Articles concerning teat development/placement in bulls as predictor in daughters:
1) A Well Balanced Bull & Masculinity…Gerald Fry http://www.bovineengineering.com/balanced_bull.html
"We consider that a well balanced and well shaped udder in the cow is largely due to the way the rudimentary teats are placed on the sire. If they are crowded close together, the result is likely to be narrow pointed udders. If they are placed well apart, of good size, and well forward of the
scrotum, the effect, we think, will be to influence largely the production of well-shaped udders in the resulting heifers and counteract the tendency to ill-shaped udders inheritable from dams deficient in this respect. We believe the future excellence of the Guernsey cow will be greatly aided by close
attention on the part of her breeders to this point".
Van Pelt's cow demonstrationVan Pelt's cow demonstration"
As an indication of the size of the udders and the place-
ment of the teats on the progeny of the bull the rudimentary
teats which should be found forward on the scrotum should
be recognized as an index. It is believed that if these teats
are large the teats of the female progeny will be large, and if
the rudimentary’s are placed far apart the teats on his daughters will be placed far apart. In addition to being a desirable
trait, this is an indication that the udder will be both long
Mammary veins and milk wells are important points to observe in selecting sires, for, as in the cow, they indicate the volume of blood flowing to the lower parts of the body. Insomuch as it is so important that there be a great flow of blood through the udder of the cow, it is necessary that the
characteristics of the bull indicate that he will transmit that trait to his descendants.
Bulls differ greatly in size, length and development of
mammary veins much as do cows. Some of them have large
veins that pass as far forward as the shoulder pits. Others
have veins that are small and short with no signs of branches
and ending in milk wells that are so small that they are
difficult to find. It is not to be expected that a bull's veins and
wells will be as large as those of the cow for the Same reason
that the veins of a young heifer or a cow far advanced in the
period of lactation will not be as large as those of an older
cow or one that is giving a large flow of milk. Heavy production
develops the size, and it is noticeable that cows well fed and forced to yield large amounts of ilk for a long period exhibit greater veins and wells than those that have never been stimulated to do their best. Nevertheless, the presence of large, tortuous, long, branching veins and large, numerous
milk wells on the sire indicate that his heifers will have correspondingly desirable veins and wells. When the heifers come into milk they may be developed by good care and feeding. Other things being equal, they will be more productive than the descendants of a bull less developed in these respects.