Effects of age, season and year on egg production and layer bird mortality

Abstract

Egg production and layer bird mortality data obtained from 5 different farms in Zaria over a six-year period (1994 - 1999) were subjected to least squares analysis to determine the effects of age, season and year. It was demonstrated that age had a highly significant influence (P<0.01) on egg production in that birds falling within the age group 30 - 39 weeks produced the highest number of eggs (3255±109), while birds over 100 weeks of age produced the least number of eggs (1206±412). Similarly, seasonal variation in egg production was also significant (P<0.05); the highest egg production (2926±90) was obtained during the early dry season, and the lowest (2423±95) during the late wet season. Mortality was generally low (0.0 - 0.9%) and not significantly different from 20 - 49 weeks of age (P>0.05). However, from 50 to 100 weeks of age, highly significant differences (P<0.01) in mortality were observed with 90 - 100 weeks age group recording the highest mortality of 15.7±1.3 %. Furthermore, yearly variations in egg production and mortality were highly significant (P<0.01) with 1999 producing the most eggs (4410±102) and recording the least mortality (1.4%). It was concluded that due to the significant seasonal, age and yearly variations, data on egg production and mortality need to be adjusted for these effects for unbiased comparison between and within farms.