The effect of the age of sire and dam on the quality of offspring in dairy cows.. by Allen Charles Loring 1889-

Author:Allen, Charles Loring, 1889- [from old catalog]
Language: eng
Format: epub, pdf
Tags: Cattle, Heredity
Publisher: Washington, D. C.
Published: 1922-03-25T05:00:00+00:00

Allen: Effect of Parents' x^ge on Quality of Dairy Cows 171

46.9

45.1

Great Grand Sire

49.5

46.6

Grand Sire.

47.1 43.1

Sire

Grand Dam. 66.7

66.7

42.1

43.6

Grand Sire.

Dam.

61.9

63.1

Grand Dam. 61.0

64.7

Great Grand Dam 62.5

65.7

AN AGE-PEDIGREE OF THE TWO CLASSES OF COWS

^"■iGURE 12. This shows the average age of the ancestors of the superior cows (Bold-face type), and of the inferior cows (Italics). It is evident that there are no significant differences in the age of the forebears of the two classes. (See text, p. 169.)

the sires of the Superior Class average less than four years of age, 46.4 months to be exact, and that the sires of the Inferior Class average somewhat younger. The largest number of offspring were born when their sires were from two and one-half to three years of age. This means that these bulls sired a larger percentage of their offspring between twenty-two and twenty-seven months of age than at any other time.

Table II shows very clearly just how our purebred sires are used. It indicates that improvement has been based on the selection of young sires rather than on the use of tried sires.

THE PROVEN SIRE

A bull cannot be called a proven sire until his first crop of heifers come in milk and can hardly be so called until these heifers have milked at least one year. Thus a bull can hardly

be called a proven sire until he is five years of age. In general practice, the percentage of cows sired by unproven bulls is probably much higher than the percentage shown for the animals included in this study. This means that even the breeders who are making records use a tried sire for only a small percentage of their cows. That the tried sire is more valuable is indicated by the fact that 21.1 percent of the Superior cows are daughters of tried sires, whereas only 15.9 percent of the Inferior cows are daughters of bulls of an equal age. This may seem to conflict with the idea that the bull when old is not more valuable, but the paper referred to above shows that he is not more valuable as a parent.

FREQUENCY DISTRIBUTION ACCORDING TO AGE OF DAM

The frequency curve for the dams, Figure 13, is very much more irregular than the curve for the sires but on the

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