Use of Mathematical Modeling in Evaluating Production Performance of Commercial Layers Under Sudan Conditions (Khartoum state).

Abstract

The model of wood (1967) which is used to fit the lactation yield data of dairy cattle on time had been adopted here to fit egg production curve for two hybrid layer strains and their standard manual. The strains are Hyline W98 and Lohmman LSL which kept under Sudan conditions. The egg production performance data of four poultry farms in different size in Khartoum state were used. Two of those farms reared Lohmman LSL hybrid strain while the other two farms reared Hyline W98 hybrid strain. The traits of age at the first lay, age at 50%, H.D production, age at peak production, percentage at peak, mortality rate, feed intake and production period were calculated and tested for the significance of difference between the two layer hybrid strains using t-test. The difference between each hybrid strain and the standard reported on its manual was also tested using single sample t-test. The weekly H.D egg production from 5% production for each farm was regressed on time according to wood (1967) lactation curve equation:- Y= a x b . e x p (-cx) Where:- Y = egg production. a = initial egg production. x = age in week. b = rate of increase to the peak. c = rate of decrease from the peak. No significant difference between the two hybrid strains and their standard values were found in most of the production traits. There is a significant difference (P<0,05) in mortality rate up to the end of production in each hybrid strain when compared to its standard manual. Hyline W98 feed consumption was significantly (P<0,05) III lower than that of Lohmman LSL where as feed conversion ratio ofHyline W98 was significantly (P<0,05) improved. Egg weight of Lohmman LSL was significantly (P<0,05) higher than that of Hyline W98 while the later has longer production cycle. Mortality rate of Hyline W98 was higher during the period from first lay up to the end of production than that of lohmman LSL but the difference was not significant. The components of the production curve were examined for significance of different between the two hybrid strains using t-test. The components of the production curve were:- a = age of first egg. b = rate of increase of curve to peak. c = rate of decrease of curve from the peak. b/c = week of the peak. b + 1 lin c = persistency of the peak of the curve. No significant differences between the two hybrid strains and their corresponding standard values in production curve parameters. The study results concluded that the formula of wood (1967) could be precisely fitted the data of the egg production and therefor it can be used for the prediction and evaluation of egg production. The study also concluded that the two hybrid strains perform under Sudan conditions were similar to their standard manuals which indicating that these hybrid strains have a good adaptability to the tropical environments. Further more, there are no differences between the two hybrid strains in most of the traits examined.