Explain how the persistency of production (Past Production) of a laying hen is measured?

The persistency of production, also known as past production, of a laying hen refers to its ability to maintain consistent egg production over time, particularly during the latter stages of its laying cycle. Measuring persistency is important for evaluating the long-term productivity and profitability of laying hens. One common method used to measure persistency is through the calculation of the persistency index.

The persistency index is calculated by comparing the actual egg production of a hen at a certain age to the expected egg production based on a reference curve or standard. The reference curve represents the typical pattern of egg production decline over time in a laying flock. The persistency index is calculated using the following formula:

[ \text{Persistency Index} = \frac{{\text{Actual Egg Production at Specific Age}}}{{\text{Expected Egg Production at Specific Age}}} \times 100 ]

The expected egg production at a specific age is determined based on the reference curve or standard for the given breed, strain, or production system. It represents the average egg production level expected for hens of that age group.

To measure persistency, egg production data is collected regularly throughout the laying cycle of the flock. This data includes the number of eggs laid by individual hens at specific ages or time intervals. The persistency index is then calculated for each hen by comparing its actual egg production to the expected production at each age point.

A higher persistency index indicates that a hen is maintaining egg production levels relatively close to the expected values for its age, suggesting better persistency of production. Conversely, a lower persistency index indicates a greater deviation from expected production levels, indicating reduced persistency.

By monitoring persistency of production in laying hens, producers can identify hens that are maintaining consistent egg production levels over time and make informed management decisions regarding flock management, culling, and replacement strategies to optimize long-term productivity and profitability.