Prediction of live body weight through bird age and-or shank length in different fowl types

الملخص EN

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.