This study was designed to describe and to fit linear statistical models to
predict live body weight (LBW) through shank length (SL) and LBW or SL
through bird age in three breeds of chickens: Fayoumi (PP), Golden Montazah
(GM) and Dandarawi (Dand) and two breeds of ducks: Pekin and Moscuvy and
Japanese quail . The data of SL in „mm‟ and LBW in grams were collected from
each bird in biweekly intervals up to 12 weeks of age for chickens , ten weeks
for ducks and up to 6 weeks of age for quail.
The following results were obtained
1. There was a definite relationship (P≤0.001) between LBW and SL for all
studied sex groups, except for Moscuvy males. SL was positively correlated
with LBW ranging from 0.794 to 0.977.
2. As SL increased by one mm for studied groups, LBW progressively
(P≤0.001) increased ranging from 9.12g (Dandarawi males) to 55.41g (Pekin
females), indicating that 63% to 95.5% of the variation in LBW were
explained by SL.
3. The cubic form had higher value for coefficient of determination „R2‟ and
lower standard error of estimate „SE‟ than quadratic, logarithmic and
exponential models in Moscuvy males. The cubic and quadratic forms had
the best fit for predicting LBW from SL for ducks males, regardless of ducks
breed.
4. Age in days significantly increased (P≤0.001) LBW of different types of
fowl of both sexes or each sex separately. All groups showed positive
regression coefficient ranging from 4.320g/one-day in case of Japanese quail
males to 59.499g/ one-day in case of Moscuvy males.
5. Regardless of breed, males of both chickens and ducks had higher regression
coefficients than their females. On the contrary, females in the case of
Japanese quail showed higher rate of increase of LBW as influenced by age
than their males.
6. Similarly, trends of positive significant influence of age in days on SL in
millimeters but lower in magnitude than LBW were observed in most
studied groups or sex groups.
7. There were definite relationships between LBW and SL and bird age
significantly affected either LBW or SL. Comparing „ R 2‟ of fitted equations
indicated that linear model was found to be suitable for predicting LBW
through bird age (with R 2 ranging from 0.809 to 0.966) or SL (with R2
ranging from 0.630 to 0.955).
8. In the absence of age, shank length can be used to predict live body
weight.