Build and Performance

Judging in this way does not settle all the problems in choosing a cow or bull, especially in everyday farming operations. The solutions would come if all milk cows were tested for ability to produce, and sold and handled on that basis. But in all probability it will be many years before most milk cows are so tested. It is important, therefore, to obtain every bit of information that may be used to provide the soundest possible basis for selecting animals by their appearance, body form, or physical characteristics.

As a start toward getting this knowledge, all available information about the relation between build and performance in several species of animals was studied. The investigators learned, for example, a great deal concerning the mechanics of the horse and the relation of its form to its strength and adaptability. Some data were obtained pertaining to the form of meat animals and its significance as to carcass value. Leading anatomists, physiologists, athletic directors, and other specialists were asked for precise information that would indicate, for instance, whether a specific shape among humans would indicate a better constitution or stamina than some other form. Medical colleges had records of thousands of autopsies, but in most cases pathological conditions were involved, and their data helped little. Veterinarians offered many ideas and opinions, but none of those interviewed could supply specific data to clarify the subject.

Theories taught in the show ring and classroom implied that there were certain relationships between the external form and proportions of the dairy cow and the size of her body cavities and chest and abdominal organs. They also implied that large cavities and internal organs were essential for strong constitution and good feeding capacity, and thus for efficient and high production.

Soon after our studies began, we made arrangements with Swift & Co. to obtain measurements of cows purchased for slaughter, and to weigh and measure their internal organs and carcasses. Ante mortem and post mortem data were obtained on nearly 400 cows. Most of the cows, selected for the study at the time they were bought in the yards, showed indications of being identified with one of the dairy breeds and of having been kept for dairy purposes. No record of their producing ability was obtainable, but our data provided ample material for our study, which was published in 1939.

In the meantime, a similar study was started at Beltsville, where cows in the experimental breeding herd were slaughtered when they had fulfilled their purpose of demonstrating their producing capacity and leaving offspring for comparison with themselves.

Before slaughter, each cow was photographed and her form measured. At the time of slaughter, internal organs and endocrine glands were weighed. The dimensions of the chest cavity were measured for length, depth, and width at every rib or vertebra. Thirty-seven ante mortem and eighty-two post mortem items were included for each cow. Since every cow had a record of production, the data thus obtained provided a basis for determining not only the relationship between external form and internal anatomy, but also the interrelationships between external form, size of organs and body cavities, and capacity for milk production.

The study had not long been under way when a number of the State agricultural experiment stations became interested, and a cooperative arrangement was made with more than 20 of them to handle in the same way the cows to be discarded from their herds. The information was catalogued according to the plan followed at Beltsville.

When approximately 600 cows had been studied in this way, a report was prepared on the average body form and anatomy of cows of the more prominent dairy breeds studied, and how much the form and anatomy of individuals and breeds varied. It has served as a useful guide in subsequent anatomical studies. Correlation studies are planned when data on a sufficiently large number of cows are available to justify statistical analyses.

Pregnancy is a disturbing factor in interpreting results of many studies of inheritance, growth, nutrition, physiology, lactation, body form, and anatomy of animals. More specific information is needed on what takes place in the pregnant uterus. In the course of the anatomical studies of more than 900 cows, pregnant animals have sometimes been slaughtered. In such cases, records were kept of the weight of the uterus and its contents, the fetus, the amniotic fluids, and the fetal membranes. An analysis of these records, which are available for 115 pregnancies, has shown the rate of growth of the various parts and their relation to one another. It has shown the changes in body form of the fetus during successive stages of gestation, and the breed and sex differences in weight of fetus. The results are particularly valuable from a scientific point of view.