268 
STATE AGRICULTURAL SOCIETY. 
And although it cannot be stated that in the cow, as also 
among other of the domestic animals, these processes can¬ 
not go on safely for a limited period together, still, natural 
historians and physiologists, when speaking of the periods at 
which wild animals reproduce their young, assume the rule in 
general terms. For, they say, “ the duration of lactation being, 
in general, equal in duration to that of gestation,”* therefore 
such or such an animal produces young once in so often, mak¬ 
ing the time, at least, double that of the known length of 
pregnancy. They also, however, state as a law, that habits of 
domestication tend to increase the power of reproduction 
within certain limits, both as regards frequency of occurence, 
and the number produced at a birth, and so far, indirectly, 
acknowledge that a yield of milk in excess of that required 
by the animal, may be brought about by following correct 
principles in breeding. But we may also be allowed to reason, 
that a sudden demand of 70 per cent, more milk from one set 
of cows, over others of the same breeds, subjected in all other 
respects to the same care and treatment, is too great a varia¬ 
tion from the natural law, to be permitted without a check 
somewhere; and it is seen that w’here tliis excess is demanded 
abortions occur. • 
The affirmative results obtained by the commission, this 
year, may therefore be briefly stated as follows, viz: 
1st. That cows, which have first calved at under three 
years of age, are more liable to abort during their subsequent 
pregnancies, than those who first calved at three years old or 
over, in the proportion of five to three; and that 83 per cent, 
of the cows raised on the farms reporting them, do first .calve 
at under three years of age. 
2d. That cows, subjected to removals at any tjme, are liable 
to abort, over those raised on the farms, in the proportion of 7 
to 4J; and that 63 per cent, are thus removed. 
8d. That cows, subjected to removals during pregnancy, 
are liable to abort, over those moved while not pregnant, in 
* Floureng ; Phisioligie comparee. Paris, 1856, p. 32. 
