The Importance of Uniformity of Get in Evaluating a Sire

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Abstract
A study was made to determine the value of considering the uniformity of gets in fat production when selecting proved sires. 256 sire-progenies were investigated. Variance, (S X 2)/(n[long dash]1), was used as the measure of uniformity. The differences in the uniformity of the progenies were large and highly significant. The most uniform get had a range in fat production (difference between lowest and highest producing daughters) of 95 lb. and the most variable one had a range of 728 lb. Only a small portion of the differences, however, was repeatable in future daughters of the same sires. The best estimate of the relationship between the uniformity of the 1st 10 and 2d 10 daughters of a sire was a correlation of 0.11 with only 0.03 being directly attributable to the sire. The sires of the most uniform progenies produced future daughters with a range of only 20 lb. less than those produced by the sires of the most variable gets. The small effect that the sires were able to exert upon the uniformity of their gets was directly associated with their degree of inbreeding and was, therefore, non-hereditary in that it could not be passed from sire to son in other than an inbred population. Thus in the data studied there was no justification for considering the uniformity of fat records of progenies when selecting proved sires. A similar conclusion appears appropriate regarding selection for uniformity in any character which depends upon several gene pairs and which is not highly hereditary.

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