Genetic effects of aging on fitness and nonfitness traits in laying hens housed three per cage

Ledur, Mônica Corrêa; McMillan, I.; Asselstine, L; Fairfull, R. W.

doi:10.1093/ps/82.8.1223

Cited by 10 publications

(6 citation statements)

References 17 publications

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“…Relatively, the magnitude of heritability estimates of most increment traits for 20-and 30-wk intervals were moderate. This increasing trend may indicate that additive genetic variance increased with age for egg weight (Ledur et al, 2003;Niknafs et al, 2012). Two previous studies reported that egg weight increments from 210 to 310 d were much more affected by environmental factors (Poggenpoel and Duckitt, 1988;Shalev and Pasternak, 1993), implying a larger contribution of environmental variance, similar to our results.…”

Section: Discussionsupporting

confidence: 90%

Genetic analysis for dynamic changes of egg weight in 2 chicken lines

Liu

et al. 2014

Poultry Science

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One of the main concerns for poultry producers is how to maintain egg uniformity and stability in size and weight following the rapid growth during the early laying period. In this study, we aimed to investigate the increase in egg weight with advancing hen age, and to estimate genetic parameters of these increment traits in 2 pure lines of chickens (i.e., 2,010 White Leghorn and 1,200 brown-egg dwarf hens), using the restricted maximum likelihood method with the DMU procedure. We collected age at first egg (AFE), first egg weight (FEW) and kept records of egg weight per 10 wk from 30 to 60 wk of age. Meanwhile, the increments of egg weight were calculated for the evaluation of age-dependent dynamic changes. The increment of egg weight gained dramatically before 30 wk of age and became slower with the advance of age. Heritability estimates of AFE were larger than 0.32, and the low to moderate genetic correlations between AFE and FEW were observed in the 2 lines. The FEW showed high variation level compared with egg weights at later ages in the 2 lines, and had moderate heritability estimates in White Leghorns (0.20) and dwarf hens (0.33). Egg weights at different ages were highly heritable in the 2 lines (h(2) ≥ 0.35), and had strong genetic and phenotypic correlations among different ages. The estimates of heritability for most increment traits were low to moderate, especially those increments for 10-wk intervals ranging from 0.00 to 0.14. The genetic correlations among 3 consecutive egg weight increments for 10-wk intervals were low to moderate. Our results in the 2 lines should provide important insights into the genetic architecture of increment traits and offer some suggestions for producing uniform and stable eggs in response to advancing age.

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Section: Discussionsupporting

confidence: 90%

Genetic analysis for dynamic changes of egg weight in 2 chicken lines

Liu

et al. 2014

Poultry Science

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“…The direct additive effects model without any maternal effects was suitable for egg production (Ghorbani et al., 2012; Le Bihan‐Duval et al., 1998; Norris & Ngambi, 2006), which was true in the present study also. A comprehensive review of the literature revealed that additive genetic variation increased with age for egg production and egg weight (Engstrom et al., 1992; Ledur et al., 2003; Niknafs et al., 2012). However, some authors reported maternal effects in addition to the direct additive effects for the egg production and egg weight (Jasouri et al., 2017; Misztal & Besbes, 2000; Yousefi et al., 2013).…”

Section: Discussionmentioning

confidence: 99%

Estimation of breeding value, genetic parameters and maternal effects of economic traits in rural male parent line chicken using pedigree relationships in an animal model

Rajkumar

Prince

Haunshi

et al. 2020

J Animal Breeding Genetics

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Breeding value (BV), genetic parameters and additive genetic, and maternal effects were evaluated on growth and production traits utilizing data from eight generations employing animal model in a rural male parent line (PD‐6) chicken at ICAR‐Directorate of Poultry Research, Hyderabad, India. The least squares means (LSM) for body weight (BW) and shank length (SL) up to 6 weeks of age varied significantly (p ≤ .01) among the generations and hatches. BW increased significantly (p ≤ .01) over the generations and decreased with the hatches. Sex also had a significant effect on BW and shank length except for BW at 0 day (BW0). LSM for BW (BW6) and Shank length (SL6) at 6 weeks of age were 598.84 ± 0.79 g and 74.57 ± 0.04 mm, respectively. Males recorded significantly (p ≤ .01) higher BWs and shank length. All the production traits were significantly (p ≤ .01) influenced by the generation effect. The overall LSM for age at sexual maturity (ASM), egg production at 40 weeks (EP40) and egg weight at 40 weeks (EW40) were 164.93 ± 0.23 days, 74.66 ± 0.40 eggs and 54.79 ± 0.08 g, respectively. Model 3 with additive, maternal permanent environmental and residual effects was the appropriate model for BW2, BW4, BW6, SL4 and SL6, whereas Model 4 with maternal effects was the best for BW0. The heritability estimates for BW6 and SL6 were 0.22 ± 0.02 and 0.18 ± 0.02, respectively. Model 1 with additive direct and residual effects was the best appropriate model for all the production traits. The heritability estimates of EP40 and EW40 were 0.16 ± 0.04 and 0.34 ± 0.05, respectively. BW and shank length were highly correlated with significant (p ≤ .05) positive association from different components. The correlation coefficient from direct additive component between egg production and BW40 was negative, while it was positive with less magnitude between egg production and BW20. The egg production and egg weights had a negative association at different ages. BV of SL6, the primary trait of selection, was significant (p ≤ .05) across the generations and increased linearly with an average genetic gain of 1.05 mm per generation. BV of BW6 was also significant (p ≤ .05) and increased linearly as correlated response with an average genetic response of 22.34 g per generation. BV of EP40 showed an increasing trend with a genetic gain of 0.02 eggs per generation. The EW 40 also increased linearly with an average genetic gain of 0.06 g. The average inbreeding coefficient of the population was 0.015. The study concluded that the population was in ideal status with a linearly increasing trend of average BV with negligible inbreeding over the eight generations of selection.

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“…Although the use of egg specific gravity for the genetic improvement of eggshell quality is sometimes controversial, the additive variability of egg specific gravity accounts for ca. 20%-45% of the total trait variability (Nirasawa et al, 1998;Ledur et al, 2003;Begli et al, 2010;Rozempolska-Rucińska et al, 2011), thereby making it a predictor candidate in effective selection for eggshell quality. The objections against the use of egg specific gravity as a trait that defines eggshell quality in a broad sense are mainly related to the fact that the reliability of this measurement largely depends on environmental factors, e.g., the duration of egg storage or the lag of measurement time (Voisey and Hamilton, 1977;Sloan et al, 2000).…”

Section: Discussionmentioning

confidence: 99%