of cattle.

Although by carefully selecting the best animals (as Nature effectually
does by the law of battle) close interbreeding may be long carried on
with cattle, yet the good effects of a cross between almost any two
breeds is at once shown by the greater size and vigour of the
offspring; as Mr. Spooner writes to me, "crossing distinct breeds
certainly improves cattle for the butcher." Such crossed animals are of
course of no value to the breeder; but they have been raised during
many years in several {119} parts of England to be slaughtered;[251]
and their merit is now so fully recognised, that at fat-cattle shows a
separate class has been formed for their reception. The best fat ox at
the great show at Islington in 1862 was a crossed animal.

The half-wild cattle, which have been kept in British parks probably
for 400 or 500 years, or even for a longer period, have been advanced
by Culley and others as a case of long-continued interbreeding within
the limits of the same herd without any consequent injury. With respect
to the cattle at Chillingham, the late Lord Tankerville owned that they
were bad breeders.[252] The agent, Mr. Hardy, estimates (in a letter to
me, dated May, 1861) that in the herd of about fifty the average number
annually slaughtered, killed by fighting, and dying, is about ten, or
one in five. As the herd is kept up to nearly the same average number,
the annual rate of increase must be likewise about one in five. The
bulls, I may add, engage in furious battles, of which battles the
present Lord Tankerville has given me a graphic description, so that
there will always be rigorous selection of the most vigorous males. I
procured in 1855 from Mr. D. Gardner, agent to the Duke of Hamilton,
the following account of the wild cattle kept in the Duke's park in
Lanarkshire, which is about 200 acres in extent. The number of cattle
varies from sixty-five to eighty; and the number annually killed (I
presume by all causes) is from eight to ten; so that the annual rate of
increase can hardly be more than one in six. Now in South America,
where the herds are half-wild, and therefore offer a nearly fair
standard of comparison, according to Azara the natural increase of the
cattle on an estancia is from one-third to one-fourth of the total
number, or one in between three and four