Ba. Shalev et H. Pasternak, INCREMENTAL CHANGES IN AND DISTRIBUTION OF CHICK WEIGHT WITH HEN AGE IN 4 POULTRY SPECIES, British Poultry Science, 36(3), 1995, pp. 415-424
1. It is proposed that a general biological pattern exists for chick w
eight increase with hen age for the various commercial species of poul
try and that one general equation can be used for the estimation of ch
ick weight increment. 2. The parameters estimated for this equation ar
e based on (a) chick weights as a percentage of annual mean chick weig
ht, and (b) age, from onset of lay, as a percentage of maximum age of
the hen; both serving as common denominators. Hence, if the annual mea
n chick weight is known for any species, breed or strain, then the inc
rease in chick weight can be predicted for the whole season, or for an
y particular hen age. 3. For early prediction, first-month chick weigh
t can be used to estimate the annual mean weight and consequently the
chick weight curve for the full season. Although such prediction will
be somewhat less accurate, it still can be used for general planning.
4. Results indicate that chick weights of various avian species are no
rmally distributed. Therefore, at each point of hen age, the chick wei
ght distribution can be estimated by employing the computerised Burr's
(1967) equation. This may be useful for segregating chicks by size, t
hus improving uniformity and reducing competition within the flock. 5.
Computation results show that coefficient of variation (CV) of chick
weights, originating from 22 and 62 week dam ages, is increased by up
to about 75%. The CV may thus be used as a quality indicator.