With apologies to that old popular song, at last year’s NADA convention, Ken McDowell reported that he has not had one open heifer in his 30 years of managing the Rotakawa herd in New Zealand. Ken said the major factor in this remarkable achievement is almost certainly his practice of not breeding his heifers until they are in their second year, producing their first calf at three years of age.

That, of course, goes against the common practice in the American cattle industry of breeding at 14 to15 months of age. And I had to credit Ken with a revolutionary and worthwhile idea.

Well, it turns out that Ken’s “idea” predates us all. Manley Miles wrote on this subject in his watershed book, “Stock Breeding” in 1878. In his third chapter on Heredity of Diseases, he relates how the diseases that a woman is carrying may not show up before she has her first child….

Let it be observed, this tendency to cancerous disease is most commonly derived from a parent who is not yet manifestly cancerous; for, most commonly, the children are born before the cancer is evident in the parent; so that, as we may say, that which is still future to the parent is transmitted potentially to the offspring.

If that’s correct, I believe we can assume that the defects that only show up with age will have more completely surfaced in a heifer that is 26-27 months old than in one that is just a yearling. How many of us have bred a “nice looking heifer” at 15 months, only to find out that her toes are crossing by the next breeding season? Or perhaps that defect we thought she would grow out of has only become exaggerated? If a heifer is saddled with these deformities and still is required to calve at two years old, what does this do to her system?

Miles likens this to an engine with an unbalanced flywheel. At idle, the engine appears to be working, but when increased in RPM, the defect becomes very apparent. Dr. Weston A. Price has stated that a person only extracts, at most, 1/2 of the minerals from their food. During periods of stress, a doubling of nutrition is needed. Pregnancy and calving are two of the most stressful times in a cow’s life. If our heifer is a coming 2-year old, and is trying to fulfill her now double nutrient requirements at the same time she is still maturing her own body, how can we expect full development her genetic potential? What incipient health problems are we exposing her to? And what is this doing to the genetic potential of her developing fetus?

Miles goes on to quote a certain Dr. Duncan, who says “child bearing by an immature mother is properly held to be dangerous to the continued general health of the mother, and to prevent her complete development in the size and a beauty….Many other authorities might be cited to the same effect, were it not that the influence of early breeding in arresting the development of the mother is so often observed by intelligent breeders as to render it unnecessary.”

A century ago, it appears that waiting until the second year of a heifer’s life before breeding was standard procedure. Earlier breeding was only practiced by those who did not know what they were doing! Miles references William Youatt, speaking of yearling heifers, “…at the time when they are most rapidly growing themselves, a sufficient quantity of nutriment cannot be devoted to the full development of the fetus, and both the mother and calf must inevitably suffer…The custom….can not be too much reprobated.”

Miles goes on to relate his general observations of young oviparous mothers having eggs which, “a larger proportion are not fertile, the yolk being frequently wanting or imperfect.” If we keep replacement heifers from our two year old first calf heifers, are we promoting infertile, imperfect animals for the future of our herds?

He then prints a chart showing the distribution of eggs over the life of birds…

Fowl produced 600 eggs over nine years distributed thusly
First year 15-20
Second year 100- 120
Third year 120 -135
Fourth year 100- 115
Fifth year 60 – 80
Sixth year 50 -60
Seventh year 35 – 40
Eight year fifteen- twenty
Ninth year one – ten

If I may be allowed to relate this to cattle, by waiting until the second year we may be eliminating the infertile, imperfect eggs from the first breeding season, allowing the heifer to grow up, and be productive until she is 12-15 years of age or beyond. She will be more developed and her flywheel more balanced and ready for the stress of pregnancy and calving. Will she also will imprint her first calf with a higher genetic potential. Well, actually Dr. Duncan indicates that a similar thesis pertains to women:

The influence of diminished fecundity in young mothers upon their offspring that they necessarily inherit the same peculiarity, would tend to predisposed to baroness and sterility in the breed or family in which early breeding is practiced; while the defective development of the mother, arising from the same cause, would become a constitutional peculiarity in the offspring.

As the retarded development of the mother and the defective condition of the germ and egg are both the result of immaturity and a consequent deficiency in a constitutional vigor, which, as we have seen, will undoubtedly be transmitted, they must have a marked influence in producing conditions of the system that predispose to disease.

The conclusion would seem to be inescapable. With early breeding, we are building into our cows and their offspring; all of the diseases so many cattlemen currently have to vaccinate against; the defects in form. By breeding at too young an age, we set in motion those things we commonly complain about: open second calf heifers; a national average of only 7 calves in the lifetime of a cow; a gradual decline in the fecundity and constitutional vigor of our animals.