. The effect of the age of sire and dam on the quality of offspring in dairy Cattle; Heredity. i68 The [ournal oi Hereclitv. JOHANNA DE KOL CONCORDIA Figure 11. At three and a half years of age her record was 19037 pounds of milk and 671 pounds ot butterfat. Her sire, Sir Clothilde Concordia, was two years nine months of age when she was born, while her dam, Cold Spring Johanna De Kol 2nd, was three years and a half old. The great number of cases where the parents of high producing cows are as young, or younger than these, leaves no doubt that the off-spring of immature parents are jus
. The effect of the age of sire and dam on the quality of offspring in dairy Cattle; Heredity. i68 The [ournal oi Hereclitv. JOHANNA DE KOL CONCORDIA Figure 11. At three and a half years of age her record was 19037 pounds of milk and 671 pounds ot butterfat. Her sire, Sir Clothilde Concordia, was two years nine months of age when she was born, while her dam, Cold Spring Johanna De Kol 2nd, was three years and a half old. The great number of cases where the parents of high producing cows are as young, or younger than these, leaves no doubt that the off-spring of immature parents are just as good producers or transmitters of production as those born when the same parents are mature. Photo by U. S. Department of Agriculture. (See text, p. 173.) In practical breeding, it would be very advantageous to know definitely whether the young born of immature parents are as ^'aluable for production, and for reproducing their kind, as those born of more mature parents. It is the aim of this paper to show whether the parentage of a group of high producing or superior cows aver- ages older than the parentage of a group of comparatively low producing or inferior cows. The paper also attempts to show the percentage distribution of offspring for the various ages of both sire and dam; the age when cows actually make their best records; and whether the offspring of very young or very old animals are inferior. METHOD The data reported in this paper were taken from Volume 27 of the Ad- vanced Registry Year book and the Herd Books of the Holstein Friesian Association of America. The superior class of animals chosen include those that up to April 30th, 1916, had made records of 24 pounds or more of butterfat in seven days. This included all of the so-called thirty pound cows since 24 pounds of l)utterfat is equal to 30 pounds of eighty percent butter. For purposes of more careful study, this class was divided into three groups as follows: Group I—All cows producing over pound
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