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Ultrasonic eggshell thickness measurement for selection of layers

This study aimed to develop a methodology for using ultrasonic technology (USG) to record eggshell thickness for selection of layers. Genetic correlations between eggshell strength and its thickness have been reported to be around 0.8, making shell thickness a selection index candidate element. Applying ultrasonic devices to measure shell thickness leaves an egg intact for further handling. In this study, eggs from 2 purebred populations of Rhode Island White (RIW) and Rhode Island Red (RIR) hens were collected on a single day in the 33rd week of the farm laying calendar from 2,414 RIR and 4,525 RIW hens. Beginning from the large end of the egg, measurements were taken at 5 latitudes: 0º (USG0), 45º (USG45), 90º (USG90), 135º (USG135), and 180º (USG180). To estimate the repeatability of readings, measurements were repeated at each parallel on 3 meridians. Electronic micrometer measurement ( EMM: ) were taken with an electronic micrometer predominantly at the wider end of eggs from 2,397 RIR and 4,447 RIW hens. A multiple-trait statistical model fit the fixed effect of year-of-hatch × hatch-within-year, and random effects due to repeated measurements (except EMM) and an animals additive genetic component. The shell was thinnest in the region where chicks break it upon hatching (USG0, USG45). Heritabilities of shell thickness in different regions of the shell ranged from 0.09 to 0.19 (EMM) in RIW and from 0.12 to 0.23 (EMM) in RIR and were highest for USG45 and USG0. Because the measurement repeatabilities were all above 0.90, our recommendation for balancing egg strength against hatching ease is to take a single measurement of USG45. Due to high positive genetic correlations between shell thickness in different regions of the shell its thickness in the pointed end region will be modified accordingly, in response to selection for USG45.

Microsatellite markers may be ineffective in selection of laying hens for polygenic production traits

Previous research on mapping QTL in a reference family of laying hens indicated that 5 microsatellite loci (MCW0133, MCW0170, MCW0114, MCW0139, and LEI0074) were significantly associated with genome regions affecting shell strength as well as egg and yolk weights. The aim of our investigation was to verify if those markers could be useful in selection of laying hens. The study involved 2 breeds of randomly segregating populations: Rhode Island Reds selected divergently and Green-legged Partridgenous chickens selected upwardly, over 4 generations, for the mentioned egg quality traits. The influence of marker genotype on bird performance was assessed through the prediction of breeding values using a model that distinguished the marker effect from that of the polygenic effect and by comparing breeding values between different genotypes at given marker loci. The effects of the linked QTL regions appeared too small to significantly differentiate the outcomes of classifications fitting or not fitting the marker genotype. Comparison of breeding values between microsatellite genotypes for laying and egg traits revealed that antagonistic pleiotropic effects exist between these 2 groups of traits, adding to the difficulty of accounting for marker genotypes in the selection of laying hens.

Genetic correlations between behavioural responses and performance traits in laying hens

Objective The aim of the study was to evaluate genetic correlations between the behavioural profile and performance in laying hens as an indirect answer to the question whether the observed behavioural responses are associated with increased levels of stress in these birds. Methods The assessment of birds’ temperament was carried out using the novel objects test. The behavioural test was conducted in two successive generations comprising 9,483 Rhode Island White (RIW) birds (approx. 4,700 individuals per generation) and 4,326 Rhode Island Red (RIR) birds (approx. 2,100 individuals per generation). Based on the recorded responses, the birds were divided into two groups: a fearful profile (1,418 RIW hens and 580 RIR hens) and a brave/curious profile (8,065 RIW hens and 3,746 RIR hens). The birds were subjected to standard assessment of their performance traits, including SM, age at sexual maturity; ST, shell thickness; SG, egg specific gravity; EW, mean egg weight; IP, initial egg production; and HC, number of hatched chicks. The pedigree was three generations deep (including two behaviour-recorded generations). Estimation of the (co)variance components was performed with the Gibbs sampling method, which accounts for the discrete character of the behavioural profile denotation. Results The analyses revealed negative correlations between the performance traits of the laying hens and the behavioural profile defined as fearful. In the group of fearful RIW birds, delayed sexual maturation (0.22) as well as a decrease in the initial egg production (−0.30), egg weight (−0.54), egg specific gravity (−0.331), shell thickness (−0.11), and the number of hatched chicks (−0.24) could be expected. These correlations were less pronounced in the RIR breed, in which the fearful birds exhibited a decline in hatchability (−0.37), egg specific gravity (−0.11), and the number of hatched chicks (−0.18). There were no correlations in the case of the other traits or they were positive but exhibited a substantial standard error, as for the egg weight. Conclusion To sum up the results obtained, it can be noted that behavioural responses indicating fearfulness, i.e. escape, avoidance, and approach-avoidance may reflect negative emotions experienced by birds. The negative correlations with performance in the group of fearful hens may indirectly indicate a high level of stress in these birds, especially in the white-feathered birds, where stronger performance-fearfulness correlations were found. Fearful birds should be eliminated from breeding by inclusion of the behavioural profile in the selection criterion in the case of laying hens.

Preliminary Evaluation of the use Value of Jumping Horses Based on Their Results Achieved in Grand Prix Competitions

Abstract The aim of the work was preliminary evaluation of predispositions of Polish racehorses to sports. The tests covered 273 horses taking part in CC class and CC1 class competitions in the finals of the big tour. The probability of achieving the best result in the competitions depending on the horse breed was evaluated using multivariate analysis of variance. With the use of Spearman’s rank correlations, the initial correspondence between the horse’s rank in breeders’ ranking and the ranking based on sport results was defined. It was stated that horses starting in Grand Prix competitions represented only 6.85% of all horses registered in the Polish Equestrian Federation. In the group, foreign breeds were predominant. The proportion of native breeds was marginal. The lack of a significant influence of the race on differentiation of sports results of horses proves that the best specimens were chosen within individual races. The preliminary results revealed lack of rank agreement between the evaluation of the breeding value and sports achievements of an individual. This suggests the necessity of performing broader analyses covering different aspects

Eggshell Qualities as Indicative of Eggshell Strength for Layer Selection

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.

Evaluation of breeding value based on scores achieved in the Polish Championships for Young Horses.

Abstract Genetic improvement of show jumping horses is problematic, given the multitude of physical traits that determine sport usability and the specific mental predispositions required during training and competitions. The Polish Championships for Young Horses (PCYH) provide an opportunity to evaluate usability traits in Polish horses, which, however, is not a basis for evaluation of the breeding value. The aim of the study was to propose a model for evaluation of the breeding value of horses taking part in the Championships. In total, 1232 starts of 894 4-, 5-, 6-, and 7-year-old horses were analysed. Indices of BLUP breeding values were calculated based on 7 traits with known genetic parameters (ranking in the championship, style rating on days 1, 2, and 3, and penalty points on days 1, 2, and 3). A low and irregular genetic trend, significant only in the case of penalties scored on days 1 and 2 of the championships, was shown. Compatibility of the evaluation of the breeding value estimated on the basis of scores achieved in the Polish Championships for Young Horses with the scores of the performance test carried out in Training Centres was shown. It was also demonstrated that the “sum penalty” and “sum style” measured during the three days of the Championships is sufficient for evaluation of the BLUP breeding value. It was suggested that the evaluation combined with the results achieved at the PCYH (in four age categories) would provide a more detailed picture of the genetic predispositions of jumping horses.