STUDIES ON FACTORS INFLUENCING EGG PRODUCTIVITY IN POULTRY

Abstract

Seasonal variation, as such, in egg production appears to be absent in local birds over the periods of observation, but November egg number is consistently on the low side. Tests showed that there was correlation between ‘body weight’ and ‘egg weight’, and a possible inverse correlation was observed between ‘age at first egg’ and ‘egg number’. No correlation was observed between ‘egg number’ and ‘body weight’, ‘egg number’ and ‘egg weight’ and between ‘egg mass’ and ‘body weight’. ‘Deep litter’ and possibly ‘battery system’ appear to be superior to ‘semi-intensive’ treatment with regard to egg production. Egg number, egg weight and body weight have proved significantly with selection and outcrossing and analyses of various allowed significant difference between familiar with regard to egg number, egg weight and body weight, both for strain I (Canton and strain II) (cross breeds). Selection has led to a slight deterioration in ‘age at first egg’ out outcrossing has shown slight improvement. In the leant broody local birds and in the crosses, non-broody, upon accounts for about 49% of the total hen-days, and brooding only accounted for 6.1% and 2.2%, respectively, of the total hen-days. Outcrossing of the local birds with Brown Leghorns have resulted in a reduction of broodiness and sex-linked inheritance of brooding appears to be absent with regard to the above birds. It is established that broodiness decreases egg production in local birds. The significant differences between families of local birds with regard to incidence of broodiness suggests that selection is likely to lend to a reduction of broodiness in subsequent generations. Using the pigeon crop-sac method, pituitary Prolactin content has been estimated in hens in different clinical states, canton-type birds, Brown Leghorns and Cross-breeds were used. Broody birds had a significantly higher level than the laying birds. It appears that breed differences are absent with regard to pituitary Prolactin content within similar clinical states. It is suggested that there are two ‘thresholds’ of Prolactin in hens, the lower one causing a cessation of laying without any broody symptoms, and the higher one causing broodiness. Due to the large amount of variation existing between families, it is suggested that there is room for further improvement by selection and outcrossing. It is felt, however, that combined genetical and environment would give the quickest results.