Comparative egg production analysis of isa brown laying strain raised in three poultry farms in a tropical environment

Abstract

Data from egg production records involving a total of 1,208 intensively-managed Isa-brown laying strain obtained from three poultry Farms A, B and C located in Calabar Municipality were used for this study. Percent henday production was computed for a period ranging from point-of-lay, 24 weeks of age (Farms A and C) and 20 weeks of age (Farms B). The 40 weeks in-lay for the three farms, was further sub-divided into four discrete production (10- weekly) phases (weeks 1-10; 11-20; 21-30; 31-40) in each of the farms. Maximum hen-day production was obtained as follows: Farm A (70.40% in week 18); Farm B (85.50% in week 20) and Farm C (79.30% in week 25). The percentage hen/day production pattern were fitted into two regression models namely – the simple linear model and
exponential function using the age-in-lay as the predictor variable and percentage Hen-day production as the dependent variable. Irrespective of the function used, the rate of increase in percentage egg production was highest within the first quarter (1-10 week) of production in each farm. As the production phase lengthened, the predicted rate of increase in production declined and the predictive ability of the simple linear model as judged by the R2 value became comparatively lower when compared to exponential function. The egg production pattern revealed a period of rapidly increasing production, attainment of peak, and the phase of a gradual declining production. Based on these findings, partitioning the laying period into phases could be a step forward in explaining the concept of phase feeding in which layers are fed at different protein levels at different phases based on their level of production.