Vle CONG, INTERN. REPROD. ANIM. INSEM. ARTIF., PARIS, 1968, VOL. Ii

years) outproduce their contemporaries, whereas their mature
paternal sisters (over 2 years at calving) have a lower contemp.
comparison. The opposite type is the late maturing, the daugh-
ters of which are lower producers at the young age, but the older
age groups have favorable contemporary comparisons.

Contemporary Comparisons within age groups fer yields in
305 days:

Under 2 years Over 2 years

No. of weighted | No. of weighted

Size | dahghet SIEL ST . il Bhagie v SEERAL st ae
yield yield

ters rence ters rence
Baron 225 6084 Kg +379 Kg 224 5951 Kg +119 Kg
Adi 136 G4 w356, ! 98 5869 " +151 "
Nez. 82 S410 W w730 100 5905 * 4140 ¥
Thor 428 5468 " - 34 " 828 BTG | M gy

Contemporary Comparisons for Rate of Gain by Bull-Calves:

- gty Weighted difference

Sire i in Kg. life-weight
in 400 days

Baron 268 - 10,8 Kg

Adi 178 = A Brdsesls

Nrz. 145 v 2 e

Thor 420 F1 1902 1

Progeny tests for rate of gain are carried out as within
herd and season ccntemporary comparisons of the male offspring
of Sires, raised for beef intensively in many herds, at 400 days.

Sires with daughters of the late maturing type have sons with
larger growth rates and are gaining well till a later period of
age, and vice versa.

This biological character of different rates of maturing,
known to exist between different breeds, exists also between
Sires of the same breed. It is necessary to ccnsider, that
Insemination of heifer-calves and culling of bull-calves for
beef should be carried out according to physiological and not
physical criteria, or in practical terms, according to age and
not according to weight.

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