we should.
It would be possible if we knew both lung capacity and genomic make-up of a sample group of heifers to develop a genetic evaluation system to breed for lung capacity without having to directly measure lung capacity on every animal.
Lessons from Secretariat
Let’s let our thinking move beyond dairy cows to race horses. For those breeders not familiar with Secretariat, he was perhaps the greatest racehorse in history. He won every race in the Triple Crown, the three biggest races that horse greatness is judged by. Not only did he win all the races, but he won that last one by 31-lengths. Destroying the competition. Charles Hatton of Daily Racing Form comments on Secretariat as follows “ Secretariat had depth of barrel, with well-sprung ribs for heart and lung room …. with the big rear end, the straight legs, huge lung and blood-pumping capacity, and his great size, he was a phenomenon waiting to happen ….. He lost only five times in his career … He was on the threshold of track or stakes records in most of his races and he broke them in his Triple Crown races … after his death, at 19 years, in 1989 post mortem examination revealed that his heart was two-and-a-half times the size of a normal heart for a horse his size. Not enlarged. Just big. There’s an equine gene for it. He had that too.” If there’s a gene for heart size in horses then likely there is a gene for lung capacity in dairy cattle.
The Bullvine Bottom Line
Breeders select and care for their animals so they can maximize their lifetime profit. We know and are learning more every year about the genetic makeup of our dairy animals. It is time to think about how our animals’ lungs operate in order to complement the balanced nutrition, sound management, high-calibre genetics and cow friendly environments that we provide. Maximizing oxygen intake is important.
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