Eggshell Qualities as Indicative of Eggshell Strength for Layer Selection

ABSTRACT The study aimed at investigating which of four traits is the most representative of eggshell strength (destructive eggshell thickness measurement, eggshell weight, egg specific gravity, ultrasonic measurement of eggshell thickness) and could be used for selection purposes. To date, investigations focused mostly on pairwise (eggshell strength vs. another eggshell feature) analyses, resulting in two-, maybe three-trait, models when eggshell traits are considered. Since the covariance estimates are also model dependent, we collected five eggshell traits within one analysis, which better reflects what occurs in nature. The eggs were collected from 4571 Rhode Island White and 2426 Rhode Island Red hens. A multiple-trait animal model and the REML method were employed to compute variance components for calculation of heritabilities and genetic correlations between the traits. On average, the highest correlations were found between the destructive measurement and the other quality traits. It is concluded, however, that the ultrasonic eggshell thickness measurement, also with high genetic correlations with the other traits and leaving an egg intact for further handling, can suit best, as an indirect criterion, the selection for eggshell strength

Eggshell Qualities as Indicative of Eggshell Strength for Layer Selection

<div><p>ABSTRACT The study aimed at investigating which of four traits is the most representative of eggshell strength (destructive eggshell thickness measurement, eggshell weight, egg specific gravity, ultrasonic measurement of eggshell thickness) and could be used for selection purposes. To date, investigations focused mostly on pairwise (eggshell strength vs. another eggshell feature) analyses, resulting in two-, maybe three-trait, models when eggshell traits are considered. Since the covariance estimates are also model dependent, we collected five eggshell traits within one analysis, which better reflects what occurs in nature. The eggs were collected from 4571 Rhode Island White and 2426 Rhode Island Red hens. A multiple-trait animal model and the REML method were employed to compute variance components for calculation of heritabilities and genetic correlations between the traits. On average, the highest correlations were found between the destructive measurement and the other quality traits. It is concluded, however, that the ultrasonic eggshell thickness measurement, also with high genetic correlations with the other traits and leaving an egg intact for further handling, can suit best, as an indirect criterion, the selection for eggshell strength.</p></div

Analysis of Behavioural Profile of Hens with the Use of Computer Software

ABSTRACT The aim of the study was to evaluate the emotional reactivity of hens with the use of physical parameters such as movement velocity and position of the selected parts of the body analysed by computer software - Tracker®. 200 Rhode Island White hens kept individually in a laying hen breeding farm were used in the study. The analysis of hens behaviour was performed with the use of Novel Object Test. Afterwards the video clips were analysed to determine behavioural reactivity with the use of Tracker® software by analysis of two control points: the upper part of the head and the peak of the tail. The results suggest that it is possible to use Tracker® software for evaluation of hens behavioural profile and this sort of analysis enables to classify hens to the groups of timid or curious/courageous birds based on the parameters of movement velocity of the upper part of the head and the peak of the tail and on the basis of the ratio between the position of the head and the tail